diff --git a/.gitignore b/.gitignore index 589eb99..9a7759f 100644 --- a/.gitignore +++ b/.gitignore @@ -70,4 +70,6 @@ playwright_profile captured/ xhr_captured/ -xhr_captured_async/ \ No newline at end of file +xhr_captured_async/ + +docs_md/external/ \ No newline at end of file diff --git a/docs_md/articles/alzheimer-disease_app.statdx.com_document_content_2aad3ac4-44fd-43e5-8e50-a86987483af3_430ffae3_20251014T193414Z.md b/docs_md/articles/alzheimer-disease_2aad3ac4-44fd-43e5-8e50-a86987483af3.md similarity index 98% rename from docs_md/articles/alzheimer-disease_app.statdx.com_document_content_2aad3ac4-44fd-43e5-8e50-a86987483af3_430ffae3_20251014T193414Z.md rename to docs_md/articles/alzheimer-disease_2aad3ac4-44fd-43e5-8e50-a86987483af3.md index 13f4fa7..0b59c7a 100644 --- a/docs_md/articles/alzheimer-disease_app.statdx.com_document_content_2aad3ac4-44fd-43e5-8e50-a86987483af3_430ffae3_20251014T193414Z.md +++ b/docs_md/articles/alzheimer-disease_2aad3ac4-44fd-43e5-8e50-a86987483af3.md @@ -1,5 +1,12 @@ -# Alzheimer Disease - +--- +title: "Alzheimer Disease" +docid: "2aad3ac4-44fd-43e5-8e50-a86987483af3" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Neurodegeneration" + - "Alzheimer Disease" +--- # KEY FACTS - ## Terminology @@ -348,4 +355,4 @@ - FDG hypometabolism develops in parietal lobes, precuneus, posterior cingulate gyrus, posterior temporal lobes, and frontal lobes in advanced cases - Tau PET shows NFTs in posterolateral temporal neocortex, temporooccipital regions, and, eventually, parietal and cingulate regions - 47897414-6c3f-419d-8061-50a189ef4e1f + 47897414-6c3f-419d-8061-50a189ef4e1f \ No newline at end of file diff --git a/docs_md/articles/alzheimer-disease_app.statdx.com_document_content_f71f5cf5-b1af-4c6d-b145-b4c10eec7b58_3bf23d8b_20251014T193423Z.md b/docs_md/articles/alzheimer-disease_f71f5cf5-b1af-4c6d-b145-b4c10eec7b58.md similarity index 97% rename from docs_md/articles/alzheimer-disease_app.statdx.com_document_content_f71f5cf5-b1af-4c6d-b145-b4c10eec7b58_3bf23d8b_20251014T193423Z.md rename to docs_md/articles/alzheimer-disease_f71f5cf5-b1af-4c6d-b145-b4c10eec7b58.md index c0bb23d..17dcc7d 100644 --- a/docs_md/articles/alzheimer-disease_app.statdx.com_document_content_f71f5cf5-b1af-4c6d-b145-b4c10eec7b58_3bf23d8b_20251014T193423Z.md +++ b/docs_md/articles/alzheimer-disease_f71f5cf5-b1af-4c6d-b145-b4c10eec7b58.md @@ -1,5 +1,14 @@ -# Alzheimer Disease - +--- +title: "Alzheimer Disease" +docid: "f71f5cf5-b1af-4c6d-b145-b4c10eec7b58" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Alzheimer Disease" +--- # KEY FACTS - ## Terminology @@ -313,4 +322,4 @@ - Helps distinguish AD from frontotemporal dementia - May identify early AD when MR normal - 5dea6eed-cbf2-4d32-8c2b-43f74913fca6 + 5dea6eed-cbf2-4d32-8c2b-43f74913fca6 \ No newline at end of file diff --git a/docs_md/articles/amyotrophic-lateral-sclerosis-als_23de52b7-d9bd-441c-a18c-95c8afccb470.md b/docs_md/articles/amyotrophic-lateral-sclerosis-als_23de52b7-d9bd-441c-a18c-95c8afccb470.md new file mode 100644 index 0000000..6313386 --- /dev/null +++ b/docs_md/articles/amyotrophic-lateral-sclerosis-als_23de52b7-d9bd-441c-a18c-95c8afccb470.md @@ -0,0 +1,341 @@ +--- +title: "Amyotrophic Lateral Sclerosis (ALS)" +docid: "23de52b7-d9bd-441c-a18c-95c8afccb470" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Amyotrophic Lateral Sclerosis (ALS)" +--- +# KEY FACTS + +- ## Terminology + + + - Amyotrophic lateral sclerosis (ALS) + - Selective degeneration of somatic motor neurons of brainstem/spinal cord & large pyramidal neurons of motor cortex + - Eventual loss of corticospinal tract (CST) fibers +- ## Imaging + + + - Small percentage demonstrate CST hyperintensity + - As CST is normally slightly hyperintense, especially at 3.0 T, this finding lacks sensitivity & specificity + - T2-hyperintense CST may be specific for ALS when seen on corresponding PD images + - Consider FLAIR & PD in suspected ALS + - DWI hyperintensity (↓ diffusivity) in CST + - Hypointense gray matter in precentral gyrus (motor cortex) +- ## Top Differential Diagnoses + + + - Primary lateral sclerosis + - Wallerian degeneration + - Hypertrophic olivary degeneration + - Metabolic diseases involving bilateral CSTs + - Demyelinating & inflammatory diseases + - Neoplasms: Brainstem glioma, malignant lymphoma + - CST can appear hyperintense on 3T MR normally +- ## Pathology + + + - Majority of ALS cases are sALS + - 5-10% are familial (fALS) +- ## Clinical Issues + + + - UMN signs: Babinski sign, spasticity, hyperreflexia + - LMN signs: Asymmetric muscle weakness, atrophy, fasciculations, hyporeflexia + - Bulbar signs: Slurred speech, dysphagia + - Classic ALS: Both UMN & LMN affected + - Peaks in 6th-8th decades of life + - Complete disability & death within 1 decade + - Some patients with familial, juvenile-onset ALS survive for longer periods (2-3 decades) + +# TERMINOLOGY + +- ## Abbreviations + + + - Amyotrophic lateral sclerosis (ALS) +- ## Synonyms + + + - Lou Gehrig disease, motor neuron disease (MND) +- ## Definitions + + + - Selective degeneration of somatic motor neurons of brainstem/spinal cord {lower motor neurons (LMN) & large pyramidal neurons of motor cortex [upper motor neurons (UMN)]} + - Eventual loss of corticospinal tract (CST) fibers + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Bilateral hyperintensities along CST extending from corona radiata to brainstem on T2WI/PD/FLAIR + - ### Location + + + - Hallmark is CST & LMN degeneration + - LMN in anterior horn of spinal cord & brainstem + - Corticospinal UMN in precentral gyrus (motor cortex) + - White matter (WM) & gray matter (GM) + - Frequently, prefrontal motor neurons involved in planning or orchestrating work of UMN & LMN + - ### Size + + + - Atrophy of motor system, particularly pyramidal tract, in advanced stages of ALS + - ### Morphology + + + - Oval or thin, curvilinear hyperintensities conforming to CST +- ## CT Findings + + + - ### NECT + + + - Serial CT exams may show progressive atrophy + - Frontal, anterior temporal lobes → precentral gyrus → postcentral gyrus, anterior cingulate gyrus, corpus callosum, tegmentum +- ## MR Findings + + + - ### T1WI + + + - Different T1 appearances of CST + - Isointensity (most common) may reflect ↑ content of free radicals + - Hypointense or mild hyperintense signal + - CST differs between ALS patients & normal subjects only at internal capsule + - T1 hyperintensity in anterolateral cervical cord is associated with younger patients & rapid disease progression + - ### T2WI + + + - Hyperintense CST + - Hyperintensity can occur anywhere from subcortical WM of precentral gyrus to posterior limb internal capsules, cerebral peduncles, & pons + - As CST is normally slightly hyperintense especially at 3.0 T, this finding lacks sensitivity & specificity + - T2 hyperintense CST may be specific for ALS when seen on corresponding PD images + - Hypointense GM in precentral gyrus (motor cortex) + - Nonspecific; may be due to iron & heavy metals accumulating in cortex of aged patients + - ### PD/intermediate + + + - Hyperintense CST + - ### FLAIR + + + - More sensitive & less specific than T2 FSE for detecting hypointensity in precentral gyrus + - Hyperintense CST + - More frequently seen on FLAIR than on T2/T1/PD + - ### T2* GRE + + + - Hypointensity in precentral gyri + - ### DWI + + + - Hyperintensity in CST + - May be seen in absence of T2 hyperintensity + - Diffusion tensor imaging (DTI) + - ROI-based approaches & tractography demonstrates significant changes in diffusion parameters along CST + - Most common finding: ↓ fractional anisotropy (FA) in CST due to UMN degeneration + - ↓ FA in CST; most significant in posterior limb internal capsule & correlates with disease severity + - ↑ mean diffusivity (MD) along CST which correlates with disease duration + - ↑ MD in corpus callosum, frontal & temporal WM + - ↓ FA & ↑ MD in cervical cord correlate with disease severity & duration respectively + - ¹H-MRS useful for assessing UMN involvement + - ↓ NAA, ↓ NAA/Cr, ↓ NAA/Cho, & ↓ NAA/(Cr + Cho) in motor cortex + - NAA present primarily in neurons; these metabolic changes reflect loss or dysfunction of motor neurons + - ↓ NAA/Cr:NAA/Cho ratio along CST; most pronounced in precentral gyrus & corona radiata + - ↓ NAA in pons & upper medulla in patients with prominent UMN or bulbar signs + - ↑ Cho in posterior limb internal capsule + - ↑ myo-inositol (mI) in motor cortex + - ↓ NAA:mI ratio has better sensitivity & specificity in detecting ALS than any other metabolites + - Magnetization-transfer ratio (MTR) measurements + - ↓ MTR in CST + - CST hyperintensity on T1 MT contrast-enhanced images: 80% sensitivity, 100% specificity + - May detect CST degeneration of ALS at early stage + - Voxel-based morphometry (VBM) + - Regional GM loss in motor cortex, frontal, temporal, parietal, & limbic regions + - Frontal severe atrophy in ALS & frontotemporal dementia + - WM loss in corpus callosum, cerebellum, frontotemporal, & occipital regions + - ↓ Brain parenchymal fraction (BPF) & very mild global brain atrophy + - Functional MR + - Pattern of cortical reorganization + - ↑ activation of contralateral sensorimotor cortex, supplementary motor area, basal ganglia, & cerebellum during motor tasks +- ## Nuclear Medicine Findings + + + - PET, Tc-99m HMPAO SPECT + - ↓ regional cerebral metabolism/perfusion throughout brain with marked changes in sensorimotor cortex & putamen + - ↑ ALS severity correlated with ↓ GM perfusion +- ## Imaging Recommendations + + + - Best imaging tool: MR with T2, PD, FLAIR, DTI + +# DIFFERENTIAL DIAGNOSIS + +- ## Primary Lateral Sclerosis + + + - Neurodegeneration restricted to UMN + - T2WI shows changes in motor pathways + - *ALS2* mutations reported + - Autosomal recessive disease with juvenile onset + - Infantile-onset hereditary spastic paraplegia + - Spastic paralysis with ascending progression, only UMN involvement + - Mutations described in alsin & spastin genes +- [Wallerian Degeneration](/document/wallerian-degeneration/e4bb682d-6534-4176-9d39-34c1a42f3771) + - Dynamic signal intensities change along CST in patients with various cortical/subcortical lesions +- [Hypertrophic Olivary Degeneration](/document/hypertrophic-olivary-degeneration/78257543-6d52-4879-84b1-445f3611d996) + - Secondary degeneration of inferior olivary nucleus (ION), usually caused by primary lesions in dento-rubro-olivary pathway +- ## Conditions With T2-Hyperintense Lesions Along CST + + + - Metabolic diseases may involve CST bilaterally + - [X-linked adrenoleukodystrophy, Wilson disease](/document/wilson-disease/3d4d4876-4ce4-4af0-9e75-1a419bdd813c) + - Hypoglycemic coma: Reversible CST changes + - [Demyelinating & inflammatory diseases](/document/adem/a3fafeb7-5861-4364-beb8-c0e30220564e) + - [Multiple sclerosis, ADEM, Behçet disease, AIDS, cervical myelopathy](/document/behet-disease/4e447bb6-0f14-40e1-929a-4c1465feec0a) + - Neoplasms: Brainstem glioma, malignant lymphoma + - [Intoxication: Heroin inhalation](/document/drug-abuse/e4502a67-4b96-4d98-a167-6e90f6b65faf) +- ## Normal Individuals + + + - CST can appear hyperintense on 3T MR (normal fully myelinated brain at any age) & mimic ALS + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Sporadic ALS (sALS) etiology is largely unknown + - Proposed potential mechanisms include + - Abnormal RNA processing, SOD1-mediated toxicity, excitotoxicity, cytoskeletal derangements, mitochondrial dysfunction + - Viral infections, apoptosis, growth factor abnormalities, & inflammatory responses + - Pathological hallmarks include loss of MNs with intraneuronal ubiquitin-immunoreactive inclusions in UMN & TDP-43 immunoreactive inclusions in degenerating LMN + - ↑ expression of cyclooxygenase-2 in spinal cord, frontal cortex, & hippocampus + - Apoptosis, free radical-mediated oxidative stress, excessive glutamate-mediated excitotoxicity + - Dopamine deficiency probably has important role + - Biochemical studies have shown ↓ glutamate levels in CNS tissue & ↑ levels in CSF + - Mutations in single gene can lead to selective degeneration of motor neurons + - ### Genetics + + + - 90-95% of cases are sALS + - 5-10% of cases are familial (fALS) + - Most common ALS-related gene mutation occurs in *C9ORF72*, *SOD1*, *TARDBP*, & *FUS* + - In European population: Most common is *C9ORF72*repeats + - In Asian population: Most common is *SOD1* mutation + - Rare autosomal recessive juvenile-onset ALS + - *ALS2* gene on chromosome 2q encodes alsin + - ### Associated abnormalities + + + - ALS-plus syndrome: MND with other symptoms or signs outside of voluntary motor system + - 2–3% of cases, ALS is accompanied by frontotemporal dementia + - ~ 50% of cases show cognitive impairment + - Can be associated with frontotemporal dementia (FTD), autonomic insufficiency, parkinsonism, supranuclear gaze paresis, &/or sensory loss + - ALS-like MND can occur as paraneoplastic syndrome +- ## Gross Pathologic & Surgical Features + + + - Focal atrophy of motor cortex & along course of CST + - Atrophy of anterior & lateral portions of spinal cord +- ## Microscopic Features + + + - Loss of cortical motor neurons (pyramidal & Betz cells) & astrocytosis + - Retrograde axonal loss & gliosis in CST + - "Senescent changes" with lipofuscin pigment atrophy + - Various cytoplasmic inclusions with chromatolysis + - Proximal & distal axonopathy with axonal spheroids + - Surviving motor neurons are smaller & abnormal + - Frequently undetected CST pathology in progressive muscular atrophy variant of ALS + - Bunina bodies (eosinophilic aggregates are positive for cystatin C) are unique for ALS + - Other intracellular inclusions: Neurofilament inclusions, ubiquitinated inclusions, TDP-43 inclusions, & immunoreactive inclusions to*FUS* + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - UMN signs: Babinski sign, spasticity, hyperreflexia + - LMN signs: Asymmetric muscle weakness, atrophy, fasciculations, hyporeflexia + - Split-hand syndrome: Frequent pattern of weakness & atrophy in ALS involving thenar muscles more than hypothenar muscles + - Bulbar signs: Slurred speech, dysphagia + - Difficulty walking, unexplained weight loss + - Hypoxia, cardiac arrhythmia + - ### Other signs/symptoms + + + - El Escorial criteria diagnosis of ALS: Evidence of UMN findings, LMN findings, & progression + - 4 regions or levels: Bulbar, cervical, thoracic, lumbosacral + - ### Clinical profile + + + - Classic ALS: Both UMN & LMN affected + - UMN-dominant ALS can be difficult to distinguish from primary lateral sclerosis + - Predominantly bulbar form usually leads to more rapid deterioration & death + - fALS associated with *SOD1* abnormality has mean age at 42 years limb onset, slow evolution +- ## Demographics + + + - ### Age + + + - Peaks in 6th to 8th decades; can occur in young adults + - ### Sex + + + - M:F = 1.5:1.0 + - ### Ethnicity + + + - Slightly higher in Non-Hispanics white population + - ### Epidemiology + + + - Incidence: 1-3 cases/100,000 people + - Prevalence: 2.7-7.4 cases/100,000 people +- ## Natural History & Prognosis + + + - Progressive (distal to proximal) + - Median survival from diagnosis to death: 3-4 years + - 10% of patients survive > 10 years + - Some patients with familial, juvenile-onset ALS survive for longer periods (2-3 decades) +- ## Treatment + + + - Riluzole (glutamate release inhibitor & insulin-like growth factor) may prolong survival + - ↑ NAA/Cr in precentral gyrus & supplementary motor area after riluzole therapy + - This suggests population of sublethally injured, metabolically compromised neurons that are amenable to therapeutic rescue + - No improvement in perirolandic neuronal integrity (no change in NAA:Cr ratio) was detected after gabapentin treatment, which agrees with equivocal clinical effectiveness + - Baclofen, dantrolene, or diazepam for spasticity + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - FLAIR & PD MR in all patients with suspected ALS +- ## Image Interpretation Pearls + + + - High T2 signal intensity in posterior limb of IC is suggestive for ALS when also visible on PD MR + - T1- & PD-weighted images differentiate real degeneration from normal areas + - DTI can assess CST lesions before pyramidal symptoms + + c693ffa3-6052-4eb1-8840-2ce1ab8bebf8 \ No newline at end of file diff --git a/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_ea9de9f0_20251014T184508Z.md b/docs_md/articles/attention-control-network_a1bedda5-6478-40b2-98e7-6c5f5363b06f.md similarity index 94% rename from docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_ea9de9f0_20251014T184508Z.md rename to docs_md/articles/attention-control-network_a1bedda5-6478-40b2-98e7-6c5f5363b06f.md index 6eaa96e..89f24ee 100644 --- a/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_ea9de9f0_20251014T184508Z.md +++ b/docs_md/articles/attention-control-network_a1bedda5-6478-40b2-98e7-6c5f5363b06f.md @@ -1,5 +1,12 @@ -# Attention Control Network - +--- +title: "Attention Control Network" +docid: "a1bedda5-6478-40b2-98e7-6c5f5363b06f" +breadcrumbs: + - "Brain" + - "Anatomy" + - "Brain Network Anatomy" + - "Attention Control Network" +--- # IMAGING ANATOMY - ## Overview @@ -75,4 +82,4 @@ - Right-dominant network for attention in most individuals - Lesions of right ventral attention network may produce hemispatial neglect - 6e3d29ca-3af0-4a42-b125-7ec5fad53f3f + 8145fc24-f946-49ef-9ae0-c4315a58d768 \ No newline at end of file diff --git a/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_068cbfb3_20251014T185127Z.md b/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_068cbfb3_20251014T185127Z.md deleted file mode 100644 index caa4fac..0000000 --- a/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_068cbfb3_20251014T185127Z.md +++ /dev/null @@ -1,78 +0,0 @@ -# Attention Control Network - -# IMAGING ANATOMY - -- ## Overview - - - - Attention control network is a constellation of distributed brain networks processing attention to external stimuli and symbols - - Many aliases: Task-positive network, frontoparietal network, executive control network, and central executive network, each referring to subsets of the attention control network - - Terminology is not standard in the literature, and different authors use many of these terms interchangeably or to refer to different subsets of a broader attentional network -- ## Dorsal Attention Network - - - - Function: Voluntary control of attentional focus and goal-directed behavior - - Regions: Intraparietal sulcus, frontal eye fields, middle temporal, dorsolateral prefrontal cortex - - Intraparietal sulcus - - Weighting of sensory inputs: Direct control of relative "value" or "attention" to sensory stimuli - - Topographically organized by stimulus modality and spatial location - - Frontal eye fields and supplementary eye fields - - Control of direction of gaze to attentionally relevant stimuli - - Middle temporal (MT) - - Motion perception, dynamic features of attention - - Dorsolateral prefrontal cortex (DLPFC) - - Shared with ventral attention network, representations of objects and symbols, working memory -- ## Ventral Attention Network - - - - Function: Control of reorienting to relevant stimuli, working memory - - Aliases: Frontoparietal control network, executive control network - - Regions: Supramarginal and angular gyri, inferior frontal gyrus, dorsolateral prefrontal cortex, ventral anterior cingulate cortex - - Inferior parietal lobule (supramarginal and angular gyri) - - Inferior frontal gyrus - - DLPFC - - Ventral anterior cingulate cortex -- ## Salience Network - - - - Function: Detection of novel or salient stimuli - - Aliases: Novelty detection network, cingulo-opercular network - - Regions: Frontoinsula, dorsal anterior cingulate cortex - - Frontoinsula - - "Sensory" arm of salience network - - Mid superior insula: Detection of stimulus salience - - Mid inferior insula: Detection of emotive salience - - Anterior insula: Control of attention - - Dorsal anterior cingulate cortex - - "Motor" arm of salience network - - More anterior (pregenual) cingulate more associated with emotive salience, merges with ventral attention network - -# ANATOMY IMAGING ISSUES - -- ## Imaging Recommendations - - - - Specific subnetworks may be activated by specific tasks (e.g., oddball task for salience network, n-back task for dorsal attention network) -- ## Imaging Pitfalls - - - - Many fMRI tasks have differential stimulus attention between active and control conditions - - Activation in attentional regions may not be task specific, but a general consequence of differential attention between conditions -- ## Network Relationships - - - - Attention control network is anticorrelated to default mode network: When one is active, the other tends to be less active - - Allows focus of attention to shift between external and internal stimuli - - Gradients of anticorrelation across the attention control network are seen with specific subregions of each network hub showing greatest anticorrelation - - Attentional regions typically located in association cortex in regions spatially "equidistant" from primary sensory areas - - Flow of information from primary sensory to unimodal sensory association cortex to polymodal association cortex - -# CLINICAL IMPLICATIONS - -- ## Clinical Importance - - - - Right-dominant network for attention in most individuals - - Lesions of right ventral attention network may produce hemispatial neglect - - 8145fc24-f946-49ef-9ae0-c4315a58d768 diff --git a/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_2536cd31_20251014T184836Z.md b/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_2536cd31_20251014T184836Z.md deleted file mode 100644 index 6eaa96e..0000000 --- a/docs_md/articles/attention-control-network_app.statdx.com_document_content_a1bedda5-6478-40b2-98e7-6c5f5363b06f_2536cd31_20251014T184836Z.md +++ /dev/null @@ -1,78 +0,0 @@ -# Attention Control Network - -# IMAGING ANATOMY - -- ## Overview - - - - Attention control network is a constellation of distributed brain networks processing attention to external stimuli and symbols - - Many aliases: Task-positive network, frontoparietal network, executive control network, and central executive network, each referring to subsets of the attention control network - - Terminology is not standard in the literature, and different authors use many of these terms interchangeably or to refer to different subsets of a broader attentional network -- ## Dorsal Attention Network - - - - Function: Voluntary control of attentional focus and goal-directed behavior - - Regions: Intraparietal sulcus, frontal eye fields, middle temporal, dorsolateral prefrontal cortex - - Intraparietal sulcus - - Weighting of sensory inputs: Direct control of relative "value" or "attention" to sensory stimuli - - Topographically organized by stimulus modality and spatial location - - Frontal eye fields and supplementary eye fields - - Control of direction of gaze to attentionally relevant stimuli - - Middle temporal (MT) - - Motion perception, dynamic features of attention - - Dorsolateral prefrontal cortex (DLPFC) - - Shared with ventral attention network, representations of objects and symbols, working memory -- ## Ventral Attention Network - - - - Function: Control of reorienting to relevant stimuli, working memory - - Aliases: Frontoparietal control network, executive control network - - Regions: Supramarginal and angular gyri, inferior frontal gyrus, dorsolateral prefrontal cortex, ventral anterior cingulate cortex - - Inferior parietal lobule (supramarginal and angular gyri) - - Inferior frontal gyrus - - DLPFC - - Ventral anterior cingulate cortex -- ## Salience Network - - - - Function: Detection of novel or salient stimuli - - Aliases: Novelty detection network, cingulo-opercular network - - Regions: Frontoinsula, dorsal anterior cingulate cortex - - Frontoinsula - - "Sensory" arm of salience network - - Mid superior insula: Detection of stimulus salience - - Mid inferior insula: Detection of emotive salience - - Anterior insula: Control of attention - - Dorsal anterior cingulate cortex - - "Motor" arm of salience network - - More anterior (pregenual) cingulate more associated with emotive salience, merges with ventral attention network - -# ANATOMY IMAGING ISSUES - -- ## Imaging Recommendations - - - - Specific subnetworks may be activated by specific tasks (e.g., oddball task for salience network, n-back task for dorsal attention network) -- ## Imaging Pitfalls - - - - Many fMRI tasks have differential stimulus attention between active and control conditions - - Activation in attentional regions may not be task specific, but a general consequence of differential attention between conditions -- ## Network Relationships - - - - Attention control network is anticorrelated to default mode network: When one is active, the other tends to be less active - - Allows focus of attention to shift between external and internal stimuli - - Gradients of anticorrelation across the attention control network are seen with specific subregions of each network hub showing greatest anticorrelation - - Attentional regions typically located in association cortex in regions spatially "equidistant" from primary sensory areas - - Flow of information from primary sensory to unimodal sensory association cortex to polymodal association cortex - -# CLINICAL IMPLICATIONS - -- ## Clinical Importance - - - - Right-dominant network for attention in most individuals - - Lesions of right ventral attention network may produce hemispatial neglect - - 6e3d29ca-3af0-4a42-b125-7ec5fad53f3f diff --git a/docs_md/articles/brain-tumor-in-child-1-year_7d64f5fb-c62c-4861-8ff4-654a12074605.md b/docs_md/articles/brain-tumor-in-child-1-year_7d64f5fb-c62c-4861-8ff4-654a12074605.md new file mode 100644 index 0000000..25cca4f --- /dev/null +++ b/docs_md/articles/brain-tumor-in-child-1-year_7d64f5fb-c62c-4861-8ff4-654a12074605.md @@ -0,0 +1,158 @@ +--- +title: "Brain Tumor in Child > 1 Year" +docid: "7d64f5fb-c62c-4861-8ff4-654a12074605" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Clinically Based Differentials" + - "Brain Tumor in Child > 1 Year" +--- +# ESSENTIAL INFORMATION + +- ## Key Differential Diagnosis Issues + + + - General rule: Decreased diffusion = higher grade +- ## Helpful Clues for Common Diagnoses + + + - **Posterior Fossa** (most common location) + - **Pilocytic astrocytoma** + - Low-density NECT + - Solid, enhancing nodule and cyst: Classic appearance + - Solid nodule has increased diffusion = good prognosis + - Off midline compared to classic 4th ventricular tumors but may pedunculate into ventricle + - Characterized by *KIAA1549*::*BRAF* fusion + - **Medulloblastoma** + - Hyperdense posterior fossa mass on NECT + - Decreased diffusion + - Molecular subgroups predicts outcome + - WNT-activated: Up to 90% overall survival, 4th ventricle and cerebellopontine angle (CPA) location, rarest subgroup + - SHH-activated: Poor to good prognosis, cerebellar hemispheric location, + *TP53* mutation = poor prognosis + - Group 3: Worst prognosis with frequent metastases, midline 4th ventricle + - Group 4: Intermediate prognosis with occasional metastases, midline 4th ventricle, minimal to no enhancement, most common subgroup + - **Ependymoma** + - Less common than pilocytic astrocytoma and medulloblastoma + - 60% posterior fossa + - "Plastic" tumor in 4th ventricle, extrudes through foramina + - Can have mixed calcification and cysts + - Molecular subgroups predict outcome + - Posterior fossa type A: Younger children, lateral location, characterized by H3 K27 alteration, poor outcome + - Posterior fossa type B: Adolescents, midline location, good outcome, uncommon + - **Diffuse midline glioma, H3 K27-altered** + - **Diffuse intrinsic pontine glioma** + - T2-hyperintense expansion of pons, little to no enhancement + - Can also involve cerebellum and spinal cord + - Poor prognosis + - **Supratentorial**(more common in infants and adolescents) + - **Craniopharyngioma** + - Nearly 1/2 of pediatric suprasellar masses, typically adamantinomatous + - 90% calcification/cystic/enhance + - Squamous cell from Rathke cleft + - **Pilocytic astrocytoma** + - Commonly involves optic pathway or around 3rd ventricle, tectal plate + - Optic "gliomas" are commonly associated with *NF1* + - Heterogeneous appearance and enhancement + - Pilomyxoid astrocytoma variant is more locally aggressive and more likely to present with leptomeningeal metastases + - Similar genetic and molecular characteristics; was removed as separate grading designation in WHO 2016 + - Supratentorial likely to have *BRAF*V600E mutation + - **Diffuse low-grade glioma, pediatric** + - Hemispheres, thalami (can be bithalamic), tectum + - 50% of brainstem "gliomas" are low-grade diffusely infiltrating astrocytomas + - Can be poorly marginated or focal + - Hypointense on T1WI, hyperintense on T2WI, little to no enhancement + - WHO 2021 has 4 tumor types in this family + - **Diffuse astrocytoma, MYB- or MYBL1-altered** + - **Diffuse low-grade glioma, MAPK pathway-altered** + - **Polymorphous low-grade neuroepithelial tumor of the young** (PLNTY): Commonly cortical with heterogeneous T2 signal from calcification + - **Angiocentric glioma** + - **Subependymal giant cell astrocytoma** + - Seen in tuberous sclerosis + - Location at foramina of Monro is typical + - Look for cortical/subcortical tubers and subependymal nodules + - Heterogenous calcification, marked enhancement +- ## Helpful Clues for Less Common Diagnoses + + + - **Intraaxial: Peripheral and Cortical** + - **Dysembryoplastic neuroepithelial tumor** + - Bubbly-appearing, cortically based mass + - Bright ring sign on FLAIR MR + - Almost all in patients < 20 years old, chronic epilepsy + - **Pleomorphic xanthoastrocytoma** + - Cortically based tumor (temporal lobe most common) + - Enhancing mass + cyst, dural reaction (tail) common + - Majority demonstrate *BRAF*V600E mutation + - **Ganglioglioma** + - Temporal lobe predilection with seizure presentation + - Solid or solid with cyst, ± enhancement + - **Oligodendroglioma** + - Cortically based, frontal lobe predominance + - Calcification common + - Predominantly T2 hyperintense ± enhancement + - Characterized by 1p/19q codeletion; if 1p/19q intact, represents astrocytoma with poorer outcome + - **Intraaxial: Deep and Hemispheric** + - **Diffuse high-grade glioma, pediatric** + - Diffusely infiltrating, heterogeneous, ± enhancement + - WHO 2021 has 4 tumor types in this family (all have poor outcome) + - **Diffuse midline glioma, H3 K27-altered**: Central location, involves thalami and brainstem + - **Diffuse hemispheric glioma, H3 G34-mutant** + - **Diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype** + - **Infant-type hemispheric glioma** + - **CNS embryonal tumor** + - Primitive neuroepithelial tumor terminology removed from 2016 WHO CNS tumors + - Infant with large, bulky, complex hemispheric mass + - Calcification, hemorrhage, necrosis common + - Peritumoral edema sparse/absent, less than expected for size + - **Supratentorial ependymoma** + - Diffuse infiltrating, heterogeneously enhancing tumor + - Origin is periventricular from ependymal rests + - Molecular subgroups predict outcome + - *ZFTA* fusion-positive, younger children, poor outcome + - *YAP1* fusion-positive, older children, good outcome, rare + - **Extraaxial** + - **Choroid plexus tumor** + - Intraventricular: Lateral > 4th > 3rd ventricles + - Densely enhancing, frond-like + - Although **choroid plexus carcinoma** may show parenchymal invasion, it is not reliably distinguished from **papilloma** on imaging + - **Neurofibromatosis type 2** + - Vestibular **schwannomas** + - If multiple schwannomas, think neurofibromatosis type 2 + - Look for "hidden" dural-based**meningiomas** + - **Midline Pineal and Suprasellar Location** + - **Germ cell tumor** + - Organized by cell lineage and maturity + - Germinomatous germ cell tumor + - **Germinoma**: Common in older children and adolescents, excellent prognosis + - Homogeneous with enhancement and decreased diffusion in pure germinomas + - Nongerminomatous germ cell tumors + - **Teratoma**: Fetal life to adolescence; mature teratomas may have fat and calcification; smaller teratomas that are easily resected have good prognosis; **immature teratomas** have poor prognosis + - **Embryonal carcinoma****,** **yolk sac tumor****, and** **choriocarcinoma**: Rare; older children and adolescents, poor prognosis + - Heterogeneous with enhancement + - **Mixed germ cell tumor**: Includes germinomatous and nongerminomatous components + - Worse prognosis than pure germinomas due to nongerminomatous components + - Suprasellar + pineal lobular, enhancing masses together best clue + - Engulfs pineal calcification on CT + - **Pineoblastoma** + - Decreased diffusion + - Look for CSF spread (ventricles, ependyma) + - Difficult to distinguish from germinoma + - "Exploding" pineal calcification on CT + - Pineoblastoma more common than lower grade varieties, such as **pineocytoma** and **pineal parenchymal tumor of intermediate differentiation** +- ## Helpful Clues for Rare Diagnoses + + + - **Atypical Teratoid-Rhabdoid Tumor** + - Heterogeneous intracranial mass in infants and children + - 50% infratentorial; early CSF spread + - Typically decreased diffusion, greater amount of cysts than medulloblastoma + - **Astroblastoma,****MN1****-Altered** + - Typically peripheral, well circumscribed + - Solid and cystic heterogeneous enhancement + - **Central Neurocytoma** + - "Bubbly," lobulated mass in body of lateral ventricle + - Often along septum pellucidum + - **Dysplastic Cerebellar Gangliocytoma** + - Not associated with PTEN hamartoma syndrome in children + - T2-hyperintense, striated cerebellum with enlarged folia \ No newline at end of file diff --git a/docs_md/articles/brain-tumor-in-newborn-infant_12b32579-c99b-41c0-95fd-f2ad1fc4a4fd.md b/docs_md/articles/brain-tumor-in-newborn-infant_12b32579-c99b-41c0-95fd-f2ad1fc4a4fd.md new file mode 100644 index 0000000..79c7a84 --- /dev/null +++ b/docs_md/articles/brain-tumor-in-newborn-infant_12b32579-c99b-41c0-95fd-f2ad1fc4a4fd.md @@ -0,0 +1,122 @@ +--- +title: "Brain Tumor in Newborn/Infant" +docid: "12b32579-c99b-41c0-95fd-f2ad1fc4a4fd" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Clinically Based Differentials" + - "Brain Tumor in Newborn/Infant" +--- +# ESSENTIAL INFORMATION + +- ## Key Differential Diagnosis Issues + + + - Newborn/infant brain tumors + - Typically large, bulky, inhomogeneous + - 60-70% supratentorial + - Infratentorial more common in older children + - Immature, high-grade tumors more common +- ## Helpful Clues for Common Diagnoses + + + - **Teratoma** + - Most common fetal and congenital brain tumor + - Midline, supratentorial + - Small, lobular or holocranial + - Contents + - Ca⁺⁺, cysts + - Fat in mature teratoma, less commonly in immature teratoma; enhancing soft tissue + - Look for associated congenital brain anomalies + - **Infant-Type Hemispheric Glioma** + - Large, heterogeneous, hemispheric + - High-grade cellular astrocytoma + - Better outcome than other histone-associated pediatric high-grade gliomas + - **Medulloblastoma** + - SHH-activated and non-WNT/non-SHH (group 3) more common in infants + - Posterior fossa mass with hydrocephalus + - Restricts on DWI (best MR clue) + - Enhancement usual (may be late/slow) + - Sparse Ca⁺⁺: ~ 20%; hemorrhage rare + - Hypercellularity reflected on imaging + - Hyperdense (NECT), hypointense (T2) + - SHH-activated + - Cerebellar hemisphere, not centered in 4th ventricle + - Intense enhancement + - Additional *TP53* mutation carries poor prognosis + - Group 3 + - Classic 4th ventricular location + - Enhancement common, group 4 has less enhancement + - Poor prognosis when presenting with dissemination + - **Ependymoma,****Posterior Fossa Type A** + - Posterior fossa A ependymomas characterized by ↓ H3 K27 expression + - Younger children, poor outcome + - Lateral in 4th ventricle, extends through foramina of Luschka + - Heterogeneous enhancement + - Ca⁺⁺ ± hemorrhage + - **Supratentorial Ependymoma** + - Periventricular/extraventricular > intraventricular + - Derived from periventricular ependymal rests + - Large, bulky; Ca⁺⁺: ~ 50% + - Variable necrosis, hemorrhage + - *ZFTA* fusion-positive: Seen in infants and older children, poor prognosis + - *YAP1* fusion-positive: Usually seen in infants, good prognosis + - **Choroid Plexus Papilloma** + - Choroid plexus papilloma (CPP): Lobulated intraventricular mass + - Lateral > 4th > 3rd + - NECT: Isointense to dense + - Isointense to slightly hyperintense on T2WI + - Vividly enhancing + - Hydrocephalus common +- ## Helpful Clues for Less Common Diagnoses + + + - **Pilocytic Astrocytoma, Pilomyxoid Variant** + - Younger age presentation than typical pilocytic astrocytoma (PA) + - Often presents as large, enhancing, infiltrative mass involving optic pathway + - Despite low-grade tumor, it can have leptomeningeal seeding + - **Atypical Teratoid-Rhabdoid Tumor** + - Medulloblastoma-like, + + - Metastases at diagnosis more common + - Cysts, hemorrhage more common + - Variable contrast enhancement + - Cerebellopontine angle cistern location more common + - Seeding via CSF pathway common + - **CNS Embryonal Tumor** + - Previously primitive neuroectodermal tumor (PNET) + - Large, complex mass + - Restricts on DWI + - Heterogeneous signal enhancement + - Ca⁺⁺ more common than in posterior fossa PNETs + - Hemorrhage, necrosis common + - Hemispheric + - Mean diameter: 5 cm + - Especially newborn/infants + - Minimal peritumoral edema + - Suprasellar: Early neuroendocrine, visual disturbances + - **Desmoplastic Infantile Ganglioglioma/Astrocytoma** + - Desmoplastic infantile gangliogliomas(DIGs)/astrocytoma often have large cyst + - Cortically based, enhancing tumor nodule + - Enhancing adjacent pia and dura; low grade + - Good outcome with complete surgical resection +- ## Helpful Clues for Rare Diagnoses + + + - **Choroid Plexus Carcinoma** + - Similar to CPP, + + - Brain invasion; Ca⁺⁺, cysts, bleed + - Ependymal, subarachnoid space seeding (can be seen with both CPP, choroid plexus carcinoma) + - **Embryonal Tumor With Multilayered Rosettes** + - Rare malignant embryonal brain tumor + - Young children (< 5 years) + - Histologic differentiation varies + - Neuronal, astrocytic, ependymal, melanotic, etc. + - Imaging appearance reflects variable differentiation + - Medulloepithelioma, ependymoblastoma, and embryonal tumor with abundant neuropil and true rosettes (ETANTR) all have similar molecular features and are grouped as embryonal tumor with multilayered rosettes (ETMR) + - **Neurocutaneous Melanosis (Melanoma/Melanocytoma)** + - Giant or multiple cutaneous melanocytic nevi, + + - Melanosis: Bright T1 lesions in amygdala, cerebellum without fat saturation + - T2 hypointense to isointense, no enhancement + - Melanoma: Melanosis + diffuse leptomeningeal enhancement + - Degeneration into malignant melanoma common \ No newline at end of file diff --git a/docs_md/articles/craniopharyngioma_00e66680-6731-4287-b5a1-3f0b3f09053b.md b/docs_md/articles/craniopharyngioma_00e66680-6731-4287-b5a1-3f0b3f09053b.md new file mode 100644 index 0000000..21c9cc9 --- /dev/null +++ b/docs_md/articles/craniopharyngioma_00e66680-6731-4287-b5a1-3f0b3f09053b.md @@ -0,0 +1,321 @@ +--- +title: "Craniopharyngioma" +docid: "00e66680-6731-4287-b5a1-3f0b3f09053b" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Neoplasms" + - "Craniopharyngioma" +--- +# KEY FACTS + +- ## Terminology + + + - Benign, partially cystic sellar region tumor derived from remnants of craniopharyngeal duct/Rathke pouch epithelium + - 2 types + - Adamantinomatous (cystic mass in childhood) + - Papillary (solid mass in older adults) +- ## Imaging + + + - General features + - Multilobulated, often large (> 5 cm) + - Occasionally giant, multicompartmental + - CT: Cystic (90%), Ca⁺⁺ (90%), enhancing (90%) + - MR: Signal varies with cyst contents + - Cysts variably hyperintense on T1WI and T2WI + - Solid portions enhance heterogeneously; cyst walls enhance strongly + - Cyst contents show broad lipid peak (0.9-1.5 ppm) on MR spectroscopy +- ## Pathology + + + - Most common pediatric intracranial tumor of nonglial origin + - WHO grade 1 +- ## Clinical Issues + + + - Bimodal age distribution + - Peak 5-15 years; adults 45-60 years (commonly papillary) + - Pediatric patient with morning headache, visual defect, short stature + - Endocrine disturbances include growth hormone (GH) deficiency, luteinizing hormone (LH)/follicle-stimulating hormone (FSH) deficiency + - Others = hypothyroidism > adrenal failure > diabetes insipidus + - Surgical resection is primary therapy + - Surgery, radiation therapy, or cyst aspiration for recurrent tumors + +# TERMINOLOGY + +- ## Abbreviations + + + - Craniopharyngioma (CP) +- ## Synonyms + + + - Craniopharyngeal duct tumor, Rathke pouch tumor, adamantinoma +- ## Definitions + + + - Benign, partially cystic sellar region tumor derived from Rathke pouch epithelium + - 2 histologies: Adamantinomatous and papillary + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - CT: Partially Ca⁺⁺ mixed solid/cystic suprasellar mass in child + - MR: Complex signal intensity suprasellar mass + - ### Location + + + - Surgical division of CPs into 3 groups + - Sellar + - Prechiasmatic + - Retrochiasmatic + - Imaging locations of CPs (adamantinomatous type) + - Suprasellar (75%) + - Suprasellar + intrasellar component (21%) + - Entirely intrasellar (4%) + - Often extends into multiple cranial fossae: Anterior (30%), middle (23%), posterior, &/or retroclival (20%) + - Rare ectopic locations + - Optic chiasm, 3rd ventricle + - Other: Nasopharynx, paranasal sinuses, pineal gland, sphenoid (clivus), cerebellopontine angle + - ### Size + + + - Variable; often large at presentation (> 5 cm) + - Occasionally giant, multicompartmental + - ### Morphology + + + - Multilobulated, multicystic +- ## CT Findings + + + - ### NECT + + + - Adamantinomatous type (90% rule) + - 90% mixed solid (isodense), cystic (hypodense) + - 90% calcify + - 90% enhance (solid = nodule; rim = capsule) + - Papillary type: Often solid, isodense, rarely calcifies +- ## MR Findings + + + - ### T1WI + + + - Signal varies with cyst contents + - Short T1 due to high protein content + - Classic (adamantinomatous type) + - Hyperintense cyst + heterogeneous nodule + - Less common (papillary type) + - Isointense solid component + - ### T2WI + + + - Cysts are variably hyperintense + - Solid component = heterogeneous (iso-/hyperintense, Ca⁺⁺ portions hypointense) + - Hyperintense signal in brain parenchyma adjacent to tumor may indicate + - Gliosis, tumor invasion, irritation from leaking cyst fluid + - Edema from compression of optic chiasm/tracts + - Hypointense T2* = Ca⁺⁺ + - ### FLAIR + + + - Cyst contents typically hyperintense + - ### DWI + + + - Variable depending upon character of cyst fluid + - ### T1WI C+ + + + - Solid portions enhance heterogeneously; cyst walls enhance strongly + - ### MRA + + + - Vascular displacement &/or encasement + - ### MRS + + + - Cyst contents show broad lipid spectrum (0.9-1.5 ppm) +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR with thin sagittal, coronal sequences + - ### Protocol advice + + + - Pre-/postcontrast T1WI, T2, FLAIR, GRE, DWI, MRS + +# DIFFERENTIAL DIAGNOSIS + +- [Rathke Cleft Cyst](/document/rathke-cleft-cyst/8f1561f7-92a7-485c-a0ae-2e2d5c8c1628) + - Noncalcified, less heterogeneous + - Look for intracystic nodule on T2 + - Does not enhance + - Claw sign (enhancing pituitary draped around cyst) + - Small Rathke cleft cyst (RCC) may be indistinguishable from rare intrasellar CP + - RCCs express CK8 and CK20 (CPs generally do not) +- ## Suprasellar Arachnoid Cyst + + + - No Ca⁺⁺, enhancement +- ## Hypothalamic/Chiasmatic Astrocytoma + + + - Solid or with small cystic/necrotic components + - Ca⁺⁺ is rare; robust enhancement is common +- ## Pituitary Adenoma + + + - Rare in prepubescent children + - Isointense with brain + - Enhances strongly + - Can mimic CP when cystic and hemorrhagic +- ## Epidermoid/Dermoid Tumors + + + - Minimal or no enhancement +- ## Thrombosed Aneurysm + + + - Contains blood products; use SWI + - Look for residual patent lumen, phase artifact +- [Germinoma or Mixed Germ Cell Tumor With Cystic Component(s)](/document/germinoma/078b68a2-67de-457e-818a-63655cec95aa) + - Cerebrospinal fluid spread is common, Ca⁺⁺ is rare + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - 2 proposed theories + - CPs arise from remnants of craniopharyngeal duct and Rathke pouch epithelium + - CPs arise from squamous epithelial cells in pars tuberalis of adenohypophysis + - ### Genetics + + + - No known genetic susceptibility (rare reports of siblings, parent-child) + - Small subset of CPs are monoclonal tumors that arise from oncogenes at specific loci + - Adamantinomatous: *CTNNB1* mutations and aberrant nuclear expression of β-catenin in up to 95% of cases + - Papillary:*BRAF* V600E mutations in 81-95% of cases +- ## Staging, Grading, & Classification + + + - WHO grade 1 + - MIB-1 labeling index > 7% predicts recurrence +- ## Gross Pathologic & Surgical Features + + + - Solid tumor with variable cysts + - Adamantinomatous cysts often contain thick "crankcase oil" fluid + - Epithelial fronds penetrate adjacent hypothalamus/chiasm +- ## Microscopic Features + + + - Adamantinomatous (mostly pediatric) + - Multistratified squamous epithelium with nuclear palisading + - Nodules of "wet" keratin + - Dystrophic Ca⁺⁺ + - Papillary (mostly adults) + - Sheets of squamous epithelium form pseudopapillae + - Villous fibrovascular stroma + - Malignant transformation, distant metastases rare + - May occur with varied histologies, resulting in poor prognosis + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Symptoms vary with location, size of tumor, age of patient + - Visual disturbances (60-85%) + - Bitemporal hemianopsia + - ### Other signs/symptoms + + + - Endocrine disturbances (52-87%) + - Growth hormone (GH) deficiency (75%) > luteinizing hormone (LH)/follicle-stimulating hormone (FSH) deficiency > hypothyroidism > adrenal failure > diabetes insipidus + - Headaches + - Cognitive impairment (~ 50%) + - ### Clinical profile + + + - Pediatric patient with morning headache, visual defect, short stature +- ## Demographics + + + - ### Age + + + - Bimodal distribution (peak 5-15 years, with smaller peak 45-60 years) + - Papillary CP: 40-55 years + - ### Sex + + + - M = F + - ### Ethnicity + + + - More common in Japanese children + - ### Epidemiology + + + - Most common pediatric intracranial tumor of nonglial origin + - Comprise 1.2-4.6% of all intracranial tumors across all ages + - 6-11% of all pediatric intracranial tumors + - Incidence = 0.5-2.5 new cases per 1 million per year + - ~ 54% of all pediatric sellar/chiasmatic region tumors are CPs +- ## Natural History & Prognosis + + + - Typically slow-growing benign neoplasm + - Prognosis based upon size, extent of tumor at presentation + - < 5 cm, recurrence rate: 20% + - > 5 cm, recurrence rate: 83% + - Overall 10-year survival: 64-96% +- ## Treatment + + + - Methods of primary treatment + - Radical surgery = gross total resection + - Complications = hypothalamic injury, endocrine symptoms, vasa vasorum injury, and pseudoaneurysm + - Surgery may occur via craniotomy, transnasal, transorbital, or endoscopic routes + - Less invasive surgery = subtotal resection + radiation therapy + - Biopsy, cyst drainage, and radiation therapy + - Treatment for residual or recurrent tumor + - Surgery, radiation therapy, or cyst aspiration + - Cyst instillation with intracavitary radioisotopes, bleomycin, or other sclerosing agents + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Preoperative ophthalmologic and endocrine evaluations +- ## Image Interpretation Pearls + + + - Use NECT to detect Ca⁺⁺ if MR diagnosis is in question + - Adamantinomatous CP = 90% rule (90% cystic, calcified, enhancing) + - Papillary CP is typically solid and primarily adult neoplasm + + c497473c-5835-4221-bfa1-0d2be04bee73 \ No newline at end of file diff --git a/docs_md/articles/creutzfeldt-jakob-disease-cjd_app.statdx.com_document_content_e1b27954-6591-4bb0-a659-b13790492620_46d03a76_20251014T193441Z.md b/docs_md/articles/creutzfeldt-jakob-disease-cjd_e1b27954-6591-4bb0-a659-b13790492620.md similarity index 97% rename from docs_md/articles/creutzfeldt-jakob-disease-cjd_app.statdx.com_document_content_e1b27954-6591-4bb0-a659-b13790492620_46d03a76_20251014T193441Z.md rename to docs_md/articles/creutzfeldt-jakob-disease-cjd_e1b27954-6591-4bb0-a659-b13790492620.md index e247a1b..c4b0ff5 100644 --- a/docs_md/articles/creutzfeldt-jakob-disease-cjd_app.statdx.com_document_content_e1b27954-6591-4bb0-a659-b13790492620_46d03a76_20251014T193441Z.md +++ b/docs_md/articles/creutzfeldt-jakob-disease-cjd_e1b27954-6591-4bb0-a659-b13790492620.md @@ -1,5 +1,14 @@ -# Creutzfeldt-Jakob Disease (CJD) - +--- +title: "Creutzfeldt-Jakob Disease (CJD)" +docid: "e1b27954-6591-4bb0-a659-b13790492620" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Creutzfeldt-Jakob Disease (CJD)" +--- # KEY FACTS - ## Terminology @@ -317,4 +326,4 @@ - Lack of BG findings does not rule out CJD - 94600a52-3136-46e8-a827-05e281f28d7e + 94600a52-3136-46e8-a827-05e281f28d7e \ No newline at end of file diff --git a/docs_md/articles/crossed-cerebellar-diaschisis_c1e384b3-3c6e-4f67-bf79-5187bd6a1b86.md b/docs_md/articles/crossed-cerebellar-diaschisis_c1e384b3-3c6e-4f67-bf79-5187bd6a1b86.md new file mode 100644 index 0000000..cf0e397 --- /dev/null +++ b/docs_md/articles/crossed-cerebellar-diaschisis_c1e384b3-3c6e-4f67-bf79-5187bd6a1b86.md @@ -0,0 +1,188 @@ +--- +title: "Crossed Cerebellar Diaschisis" +docid: "c1e384b3-3c6e-4f67-bf79-5187bd6a1b86" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Crossed Cerebellar Diaschisis" +--- +# KEY FACTS + +- ## Terminology + + + - Diaschisis: Sudden loss of function in brain connected to (but at distance from) damaged area + - CCD: ↓ blood flow/metabolism in cerebellar hemisphere contralateral to supratentorial infarct +- ## Imaging + + + - Acute: CT/MR perfusion shows ↓ CBF in cerebellar hemisphere opposite acute hemispheric infarct + - ↑ TTP, ↓ CBF in cerebellum contralateral to infarct + - Add DTI as subtle cases may show ↓ FA when conventional MR normal + - F-18 FDG PET/CT shows diffusely reduced uptake in contralateral cerebellar hemisphere + - Chronic: CT or MR shows atrophic cerebellar hemisphere opposite old cerebral hemispheric infarct/insult +- ## Top Differential Diagnoses + + + - Superior cerebellar artery infarct + - CCD involved > just SCA territory + - Encephalomalacia + - Trauma, infection, surgery + - Cerebellitis + - Cerebellum swollen, hyperintense (not shrunken, atrophic) + - Bilateral > unilateral +- ## Pathology + + + - CPC tract + - Input to cerebellum via CPC tracts 40x all other afferent sources combined + - Injury at any point along CPC can result in ↓ CBF, metabolism in contralateral cerebellar hemisphere + - Most common cause: MCA infarct + - Others: Status epilepticus, neoplasm, trauma, surgery,migraine, Rasmussen encephalitis, etc. + - Occurrence & severity of CCD related to degree of low supratentorial perfusion & decrease in ADC value of infarct + +# TERMINOLOGY + +- ## Abbreviations + + + - Crossed cerebellar diaschisis (CCD) +- ## Definitions + + + - Diaschisis: Sudden loss of function in brain connected to (but at distance from) damaged area + - CCD: Decreased blood flow/metabolism in cerebellar hemisphere contralateral to supratentorial infarct + - Caused by interrupted afferent input through corticopontocerebellar tract (CPC) + - CCD occurs in both acute & chronic phases + - Acute CCD results from functional deafferentation + - Subacute, chronic CCD reflects transneuronal degeneration + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Acute: CT/MR perfusion shows ↓ cerebral blood flow (CBF) in cerebellar hemisphere opposite acute cerebral hemispheric infarct + - Chronic: CT or MR shows atrophic cerebellar hemisphere opposite old cerebral hemispheric infarct/insult + - ### Location + + + - Cerebellar hemisphere opposite cerebral hemispheric infarct +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - Acute: CT or MR perfusion + - PET/CT also effective but expensive; variable availability + - Chronic: MR with T2WI, FLAIR, DTI + - ### Protocol advice + + + - Add DTI as subtle cases may show ↓ fractional anisotropy (FA) when conventional MR normal +- ## CT Findings + + + - ### NECT + + + - Acute: Normal + - Chronic: Cerebellar atrophy contralateral to supratentorial infarct + - ### CTA + + + - Middle cerebral artery (MCA) occlusion + - Cerebellar vessels appear normal + - CT perfusion + - ↑ TTP, ↓ CBF in cerebellum contralateral to infarct +- ## MR Findings + + + - ### T1WI + + + - Unilateral cerebellar atrophy + - ### T2WI + + + - Folia shrunken, fissures enlarged + - ### FLAIR + + + - Except for atrophy, cerebellum usually normal + - ### MRA + + + - Posterior fossa vasculature normal + - DTI + - Shows ↓ FA in middle cerebellar peduncle + - Visualizes altered CPC in chronic CCD that may not be seen on conventional MR + - Arterial spin labeling (ASL) perfusion + - ↓ CBF in cerebellum contralateral to cerebral hemispheric abnormality +- ## Nuclear Medicine Findings + + + - ### PET/CT + + + - F-18 FDG PET/CT shows diffusely reduced uptake in contralateral cerebellar hemisphere + - L-(methyl-11C) methionine (MET) uptake not reduced + - ### Tc-99m sulfur colloid + + + - Tc-99m ECD, HMPAO SPECT can demonstrate distant areas of ↓ CBF, metabolism (diaschisis) + +# DIFFERENTIAL DIAGNOSIS + +- ## Superior Cerebellar Artery Infarct + + + - CCD involves most of cerebellum, not just superior cerebellar artery (SCA) territory + - Contralateral MCA infarct absent +- ## Encephalomalacia + + + - No history of trauma, contralateral MCA infarct +- [Cerebellitis](/document/cerebellitis/2a2d695e-63be-4839-9e1a-cd8813b005d6) + - Cerebellum swollen, not shrunken + - Bilateral > unilateral + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - CPC tract + - Large afferent pathway derived from very extensive areas of cortex + - Input to cerebellum via CPC tracts 40x all other afferent sources combined + - 1st-order neurons arrive in ipsilateral pons + - Synapse with 2nd-order neurons + - Then cross to opposite cerebellar hemisphere via middle cerebellar peduncle + - Injury at any point along CPC can result in ↓ CBF, metabolism in contralateral cerebellar hemisphere + - Most common cause: MCA infarct + - Others: Status epilepticus, neoplasm, trauma, surgery, migraine, Rasmussen encephalitis, etc. + - Occurrence & severity of CCD related to degree of low supratentorial perfusion & decrease in ADC value of infarct + +# CLINICAL ISSUES + +- ## Natural History & Prognosis + + + - CCD represents temporal continuum + - Early, reversible functional hypometabolism + - Cerebellum recovers (typical) + - Irreversible degeneration in up to 20% + - Cerebellar atrophy + - Can be seen decades after initial insult + + d7407fea-fff9-488b-9712-71a4e559c250 \ No newline at end of file diff --git a/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_8bf4b8d9_20251014T195833Z.md b/docs_md/articles/csf-like-parenchymal-lesions_24559f7a-ed5a-4ab6-90ba-769f0b5c1197.md similarity index 96% rename from docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_8bf4b8d9_20251014T195833Z.md rename to docs_md/articles/csf-like-parenchymal-lesions_24559f7a-ed5a-4ab6-90ba-769f0b5c1197.md index cefda7c..41b4814 100644 --- a/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_8bf4b8d9_20251014T195833Z.md +++ b/docs_md/articles/csf-like-parenchymal-lesions_24559f7a-ed5a-4ab6-90ba-769f0b5c1197.md @@ -1,5 +1,13 @@ -# Enlarged Perivascular Spaces - +--- +title: "CSF-Like Parenchymal Lesion(s)" +docid: "24559f7a-ed5a-4ab6-90ba-769f0b5c1197" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Generic Imaging Patterns" + - "CSF-Like Parenchymal Lesion(s)" +--- # ESSENTIAL INFORMATION - ## Key Differential Diagnosis Issues @@ -144,4 +152,4 @@ - NCC - Porencephalic cyst - Neuroglial cyst - - Hydatid cyst + - Hydatid cyst \ No newline at end of file diff --git a/docs_md/articles/neurocysticercosis_app.statdx.com_document_content_6cb71737-f574-4121-a8fb-02eeada9f9f7_47a28ee9_20251014T195847Z.md b/docs_md/articles/cyst-with-nodule_6cb71737-f574-4121-a8fb-02eeada9f9f7.md similarity index 96% rename from docs_md/articles/neurocysticercosis_app.statdx.com_document_content_6cb71737-f574-4121-a8fb-02eeada9f9f7_47a28ee9_20251014T195847Z.md rename to docs_md/articles/cyst-with-nodule_6cb71737-f574-4121-a8fb-02eeada9f9f7.md index 5533540..070dea9 100644 --- a/docs_md/articles/neurocysticercosis_app.statdx.com_document_content_6cb71737-f574-4121-a8fb-02eeada9f9f7_47a28ee9_20251014T195847Z.md +++ b/docs_md/articles/cyst-with-nodule_6cb71737-f574-4121-a8fb-02eeada9f9f7.md @@ -1,5 +1,13 @@ -# Neurocysticercosis - +--- +title: "Cyst With Nodule" +docid: "6cb71737-f574-4121-a8fb-02eeada9f9f7" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Generic Imaging Patterns" + - "Cyst With Nodule" +--- # ESSENTIAL INFORMATION - ## Key Differential Diagnosis Issues @@ -126,4 +134,4 @@ - Adult: Hemangioblastoma, GBM, metastases - Any age: NCC, abscess, other infections - Multiple lesions - - Metastases (50-55%), NCC (50-70%), hemangioblastoma (VHL), abscesses (septic emboli), toxoplasmosis, parasites + - Metastases (50-55%), NCC (50-70%), hemangioblastoma (VHL), abscesses (septic emboli), toxoplasmosis, parasites \ No newline at end of file diff --git a/docs_md/articles/dementia-with-lewy-bodies_app.statdx.com_document_content_e8e46d1d-46d2-4e5a-880f-f025a84c5871_01610362_20251014T193405Z.md b/docs_md/articles/dementia-with-lewy-bodies_app.statdx.com_document_content_e8e46d1d-46d2-4e5a-880f-f025a84c5871_01610362_20251014T193405Z.md deleted file mode 100644 index ef62bf6..0000000 --- a/docs_md/articles/dementia-with-lewy-bodies_app.statdx.com_document_content_e8e46d1d-46d2-4e5a-880f-f025a84c5871_01610362_20251014T193405Z.md +++ /dev/null @@ -1,266 +0,0 @@ -# Dementia With Lewy Bodies - -# KEY FACTS - -- ## Terminology - - - - Progressive neurodegenerative dementia - - Parkinsonism, visual hallucinations prominent - - Caused by abnormal accumulation of α-synuclein protein -- ## Imaging - - - - MR may differentiate Alzheimer disease (AD) from dementia with Lewy bodies (DLB) - - PET, SPECT most useful for DLB diagnosis - - Voxel-based morphometry - - Relatively preserved hippocampal/medial temporal lobe volume in DLB vs. AD - - ↓ volume of hypothalamus, substantia innominata, & putamen in DLB vs. AD - - FDG PET - - ↓ in glucose metabolism in occipital cortex, especially primary visual cortex - - F-18 fluorodopa-PET: ↓ striatal dopamine uptake in DLB vs. AD - - SPECT: Occipital lobe hypoperfusion, especially visual cortex - - 123 FP-CIT SPECT: ↓ uptake in striatum in DLB vs. AD -- ## Top Differential Diagnoses - - - - Parkinson disease-associated dementia (PDD) - - Similar clinical, pathological, imaging features with DLB - - AD - - Frontotemporal lobar degeneration (FTLD) - - Vascular dementia -- ## Pathology - - - - Pathologic aggregation of α-synuclein protein in neurites (LB) -- ## Diagnostic Checklist - - - - Unlike AD, medial temporal lobe atrophy not prominent feature - -# TERMINOLOGY - -- ## Abbreviations - - - - Dementia with Lewy bodies (DLB) -- ## Definitions - - - - Neurodegenerative dementia characterized by cognitive fluctuations, visual hallucinations, & motor parkinsonism - - Caused by pathologic aggregation of α-synuclein protein in neurites (LB) - -# IMAGING - -- ## General Features - - - - ### Best diagnostic clue - - - - MR may differentiate Alzheimer disease (AD) from DLB - - PET, SPECT most useful for DLB diagnosis -- ## Imaging Recommendations - - - - ### Best imaging tool - - - - PET or SPECT -- ## MR Findings - - - - ### T1WI - - - - Mild generalized atrophy - - ### T2WI - - - - Nonspecific white matter (WM) hyperintensities - - ### MRS - - - - ↓ WM NAA/Cr in DLB vs. healthy controls (HC) - - ↑ Cho/Cr ratios in DLB vs. HC - - Normal levels of NAA/Cr & myoinositol in DLB vs. AD - - Voxel-based morphometry - - Relatively preserved hippocampal/medial temporal lobe volume in DLB vs. AD - - ↓ volume of hypothalamus, substantia innominata, & putamen in DLB vs. AD - - ↓ gray matter in temporal, parietal, & occipital regions vs. HC - - DTI - - ↑ mean diffusivity in amygdala - - ↓ fractional anisotropy in pons & left thalamus vs. AD - - ↓ fractional anisotropy in inferior longitudinal fasciculus & inferior occipitofrontal fasciculi vs. HC -- ## Nuclear Medicine Findings - - - - ### PET - - - - FDG PET: ↓ glucose metabolism in occipital cortex & visual association cortex with relative preservation of posterior cingulate - - F-18 fluorodopa-PET: ↓ striatal dopamine uptake in DLB vs. AD - - ### MIBG scintigraphy - - - - ↓ myocardial uptake in DLB due to ↓ postganglionic sympathetic cardiac innervation - - SPECT - - Occipital lobe hypoperfusion, especially visual cortex - - 123 FP-CIT SPECT: Visualize DAT (dopamine transporter) loss - - ↓ uptake in striatum in DLB - -# DIFFERENTIAL DIAGNOSIS - -- [Parkinson Disease-Associated Dementia](/document/parkinson-disease/0bc3188a-935b-416d-b1a0-25b2d52c6399) - - Dementia typically develops at least 12 months after onset of initial parkinsonian symptoms - - Similar clinical, pathologic, imaging features to DLB - - Less pronounced atrophy in temporal, occipital, & parietal lobes vs. DLB -- [Alzheimer Disease](/document/alzheimer-disease/f71f5cf5-b1af-4c6d-b145-b4c10eec7b58) - - Parietal/temporal cortical atrophy - - Disproportionate hippocampal volume loss - - Amyloid uptake of cerebral cortex in PiB-PET - - More severe, faster rate of progression than DLB -- [Frontotemporal Lobar Degeneration](/document/frontotemporal-lobar-degeneration/49510d0e-acf7-45cb-9eb1-53f8193b0b6d) - - Asymmetric frontal, anterior temporal lobar atrophy - - Behavioral variant: Both frontal lobes atrophic - - Semantic variant: Asymmetric anterior temporal lobe atrophy -- [Vascular Dementia](/document/vascular-dementia/f59dab57-c511-4369-8fcc-592421a4b8d1) - - 2nd most common dementia (15-30%) - - WM & deep gray lacunae - - Infarcts of different ages - - Hyperintense lesions on T2WI, hypodense areas on CT, & focal atrophy suggestive of chronic infarcts - -# PATHOLOGY - -- ## General Features - - - - ### Etiology - - - - Accumulation of α-synuclein protein (LB) - - LB, neuronal loss in substantia nigra → dopamine depletion - - Loss of cholinergic neurons in nucleus basalis of Meynert - - → cognitive impairment, visual hallucinations - - ### Genetics - - - - Majority of DLB is sporadic; some are familial - - α-synuclein gene mutation on chromosome 4 (*A53T*, *E46K* mutation) - - Similar inheritance, similar genetic risk for PD - - Other genes associated with DLB include *SNCA*, *APP*, *PSEN1*/*PSEN2*, *MAPT*, *GBA*, & *APOE* -- ## Staging, Grading, & Classification - - - - 3 major forms: Brainstem dominant, limbic/transitional, diffuse neocortical -- ## Gross Pathologic & Surgical Features - - - - Nonspecific & overlap with other neurodegenerative dementias - - Cortical atrophy is less than AD - - Atrophy affects frontal, temporal, & parietal lobes, relative sparing of occipital lobes - - Amygdala & cingulate gyri can show severe atrophy -- ## Microscopic Features - - - - LB in substantia nigra, neocortex, limbic system - - α-synuclein protein aggregates: Pale eosinophilic inclusions - - α-synuclein - - Physiologic function: Synaptic transmission, neuroprotective effect - - Predominantly expressed in neurons - - Lewy neurites in hippocampus, amygdala, brainstem nuclei - - Neuronal loss in substantia nigra, locus ceruleus, nucleus basalis of Meynert, dorsal raphe nuclei - - Relative preservation of cortical neurons - - Superficial microvacuolation of cerebral cortex, especially temporal cortex in severe cases - - 80% have associated AD-like pathology - - Neuritic/diffuse plaques or neurofibrillary tangles - -# CLINICAL ISSUES - -- ## Presentation - - - - ### Most common signs/symptoms - - - - Cognitive fluctuations, visual hallucinations, parkinsonism - - Dysautonomia & sleep disorders - - Clinical criteria for DLB diagnosis - - Core clinical features - - Fluctuating cognition with pronounced variations in attention & alertness - - Recurrent visual hallucinations (typically well formed & detailed) - - REM sleep behavior disorder (May precede cognitive decline) - - 1 or more spontaneous cardinal features of parkinsonism (bradykinesia, rest tremor, rigidity) - - Supportive clinical features - - Severe sensitivity to antipsychotic agents - - Postural instability, repeated falls - - Syncope or other transient episodes of unresponsiveness - - Severe autonomic dysfunction (constipation, orthostatic hypotension, urinary incontinence) - - Hypersomnia, hyposmia, hallucinations in other modalities, systematized delusions - - Apathy, anxiety, & depression - - Indicative biomarkers - - ↓ dopamine transporter uptake in basal ganglia by SPECT or PET - - Abnormal (low-uptake) I-123-MIBG myocardial scintigraphy - - Polysomnographic confirmation of REM sleep without atonia - - Supportive biomarkers - - Relative preservation of medial temporal lobe structures on CT/MR - - Generalized low uptake on SPECT/PET perfusion/metabolism scan with ↓ occipital activity ± cingulate island sign on FDG PET imaging - - Prominent posterior slow-wave activity on EEG with periodic fluctuations in pre-alpha/theta range - - Probable DLB - - ≥ 2 core clinical features of DLB with or without indicative biomarkers; **or** - - Only 1 core clinical feature but with ≥ 1 indicative biomarkers - - Probable DLB should not be diagnosed on basis of biomarkers alone - - Possible DLB - - Only 1 core clinical feature of DLB with no indicative biomarker evidence; **or** - - ≥ 1 indicative biomarkers but no core clinical features - - DLB is less likely - - Presence of any other physical illness or brain disorder, including cerebrovascular disease, sufficient to account in part or in total for clinical picture - - If parkinsonian features are only core clinical feature & appear for 1st time at stage of severe dementia -- ## Demographics - - - - ### Age - - - - 55-85 years; age is only risk factor - - Average at presentation is 75 years - - ### Ethnicity - - - - LB formation more common in African Americans than Caucasians, but clinical diagnosis of DLB is not significantly different - - ### Sex - - - - M:F = 4:1 - - ### Epidemiology - - - - 5% of general population & 30% of dementia cases - - 2nd most common neurodegenerative dementia (after AD) - - Incidence rate of 0.1% per year in general population & 3.2% for new dementia cases -- ## Natural History & Prognosis - - - - Average survival after diagnosis < 8 years -- ## Treatment - - - - ### Options, risks, complications - - - - No disease-modifying treatments for DLB - - Symptomatic, targeted toward specific disease manifestations - - Cholinesterase inhibitor for cognitive features - - DLB responds better to cholinesterase inhibitor than AD - - Treatment against hallucination should be conservative due to neuroleptic hypersensitivity of DLB - -# DIAGNOSTIC CHECKLIST - -- ## Image Interpretation Pearls - - - - No characteristic features on standard MR - - Clinical dementia + no/relatively mild medial temporal lobe atrophy - - Unlike AD, medial temporal lobe atrophy is not prominent - - 2eb83d9f-537e-4b39-96ac-8099cafa2337 diff --git a/docs_md/articles/dementia-with-lewy-bodies_app.statdx.com_document_content_e8e46d1d-46d2-4e5a-880f-f025a84c5871_3e5608ea_20251014T190919Z.md b/docs_md/articles/dementia-with-lewy-bodies_e8e46d1d-46d2-4e5a-880f-f025a84c5871.md similarity index 96% rename from docs_md/articles/dementia-with-lewy-bodies_app.statdx.com_document_content_e8e46d1d-46d2-4e5a-880f-f025a84c5871_3e5608ea_20251014T190919Z.md rename to docs_md/articles/dementia-with-lewy-bodies_e8e46d1d-46d2-4e5a-880f-f025a84c5871.md index 511a257..35d520d 100644 --- a/docs_md/articles/dementia-with-lewy-bodies_app.statdx.com_document_content_e8e46d1d-46d2-4e5a-880f-f025a84c5871_3e5608ea_20251014T190919Z.md +++ b/docs_md/articles/dementia-with-lewy-bodies_e8e46d1d-46d2-4e5a-880f-f025a84c5871.md @@ -1,5 +1,14 @@ -# Dementia With Lewy Bodies - +--- +title: "Dementia With Lewy Bodies" +docid: "e8e46d1d-46d2-4e5a-880f-f025a84c5871" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Dementia With Lewy Bodies" +--- # KEY FACTS - ## Terminology @@ -263,4 +272,4 @@ - Clinical dementia + no/relatively mild medial temporal lobe atrophy - Unlike AD, medial temporal lobe atrophy is not prominent - f336b865-74c1-456e-9130-6db7efb9e7b3 + 2eb83d9f-537e-4b39-96ac-8099cafa2337 \ No newline at end of file diff --git a/docs_md/articles/empty-sella_39a0d2d1-1439-4558-8f5d-86a2a6d93e3a.md b/docs_md/articles/empty-sella_39a0d2d1-1439-4558-8f5d-86a2a6d93e3a.md new file mode 100644 index 0000000..15bb0cd --- /dev/null +++ b/docs_md/articles/empty-sella_39a0d2d1-1439-4558-8f5d-86a2a6d93e3a.md @@ -0,0 +1,311 @@ +--- +title: "Empty Sella" +docid: "39a0d2d1-1439-4558-8f5d-86a2a6d93e3a" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Miscellaneous" + - "Empty Sella" +--- +# KEY FACTS + +- ## Terminology + + + - Sella partially filled with arachnoid-lined CSF collection + - Primary empty sella + - Common normal variant (15% of brain MRs), incidental finding + - Normal or increased CSF pressure + - Near-normal volume of compressed pituitary tissue + - Secondary empty sella + - Prior pituitary surgery, radiation, or injury +- ## Imaging + + + - Intrasellar CSF, pituitary flattened against sellar floor + - Bony sella may be normal or moderately enlarged (secondary to pulsatile CSF) + - Bony margins intact, not eroded/demineralized + - Infundibular stalk, pituitary gland enhance normally + - Fluid exactly like CSF + - Suppresses completely on FLAIR + - Does not restrict on DWI +- ## Top Differential Diagnoses + + + - Idiopathic intracranial hypertension + - Secondary intracranial hypertension + - Arachnoid cyst + - Pituitary apoplexy + - Pituitary anomalies +- ## Pathology + + + - "Deficient" diaphragma sellae + - Dural covering of sella is incomplete (widened) + - Leaves large opening for infundibular stalk + - Allows intrasellar herniation of arachnoid with CSF from suprasellar subarachnoid cistern above +- ## Clinical Issues + + + - Mostly incidental, asymptomatic (adults) + - F:M = 5:1 + - Headache, visual disturbances if related to intracranial hypertension + - Frequent endocrine abnormalities in children + +# TERMINOLOGY + +- ## Abbreviations + + + - Empty sella (ES) +- ## Definitions + + + - Herniation of suprasellar arachnoid and cerebrospinal fluid (CSF) through wide diaphragma sellae into bony sella turcica + - Sella turcica is partially filled with CSF + - Rarely completely empty + - Pituitary gland + - Almost never completely absent + - Thin, flattened rim of residual pituitary tissue + - Generally at posteroinferior sellar floor + - Primary or secondary + - Primary empty sella + - Common normal variant (15% of brain MRs), incidental finding + - Normal or increased CSF pressure + - Near-normal volume of compressed pituitary tissue + - No history of trauma, surgery, radiation + - Patients typically endocrinologically normal + - Secondary empty sella + - Many etiologies + - Surgery + - Radiation + - Bromocriptine therapy + - Trauma + - Sheehan syndrome (postpartum pituitary necrosis) + - Pituitary apoplexy + - Pituitary abscess + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Intrasellar CSF with pituitary gland flattened against sellar floor + - Bony sella may be normal or large + - ### Location + + + - Intrasellar CSF + - ### Size + + + - Variable +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - Sagittal T1WI + - Coronal T2WI +- ## CT Findings + + + - ### NECT + + + - CSF-like herniation of CSF into bony sella + - Bony sella typically appears normal + - May also be moderately enlarged (secondary to pulsatile CSF) + - Bony margins intact, not eroded/demineralized + - ### CECT + + + - Infundibular stalk and pituitary gland enhance normally + - Occasionally intrasellar CSF collection may be asymmetric + - Stalk may appear tilted to one side +- ## MR Findings + + + - ### T1WI + + + - Primary empty sella + - Fluid looks exactly like CSF + - Stalk usually midline + - Gland + stalk = anchor sign on coronal imaging + - Stalk may be tilted to one side if intrasellar CSF herniation is asymmetric + - 3rd ventricle, hypothalamus usually normal + - Rare: Herniation of optic chiasm, anterior 3rd ventricle into sella + - Secondary empty sella + - Look for changes of transsphenoidal hypophysectomy + - Defect in sellar floor + - Fat packing + - May cause distortion of stalk, chiasm + - Stalk and pituitary remnant(s) may be scarred/adhesed to side or bottom of sella turcica + - ### T2WI + + + - Fluid exactly like CSF + - ### FLAIR + + + - Intrasellar fluid suppresses completely on FLAIR + - ### DWI + + + - No restriction + - ### T1WI C+ + + + - Primary empty sella + - Stalk, gland enhance normally + - No other abnormalities + - Secondary empty sella + - Gland and stalk may be adhesed/distorted + +# DIFFERENTIAL DIAGNOSIS + +- [Idiopathic Intracranial Hypertension](/document/idiopathic-intracranial-hypertensi-/d7a0a1b6-1d94-473c-9fe9-021443969f9f) + - Often not truly "idiopathic" (e.g., dural venous sinus stenosis) + - Usually obese female, 20-40 years + - Headache, papilledema + - Intraoptic protrusion of optic nerve head + - Enlarged optic nerve sheaths ± empty sella + - Ventricles may appear slit-like + - Subarachnoid spaces (cisterns, surface sulci) may be small +- ## Secondary Intracranial Hypertension + + + - Increased intracranial pressure caused by + - Obstructive hydrocephalus (intra-/extraventricular) + - Mass (neoplasm, etc.) + - Dilated anterior recesses of 3rd ventricle herniate into sella + - Look for mass, evidence for transependymal CSF migration +- [Arachnoid Cyst](/document/arachnoid-cyst/d25aaeb3-5b3c-4483-99dc-2757468eedb9) + - Suprasellar arachnoid cyst may herniate into bony sella + - Bony sella often enlarged, eroded/expanded + - Look for 3rd ventricle or optic chiasm displaced by CSF-containing mass + - Cyst walls may be visible on thin-section imaging +- [Pituitary Apoplexy](/document/pituitary-apoplexy/43efc995-d33c-4ac1-be70-e3237eec9fc9) + - Acute: Pituitary gland usually enlarged, not small + - Usually hemorrhagic + - Look for rim enhancement around periphery of enlarged, nonenhancing gland + - Chronic: May cause empty sella +- [Pituitary Anomalies](/document/pituitary-anomalies/09ca9b54-a3d9-43fd-a9cc-4c0212b578a1) + - Ectopic posterior pituitary "bright spot" + - May cause small pituitary gland + - Infundibular stalk short, "stubby" + - Bony sella often small, shallow appearing + - Sella can appear partially empty + - Persisting embryonal infundibular recess of 3rd ventricle + - Can mimic empty sella (rare) + - Pituitary stalk duplication + - Rare + - Look for 2 thin stalks + - Sella may appear partially empty +- [Sheehan Syndrome](/document/pituitary-apoplexy/43efc995-d33c-4ac1-be70-e3237eec9fc9) + - Original clinical description + - Postpartum hemorrhage + - Pituitary necrosis + - Lactation failure + - Hypopituitarism + - Anterior pituitary necrosis + - Leaves small residual pituitary gland + - Result = empty sella + - May occur years after pregnancy + - Slow clinical progression over years suggests factors other than ischemia may be involved + - Necrosis may be caused by antihypothalamus, antipituitary antibodies + - Pituitary autoimmunity may perpetuate hypopituitarism +- [Epidermoid Cyst](/document/epidermoid-cyst/704c5ddf-e1f7-4a5d-a1b8-5b0e603170d9) + - True intrasellar epidermoid cyst very rare + - Off midline > midline + - Usually extension from cerebellopontine angle epidermoid + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Primary empty sella + - Deficient diaphragma sellae + - Dural covering of sella is incomplete (widened) + - Leaves widened dural opening for infundibular stalk + - Allows intrasellar herniation of arachnoid with CSF from suprasellar subarachnoid cistern above + - Compresses pituitary gland against sellar floor + - Traction on infundibular stalk may cause alteration in visual system + - Pulsatile CSF may gradually enlarge sella + - Secondary empty sella + - Common: Surgery, bromocriptine therapy, radiation + - Less common: Pituitary apoplexy, pituitary abscess + - Rare: Pituitary necrosis in viral hemorrhagic fever (e.g., hanta) +- ## Gross Pathologic & Surgical Features + + + - Diaphragma sellae appears widened, gaping + - Intrasellar herniation of arachnoid-containing CSF + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Incidental, usually asymptomatic + - Headache + - Visual disturbances 1-15% + - Idiopathic intracranial hypertension (IIH) + - Optic chiasm herniation into ES may cause visual symptoms + - Endocrine disturbances + - 20% of adults have subtle laboratory abnormalities + - Majority (70%) of children with ES have endocrine abnormalities +- ## Demographics + + + - ### Age + + + - Peak incidence between 50-60 years + - Increased CSF pressure presents earlier (30-40 years) + - ### Sex + + + - F:M = 5:1 + - ### Epidemiology + + + - 10-15% found incidentally on imaging +- ## Natural History & Prognosis + + + - Both primary and secondary empty sella usually benign, do not require treatment + - If related to IIH, can result in vision loss or CSF leak + - Hormonal replacement therapy may be required in some cases + - Surgery (rare) + - "Chiasmapexy" to elevate optic chiasm if severe visual disturbances caused by inferior displacement of optic chiasm into empty sella + - CSF rhinorrhea may require surgical intervention + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Incidental, normal variant in older adults + - Additional findings of IIH in younger females (e.g., dilated optic nerve sheaths, papilledema, dural venous sinus narrowing) + - Look for endocrine abnormalities in children +- ## Image Interpretation Pearls + + + - Intrasellar fluid follows CSF **exactly**on all sequences + + 8bb93cd6-d836-4878-89c3-865ebc070aea \ No newline at end of file diff --git a/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.md b/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.md deleted file mode 100644 index cefda7c..0000000 --- a/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.md +++ /dev/null @@ -1,147 +0,0 @@ -# Enlarged Perivascular Spaces - -# ESSENTIAL INFORMATION - -- ## Key Differential Diagnosis Issues - - - - Key imaging questions - - Does lesion follow CSF on all modalities/sequences? - - Is there any associated mass effect? - - Does lesion enhance? - - Included - - CSF-like cystic mass(es), e.g., enlarged perivascular spaces (PVS), neuroglial cysts - - Excluded - - Cystic neoplasms, abscess, resolving hematoma (rarely exactly like CSF) - - Developmental cysts that do not behave exactly like CSF (e.g., epidermoid, neurenteric cysts) -- ## Helpful Clues for Common Diagnoses - - - - **Enlarged Perivascular Spaces** - - PVS - - Can be seen at all ages but ↑ with age - - Filled with interstitial fluid but follow CSF on all sequences - - Most have no abnormality in surrounding parenchyma on FLAIR - - ~ 25% have thin, hyperintense rim - - Bilateral > unilateral - - Multiple > solitary - - "Clusters" of variably sized, CSF-like cysts characteristic - - Can occur anywhere but most common locations = basal ganglia (BG), hemispheric white matter (WM), midbrain, dentate nuclei - - Variant (mostly in older adults) = "état criblé" ("cribriform state") with multiple tiny cysts in BG - - Classification - - Type I: BG - - Type II: High convexity WM - - Type III: Midbrain - - Large PVS cause mass effect, assume bizarre configurations, and can mimic cystic neoplasm - - **Encephalomalacia** - - Etiology varies (trauma, infarction, etc.) - - Can be solitary, multifocal, multicystic - - CSF-like ± adjacent FLAIR hyperintensity - - **Lacunar Infarction** - - Solitary or multiple - - Typically along single long, unpaired penetrating arteries &/or vascular watershed zones - - BG, thalamus, WM common - - Multifocal BG infarcts + surrounding gliosis = "état lacunaire" or "lacunar state" - - **Neurocysticercosis** - - Most neurocysticercosis (NCC) cysts are actually in sulci - - Cysts in vesicular stage smooth, thin walled, with scolex generally visible as "dot" within cyst - - Multiple lesions in mixed stages common - - Some enhance, some do not - - Ca⁺⁺ (multiple = starry-sky pattern) -- ## Helpful Clues for Less Common Diagnoses - - - - **Porencephalic Cyst** - - CSF-filled parenchymal cavity - - Communicates with ventricle &/or pial surface - - Lined by reactive gliosis/astrocytic proliferation - - Does not enhance - - Etiology varies (trauma, infarction, etc.) - - **Multiple Sclerosis** - - Chronic "burned-out" lesions - - Appear as CSF foci with hyperintense rinds on FLAIR - - Look for faint T1 hyperintensity surrounding lesions ("lesion within lesion") - - Obtain sagittal FLAIR to look for other lesions along callososeptal interface - - **Hippocampal Sulcus Remnants** - - "String of beads" cysts medial to temporal horns of lateral ventricles - - Developmental variant, incidental - - Remnants of vestigial primary embryonic hippocampal sulcus - - Imaging - - Between hippocampus, dentate gyrus - - Follow CSF on all sequences - - No surrounding gliosis - - **Connatal Cysts** - - Single or multiple - - Location - - Intra- or periventricular (may actually be cysts of anterior choroid plexus) - - Small cyst adjacent to tip of frontal horn may be normal anatomic variant - - Lined with ependyma - - Present at birth - - Usually transient - - Occasionally seen in older patients - - No septations, no hemosiderin - - Generally isolated without associated abnormalities -- ## Helpful Clues for Rare Diagnoses - - - - **Neuroglial Cyst** - - Benign, glial-lined, nonenhancing CSF-like cyst - - No surrounding signal abnormality - - Does not communicate with ventricle - - Subcortical WM, choroidal fissure common sites - - Does not restrict on DWI - - No enhancement - - **Cryptococcosis** - - Opportunistic fungal infection - - Nonenhancing, gelatinous pseudocysts in PVS - - BG, thalamus, brainstem, cerebellum, dentate nucleus, periventricular WM - - Multifocal > > solitary lesions - - Most patients have HIV/AIDS - - **Parasites, Miscellaneous** - - Other than NCC, parasitic brain cysts uncommon - - Hydatid cyst - - Unilocular cyst, isointense to CSF - - T2-hypointense rim, no enhancement - - **Mucopolysaccharidoses** - - Group of lysosomal storage disorders - - PVS dilated by accumulated glycosaminoglycans - - Corpus callosum, peritrigonal WM - - Multiple, bilateral - - Dilated PVS in deep periventricular WM - - FLAIR-hyperintense rim surrounding dilated PVS - - **Germinolytic Cysts** - - Periventricular/subependymal cysts - - Cyst(s) along caudothalamic groove probably resulting from germinolysis - - Glial (not ependymal)-lined cysts/pseudocysts - - Distinguish from "connatal" cysts (intraventricular anterior choroid plexus cysts) - - Many etiologies, including inherited metabolic disorders (e.g., Zellweger, infantile Refsum), congenital infections (CMV) - - CSF-like; ± septations, hemosiderin; do not enhance - - Look for associated abnormalities - - Leukoencephalopathy - - Delayed myelination - - Polymicrogyria, pachygyria, heterotopias - - **Miscellaneous Congenital Malformations** - - Several have parenchymal CSF-like cysts as part of syndrome - - van der Knaap leukoencephalopathies (megaloencephalic leukoencephalopathy with subcortical cysts, anterior temporal lobe cavitations) - - Congenital muscular dystrophy (cerebellar cysts common, may represent dilated PVS) - - Dorsal interhemispheric CSF cyst - - Corpus callosal dysgenesis - - Holoprosencephaly -- ## Alternative Differential Approaches - - - - **Based on location** - - Deep gray nuclei - - Enlarged PVS - - Lacunar infarction - - Cryptococcosis - - Periventricular WM - - Multiple sclerosis - - Connatal cysts - - Germinolytic cysts - - Lobar - - Encephalomalacia - - NCC - - Porencephalic cyst - - Neuroglial cyst - - Hydatid cyst diff --git a/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_40ec4a22_20251014T200033Z.md b/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_40ec4a22_20251014T200033Z.md deleted file mode 100644 index cefda7c..0000000 --- a/docs_md/articles/enlarged-perivascular-spaces_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_40ec4a22_20251014T200033Z.md +++ /dev/null @@ -1,147 +0,0 @@ -# Enlarged Perivascular Spaces - -# ESSENTIAL INFORMATION - -- ## Key Differential Diagnosis Issues - - - - Key imaging questions - - Does lesion follow CSF on all modalities/sequences? - - Is there any associated mass effect? - - Does lesion enhance? - - Included - - CSF-like cystic mass(es), e.g., enlarged perivascular spaces (PVS), neuroglial cysts - - Excluded - - Cystic neoplasms, abscess, resolving hematoma (rarely exactly like CSF) - - Developmental cysts that do not behave exactly like CSF (e.g., epidermoid, neurenteric cysts) -- ## Helpful Clues for Common Diagnoses - - - - **Enlarged Perivascular Spaces** - - PVS - - Can be seen at all ages but ↑ with age - - Filled with interstitial fluid but follow CSF on all sequences - - Most have no abnormality in surrounding parenchyma on FLAIR - - ~ 25% have thin, hyperintense rim - - Bilateral > unilateral - - Multiple > solitary - - "Clusters" of variably sized, CSF-like cysts characteristic - - Can occur anywhere but most common locations = basal ganglia (BG), hemispheric white matter (WM), midbrain, dentate nuclei - - Variant (mostly in older adults) = "état criblé" ("cribriform state") with multiple tiny cysts in BG - - Classification - - Type I: BG - - Type II: High convexity WM - - Type III: Midbrain - - Large PVS cause mass effect, assume bizarre configurations, and can mimic cystic neoplasm - - **Encephalomalacia** - - Etiology varies (trauma, infarction, etc.) - - Can be solitary, multifocal, multicystic - - CSF-like ± adjacent FLAIR hyperintensity - - **Lacunar Infarction** - - Solitary or multiple - - Typically along single long, unpaired penetrating arteries &/or vascular watershed zones - - BG, thalamus, WM common - - Multifocal BG infarcts + surrounding gliosis = "état lacunaire" or "lacunar state" - - **Neurocysticercosis** - - Most neurocysticercosis (NCC) cysts are actually in sulci - - Cysts in vesicular stage smooth, thin walled, with scolex generally visible as "dot" within cyst - - Multiple lesions in mixed stages common - - Some enhance, some do not - - Ca⁺⁺ (multiple = starry-sky pattern) -- ## Helpful Clues for Less Common Diagnoses - - - - **Porencephalic Cyst** - - CSF-filled parenchymal cavity - - Communicates with ventricle &/or pial surface - - Lined by reactive gliosis/astrocytic proliferation - - Does not enhance - - Etiology varies (trauma, infarction, etc.) - - **Multiple Sclerosis** - - Chronic "burned-out" lesions - - Appear as CSF foci with hyperintense rinds on FLAIR - - Look for faint T1 hyperintensity surrounding lesions ("lesion within lesion") - - Obtain sagittal FLAIR to look for other lesions along callososeptal interface - - **Hippocampal Sulcus Remnants** - - "String of beads" cysts medial to temporal horns of lateral ventricles - - Developmental variant, incidental - - Remnants of vestigial primary embryonic hippocampal sulcus - - Imaging - - Between hippocampus, dentate gyrus - - Follow CSF on all sequences - - No surrounding gliosis - - **Connatal Cysts** - - Single or multiple - - Location - - Intra- or periventricular (may actually be cysts of anterior choroid plexus) - - Small cyst adjacent to tip of frontal horn may be normal anatomic variant - - Lined with ependyma - - Present at birth - - Usually transient - - Occasionally seen in older patients - - No septations, no hemosiderin - - Generally isolated without associated abnormalities -- ## Helpful Clues for Rare Diagnoses - - - - **Neuroglial Cyst** - - Benign, glial-lined, nonenhancing CSF-like cyst - - No surrounding signal abnormality - - Does not communicate with ventricle - - Subcortical WM, choroidal fissure common sites - - Does not restrict on DWI - - No enhancement - - **Cryptococcosis** - - Opportunistic fungal infection - - Nonenhancing, gelatinous pseudocysts in PVS - - BG, thalamus, brainstem, cerebellum, dentate nucleus, periventricular WM - - Multifocal > > solitary lesions - - Most patients have HIV/AIDS - - **Parasites, Miscellaneous** - - Other than NCC, parasitic brain cysts uncommon - - Hydatid cyst - - Unilocular cyst, isointense to CSF - - T2-hypointense rim, no enhancement - - **Mucopolysaccharidoses** - - Group of lysosomal storage disorders - - PVS dilated by accumulated glycosaminoglycans - - Corpus callosum, peritrigonal WM - - Multiple, bilateral - - Dilated PVS in deep periventricular WM - - FLAIR-hyperintense rim surrounding dilated PVS - - **Germinolytic Cysts** - - Periventricular/subependymal cysts - - Cyst(s) along caudothalamic groove probably resulting from germinolysis - - Glial (not ependymal)-lined cysts/pseudocysts - - Distinguish from "connatal" cysts (intraventricular anterior choroid plexus cysts) - - Many etiologies, including inherited metabolic disorders (e.g., Zellweger, infantile Refsum), congenital infections (CMV) - - CSF-like; ± septations, hemosiderin; do not enhance - - Look for associated abnormalities - - Leukoencephalopathy - - Delayed myelination - - Polymicrogyria, pachygyria, heterotopias - - **Miscellaneous Congenital Malformations** - - Several have parenchymal CSF-like cysts as part of syndrome - - van der Knaap leukoencephalopathies (megaloencephalic leukoencephalopathy with subcortical cysts, anterior temporal lobe cavitations) - - Congenital muscular dystrophy (cerebellar cysts common, may represent dilated PVS) - - Dorsal interhemispheric CSF cyst - - Corpus callosal dysgenesis - - Holoprosencephaly -- ## Alternative Differential Approaches - - - - **Based on location** - - Deep gray nuclei - - Enlarged PVS - - Lacunar infarction - - Cryptococcosis - - Periventricular WM - - Multiple sclerosis - - Connatal cysts - - Germinolytic cysts - - Lobar - - Encephalomalacia - - NCC - - Porencephalic cyst - - Neuroglial cyst - - Hydatid cyst diff --git a/docs_md/articles/epilepsy-adult_c936f9e1-b6c6-4c4a-afc6-f2e1a968a7b0.md b/docs_md/articles/epilepsy-adult_c936f9e1-b6c6-4c4a-afc6-f2e1a968a7b0.md new file mode 100644 index 0000000..c2b382b --- /dev/null +++ b/docs_md/articles/epilepsy-adult_c936f9e1-b6c6-4c4a-afc6-f2e1a968a7b0.md @@ -0,0 +1,72 @@ +--- +title: "Epilepsy, Adult" +docid: "c936f9e1-b6c6-4c4a-afc6-f2e1a968a7b0" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Clinically Based Differentials" + - "Epilepsy, Adult" +--- +# ESSENTIAL INFORMATION + +- ## Key Differential Diagnosis Issues + + + - Adult-onset seizures are more likely acquired + - Acute symptomatic seizure ≤ 1 week of brain injury + - Remote symptomatic seizure: Beyond 1 week + - Encephalomalacia and gliosis can also cause seizures + - Epilepsy: When 2 or more seizures occur 24 hours apart +- ## Helpful Clues for Common Diagnoses + + + - **Trauma** + - Diffuse axonal injury and contusions + - Intracranial hemorrhage (subdural hemorrhage and subarachnoid hemorrhage) can also present with seizures without parenchymal findings + - **Stroke** + - Most common cause in older adults + - **Infection** + - All cerebral and meningeal infection can cause seizure + - Meningitis, encephalitis, and abscess + - Look for herpes encephalitis + - CNS tuberculosis and neurocysticercosis are common causes outside of USA + - **Drug Use and Withdrawal** + - Withdrawal from alcohol, benzodiazepines, barbiturates + - Illicit drug use and drugs, which lower seizure threshold + - **Metabolic** + - Hyper- or hypoglycemia + - Hyponatremia, hypocalcinemia, hypomagnesemia, hypothyroidism + - Hyperammonemia from hepatic encephalopathy + - Uremic encephalopathy + - **Neoplasms** + - Glioblastoma most common in older adults + - Cortically based tumors primarily in older children to young adults + - **Neurodegenerative Disease** + - Dementia: Alzheimer + - Demyelinating disease: Multiple sclerosis +- ## Helpful Clues for Less Common Diagnoses + + + - **Oligodendroglioma, IDH-Mutant and 1p/19q-Co-Deleted** + - 70-90% present with seizures + - Cortically based T2-hyperintense mass, rare enhancement + - **Mesial Temporal Sclerosis** + - Most common cause of intractable temporal lobe seizures + - Hippocampal atrophy and sclerosis + - May see ipsilateral mammillary body and forniceal atrophy + - **Paraneoplastic and Autoimmune Encephalitis** + - Both paraneoplastic and nonparaneoplastic + - 80% have bilateral/unilateral edema of temporal lobes + - Limbic system most common, also brainstem, cerebellum, and spinal cord + - **Posterior Reversible Encephalopathy Syndrome** + - 60-75% present with seizure + - Patchy parietooccipital cortical/subcortical T2/FLAIR hyperintense edema + - Associated with hypertension, chemotherapy, high-dose steroids, immunomodulation, sepsis, kidney failure, preeclampsia/eclampsia, autoimmune disease +- ## Helpful Clues for Rare Diagnoses + + + - **Pleomorphic Xanthoastrocytoma** + - 75% of patients present with seizures + - Cortical cyst + enhancing nodule is classic + - Reactive involvement of adjacent meninges typical: Dural tail \ No newline at end of file diff --git a/docs_md/articles/epilepsy-child_a342e5b5-5b98-4003-a437-6d42a483b40e.md b/docs_md/articles/epilepsy-child_a342e5b5-5b98-4003-a437-6d42a483b40e.md new file mode 100644 index 0000000..5791861 --- /dev/null +++ b/docs_md/articles/epilepsy-child_a342e5b5-5b98-4003-a437-6d42a483b40e.md @@ -0,0 +1,132 @@ +--- +title: "Epilepsy, Child" +docid: "a342e5b5-5b98-4003-a437-6d42a483b40e" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Clinically Based Differentials" + - "Epilepsy, Child" +--- +# ESSENTIAL INFORMATION + +- ## Key Differential Diagnosis Issues + + + - Generalized seizure disorders usually nonlocalizing + - Partial complex (focal) epilepsy usually due to focal structural abnormality [i.e., focal cortical dysplasia (FCD)] + - Correlate with EEG results + - High-resolution & 3T MR helpful for subtle lesions + - 1-mm isotropic T1 for gray matter evaluation + - 3D FLAIR imaging helpful for identifying FCD + - PET & SPECT are often complimentary to MR in identifying seizure focus prior to surgical intervention + - PET: Decreased interictal metabolism in seizure focus + - SPECT: Increased ictal blood flow in seizure focus +- ## Helpful Clues for Common Diagnoses + + + - **Idiopathic Epilepsy** + - No structural cause found on MR + - Generalized: May be inherited + - Partial: Partial motor seizures, may resolve by puberty + - **Acquired Causes** + - Febrile seizure: Most common cause of seizure in children < 5 years + - Simple febrile seizure < 15 minutes without recurrence does not require imaging + - Trauma, remote stroke, or infection results in encephalomalacia &/or gliosis, which may cause epilepsy + - Benign & malignant tumors + - Toxic, metabolic, & drug abuse + - **Vascular Malformation**: Arteriovenous & cavernous malformations with hemorrhage + - **Mesial Temporal Sclerosis** + - Most common cause of intractable temporal lobe epilepsy in adults + - 2-hit hypothesis suggests initial injury with inherent vulnerability to neuronal injury + - Hippocampal atrophy & gliosis + - May see ipsilateral mammillary body & forniceal atrophy + - Look for associated FCD, especially in the ipsilateral temporal lobe (FCD type IIIa) + - **Migrational Anomalies** + - **Focal cortical dysplasia** + - Newest classification Blumcke et al 2011 + - Type I: Mild blurring of gray-white junction with mild increased T2 signal of subcortical white matter + - More common in temporal lobes, difficult to detect + - Type II: Moderate blurring of gray-white junction & increased T2 signal of subcortical white matter + - Typically frontal lobes + - Type IIb includes more dysmorphia & balloon cells: Highly associated with transmantle sign & easier to detect on MR + - Transmantle sign: T2-hyperintense comet tail from ventricle to cortex; best seen on FLAIR + - Type III: Associated with another lesion: Mesial temporal sclerosis, tumor, vascular malformation, acquired injury + - **Polymicrogyria** + - Small, pebbly, cobblestone, or micronodular-appearing gyri + - Common migrational malformation with heterogeneous causes + - TORCH infection (particularly CMV) is common cause of polymicrogyria & seizures + - Diffuse or bilateral polymicrogyria more likely genetic/syndromic + - **Heterotopic gray matter** + - Gray matter nodules within deep white matter follow gray matter signal on all MR sequences + - Subependymal most common location + - Can be found incidentally in patients without seizures + - Diffuse subependymal heterotopia is X-linked + - **Schizencephaly** + - Cleft extending from cortical surface to ventricular ependyma, gray matter lined + - Outpouching or "dimpling" of lateral ventricular contour "points" to cleft + - May be unilateral or bilateral + - Open lipped: CSF in cleft; commonly bilateral + - Closed lipped: No CSF with apposed walls, usually unilateral + - **Septo-Optic Dysplasia Plus Syndrome** + - Septum pellucidum absence + optic nerve hypoplasia ± pituitary dysfunction + - When SOD is associated with schizencephaly &/or polymicrogyria, it is referred to as SOD Plus + - **Tuberous Sclerosis Complex** + - Burden of cortical dysplasias (i.e., tubers) correlates with seizure burden + - T2-hyperintense cortical/subcortical tubers: Similar imaging to type IIb FCD + - Cortical tubers also similar in histology to FCD type IIb with balloon cells + - Subependymal nodules can enhance & calcify + - 10-15% develop subependymal giant cell astrocytoma at foramen of Monro +- ## Helpful Clues for Less Common Diagnoses + + + - **Cortically Based Glioneuronal Tumors** + - Associated cortical dysplasia with tumor common (type IIIb) + - **Ganglioglioma** + - Most common cause of tumor-associated temporal lobe epilepsy + - Cystic/solid cortically based mass + - Ca⁺⁺ (~ 50%); enhancement (~ 50%) + - Temporal lobe most common site + - **Dysembryoplastic neuroepithelial tumor** + - Discrete T2-hyperintense "bubbly" cortical mass + - Medial temporal lobe most common + - Enhancement may occur (~ 10%) but is less common than ganglioglioma + - **Holoprosencephaly** + - Spectrum of failure of cleavage of midline cerebral hemispheres & telencephalon from diencephalon + - Monoventricle due to absence of septum pellucidum + - Complete to partial absence of other midline structures: Falx & corpus callosum + - Fusion of fornices, thalami, & basal ganglia + - Incomplete separation of frontal lobes + - More severe cases may include large dorsal cyst + - **Hemimegalencephaly** + - Unilateral hemispheric overgrowth + - Dysplastic enlarged ipsilateral ventricle + - Associated with genetic/syndromic diseases + - **Sturge****-****Weber Syndrome** + - Unilateral trigeminal (V1 & V2) distribution facial port-wine stain + - Ipsilateral malformation of cortical & pial veins = leptomeningeal enhancement + - Ipsilateral enlarged choroid plexus, hemiatrophy late finding + - Gyriform Ca⁺⁺ increases over time + - **Status Epilepticus** + - Seizure > 5 minutes or > 1 seizure within 5-minute period + - Higher likelihood for irreversible brain damage + - 1/2 are associated with known history of epilepsy + - Increased T2 signal of predominantly cortex with swelling & possible decreased diffusion +- ## Helpful Clues for Rare Diagnoses + + + - **Lissencephaly Type 1: Subcortical Band Heterotopia** + - "Smooth" brain lacking normal gyri; thick cortex + - Can see subcortical smooth gray matter band in many cases + - LIS1: Posterior predilection of lissencephaly + - DCX (double cortex): X-linked + - Females: Primarily diffuse band heterotopia + - Males: Diffuse lissencephaly, more severe phenotype + - **Lissencephaly Type 2** + - Congenital muscular dystrophy: Walker-Warburg, Fukuyama, & muscle-eye-brain + - Diffuse polymicrogyria (cobblestone lissencephaly) particularly frontal lobes & sylvian fissures + - Cerebellar polymicrogyria, cysts, vermian hypoplasia, hypomyelination, & eye abnormalities can be seen + - **Rasmussen Encephalitis** + - Likely autoimmune inflammation of unilateral cerebral hemisphere + - Typically at least mesial temporal lobe & insula affected + - Hemiatrophy late \ No newline at end of file diff --git a/docs_md/articles/fragile-x-associated-tremor-ataxia-fxtas_4778fafe-9873-4c28-8f4f-299c00c72b50.md b/docs_md/articles/fragile-x-associated-tremor-ataxia-fxtas_4778fafe-9873-4c28-8f4f-299c00c72b50.md new file mode 100644 index 0000000..ee88806 --- /dev/null +++ b/docs_md/articles/fragile-x-associated-tremor-ataxia-fxtas_4778fafe-9873-4c28-8f4f-299c00c72b50.md @@ -0,0 +1,215 @@ +--- +title: "Fragile X-Associated Tremor/Ataxia (FXTAS)" +docid: "4778fafe-9873-4c28-8f4f-299c00c72b50" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Fragile X-Associated Tremor/Ataxia (FXTAS)" +--- +# KEY FACTS + +- ## Terminology + + + - Fragile X-associated tremor/ataxia syndrome (FXTAS) + - X-linked progressive neurodegenerative disorder characterized by 55-200 CGG trinucleotide repeats in *FMR1* gene +- ## Imaging + + + - Ventricular and sulcal prominence: Global volume loss + - WM and brainstem hyperintensities + - MCP atrophy with symmetric hyperintensities: MCP sign + - Decreased MCP width may be first notable sign + - Splenium of corpus callosum atrophy with hyperintensity: Corpus callosum splenium sign + - High sensitivity but lower specificity than MCP sign +- ## Top Differential Diagnoses + + + - **Middle cerebellar peduncle sign** + - Neurodegenerative, metabolic, cerebrovascular, inflammatory and demyelinating disorders + - **Corpus callosum splenium sign** + - Normal aging, radiation therapy + - Cytotoxic/transient splenial lesions +- ## Pathology + + + - Premutation expansions (55-200 CGG repeats) in 5' untranslated region of *FMR1* gene, located on X-chromosome + - **Radiological criteria** + - Major: White matter lesions in brainstem or MCP sign + - Minor: Cerebral white matter lesions, moderate to severe generalized brain atrophy +- ## Clinical Issues + + + - Kinetic tremor, cerebellar gait ataxia, cognitive dysfunction + - Usually > age 50 + - Diagnosis confirmed by molecular genetic testing + - Progressive and severe neurodegenerative disease + +# TERMINOLOGY + +- ## Abbreviations + + + - Fragile X-associated tremor/ataxia syndrome (FXTAS) +- ## Definitions + + + - X-linked progressive neurodegenerative disorder characterized by 55-200 CGG trinucleotide repeats in *FMR1* gene + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Generalized brain atrophy with hyperintensities in brainstem or middle cerebellar peduncle (MCP) + - ### Location + + + - Brainstem and middle cerebellar peduncles + - Cerebral white matter (WM), corpus callosum + - ### Size + + + - MCP atrophy, global atrophy +- ## CT Findings + + + - ### NECT + + + - Moderate to severe generalized brain atrophy + - MCP atrophy with subtle hypodensities +- ## MR Findings + + + - ### T1WI + + + - Subtle hypointensity in MCP with atrophy + - Corpus callosum splenium hypointensity + - ### FLAIR + + + - Ventricular and sulcal prominence: Global volume loss + - WM and brainstem hyperintensities + - Putaminal rim hyperintensity + - MCP atrophy with symmetric hyperintensities: MCP sign + - Decreased MCP width may be first notable sign + - Splenium of corpus callosum atrophy with hyperintensity: Corpus callosum splenium sign + - High sensitivity but lower specificity than MCP sign + - ### T2* GRE + + + - No hemorrhage + - ### T1WI C+ + + + - No enhancement + - ### MRS + + + - Decreased NAA/Cr and Ch/Cr in MCP + - DTI + - Reduced fractional anisotropy (FA) in corpus callosum + - Associated with increasing FXTAS symptom severity + - Reduced FA in MCP +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - Brain MR without contrast + - ### Protocol advice + + + - Add coronal T2/FLAIR MR + +# DIFFERENTIAL DIAGNOSIS + +- ## Middle Cerebellar Peduncle Sign + + + - **Neurodegenerative** + - Multiple systemic atrophy (MSA), olivopontocerebellar atrophy, spinocerebellar ataxia + - **Metabolic** + - Adrenoleukodystrophy, Wilson disease, hypoglycemia + - **Cerebrovascular** + - Infarcts, PRES, pontine infarct with wallerian degeneration of MCPs + - **Inflammatory and demyelinating** + - Multiple sclerosis, ADEM, Behçet disease +- ## Corpus Callosum Splenium Sign + + + - Normal aging, radiation therapy + - Cytotoxic /transient splenial lesions + - Seizure- &/or drug-related, viral encephalitis, metabolic derangement + +# PATHOLOGY + +- ## General Features + + + - ### Genetics + + + - Premutation expansions (55-200 CGG repeats) in untranslated region of *FMR1* gene, located on X-chromosome + - Full mutation (> 200 CGG repeats) leads to neurodevelopmental disease fragile X syndrome (FXS) + - 2 main molecular mechanisms + - Toxic gain of function of expanded CGG-repeat *FMR1*mRNA → binding/sequestration of CGG-binding proteins + - CGG repeat-associated non-AUG-initiated (RAN) translation → polyglycine peptide toxic to cells +- ## Staging, Grading, & Classification + + + - Diagnostic criteria for FXTAS: Clinical, radiological, and pathological + - **Radiological criteria** + - Major criteria: WM lesions in brainstem or MCP sign + - Minor criteria: Cerebral WM lesions, moderate to severe generalized brain atrophy +- ## Microscopic Features + + + - Diffuse, spongy degeneration of WM + - Eosinophilic intranuclear inclusions in neurons and astrocytes with cortex and cerebellum + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Kinetic tremor, cerebellar gait ataxia, cognitive dysfunction + - ### Other signs/symptoms + + + - Psychiatric disorders common +- ## Demographics + + + - Usually > age 50 + - More common among male patients who are hemizygous for premutation (40%) than female patients who are heterozygous for premutation (8-16%) +- ## Natural History & Prognosis + + + - Diagnosis confirmed by molecular genetic testing + - Progressive and severe neurodegenerative disease +- ## Treatment + + + - Symptomatic and supportive + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Patient presenting with ataxia and tremor with symmetric middle cerebellar peduncle hyperintensities (MCP sign) + + 863ab378-3ef7-4994-a374-6fc4bb8249e5 \ No newline at end of file diff --git a/docs_md/articles/frontotemporal-dementia_app.statdx.com_document_content_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_623c493f_20251014T193351Z.md b/docs_md/articles/frontotemporal-dementia_9f9eda8c-7e3c-4292-9861-4b8abc2c6474.md similarity index 98% rename from docs_md/articles/frontotemporal-dementia_app.statdx.com_document_content_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_623c493f_20251014T193351Z.md rename to docs_md/articles/frontotemporal-dementia_9f9eda8c-7e3c-4292-9861-4b8abc2c6474.md index 64cac5d..0aa1d7c 100644 --- a/docs_md/articles/frontotemporal-dementia_app.statdx.com_document_content_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_623c493f_20251014T193351Z.md +++ b/docs_md/articles/frontotemporal-dementia_9f9eda8c-7e3c-4292-9861-4b8abc2c6474.md @@ -1,5 +1,12 @@ -# Frontotemporal Dementia - +--- +title: "Frontotemporal Dementia" +docid: "9f9eda8c-7e3c-4292-9861-4b8abc2c6474" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Neurodegeneration" + - "Frontotemporal Dementia" +--- # KEY FACTS - ## Terminology @@ -255,4 +262,4 @@ - When analyzing images, use surface projections and normative dataset comparison to increase sensitivity - c96633b0-f435-4b0a-9f06-702857dfe4c4 + c96633b0-f435-4b0a-9f06-702857dfe4c4 \ No newline at end of file diff --git a/docs_md/articles/frontotemporal-dementia_app.statdx.com_document_content_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_2dde52e4_20251014T185357Z.md b/docs_md/articles/frontotemporal-dementia_app.statdx.com_document_content_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_2dde52e4_20251014T185357Z.md deleted file mode 100644 index 64cac5d..0000000 --- a/docs_md/articles/frontotemporal-dementia_app.statdx.com_document_content_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_2dde52e4_20251014T185357Z.md +++ /dev/null @@ -1,258 +0,0 @@ -# Frontotemporal Dementia - -# KEY FACTS - -- ## Terminology - - - - Frontotemporal dementia (FTD): Progressive neurodegenerative disorder of frontal/anterior temporal lobes -- ## Imaging - - - - F-18 FDG PET - - Helps differentiate between FTD and other causes of dementia - - Glucose hypometabolism - - Initially in frontal lobes progressing to temporal lobes - - Anterior cingulate also commonly hypometabolic - - Left-sided asymmetry could suggest underlying primary progressive aphasia (PPA) - - Hypometabolism within motor strip (precentral gyrus) could suggest motor neuron disease FTD (FTD-MND) - - Perfusion SPECT - - Similar pattern of frontal hypoperfusion as F-18 FDG PET - - Potentially less sensitive than F-18 FDG PET -- ## Clinical Issues - - - - Progressive changes in behavior, language, or motor function depending upon subtype - - Memory is less dominant clinical feature in FTDs - - No current disease-modifying treatment for FTD, only symptomatic therapy -- ## Diagnostic Checklist - - - - Clinical therapy decisions depend on proper diagnosis - - FTD important to distinguish from Alzheimer disease (AD) because AD medications do not slow progression of FTD and can worsen symptoms - - Amyloid-targeting therapies (ATTs) have no role in treating FTDs - - Image analysis - - If hypometabolism is anterior-predominant (e.g., frontal, anterior temporal, anterior cingulate), this favors FTD - - Amyloid PET can also help exclude AD pathology - -# TERMINOLOGY - -- ## Abbreviations - - - - Frontotemporal dementia (FTD) - - Alzheimer disease (AD) -- ## Definitions - - - - Progressive neurodegenerative disorder of frontal/anterior temporal lobes - - Typically subdivided into categories based on underlying molecular aggregates [TDP-43 (50%), tauopathy without amyloid (40%), and FET protein family (10%)] and main functional deficit (cognitive and behavior, language, or motor) - - Behavioral variant FTD (bvFTD) (formerly Pick disease) - - Commonly characterized by behavioral disinhibition, apathy, loss of sympathy, hyperorality, executive deficits - - Most commonly seen with TDP-43 aggregation, initially described with intracellular τ inclusions (Pick bodies) - - Prosopagnosia (inability to recognize familiar faces) has been described with right temporal variant FTD - - Language variant FTD [FTD-primary progressive aphasia (PPA)] - - Includes 2/3 subtypes of PPA, semantic variant PPA (svPPA) and nonfluent agrammatic variant PPA (nfvPPA) - - svPPA is predominantly seen with TDP-43 pathology and nfvPPA with τ pathology - - Other PPA variant, logopenic variant (lvPPA), is atypical AD variant (amyloid and τ positive) - - Motor neuron disease FTD (FTD-MND) - - Includes amyotrophic lateral sclerosis (FTD-ALS; 95% TDP-43) as well as atypical parkinsonian syndromes of progressive supranuclear palsy (PSP; tauopathy) and corticobasal degeneration (CBD; tauopathy) - - ALS classically presents with both upper motor neuron signs (spasticity, rigidity, hyperreflexia), lower motor neuron signs (muscle fasciculations, muscle atrophy), and nonmotor signs (behavioral disturbances), as seen with bvFTD (30% of cases) - - PSP usually presents with bradykinesia, rigidity, **vertical gaze palsy**, dysphagia, dysarthria - - CBD presents with parkinsonism, dystonia, apraxia, executive dysfunction, aphasia, "alien limb" phenomenon - -# IMAGING - -- ## Nuclear Medicine Findings - - - - F-18 FDG PET/CT - - Glucose hypometabolism initially in frontal lobes with progression to include regions of temporal/parietal lobes - - Anterior cingulate cortex, frontal insula, caudate nuclei, thalamus may also have hypometabolism bilaterally - - Relative sparing of motor cortex, except in FTD-MNDs, specifically ALS and CBD, which can show hypometabolism - - Hemispheric metabolic asymmetry may be present - - Hypometabolism occurs before atrophy visually evident on CT/MR - - Most sensitive diagnostic tool currently available - - Glucose hypometabolism worsens with disease progression - - May be used to distinguish between FTD and AD - - AD often shows hypometabolism in posterior cingulate/temporoparietal regions, spared with FTD - - 50% of patients with behavioral or dysexecutive AD variant do not show typical parietal and posterior cingulate hypometabolism - - Amyloid PET can be helpful in this situation if considering amyloid-targeting therapies (ATTs) - - Attenuation correction CT can show - - Preferential atrophy of frontal/temporal lobes - - Increased CSF space surrounding medial temporal lobes - - Enlargement of lateral ventricles - - Perfusion SPECT - - Pattern is similar to F-18 FDG PET with decreased radiotracer activity in frontal/temporal lobes - - SPECT generally has less sensitivity and quantitative potential compared to PET - - More sensitive than structural MR in detecting early changes -- ## Imaging Recommendations - - - - ### Best imaging tool - - - - F-18 FDG PET helps to differentiate between FTD and other causes of dementia, e.g., AD and Lewy body dementia (LBD) - - Correlates with disease progression - - Amyloid PET can help exclude AD variants that can mimic FTDs, such as lvPPA - - I-123 ioflupane scan can help in cases of suspected PSP or CBD, which will show decreased/abnormal uptake - - CT/MR documents atrophy of mainly frontal/temporal lobe structures - - Look for reversible causes of dementia, e.g., normal-pressure hydrocephalus - - Motor band sign with T2* hypointensity of precentral gyri or T2/FLAIR hyperintensity of corticospinal tracts in ALS - - F-18 FDG PET - - Patient preparation - - Patient should fast, stop IV fluids containing dextrose, and stop parenteral feeding for 4-6 hours - - Blood sugar should be < 150-200 (mg/dL) - - Patient should be placed in quiet, dimly lit room prior to and after injection (30 min) - - Radiopharmaceutical: F-18 FDG - - Dose: 5-20 mCi (185-740 MBq) - - Dosimetry: Urinary bladder receives largest dose - - Image acquisition: Image 30-60 min after injection - - SPECT - - 2nd-line study if F-18 FDG PET is not available/reimbursed - - Patient preparation - - Patient should be placed in quiet, dimly lit room prior to and after injection (30 min) - - Radiopharmaceutical - - Tc-99m exametazime (HMPAO) - - Tc-99m ethyl cysteinate dimer (ECD) - - Dose: 15-30 mCi (555 MBq to 1.1 GBq) - - Dosimetry - - Tc-99m HMPAO: Kidneys receive highest dose - - Tc-99m ECD: Bladder wall receives highest dose - - Image acquisition - - Optimal imaging time for Tc-99m HMPAO: 90 min post injection - - Optimal imaging time for Tc-99m ECD: 45 min post injection -- ## Artifacts and Quality Control - - - - Immobilize patient's head to decrease motion, attenuation correction artifacts - -# DIFFERENTIAL DIAGNOSIS - -- [Alzheimer Disease](/document/alzheimer-disease/2aad3ac4-44fd-43e5-8e50-a86987483af3) - - Most common cause of dementia generally leading to impairments in episodic memory and other cognitive domains - - Related to aggregation of amyloid-β and τ proteins; therefore, positive on amyloid PET - - Behavioral and dysexecutive variants of AD - - Clinical presentation with less memory impairment and more behavioral disinhibition/loss of executive function - - Can be clinically indistinguishable from bvFTD - - 50% of cases show F-18 FDG hypometabolism in precuneus and posterior cingulate gyrus (similar to classic AD); 50% show frontal hypometabolism with parietal sparing similar to FTD - - Must consider amyloid PET in these cases; prerequisite for ATTs - - lvPPA - - Predominant language loss with spared memory that can mimic other PPAs - - Sentence repetition and single-word meaning usually preserved - - Often have mild cognitive impairments outside of language (more than seen with svPPA or nfvPPA) - - F-18 FDG hypometabolism shows more parietal involvement than other PPAs; amyloid PET can be helpful if considering ATTs -- ## Limbic-Predominant Age-Related TDP-43 Encephalopathy - - - - Newly recognized neurodegenerative disease with predominant memory deficits related to hippocampal dysfunction - - Typically in patients > 80 years - - Often slower decline than AD, though can commonly be comorbid with AD, accelerating disease progression - - F-18 FDG PET shows marked hippocampal hypometabolism with less severe involvement of precuneus and posterior cingulate - - MR often shows marked hippocampal sclerosis -- ## Vascular Dementia - - - - 2nd most common cause of dementia - - Caused by impaired blood supply to brain regions - - Global atrophy with diffuse white matter lesions (infarcts) - - Lesions generally correlate with cognitive symptoms -- ## Lewy Body Dementia - - - - Commonly presents with hallucinations, sleep disturbances, and parkinsonian motor features - - F-18 FDG PET hypometabolism in occipital cortex - - Cardiac MIBG demonstrates sympathetic denervation (CBD and PSP do not demonstrate denervation) - - Positive α-synuclein skin test (CBD and PSP are tauopathies) -- ## Psychiatric Illness - - - - Bipolar disorder, schizophrenia, obsessive compulsive disorder -- ## Reversible Dementias - - - - Mass lesions (brain tumor), head trauma, normal-pressure hydrocephalus, vitamin B12 deficiency, hypothyroidism, infections (neurosyphilis, Lyme disease) - -# PATHOLOGY - -- ## General Features - - - - ### Etiology - - - - Heterogeneous pathologic and clinical subtypes - - Resulted from disease naming related to clinical presentation, before etiology/pathology was well understood - - Pathologic subtypes of FTD are classified based upon pattern of protein accumulation in groups encompassing disorders of frontotemporal lobar degeneration - - Etiology uncertain but associated with 3 major protein aggregates - - τ (microtubule-associated protein) - - TDP-43 (transactive response DNA binding protein of 43kD) - - FET protein family, including FUS (tumor-associated protein; fused in sarcoma) - - ### Genetics - - - - Autosomal dominant inheritance in 10-25% of FTD cases - - c9orf72 most common genetic mutation in familial FTD and familial ALS - - *SOD1*(superoxide dismutase) gene mutation in 10% of familial ALS with specific treatment, intrathecal tofersen - - Positive family history of FTD is only known risk factor - - 30-50% of individuals with bvFTD have positive family history - -# CLINICAL ISSUES - -- ## Presentation - - - - ### Most common signs/symptoms - - - - Progressive changes in behavior, personality, language, &/or motor function, depending upon clinical subtype - - Disinhibition, apathy, loss of sympathy, hyperorality, dysexecutive behaviors - - Bradykinesia, rigidity, tremor, spasticity, hyperreflexia, fasciculations, muscle atrophy in motor subtypes - - Loss of language comprehension, including word meaning or agrammatism in language subtypes - - ### Clinical profile - - - - FTD is composed of 3 main clinical subtypes - - bvFTD - - Most common, accounting for ~ 1/2 of cases - - Progressive decline in social function with personality changes, often with disinhibition - - Language presentation (PPA) - - Including variants svPPA and nfvPPA - - Motor presentation - - ALS, PSP, CBD -- ## Demographics - - - - ### Age - - - - Mean of onset: 50-60 years - - ~ 10% > 70 years - - Younger onset than AD, which is generally > 65 years -- ## Natural History & Prognosis - - - - Insidious onset of behavioral and cognitive dysfunction - - More significant behavioral, language, executive functioning impairment than memory - - Slowly progressive with eventual functional impairment - - Median survival ~ 8-10 years after diagnosis; varies widely based upon underlying pathology - - Median survival in ALS is 2-5 years -- ## Treatment - - - - No current disease-modifying treatment for FTD - - ALS with *SOD1*mutation can be treated with intrathecal tofersen (6.5-month increase in median survival at 3 years) - -# DIAGNOSTIC CHECKLIST - -- ## Consider - - - - FTD important to distinguish from AD because AD medications do not slow progression of FTD and can worsen symptoms - - FTDs are not amenable to ATTs due to lack of underlying amyloid pathology -- ## Image Interpretation Pearls - - - - When analyzing images, use surface projections and normative dataset comparison to increase sensitivity - - c96633b0-f435-4b0a-9f06-702857dfe4c4 diff --git a/docs_md/articles/frontotemporal-lobar-degeneration_app.statdx.com_document_content_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_364eb97f_20251014T193509Z.md b/docs_md/articles/frontotemporal-lobar-degeneration_49510d0e-acf7-45cb-9eb1-53f8193b0b6d.md similarity index 97% rename from docs_md/articles/frontotemporal-lobar-degeneration_app.statdx.com_document_content_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_364eb97f_20251014T193509Z.md rename to docs_md/articles/frontotemporal-lobar-degeneration_49510d0e-acf7-45cb-9eb1-53f8193b0b6d.md index 4c67954..2bc3a1f 100644 --- a/docs_md/articles/frontotemporal-lobar-degeneration_app.statdx.com_document_content_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_364eb97f_20251014T193509Z.md +++ b/docs_md/articles/frontotemporal-lobar-degeneration_49510d0e-acf7-45cb-9eb1-53f8193b0b6d.md @@ -1,5 +1,14 @@ -# Frontotemporal Lobar Degeneration - +--- +title: "Frontotemporal Lobar Degeneration" +docid: "49510d0e-acf7-45cb-9eb1-53f8193b0b6d" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Frontotemporal Lobar Degeneration" +--- # KEY FACTS - ## Terminology @@ -301,4 +310,4 @@ - Report pattern of cortical volume loss - 69c47a04-dd7a-4a23-a55b-21542ccce82a + 69c47a04-dd7a-4a23-a55b-21542ccce82a \ No newline at end of file diff --git a/docs_md/articles/granular-cell-tumor_da976b04-85a3-4bf8-ac81-e579f081293e.md b/docs_md/articles/granular-cell-tumor_da976b04-85a3-4bf8-ac81-e579f081293e.md new file mode 100644 index 0000000..c4a80c2 --- /dev/null +++ b/docs_md/articles/granular-cell-tumor_da976b04-85a3-4bf8-ac81-e579f081293e.md @@ -0,0 +1,204 @@ +--- +title: "Granular Cell Tumor" +docid: "da976b04-85a3-4bf8-ac81-e579f081293e" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Neoplasms" + - "Granular Cell Tumor" +--- +# KEY FACTS + +- ## Terminology + + + - Neoplasms that arise from pituicytes, specialized glial cells of neurohypophysis or infundibulum + - Rare low-grade, nonendocrine neoplasms of sellar region + - Formerly called pituicytoma; granular cell tumor of neurohypophysis + - Part of 2017 WHO spectrum of thyroid transcription factor 1 (TTF-1) expressing pituitary tumors of posterior lobe +- ## Imaging + + + - Enhancing, well-circumscribed sellar/suprasellar or infundibular mass + - 1.5-6.0 cm + - CT: Sellar/suprasellar mass with hyperattenuation + - Rarely calcification may be present + - Best imaging tool: C+ MR with high-resolution imaging through sellar region + - Consider granular cell tumor if sellar/suprasellar mass appears separate from anterior pituitary gland +- ## Top Differential Diagnoses + + + - Pituitary macroadenoma + - Lymphocytic hypophysitis + - Pituicytoma + - Spindle cell oncocytoma + - Rathke cleft cyst +- ## Pathology + + + - WHO grade 1 +- ## Clinical Issues + + + - Commonly asymptomatic (small lesions) + - Visual field deficit related to optic chiasm compression is most common presenting feature + - Less common symptoms: Panhypopituitarism, galactorrhea, amenorrhea, decreased libido, neuropsychological changes + - Typically present in adulthood, 5th-6th decades + - Generally benign clinical course + +# TERMINOLOGY + +- ## Abbreviations + + + - Granular cell tumor (GCT) +- ## Synonyms + + + - Formerly called pituicytoma; granular cell tumor of neurohypophysis +- ## Definitions + + + - Neoplasms that arise from pituicytes, specialized glia of neurohypophysis or infundibulum + - Rare low-grade, nonendocrine neoplasms of sellar region + - Part of 2017 WHO spectrum of thyroid transcription factor1 (TTF-1) expressing pituitary tumors of posterior lobe + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Enhancing, well-circumscribed sellar/suprasellar or infundibular mass + - ### Location + + + - Sellar and suprasellar or infundibular mass + - ### Size + + + - 1.5-6.0 cm + - ### Morphology + + + - Lobulated and well circumscribed +- ## CT Findings + + + - ### NECT + + + - Sellar/suprasellar mass with hyperattenuation + - Rarely calcification may be present +- ## MR Findings + + + - ### T1WI + + + - Sellar/suprasellar mass isointense to gray matter + - ### T1WI C+ + + + - Enhancement may be homogeneous or heterogeneous +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - C+ MR with high-resolution imaging through sellar region + +# DIFFERENTIAL DIAGNOSIS + +- [Pituitary Macroadenoma](/document/pituitary-microadenoma/283f3068-d369-4f79-bf01-0f2b82c6e49b) + - Sellar and suprasellar enhancing mass + - Arises from adenohypophysis + - May be indistinguishable +- [Lymphocytic Hypophysitis](/document/lymphocytic-hypophysitis/f30774c3-cbd0-4ab3-b3d1-e0574106db1f) + - May be indistinguishable from macroadenoma + - May present as infundibular mass + - Typically pregnant or postpartum females +- [Pituicytoma](/document/pituicytoma/d6e481d5-7742-4354-8dfe-4f04286a709a) + - May be intrasellar or suprasellar mass + - May be separate from adenohypophysis +- [Spindle Cell Oncocytoma](/document/spindle-cell-oncocytoma/1557bfb2-8315-4782-9a1e-4e70d6d20c4e) + - Imaging mimics macroadenoma + - Enhancing sellar and suprasellar mass +- [Rathke Cleft Cyst](/document/rathke-cleft-cyst/8f1561f7-92a7-485c-a0ae-2e2d5c8c1628) + - Nonenhancing cystic sellar &/or suprasellar lesion + - Intracystic nodule in up to 75% + +# PATHOLOGY + +- ## General Features + + + - ### Associated abnormalities + + + - Granular cell tumors have been found in associated with adenomas + - Small granular cell clusters have been found in up to 17% of autopsy series +- ## Staging, Grading, & Classification + + + - WHO grade 1 +- ## Gross Pathologic & Surgical Features + + + - Lobulated, well-circumscribed mass, soft but rubbery + - More firm than pituitary adenoma +- ## Microscopic Features + + + - Densely packed polygonal cells with abundant granular eosinophilic cytoplasm + - Electron microscopy: Cytoplasm is filled with phagolysosomes containing electron-dense material and membranous debris + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Commonly asymptomatic (small lesions) + - Visual field deficit related to optic chiasm compression + - ### Other signs/symptoms + + + - Panhypopituitarism, galactorrhea, amenorrhea, decreased libido, neuropsychological changes + - Rarely diabetes insipidus +- ## Demographics + + + - ### Age + + + - Typically present in adulthood, 5th-6th decades + - ### Gender + + + - F:M = 2:1 +- ## Natural History & Prognosis + + + - Rare (~ 150 reported cases) + - Generally benign clinical course +- ## Treatment + + + - Surgical resection + +# DIAGNOSTIC CHECKLIST + +- ## Image Interpretation Pearls + + + - Consider granular cell tumor if sellar/suprasellar mass appears separate from anterior pituitary gland + + 55b6bf2f-c975-435a-972b-a42c5b4cbe6d \ No newline at end of file diff --git a/docs_md/articles/hypertrophic-olivary-degeneration_78257543-6d52-4879-84b1-445f3611d996.md b/docs_md/articles/hypertrophic-olivary-degeneration_78257543-6d52-4879-84b1-445f3611d996.md new file mode 100644 index 0000000..ae36069 --- /dev/null +++ b/docs_md/articles/hypertrophic-olivary-degeneration_78257543-6d52-4879-84b1-445f3611d996.md @@ -0,0 +1,295 @@ +--- +title: "Hypertrophic Olivary Degeneration" +docid: "78257543-6d52-4879-84b1-445f3611d996" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Hypertrophic Olivary Degeneration" +--- +# KEY FACTS + +- ## Terminology + + + - Inferior olivary nucleus (ION) degeneration + - Unique type of transsynaptic neuronal degeneration + - Olivary deafferentation thought to be source of ensuing hypertrophic olivary degeneration (HOD) + - Usually caused by primary lesions in dentato-rubro-olivary pathway (Guillain-Mollaret triangle) + - Triangle of Guillain-Mollaret defined by 3 anatomic structures + - Red nucleus (RN) + - ION ipsilateral to RN + - Contralateral dentate nucleus (DN) of cerebellum +- ## Imaging + + + - ION initially hypertrophies rather than atrophies + - 3 distinct MR stages in HOD + - Hyperintense signal without hypertrophy of ION: Within first 6 months of ictus + - ↑ signal + ION hypertrophy: Between 6 months & 3-4 years after ictus + - Only ION hyperintensity: Begins when hypertrophy resolves (can persist indefinitely) + - MR also detects primary lesion located in ipsilateral CTT, SCP or contralateral DN +- ## Top Differential Diagnoses + + + - Vertebrobasilar perforating artery infarct + - Demyelination (multiple sclerosis, microvascular disease) + - Amyotrophic lateral sclerosis + - HIV/AIDS + - Rhombencephalitis +- ## Clinical Issues + + + - Palatal myoclonus (palatal "tremor"), ocular myoclonus + - Usually develops 10-11 months after primary lesion + - Clinical symptoms (tremors) rarely improve + +# TERMINOLOGY + +- ## Abbreviations + + + - Hypertrophic olivary degeneration (HOD) +- ## Synonyms + + + - Pseudohypertrophy of inferior olivary nucleus +- ## Definitions + + + - Transsynaptic degeneration of inferior olivary nucleus (ION), usually caused by primary lesions in dentato-rubro-olivary pathway (DROP) also called anatomic triangle of Guillain & Mollaret (GMT) + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - T2-hyperintense, nonenhancing enlargement of ION + - ### Location + + + - GMT is defined by 3 anatomic structures + - Red nucleus (RN) + - ION ipsilateral to RN + - Contralateral dentate nucleus (DN) of cerebellum + - Central tegmental tract (CTT or rubro-olivary pathway) connects RN to ipsilateral ION + - Superior cerebellar peduncle (SCP, dentato-rubral tract) connects DN to contralateral RN + - Inferior cerebellar peduncle (olivo-cerebellar pathway) connects ION to contralateral cerebellar cortex & contralateral DN + - 4 patterns of HOD in relation to primary lesion + - Ipsilateral HOD: Primary lesion is limited to brainstem (CTT) + - Contralateral HOD: Primary lesion is in cerebellum (DN or SCP) + - Bilateral HOD: Primary lesion involves midline/paramedian brainstem affecting brachium conjunctivum + - Bilateral HOD: Primary lesion involves both unilateral brainstem & cerebellum + - ### Size + + + - Variable (time-dependent) size of affected ION + - Normal in acute stage + - ↑ (hypertrophy) from 6 months to 3-4 years + - ↓ (atrophy) in advanced stage (> 3-4 years) + - ### Morphology + + + - Unique type of transsynaptic neuronal degeneration + - ION initially hypertrophies rather than atrophies +- ## CT Findings + + + - ### NECT + + + - May show acute primary injury (e.g., hemorrhage) in tegmentum + - HOD typically not depicted on CT +- ## MR Findings + + + - ### T1WI + + + - Acute phase: Normal ION + - Shows primary lesion in brainstem (cerebellum or tegmentum) + - After HOD ensues + - Enlargement confined to ION, isointense to slightly hypointense to gray matter + - Slightly ↑ olivary T1 signal also reported + - ± residual primary lesion + - ### T2WI + + + - 3 distinct MR stages in HOD + - Hyperintense signal without hypertrophy of ION: Within first 6 months of ictus + - Both ↑ signal & hypertrophy of ION: Between 6 months & 3-4 years after ictus + - ↑ signal only in ION: Begins when hypertrophy resolves & can persist indefinitely + - Axial MR: Disappearance of pre- & postolivary sulci in hypertrophic stage + - MR also detects primary lesion located in ipsilateral central tegmental tract or contralateral DN + - Old hematomas: Low-signal areas on T2WI revealing hemosiderin deposition + - ± ↓ size of contralateral ION with higher than normal signal intensity + - ± mild to severe atrophic changes of cerebellar cortex contralateral to HOD + - ### PD/intermediate + + + - High signal intensity of ION better detected on PD images than on T2WI + - ### FLAIR + + + - Similar to T2WI + - ### T1WI C+ + + + - No contrast enhancement of degenerated ION + - DTI + - ↑ radial diffusivity, ↑ mean diffusion & ↓ fractional anisotropy in GMT components reflecting demyelination + - ↑ fractional anisotropy & ↑ axial diffusivity in ION reflect rearrangement of regenerating axons & shrunken neurons +- ## Nuclear Medicine Findings + + + - ### PET + + + - Focal glucose hypermetabolism in medulla of patients with HOD +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR + - ### Protocol advice + + + - T2WI (include coronal or sagittal sections) + +# DIFFERENTIAL DIAGNOSIS + +- ## Other Causes of High T2 Signal Intensity in Anterior Part of Medulla + + + - [Demyelination related to multiple sclerosis](/document/multiple-sclerosis/7892b2a2-f52a-4d7f-9858-a326f2b7ab04) + - Tumor (astrocytoma, metastasis, lymphoma) + - Lesions involving corticospinal tract + - Wallerian degeneration, adrenoleukodystrophy + - [Amyotrophic lateral sclerosis](/document/amyotrophic-lateral-sclerosis-als/23de52b7-d9bd-441c-a18c-95c8afccb470) + - Vertebrobasilar perforating artery infarct + - Most medullary infarctions occur in posteroinferior cerebellar artery territory & involve posterolateral medulla (e.g., vertebral artery dissection) + - Alternatively, medullary infarcts could be related to perforating branches of anterior spinal or vertebral arteries & have paramedial location + - Infectious/inflammatory processes + - [Tuberculosis](/document/tuberculosis/6e389773-2150-4299-9ce2-0b83b13c2119) + - [Sarcoidosis](/document/neurosarcoid/fef69139-0019-4be3-9bdc-e26bc3644251) + - HIV/AIDS + - [Rhombencephalitis](/document/miscellaneous-encephalitis/1c3c0881-4046-46a1-90fc-371941c0cf2c) + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Transsynaptic degeneration caused by interruption of pathways composing GMT + - Olivary deafferentation thought to be source of ensuing HOD + - Primary lesions usually located in contralateral DN or ipsilateral CTT + - Focal brainstem insults that may lead to dentato-rubral-olivary pathway interruption + - Ischemic infarction, demyelination + - Hemorrhage (related to hypertensive disease, occult cerebrovascular malformation, or diffuse axonal injury following severe head trauma) + - Cavernous malformation + - ### Associated abnormalities + + + - Primary brainstem insult + - Most commonly pontine hemorrhage from trauma (including surgery), hypertension, tumor, & infarction + - Olivary enlargement: Histologically unusual vacuolar cytoplasmic degeneration → hypertrophy related in part to ↑ number of astrocytes + - After onset of primary lesion + - Vacuolar cytoplasmic degeneration in 6-15 months + - Gliosis follows at 15-20 months +- ## Staging, Grading, & Classification + + + - 6 phases of pathologic change + - No olivary changes within first 24 hours + - Degeneration of olivary amiculum (white matter capsule at olive periphery) at ≥ 2-7 days + - Olivary hypertrophy (mild enlargement with neuronal hypertrophy, no glial reaction) at 3 weeks + - Maximal olivary enlargement (hypertrophy of neurons & astrocytes) at 8.5 months + - Olivary pseudohypertrophy (neuronal dissolution with prevailing large gemistocytic astrocytes) after 9.5 months + - Olivary atrophy (neuronal disappearance with olivary atrophy & prominent degeneration of amiculum olivae) after 3-5 years of primary lesion +- ## Gross Pathologic & Surgical Features + + + - Focal swelling of ION + - Unilateral HOD + - Asymmetric enlargement of anterior medulla + - "Pallor" in contralateral DN + - Atrophy of contralateral cerebellar cortex + - Bilateral HOD: More difficult to observe + - No left-right asymmetry +- ## Microscopic Features + + + - Changes in hypertrophic degenerated ION + - Hypertrophic, thickened neurites + - Vacuolation of neurons + - Fibrillary gliosis + - Demyelination & astrocytic proliferation of WM + - In contralateral cerebellar cortex + - ↓ number of Purkinje cells + - Contralateral DN reduced in size, possibly due to + - Iron depletion secondary to axonal iron transport block + - Loss of cells in nucleus + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Symptomatic palatal tremor/myoclonus + - Rhythmic involuntary movement of soft palate, uvula, pharynx, & larynx + - Severe myoclonus may also affect cervical muscles & diaphragm + - ± dentato-rubral tremor (Holmes tremor) + - 2-5 Hz rest, postural, & kinetic tremor of upper extremity + - May occur before onset of palatal tremor + - Symptoms of cerebellar or brainstem dysfunction + - Associated with acute lesion within triangle of Guillain-Mollaret + - Ocular myoclonus & nystagmus + - ### Clinical profile + + + - Palatal myoclonus (palatal "tremor") + - Usually develops 10-11 months after primary lesion + - Virtually all patients who develop palatal myoclonus after brain insult will have HOD + - Not all HOD patients develop palatal myoclonus + - May result from hypermetabolism of ION +- ## Demographics + + + - ### Age + + + - Rare; reported in all ages, both sexes +- ## Natural History & Prognosis + + + - After primary brainstem injury, olivary hypertrophy typically appears in delayed fashion + - May occur between 3 weeks to 11 months (usually within 4-6 months) + - Maximum hypertrophy at 5-15 months + - Olivary hypertrophy typically resolves in 10-16 months + - Olivary hyperintensity on T2WI may persist for years after resolution of hypertrophy + - Finally ION undergoes atrophy + - Clinical symptoms (tremors) rarely improve + - Self-limiting disease & can be managed by symptomatic treatment + +# DIAGNOSTIC CHECKLIST + +- ## Image Interpretation Pearls + + + - Avoid misdiagnosis of tumor or multiple sclerosis + - Bilateral & symmetrical lesions in ION argue against subacute infarct & vertebral artery dissection + + 16a22041-bb55-47a8-b601-8617efdb98ad \ No newline at end of file diff --git a/docs_md/articles/hypothalamic-hamartoma_7f85487f-9497-44a9-b884-b98e50d41018.md b/docs_md/articles/hypothalamic-hamartoma_7f85487f-9497-44a9-b884-b98e50d41018.md new file mode 100644 index 0000000..9c5b70d --- /dev/null +++ b/docs_md/articles/hypothalamic-hamartoma_7f85487f-9497-44a9-b884-b98e50d41018.md @@ -0,0 +1,308 @@ +--- +title: "Hypothalamic Hamartoma" +docid: "7f85487f-9497-44a9-b884-b98e50d41018" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Congenital" + - "Hypothalamic Hamartoma" +--- +# KEY FACTS + +- ## Terminology + + + - a.k.a. tuber cinereum hamartoma + - Nonneoplastic; congenital gray matter heterotopia +- ## Imaging + + + - Hypothalamic mass contiguous with tuber cinereum + - Located between mammillary bodies and infundibulum + - Can be sessile or pedunculated ("collar button") + - Size ranges from few mm to several cm + - Isointense with gray matter on T1WI + - Can be slightly hyperintense on T2/FLAIR + - Large lesions can be heterogeneous, contain cysts + - No enhancement on T1 C+ +- ## Top Differential Diagnoses + + + - Chiasmatic/hypothalamic astrocytoma + - Craniopharyngioma + - Ectopic posterior pituitary + - Lipoma + - Germinoma + - Langerhans cell histiocytosis +- ## Pathology + + + - Mature but dysplastic neuronal ganglionic tissue +- ## Clinical Issues + + + - Infant with epilepsy or precocious puberty + - Cognitive, neuropsychiatric comorbidities common + - Older children with precocious puberty + - Often tall, overweight, with advanced bone age + - Shape, size of hamartoma often predicts symptoms, presentation + - Large, sessile lesions → seizures + - Small, pedunculated lesions → central precocious puberty +- ## Diagnostic Checklist + + + - If hypothalamic mass in seizure imaging, think hypothalamic hamartoma; if enhancement present, consider astrocytoma + +# TERMINOLOGY + +- ## Synonyms + + + - Tuber cinereum hamartoma, diencephalic hamartoma +- ## Definitions + + + - Nonneoplastic congenital gray matter heterotopia in region of tuber cinereum of hypothalamus + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Nonenhancing hypothalamic mass contiguous with tuber cinereum + - ### Location + + + - Tuber cinereum of hypothalamus + - Located between pons/mammillary bodies and hypothalamic infundibulum + - ### Size + + + - Variable, few mm to giant (3-5 cm) + - ### Morphology + + + - Sessile or pedunculated mass + - Similar in density/intensity to gray matter +- ## Radiographic Findings + + + - ### Radiography + + + - ± suprasellar calcifications, eroded dorsum, enlarged sella (rare) +- ## CT Findings + + + - ### NECT + + + - Homogeneous suprasellar mass + - Isodense → slightly hypodense + - Cysts and calcification are uncommon + - ± patent craniopharyngeal canal (very rare) + - ### CECT + + + - No pathologic enhancement +- ## MR Findings + + + - ### T1WI + + + - Mass located between mammillary bodies and infundibulum + - Isointense → slightly hypointense to gray matter + - ### T2WI + + + - Isointense → slightly hyperintense (secondary to fibrillary gliosis) + - ### PD/intermediate + + + - Hyperintense to CSF, slightly hyperintense to gray matter + - ### FLAIR + + + - Isointense → slightly hyperintense to gray matter + - ### T1WI C+ + + + - Nonenhancing; if enhancing, consider other diagnosis + - ### MRS + + + - ↓ NAA and NAA/Cr, mild ↑ Cho and Cho/Cr, ↑ myoinositol (mI) and mI/Cr + - ↓ NAA and ↑ Cho indicate reduced neuronal density and relative gliosis, respectively, compared to normal gray matter + - ↑ mI/Cr correlates with ↑ glial component and lesion T2 hyperintensity +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - Multiplanar MR imaging + - ### Protocol advice + + + - Thin-section sagittal and coronal T2W1, T1WI C+ MR + +# DIFFERENTIAL DIAGNOSIS + +- [Craniopharyngioma](/document/craniopharyngioma/00e66680-6731-4287-b5a1-3f0b3f09053b) + - Most common suprasellar mass in children + - Variable signal intensity cysts (90%), calcifications (90%), and enhancement (90%) + - Longstanding lesion, frequently with short stature and pituitary abnormalities +- ## Chiasmatic/Hypothalamic Astrocytoma + + + - 2nd most common pediatric suprasellar mass [± neurofibromatosis type 1 (NF1)] + - Hyperintense on T2WI MR ± contrast enhancement (heterogeneous, often vigorous) + - Optic pathway or hypothalamus ± optic tract extension +- ## Ectopic Posterior Pituitary + + + - Ectopic hyperintense focus on T1WI MR + - Often located along median eminence of hypothalamus + - No normal orthotopic posterior pituitary hyperintensity +- [Germinoma](/document/germinoma/078b68a2-67de-457e-818a-63655cec95aa) + - Thickening, abnormal enhancement of pituitary stalk rather than tuber cinereum + - Diabetes insipidus common + - ± multicentric: Suprasellar, pineal, thalamus, basal ganglia + - Early leptomeningeal metastatic dissemination +- [Langerhans Cell Histiocytosis](/document/langerhans-cell-histiocytosis-skul-/5bfd61b0-b320-46f4-b785-6c69daa8523c) + - Thickening, abnormal enhancement of pituitary stalk rather than tuber cinereum + - Diabetes insipidus common + - Look for lytic bone lesions in typical locations +- [Lipoma](/document/lipoma-brain/1bdb974e-8346-4730-9b1c-dea7b70b844d) + - Hyperintense fat signal on T1WI MR + - Hypointense on STIR or fat-saturated sequences + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Neuronal migration anomaly (occurs between gestational days 33-41) + - Affects normal hypothalamic regulation of autonomic, endocrine, neurologic, behavioral functions + - Pathogenesis of precocious puberty-induced sexual precocity + - ± luteinizing hormone-releasing hormone (LHRH) granules in hamartoma/connecting axons in some + - Activating astroglial-derived factors in tumors may stimulate endogenous LHRH secretion if no intratumoral LHRH granules + - Shape and size of hamartoma postulated to predict symptoms + - Large, sessile lesions → seizures + - Small, pedunculated lesions → central precocious puberty (CPP) + - Presentation with both seizures and CPP common + - ### Genetics + + + - *GLI3*mutation + - Pallister-Hall syndrome (PHS) + - Hamartoma or hamartoblastoma of tuber cinereum; often large mass + - Digital malformations (short metacarpals, syndactyly, polydactyly) + - Other midline (epiglottis/larynx) and cardiac/renal/anal anomalies + - Greig cephalopolysyndactyly syndrome (GCPS) +- ## Staging, Grading, & Classification + + + - Valdueza classification + - Pedunculated, CPP or asymptomatic + - Originates in tuber cinereum + - Originates in mammillary bodies + - Sessile, hypothalamus displaced, seizures + - More hypothalamic dysfunction and abnormal behavior +- ## Gross Pathologic & Surgical Features + + + - Mature neuronal ganglionic tissue projecting from hypothalamus, tuber cinereum, or mammillary bodies + - Pedunculated or sessile, rounded or nodular +- ## Microscopic Features + + + - Well-differentiated neurons interspersed with glial cells, myelinated/unmyelinated axons, variable amounts of fibrillary gliosis + - Hamartoblastomas include primitive undifferentiated cells + - Rare reports of cysts, necrosis, calcifications, fat + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Luteinizing hormone-releasing hormone (LHRH) dependent CPP presenting at very young age + - Refractory symptomatic mixed seizure types, including gelastic seizures + - Gelastic seizures are recurrent automatic bursts of laughter without mirth + - Presentation usually encompasses both epileptic seizures and encephalopathy with behavioral cognitive impairment + - May progress to partial epilepsy, partial complex seizures, generalized tonic clonic seizures + - Rarely occur in conjunction with focal cortical dysplasia or hypothalamic astrocytoma + - Other seizure types frequent with hypothalamic hamartoma (HH); always look for HH in child with epilepsy + - ### Other signs/symptoms + + + - Depression, anxiety common in adult HH patients + - ### Clinical profile + + + - Infant with gelastic seizures or precocious puberty + - Older children with precocious puberty; tall, overweight, and advanced bone age +- ## Demographics + + + - ### Age + + + - Usually present between 1-3 years of age + - ### Sex + + + - No predilection; some reports M > F + - ### Ethnicity + + + - No predilection + - ### Epidemiology + + + - Of histologically verified lesions, 3/4 have precocious puberty and 1/2 have seizures + - Up to 33% of patients with CPP have HH +- ## Natural History & Prognosis + + + - Size should remain stable; if growth is detected, surgery/biopsy is indicated + - Postsurgical hypothalamic complications include headache, mental slowing, and weight gain + - Symptomatic lesions: Sessile > > pedunculated + - Sessile lesions nearly always symptomatic + - Syndromic patients generally do poorly +- ## Treatment + + + - Medical: Hormonal-suppressive therapy, treat seizures + - Surgical: If medical therapy failure or rapid lesion growth + - Endoscopic or transcallosal surgical resection + - Recent studies have shown stereotactic laser ablation to have equivalent efficacy to open surgery with fewer complications + - Stereotactic radiosurgery and Gamma Knife surgery also potential options + - Newer, less invasive techniques include magnetic resonance imaging-guided laser interstitial thermal therapy (MRgLITT) + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - If hypothalamic mass identified in seizure imaging, think HH +- ## Image Interpretation Pearls + + + - Classic = nonenhancing hypothalamic mass + - Isointense to gray matter on T1WI, slightly ↑ signal on T2WI/FLAIR + - Hypothalamic astrocytoma, Langerhans cell histiocytosis (LCH), germ cell tumor all show some contrast enhancement + + 1e636dc4-6e35-473c-a03d-2ed82f71d5bc \ No newline at end of file diff --git a/docs_md/articles/lewy-body-dementia_app.statdx.com_document_content_f6a4382b-f0f7-4582-a703-7f695c65656f_17f89880_20251014T185404Z.md b/docs_md/articles/lewy-body-dementia_f6a4382b-f0f7-4582-a703-7f695c65656f.md similarity index 98% rename from docs_md/articles/lewy-body-dementia_app.statdx.com_document_content_f6a4382b-f0f7-4582-a703-7f695c65656f_17f89880_20251014T185404Z.md rename to docs_md/articles/lewy-body-dementia_f6a4382b-f0f7-4582-a703-7f695c65656f.md index d75f3aa..6362183 100644 --- a/docs_md/articles/lewy-body-dementia_app.statdx.com_document_content_f6a4382b-f0f7-4582-a703-7f695c65656f_17f89880_20251014T185404Z.md +++ b/docs_md/articles/lewy-body-dementia_f6a4382b-f0f7-4582-a703-7f695c65656f.md @@ -1,5 +1,12 @@ -# Lewy Body Dementia - +--- +title: "Lewy Body Dementia" +docid: "f6a4382b-f0f7-4582-a703-7f695c65656f" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Neurodegeneration" + - "Lewy Body Dementia" +--- # KEY FACTS - ## Terminology @@ -238,4 +245,4 @@ - F-18 amyloid PET - Consider recommending DaT scan in patients with positive amyloid biomarkers and any clinical concern for LBD before starting ATTs - 363e0379-1464-405c-a8e1-ad3a47aac7e8 + 363e0379-1464-405c-a8e1-ad3a47aac7e8 \ No newline at end of file diff --git a/docs_md/articles/lymphocytic-hypophysitis_f30774c3-cbd0-4ab3-b3d1-e0574106db1f.md b/docs_md/articles/lymphocytic-hypophysitis_f30774c3-cbd0-4ab3-b3d1-e0574106db1f.md new file mode 100644 index 0000000..73178f7 --- /dev/null +++ b/docs_md/articles/lymphocytic-hypophysitis_f30774c3-cbd0-4ab3-b3d1-e0574106db1f.md @@ -0,0 +1,217 @@ +--- +title: "Lymphocytic Hypophysitis" +docid: "f30774c3-cbd0-4ab3-b3d1-e0574106db1f" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Miscellaneous" + - "Lymphocytic Hypophysitis" +--- +# KEY FACTS + +- ## Terminology + + + - Lymphocytic hypophysitis (LH) + - Synonyms: Adenohypophysitis, primary hypophysitis, stalkitis + - Idiopathic inflammation of pituitary gland &/or stalk +- ## Imaging + + + - Thick stalk (> 2 mm + loss of normal "top to bottom" tapering) + - ± enlarged pituitary gland + - 75% show loss of posterior pituitary "bright spot" + - Enhances intensely, uniformly + - May have adjacent dural or sphenoid sinus mucosal thickening +- ## Top Differential Diagnoses + + + - Macroadenoma + - Pituitary hyperplasia + - Adolescent pituitary gland + - Granulomatous disease + - Ectopic posterior pituitary gland +- ## Clinical Issues + + + - Autoimmune, inflammatory disorder; other etiologies: Granulomatous disease, IgG4 disease or drug related + - Peripartum woman with headache, multiple endocrine deficiencies + - Middle-aged man with diabetes insipidus (lymphocytic infundibuloneurohypophysitis) + - Mean in women = 35 years, men = 45 years + - M:F = 1:8-9 + - Often self-limited + - Unrecognized, untreated LH can result in death from panhypopituitarism + - Conservative care (steroids, hormone replacement) +- ## Diagnostic Checklist + + + - LH can mimic pituitary adenoma + +# TERMINOLOGY + +- ## Abbreviations + + + - Lymphocytic hypophysitis (LH) +- ## Synonyms + + + - Adenohypophysitis, primary hypophysitis, stalkitis +- ## Definitions + + + - Idiopathic inflammation of pituitary gland or stalk + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Thick, nontapered stalk, ± pituitary mass + - ### Location + + + - Suprasellar, intrasellar + - ### Size + + + - Usually < 10 mm but may reach 2-3 cm + - ### Morphology + + + - Rounded pituitary gland with infundibulum that appears thickened, nontapering, or bulbous +- ## MR Findings + + + - ### T1WI + + + - Thick stalk (> 2 mm + loss of normal tapering) + - ± enlarged pituitary gland + - 75% show loss of posterior pituitary "bright spot" + - ### T2WI + + + - Iso-/hypointense + - ### T1WI C+ + + + - Enhances intensely, uniformly + - May see dural or sphenoid sinus mucosal thickening +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR + - ### Protocol advice + + + - MR: Precontrast thin-section (< 3 mm) sagittal, coronal T1 and T2 + - Coronal dynamic T1 C+ (may show delayed pituitary enhancement) + +# DIFFERENTIAL DIAGNOSIS + +- [Macroadenoma](/document/pituitary-macroadenoma/14ebde13-80bb-4c4e-833c-fcc6c992d47c) + - Sellar and suprasellar mass + - Sella turcica enlarged/eroded + - Diabetes insipidus common in LH, rare with adenoma +- [Pituitary Hyperplasia](/document/pituitary-hyperplasia/9696bc9e-f00b-4fa7-aa67-f039efd8fbed) + - Stalk usually normal + - In young female patients, late pregnancy/peripartum + - May be seen with hypothyroidism, Addison disease, end-organ failure, neuroendocrine neoplasms +- ## Adolescent Pituitary + + + - Enlarged gland with uniform enhancement +- ## Granulomatous Disease + + + - Sarcoid, Langerhans cell histiocytosis (LCH), granulomatosis with polyangiitis; systemic disease often present +- ## Pituitary "Dwarf" + + + - Stalk may appear short and stubby +- ## Ectopic Posterior Pituitary + + + - Hyperintense focus at tuber cinereum or truncated stalk + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Autoimmune, inflammatory disorder + - Other types of hypophysitis include + - Granulomatous (sarcoid, LCH, infectious, etc.) + - IgG4-related hypophysitis + - Drug-related [cancer immunotherapy (e.g., ipilimumab)] +- ## Gross Pathologic & Surgical Features + + + - Diffusely enlarged stalk/pituitary gland +- ## Microscopic Features + + + - Acute + - Dense infiltrate of B/T lymphocytes, plasma cells, occasionally eosinophils; ± lymphoid follicles + - No granulomas, giant cells, or organisms; no neoplasm + - Chronic may demonstrate extensive fibrosis + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Headache, visual impairment + - ### Clinical profile + + + - Peripartum woman with headache, multiple endocrine deficiencies + - Middle-aged man with diabetes insipidus (lymphocytic infundibuloneurohypophysitis) +- ## Demographics + + + - ### Age + + + - Mean in women = 35 years, men = 45 years + - ### Sex + + + - M:F = 1:8-9 + - ### Epidemiology + + + - Rare (1-2% of sellar lesions) +- ## Natural History & Prognosis + + + - Often self-limited + - Unrecognized, untreated LH can result in death from panhypopituitarism +- ## Treatment + + + - Conservative (steroids, hormone replacement) + +# DIAGNOSTIC CHECKLIST + +- ## Image Interpretation Pearls + + + - LH can mimic pituitary adenoma + + 1c7008d4-15aa-4440-a8e1-29841f3caa42 \ No newline at end of file diff --git a/docs_md/articles/multiinfarct-dementia_app.statdx.com_document_content_3823c4d4-5e98-46da-a717-892fef54b382_68f10467_20251014T185335Z.md b/docs_md/articles/multiinfarct-dementia_3823c4d4-5e98-46da-a717-892fef54b382.md similarity index 97% rename from docs_md/articles/multiinfarct-dementia_app.statdx.com_document_content_3823c4d4-5e98-46da-a717-892fef54b382_68f10467_20251014T185335Z.md rename to docs_md/articles/multiinfarct-dementia_3823c4d4-5e98-46da-a717-892fef54b382.md index 56f5c68..676d773 100644 --- a/docs_md/articles/multiinfarct-dementia_app.statdx.com_document_content_3823c4d4-5e98-46da-a717-892fef54b382_68f10467_20251014T185335Z.md +++ b/docs_md/articles/multiinfarct-dementia_3823c4d4-5e98-46da-a717-892fef54b382.md @@ -1,5 +1,12 @@ -# Multiinfarct Dementia - +--- +title: "Multiinfarct Dementia" +docid: "3823c4d4-5e98-46da-a717-892fef54b382" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Neurodegeneration" + - "Multiinfarct Dementia" +--- # KEY FACTS - ## Terminology @@ -190,4 +197,4 @@ - Lesions can include basal ganglia and other areas typically spared in other diseases - MR correlation helpful - 7855ad33-290d-4bb0-81a6-63126fea7e4f + 7855ad33-290d-4bb0-81a6-63126fea7e4f \ No newline at end of file diff --git a/docs_md/articles/neurodegeneration-with-brain-iron-accumulation-nbia_8e3465d1-d058-48d8-863c-1fd85cc6caee.md b/docs_md/articles/neurodegeneration-with-brain-iron-accumulation-nbia_8e3465d1-d058-48d8-863c-1fd85cc6caee.md new file mode 100644 index 0000000..73340c0 --- /dev/null +++ b/docs_md/articles/neurodegeneration-with-brain-iron-accumulation-nbia_8e3465d1-d058-48d8-863c-1fd85cc6caee.md @@ -0,0 +1,269 @@ +--- +title: "Neurodegeneration With Brain Iron Accumulation (NBIA)" +docid: "8e3465d1-d058-48d8-863c-1fd85cc6caee" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Inherited Metabolic/Degenerative Disorders" + - "Miscellaneous" + - "Neurodegeneration With Brain Iron Accumulation (NBIA)" +--- +# KEY FACTS + +- ## Terminology + + + - Neurodegeneration with brain iron accumulation (NBIA) +- ## Imaging + + + - Characteristic findings of 10 NBIA subtypes, in addition to excess iron hypointense in T2/GRE/SWI + - Pantothenate kinase-associated neurodegeneration **(PKAN)**: "Eye of tiger sign" in globus pallidus (GP) + - Phospholipase-associated neurodegeneration **(PLAN)**: Cerebellar vermis & hemisphere atrophy in 95% + - Fatty acid hydroxylase-associated neurodegeneration **(FAHN)**:****Progressive brainstem & cerebellum atrophy + - β-propeller protein-associated neurodegeneration **(BPAN)**: Iron earliest & maximum in substantia nigra (SN) + - Pathognomonic oblique T1 high signal in SN + - Mitochondrial membrane protein-associated neurodegeneration **(MPAN)**: Characteristic linear T2 hyperintensity in medial medullary lamina in GP + - Woodhouse-Sakati syndrome **(WSS)**:****Confluent ↑ T2 periventricular & deep white matter frequent + - Kufor-Rakeb disease **(KRD)**:****↓ striatal uptake in 123-Ioflupane (DaT scan) SPECT (like Parkinson/-plus) + - Aceruloplasminemia **(ACP)**:****Widespread excessive iron; maximum degree of deposition among all NBIAs + - Neuroferritinopathy **(NFT)**: Bilateral symmetric cystic degeneration lined by iron deposits in basal ganglia + - Coenzyme A synthase (COASY) protein-associated neurodegeneration **(CoPAN)**: Early in disease, swollen, ↑ T2 caudate & putamina, & mild ↑ T2 in thalami +- ## Top Differential Diagnoses + + + - Wilson disease, Huntington disease, normal aging +- ## Pathology + + + - Genetic mutations specific for each subtype + - PKAN: Pantothenate kinase 2 (*PANK2*) gene + - Iron directly causes or facilitates cellular injury, or is consequence of axonal disruption +- ## Clinical Issues + + + - Extrapyramidal signs; NFT & ACP in adults, others younger + - Most common is PKAN +- ## Diagnostic Checklist + + + - Look for characteristic imaging signs to differentiate subtypes when excessive iron deposition noted in T2/GRE/SWI + +# TERMINOLOGY + +- ## Abbreviations + + + - Neurodegeneration with brain iron accumulation (NBIA) + - Pantothenate kinase-associated neurodegeneration (PKAN) + - Phospholipase-associated neurodegeneration (PLAN) + - Fatty acid hydroxylase-associated neurodegeneration (FAHN) + - β-propeller protein-associated neurodegeneration (BPAN) + - Mitochondrial membrane protein-associated neurodegeneration (MPAN) + - Woodhouse-Sakati syndrome (WSS) + - Kufor-Rakeb disease (KRD) + - Aceruloplasminemia (ACP) + - Neuroferritinopathy (NFT) + - Coenzyme A synthase (COASY) protein-associated neurodegeneration (CoPAN) +- ## Synonyms + + + - PKAN: **Hallervorden-Spatz syndrome** + - PLAN: **Infantile neuroaxonal dystrophy (INAD)** or **Seitelberger disease** + - Atypical PLAN: Atypical neuroaxonal dystrophy **(ANAD)** + - BPAN: Static encephalopathy of childhood with neurodegeneration in adulthood******(****SENDA****)** +- ## Definitions + + + - Group of neurologic disorders with progressive extrapyramidal symptoms, intellectual impairment, & excessive brain iron deposition in MR + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - **PKAN**: Eye of tiger sign: Bilateral ↓ T2/GRE/SWI in globi pallidi (GP) with central focus of ↑ signal + - Normal to excessive iron in substantia nigra (SN) + - White matter (WM) abnormality typically absent + - **PLAN:****Cerebellar**vermis & hemisphere **atrophy** in 95% (precedes iron deposition) in **INAD**; not early in ANAD + - Abnormal posterior aspect of corpus callosum constant finding; **thin splenium**, can be vertical + - **Enlarged clava** (dorsal bulge in medulla by gracile nucleus) may be 1st MR finding in INAD + - **Optic atrophy**; ↑ T2 cerebellum & putamen + - Excessive **iron in 50%**; typically in GP + - May have excessive iron in SN & subthalamic nuclei in INAD; not commonly in ANAD + - **FAHN**: Excessive iron in bilateral GP, may be in SN also + - **Optic atrophy**; ↑ T2 subcortical & periventricular WM + - Mild cortical atrophy &**callosal**thinning + - Progressive **brainstem** & cerebellum atrophy + - **BPAN**: Excessive iron **earliest & maximum in SN** (compared to GP); brain atrophy common + - Pathognomonic bilateral symmetric linear **oblique** **T1 high signal in SN** with central low-T1 band + - **MPAN**: Excessive iron in GP always, SN almost always + - **Linear** **T2 hyperintensity in medial medullary lamina** between GP interna & externa (in 1/5 of cases) + - Cortical & cerebellar atrophy less common + - **Optic atrophy** in juvenile-onset MPAN (like PLAN) + - **WSS**: Excessive iron in GP inconsistently; may show hyperintense medial medullary lamina (like MPAN) + - Confluent ↑ T2 periventricular & deep WM frequent + - **KRD**: Generalized cerebral & cerebellar atrophy + - Excessive iron in GP, SN, putamen, & caudate in some + - **Markedly reduced** bilateral symmetrical striatal uptake in dopamine transporter imaging with **123-Ioflupane (DaT scan)**SPECT (like parkinsonism/Parkinson-plus) + - **ACP: Widespread** excessive iron**(maximum degree among all NBIAs)**in GP, putamen, caudate, thalamus, SN, red nuclei, dentate nuclei (DN) + - May see iron in cerebral & cerebellar**cortex** + - Prominent T2 hyperintensity in WM common + - Cerebral & cerebellar atrophy common + - **NFT**: Bilateral symmetric **cystic** degeneration **lined by iron** deposits in caudate, putamen, GP, SN, & DN + - Iron deposition in **frontal lobe** may be seen + - Mild cerebral & cerebellar atrophy may be seen + - Rarely, eye of tiger sign + - **CoPAN**: Extremely rare NBIA;****excessive iron in GP & SN + - Early in disease, swollen, ↑ T2 bilateral caudate & putamina, & mild ↑ T2 in dorsomedial thalami + - Disappear later when iron deposition predominates + - Calcification in CT mimicking eye of tiger in MR +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR with T2* (gradient echo) or SWI +- ## CT Findings + + + - ### NECT + + + - Cerebellar & cerebral atrophy + - Identify calcifications in basal ganglia & cortical/subcortical regions which may mimic hypointensity of iron in T2/GRE/SWI MR +- ## MR Findings + + + - ### T1WI + + + - Pathognomonic bilateral symmetric linear oblique T1 high signal in SN, with central low-T1 band in BPAN + - ### T2WI + + + - GP hypointensity with central hyperintensity of GP interna: Eye of tiger sign in PKAN + - Can see only T2 hyperintensity early in disease + - May also be seen in NFT + - GP, ± other deep nuclei & cortex dark in varying patterns, without eye of tiger = other NBIA + - GP normally hypointense on T2, at 3T, or above + - ### T2* GRE + + + - Accentuated T2-hypointense findings; maximum in SWI + - Imaging findings do not always correlate with clinical symptoms + +# DIFFERENTIAL DIAGNOSIS + +- [Eye of Tiger (PKAN) in Other Disorders](/document/parkinson-disease/0bc3188a-935b-416d-b1a0-25b2d52c6399) + - Rarely reported in NFT, corticobasal degeneration, multiple system atrophy, healthy adults +- ## Cerebellar Atrophy & Cortical T2 Hyperintensity (PLAN) in Other Disorders + + + - Congenital disorder of glycosylation, neuronal ceroid lipofuscinosis, GM2 gangliosidosis +- ## Cerebellar & Optic Atrophy (PLAN) in Other Disorders + + + - Juvenile MPAN, FAHN, Wolfram syndrome, optic atrophy 1 +- ## Cystic Changes in Basal Ganglia (NFT) in Other Disorders + + + - Hypoxic-ischemic encephalopathy, carbon monoxide poisoning, chronic lacunar infarcts, chronic microhemorrhages, enlarged perivascular spaces +- [Deep Brain Nuclei Iron Deposition in Other Disorders](/document/multiple-sclerosis/7892b2a2-f52a-4d7f-9858-a326f2b7ab04) + - Iron accumulation in basal ganglia associated with MS + - Wilson disease, Huntington disease ↑ iron in deep nuclei +- [Superficial Siderosis](/document/superficial-siderosis-classical/e3125353-614e-43ce-a00d-eeefedbd9d9b) + - Hemosiderin deposits in subpial layers of brain & spinal cord + - May mimic cortical iron deposits in ACP & NFT +- ## Hemochromatosis + + + - Liver & spleen usually affected before CNS +- [Normal Iron Deposition](/document/normal-aging-brain/2a315550-b2ea-4afe-a2ef-f93a2209f276) + - Imaging at 3T, with normal aging + +# PATHOLOGY + +- ## General Features + + + - ### Genetics + + + - **Autosomal recessive:** **PKAN**: Pantothenate kinase 2 (*PANK2*) gene on chromosome 20p13 + - **PLAN**: Calcium-independent phospholipase A2 (*PLA2G6*) gene on chromosome 22q13.1 + - **FAHN**: Fatty acid 2 hydroxylase (*FA2H*) gene on chromosome 16q23.1 + - **MPAN**: *C19orf12*gene on chromosome 19q12 + - **WSS**:****C2orf37 (*DCAF17*) gene on chromosome 2q31.1 + - **KRD**: *ATP13A2* gene on chromosome 1p36.13 + - **ACP**:****Ceruloplasmin (*CP**)*gene on chromosome 3q24-q25.1 + - **CoPAN**:****Coenzyme A synthase**(*COASY*) gene on chromosome 17q21.2 + - **Autosomal dominant:******NFT**:**Ferritin light-polypeptide (*FTL*) gene on chromosome 19q13.33 + - **X-linked dominant: BPAN**: Heterozygous mutation of *WDR45*gene on Xp11.23 +- ## Gross Pathologic & Surgical Features + + + - **Eye of tiger in PKAN**: GP central T2 hyperintensity due to neuronal loss, gliosis, & cavitation of neuropil + - Central T2 hyperintensity can be predominant MR finding in presymptomatic patients (iron deposition may be cause or effect); surrounding GP T2 hypointensity develops gradually as PKAN progresses, becoming dominant MR finding later + - **SN linear high T1 in BPAN**: Iron binding to neuromelanin released from dying SN pars compacta pigmented cells +- ## Microscopic Features + + + - Iron accumulation in GP & SN, neuronal loss, axonal swellings (spheroids) + - Neurofibrillary tangles & Lewy bodies suggest shared pathway with Alzheimer & Parkinson diseases + - Iron in liver greater than that in basal ganglia in ACP + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - **PKAN: Typical**: (< 6 years, 90% of cases) presents with gait or postural difficulties; later both pyramidal & extrapyramidal symptoms with oromandibular dystonia + - Night blindness & visual field constriction common; 2/3 have abnormal electroretinograms + - Clinical signs of pigmentary retinal degeneration in 40% only + - Wheelchair bound by 10-15 years + - **Atypical**: Mutations allowing partial enzyme function; delayed onset, milder disease + - Mainly speech & neurocognitive symptoms + - Rather than extrapyramidal symptoms + - **PLAN: INAD**: Asymptomatic at birth; developmental delay starts at 6-18 months + - Rapid progression with language & motor regression, muscular weakness, hypotonia → spastic quadriplegia + - Muscular weakness → feeding/breathing difficulty → frequent pneumonia + - Visual symptoms due to optic atrophy, nystagmus, strabismus + - Cerebellar signs, sensory abnormalities, including peripheral neuropathy + - **ANAD**: Presents between 1.5-6.5 years with parkinsonism & dystonia + - Pyramidal symptoms, abnormal eye movements, cognitive decline + - Subacute onset of dystonia-parkinsonism linked to *PLA2G6* gene mutation presenting in late adolescence or early adulthood described + - **FAHN**:****Early-onset gait abnormalities, spastic quadriparesis, ataxia, dystonia, seizures, strabismus + - *FA2H*-gene mutations have association with leukodystrophies & hereditary spastic paraplegia with clinical picture overlaps + - **BPAN: SENDA**: Global developmental delay in early childhood (static encephalopathy of childhood) + - Seizures, spasticity, & sleep disorders may be seen in early childhood + - Neurodegeneration in early adulthood with parkinsonian features, dystonia, & cognitive decline + - **MPAN**: Presents at 4-30 years (mean: 11 years)****with cognitive decline, neuropsychiatric disorders, motor neuronopathy, & peripheral neuropathy + - **Juvenile onset** with optic atrophy or **adult onset** with parkinsonian features + - **WSS**: Progressive dystonia ± choreoathetosis; progressive cognitive decline + - Specific flat T wave in ECG, polyendocrinopathy (diabetes, hypogonadism), dysmorphic facies, alopecia, sensorineural hearing loss + - **KRD**:****Originally described in Jordanian family from Kufor-Rakeb village; adolescent patients with levodopa-responsive parkinsonism & pyramidal signs; psychotic episodes with visual hallucinations + - **ACP:****Adult-onset triad** of diabetes, retinal degeneration, & neurologic symptoms (movement disorders & dementia) + - Low-serum copper & iron, **high-serum ferritin**, extremely low ceruloplasmin + - Microcytic anemia responsive to ceruloplasmin rather than iron + - **NFT: Adult-onset**extrapyramidal features & spasticity + - Neurocognitive decline is usually late + - **Low-serum ferritin** (ACP has high-serum ferritin) + - **CoPAN**: Early-onset spastic-dystonic paraparesis + - Later develop parkinsonian features, cognitive decline, obsessive-compulsive behavior, axonal neuropathy + - *COASY* gene can be associated with pontocerebellar hypoplasia type 12 +- ## Treatment + + + - Symptom palliation: Medications & deep brain stimulator + - ACP: Iron chelation with desferrioxamine & ceruloplasmin from fresh frozen plasma + + 6495a951-3f64-4979-ad63-60cd111bff50 \ No newline at end of file diff --git a/docs_md/articles/normal-aging-brain_2a315550-b2ea-4afe-a2ef-f93a2209f276.md b/docs_md/articles/normal-aging-brain_2a315550-b2ea-4afe-a2ef-f93a2209f276.md new file mode 100644 index 0000000..1adfda9 --- /dev/null +++ b/docs_md/articles/normal-aging-brain_2a315550-b2ea-4afe-a2ef-f93a2209f276.md @@ -0,0 +1,340 @@ +--- +title: "Normal Aging Brain" +docid: "2a315550-b2ea-4afe-a2ef-f93a2209f276" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Normal Aging Brain" +--- +# KEY FACTS + +- ## Terminology + + + - ↓ overall brain volume with advancing age + - Reflected in relative ↑ CSF spaces +- ## Imaging + + + - Broad spectrum of "normal" on imaging in elderly + - "Successfully aging brain" + - Smooth, thin, periventricular, high signal rim on FLAIR is normal + - White matter hyperintensities (WMHs) absent/few + - ↓ total brain volume + - Selective atrophy of white matter (not gray matter) predominates + - ± punctate hippocampal Ca⁺⁺ + - Enlarged perivascular (Virchow-Robin) spaces + - WMHs ↑ in number/size after 50 years + - Focal high signal intensity in splenium of corpus callosum + - GRE/SWI + - Increasing mineralization of basal ganglia with age + - "Black line" in visual, motor/sensory cortex + - Microbleeds are relatively common in aging patients + - Lower prevalence than in cerebral amyloid disease & Alzheimer disease +- ## Top Differential Diagnoses + + + - Mild cognitive impairment + - Alzheimer disease + - Sporadic subcortical arteriosclerotic encephalopathy + - Vascular dementia + - Frontotemporal lobar degeneration +- ## Clinical Issues + + + - WMHs correlate with age, silent stroke, hypertension, female sex +- ## Diagnostic Checklist + + + - Cannot predict cognitive function from CT/MR + - If brain volume loss appears disproportionate to age, look for potential neurodegenerative or systemic causes + +# TERMINOLOGY + +- ## Definitions + + + - ↓ overall brain volume with advancing age + - Reflected in relative ↑ CSF spaces + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - "Successfully aging brain" + - Thin, periventricular, high-signal rim + - Absent/few white matter hyperintensities (WMHs) + - Mild shrinkage of selected cerebellar regions + - ### Location + + + - Selective atrophy of white matter (WM) predominates, not gray matter (GM) + - Striatum (primarily caudate nucleus, putamen) + - ### Size + + + - ↓ total brain volume + - Absolute striatal size + - Caudate ↓ linearly with age + - Putamen remains relatively stable + - Relative striatal size (ratio of absolute size:total brain volume) + - Caudate remains relatively stable + - Putamen ↑ linearly with age + - ### Morphology + + + - Brain tissue ↓, CSF volume ↑ + - Reflects overall WM volume loss > focal WMHs + - Rounded appearance of dilated ventricles, sulci ↑ + - Strong correlation between WM volume and CSF volume: Measure of overall brain atrophy +- ## CT Findings + + + - ### NECT + + + - Enlarged ventricles, widened cortical sulci + - Patchy periventricular low densities + - ± symmetrical, punctate calcifications in globi pallidi (GP) + - ± curvilinear vascular Ca⁺⁺ + - ± punctate hippocampal Ca⁺⁺ + - ### CECT + + + - No parenchymal enhancement +- ## MR Findings + + + - ### T1WI + + + - Mild but symmetric ventricular enlargement, proportionate prominence of subarachnoid spaces + - Mild but significant age-related shrinkage of + - Posterior vermis (lobules 6, 7, and 8-10) + - Cerebellar hemispheres + - Apparent age invariance of anterior vermis, ventral pons + - Enlarged perivascular (Virchow-Robin) spaces + - Common in aging, considered reflection of cerebral small vessel disease + - Isointense to CSF on all sequences + - Conform to course of penetrating arteries + - Round/oval/curvilinear + - Smooth, well-defined margins + - Bilateral, often symmetrical; usually no mass effect + - ↑ in number, size (> 2 mm) with age + - Can be found in most areas + - Midbrain, hippocampi, basal ganglia (BG), & centrum semiovale + - Tend to cluster around anterior commissure + - Inferior 1/3 of putamen, external capsule + - ### T2WI + + + - Focal/confluent periventricular WMHs + - Number/size ↑ after 50 years; ~ universal after 65 years + - Only rough correlation with cognitive function + - Significant overlap with dementias + - Infarct-like T2-hyperintense lesions + - Seen in 1/3 of asymptomatic patients > 65 years + - 70% < 10 mm + - Mostly in BG, thalami + - Probably represent clinically silent lacunar infarcts + - ### FLAIR + + + - Smooth, thin, periventricular hyperintense rim is normal + - Focal high signal intensity in splenium of corpus callosum + - BG and thalamic foci + - Perivascular spaces suppress + - Lacunar infarcts hyperintense + - ### T2* GRE + + + - SWI: Increasing mineralization of BG with age + - Normal in GP, abnormal in thalamus + - Can see linear "waves" or conglomerate mineralization in GP + - Putaminal hypointensity less prominent until 8th decade + - Microbleeds are common in aging brain + - SWI demonstrates microbleeds in 20% of patients > 60 years and in 60-70% of patients > 80 years + - Microbleeds are relatively common in aging patients + - Lower prevalence than in cerebral amyloid disease & Alzheimer disease + - BG, brainstem, and cerebellar microbleeds indicative of chronic hypertensive encephalopathy + - Lobar and cortical microbleeds typical of amyloid angiopathy + - SWI: "Black line" in visual, motor/sensory cortex + - Common, normal in older patients + - ### DWI + + + - Small but significant ↑ water diffusibility + - ADC ↑ + - DTI: Loss of fractional anisotropy in normal-appearing WM + - ### T1WI C+ + + + - Age-related WMHs do not enhance + - If enhancing, consider acute/subacute lacunar infarct or metastases + - ### MRS + + + - Metabolite distribution varies among different brain regions + - Choline (Cho) content ↑ with aging + - Creatine (Cr) ↑ with aging + - N-acetyl aspartate (NAA) ↓ in cortex, centrum semiovale, temporal lobes +- ## Nuclear Medicine Findings + + + - ### PET + + + - Metabolic alterations common + - Global, regional changes in cerebral blood flow (CBF) + - Gradual ↓ in regional CBF of GM, WM + - Particularly in frontal lobes + - Age-related shift from anterior to posterior cortical metabolism + - Putamen receives primarily posterior cortical input + - Caudate receives relatively more anterior cortical input + - Relative glucose metabolic rate (rGMR) measured by FDG PET + - With age, rGMR ↑ in putamen and ↓ in caudate + - ↓ pre-/postsynaptic dopamine markers in BG + - Tc-99m HMPAO SPECT, Xe-133 inhalation show regional, global reduction in CBF +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR with FLAIR, DWI, T2* GRE/SWI + +# DIFFERENTIAL DIAGNOSIS + +- ## Mild Cognitive Impairment + + + - Overlap with normal on standard imaging studies + - Associated with ↓ size and number of regions of brain activation in response to memory tasks despite normal-appearing brain on conventional MR + - Higher calculated hippocampal ADCs (not visible) + - Subtle hypoperfusion, hypometabolism in parahippocampal regions, cingulum, thalamus + - ↓ NAA +- [Alzheimer Disease](/document/alzheimer-disease/f71f5cf5-b1af-4c6d-b145-b4c10eec7b58) + - Parietal and temporal cortical atrophy + - Striking volume loss in hippocampi, entorhinal cortex + - Often coexisting microvascular disease, WMHs + - Striking temporoparietal hypometabolism, hypoperfusion + - ↓ NAA, ↑ myoinositol (mI) +- [Sporadic Subcortical Arteriosclerotic Encephalopathy](/document/chronic-hypertensive-encephalopathy/1afc1f3f-203d-4cdf-8d49-2283cb13d6db) + - Associated with hypertension + - Numerous WMHs (overlap with normal) + - Multiple lacunar infarcts + - Lenticular nuclei, pons, thalamus, internal capsule, and caudate nuclei + - Diffuse, confluent regions of periventricular WM involvement (leukoaraiosis) +- [Vascular Dementia](/document/vascular-dementia/f59dab57-c511-4369-8fcc-592421a4b8d1) + - Hyperintense lesions on T2WI and focal atrophy suggestive of chronic infarcts +- [Frontotemporal Lobar Degeneration](/document/frontotemporal-lobar-degeneration/49510d0e-acf7-45cb-9eb1-53f8193b0b6d) + - Asymmetric frontal, anterior temporal atrophy + - T2 hyperintensity in frontotemporal WM + - Dilated subarachnoid space over frontal lobes signifying atrophy + - ↓ metabolic activity in frontotemporal cortices + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Previous conception of aging: Substantial cortical neuronal loss with age + - New: Predominant neuroanatomic changes + - WM alterations, subcortical neuronal loss + - Reduction in cell size > cell number + - Neuronal dysfunction rather than loss of neurons/synapses + - ↓ neuronal viability or function associated with accelerated membrane degradation &/or ↑ glial cell numbers + - Loss of synapses and dendritic pruning in selected areas rather than globally + - Some investigators consider accumulation of neurofibrillary tangles (NFTs) may be responsible for memory loss associated with aging + - ### Genetics + + + - Clearly affect aging of brain + - Apolipoprotein E (*APOE*) and 6 novel risk-associated single nucleotide polymorphisms (SNPs) on chromosome 17q25 associated with brain pathology in aging +- ## Gross Pathologic & Surgical Features + + + - Widened sulci, proportionate large ventricles + - Minor thinning of cortical mantle, predominant changes in subcortical WM +- ## Microscopic Features + + + - Degeneration of neurons and oligodendrocytes + - ↓ myelinated fibers in subcortical WM + - ↑ extracellular space, gliosis + - Iron deposition in GP, putamen + - WM capillaries lose pericytes, have thinner endothelium + - Dilated perivascular spaces of Virchow-Robin + - Extension of subarachnoid space that accompanies penetrating vessels into brain to level of capillaries + - Senile plaques + - Extracellular amyloid deposits in cerebral GM + - Lewy bodies + - Intraneuronal clumps of α-synuclein and ubiquitin proteins + - Found in 5-10% of cognitively intact individuals + - NFTs + - Tau phosphorylation, mitochondrial dysfunction may precede full NFT formation + - NFTs appear in small numbers in entorhinal and transentorhinal cortices early in aging (patients ~ 60 years) + - NFTs may induce neural dysfunction, destruction of synapses, and, eventually, neuronal death + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Normal cognitive function + - Mild cognitive impairment correlates with ↑ risk of Alzheimer disease +- ## Demographics + + + - ### Age + + + - > 60 years + - ### Sex + + + - Differences in striatal size + - Relatively constant across lifespan in men + - Variable across lifespan in women: Smaller in women aged 50-70 years than in men + - Differences in rGMR + - Caudate: Higher rGMR in women than men + - Putamen: Equal rGMR in women and men + - Greater dopamine transporters in caudate in women + - ### Epidemiology + + + - WMHs correlate with age, silent stroke, hypertension, female sex +- ## Natural History & Prognosis + + + - Parenchymal volume ↓, CSF spaces ↑ progressively + - WMHs progressively ↑ with age + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Striatum may mediate age-associated cognitive decline + - ↓ volume, functional activity with age +- ## Image Interpretation Pearls + + + - Broad spectrum of "normal" on imaging in elderly + - Cannot predict cognitive function from CT/MR + - If brain volume loss appears disproportionate to age, look for potential neurodegenerative or systemic causes + + a71a0c8f-d105-4815-9edf-3fc113d5acc4 \ No newline at end of file diff --git a/docs_md/articles/normal-pressure-hydrocephalus_app.statdx.com_document_content_834ccc3e-2116-4295-8408-0ac9a06bd2ff_2e001e66_20251014T193450Z.md b/docs_md/articles/normal-pressure-hydrocephalus_834ccc3e-2116-4295-8408-0ac9a06bd2ff.md similarity index 97% rename from docs_md/articles/normal-pressure-hydrocephalus_app.statdx.com_document_content_834ccc3e-2116-4295-8408-0ac9a06bd2ff_2e001e66_20251014T193450Z.md rename to docs_md/articles/normal-pressure-hydrocephalus_834ccc3e-2116-4295-8408-0ac9a06bd2ff.md index b74c1fb..7078549 100644 --- a/docs_md/articles/normal-pressure-hydrocephalus_app.statdx.com_document_content_834ccc3e-2116-4295-8408-0ac9a06bd2ff_2e001e66_20251014T193450Z.md +++ b/docs_md/articles/normal-pressure-hydrocephalus_834ccc3e-2116-4295-8408-0ac9a06bd2ff.md @@ -1,5 +1,12 @@ -# Normal-Pressure Hydrocephalus - +--- +title: "Normal-Pressure Hydrocephalus" +docid: "834ccc3e-2116-4295-8408-0ac9a06bd2ff" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Cerebrospinal Fluid" + - "Normal-Pressure Hydrocephalus" +--- # KEY FACTS - ## Terminology @@ -253,4 +260,4 @@ - Classic finding of NPH on radionuclide cisternography - Prominent ventricular activity at 24 hours with absent activity over convexities - 650e8453-816e-4a1a-a422-ae65a07c95e8 + 650e8453-816e-4a1a-a422-ae65a07c95e8 \ No newline at end of file diff --git a/docs_md/articles/normal-pressure-hydrocephalus_app.statdx.com_document_content_834ccc3e-2116-4295-8408-0ac9a06bd2ff_e24ff415_20251014T193502Z.md b/docs_md/articles/normal-pressure-hydrocephalus_app.statdx.com_document_content_834ccc3e-2116-4295-8408-0ac9a06bd2ff_e24ff415_20251014T193502Z.md deleted file mode 100644 index a3b0cf1..0000000 --- a/docs_md/articles/normal-pressure-hydrocephalus_app.statdx.com_document_content_834ccc3e-2116-4295-8408-0ac9a06bd2ff_e24ff415_20251014T193502Z.md +++ /dev/null @@ -1,256 +0,0 @@ -# Normal-Pressure Hydrocephalus - -# KEY FACTS - -- ## Terminology - - - - Normal-pressure hydrocephalus (NPH): Ventriculomegaly out of proportion to sulcal enlargement in setting of normal cerebrospinal fluid (CSF) pressure -- ## Imaging - - - - In-111 DTPA radionuclide cisternography - - Used in patients in whom MR is contraindicated and CT is equivocal - - Protocol - - Intrathecal injection of In-111 DTPA - - Obtain planar images with gamma camera immediately after injection and at 4, 24, and 48 hours - - Normal study - - 1 hour: Radiotracer reaches basal cisterns - - 2-6 hours: Radiotracer reaches sylvian fissures - - 12 hours: Radiotracer reaches cerebral convexities - - 24 hours: Radiotracer reaches superior sagittal sinus and is absorbed by arachnoid villi - - Normally no radiotracer enters ventricles, although transient activity in ventricles at 4 hours is still considered normal - - NPH - - Radiotracer activity in ventricles at ≥ 24 hours - - Absence of radiotracer activity in cerebral convexities by 24-72 hours - - SPECT/CT can help confirm ventricular activity -- ## Clinical Issues - - - - Symptoms: Gait disturbance, urinary incontinence, dementia - - Treatment: Ventriculoperitoneal shunt -- ## Diagnostic Checklist - - - - Ventricular dilation on anatomic imaging may related to cerebral atrophy or underlying neurodegenerative disease - - Classic finding of NPH on radionuclide cisternography - - Prominent ventricular activity at 24-72 hours with absent activity over convexities - -# TERMINOLOGY - -- ## Definitions - - - - Normal-pressure hydrocephalus (NPH): Ventriculomegaly out of proportion to sulcal enlargement in setting of normal cerebrospinal fluid (CSF) pressure - -# IMAGING - -- ## Nuclear Medicine Findings - - - - In-111 DTPA radionuclide cisternography - - Advantages - - Provides physiologic information about CSF flow - - Useful in patients who cannot receive MR or in whom CT is nondiagnostic (equivocal findings) - - May help determine who may benefit from ventriculoperitoneal (VP) shunt (controversial) - - Disadvantages - - Radiation - - Time consuming - - Normal study - - 1 hour: Radiotracer reaches basal cisterns - - 2-6 hours: Radiotracer reaches sylvian fissures - - Trident sign: Activity in anterior interhemispheric fissure and sylvian fissures - - 12 hours: Radiotracer reaches cerebral convexities - - 24 hours: Radiotracer reaches superior sagittal sinus and is absorbed by arachnoid villi - - No radiotracer activity should be seen in ventricles, although transient activity in ventricles at 4 hours is still considered normal - - NPH - - 24-48 hours: Ventricular activity is present, and no activity is seen in cerebral convexities - - Heart configuration: Appearance of radiotracer activity in lateral ventricles on anterior view - - Comma (also C-shaped) configuration: Appearance of radiotracer activity in lateral ventricles on lateral views - - Butterfly configuration: Appearance of radiotracer activity in lateral ventricles on posterior view - - Radiotracer activity in lateral ventricles at 24 hours or later is abnormal and consistent with diagnosis of NPH - - Radiotracer activity not present in cerebral convexities by 24-72 hours is abnormal and suggestive of NPH - - CSF movement patterns on cisternography - - Type I: Radiotracer activity in cerebral convexities at 24 hours - - Normal or noncommunicating hydrocephalus - - Type II: Delayed activity in cerebral convexities at 24 hours without ventricular activity - - Cerebral atrophy or aging - - Type IIIa: Radiotracer activity in cerebral convexities at 24 hours with early transient ventricular activity - - Indeterminate (can be seen with noncommunicating hydrocephalus, developing or resolving communicating hydrocephalus, or cerebral atrophy) - - Type IIIb: No radiotracer activity in cerebral convexities at 24 hours with early transient ventricular activity - - Suggestive of NPH (communicating hydrocephalus) - - Type IV: No radiotracer activity in cerebral convexities at 24 hours with persistent ventricular activity - - Suggestive of NPH (communicating hydrocephalus) -- ## Other Modality Findings - - - - MR - - 1st-line imaging to diagnose NPH - - Findings include ventriculomegaly out of proportion to sulcal enlargement, crowding of vertex sulci, acute callosal angle, enlarged sylvian fissures, hyperintense lesions in deep and periventricular white matter, flow void in cerebral aqueduct - - Contraindications include hardware incompatible with MR and claustrophobia - - CT - - Shows ventriculomegaly out of proportion to sulcal enlargement and potentially additional MR findings -- ## Imaging Recommendations - - - - ### Best imaging tool - - - - MR - - Findings - - Ventriculomegaly out of proportion to sulcal enlargement - - Hyperintense lesions in deep and periventricular white matter - - Flow void in cerebral aqueduct - - 1st-line imaging to diagnose NPH - - Advantages - - No radiation to patient - - Provides both anatomic and physiologic (CSF flow dynamics) information - - Contraindications - - Hardware incompatible with MR (cardiac pacemaker, aneurysm/embolization clips, prosthetic heart valves, etc.) - - Claustrophobia - - CT - - Findings - - Ventriculomegaly out of proportion to sulcal enlargement - - Advantages - - NECT can suggest diagnosis of NPH - - Disadvantages - - Radiation - - No physiologic information - - May be difficult to differentiate ventriculomegaly due to NPH from cerebral atrophy in setting of Alzheimer dementia or normal aging - - ### Protocol advice - - - - In-111 diethylenetriaminepentaacetic acid (DTPA) radionuclide cisternography - - In-111 DTPA - - Half-life (t1/2): 67 hours (2.8 days) - - γ energies: 173 and 247 keV - - Nonlipophilic - - Not metabolized - - Absorbed by arachnoid villi - - Dosimetry - - Spinal cord, brain, kidneys, bladder receive largest radiation dose - - Patient preparation: Same as for any lumbar puncture (LP), except need radiotracer prepared ahead of time - - Intrathecal injection of 0.5 mCi (18.5 MBq) In-111 DTPA - - LP usually performed fluoroscopically by neuroradiologist, and radiotracer injected by nuclear medicine physician - - Need appropriate cleanup and disposal of equipment due to radioactivity - - Avoid contaminating patient's skin with radiotracer - - Image acquisition - - Planar &/or SPECT/CT with gamma camera - - Low- or medium-energy, parallel hole collimator - - Immediate anterior planar imaging to confirm intrathecal placement (bring portable gamma camera to LP suite or transport patient to nuclear medicine department) - - 4-, 24-, and 48-hour (up to 72-hour) planar images of head: Anterior, posterior, both laterals - - 24-hour SPECT/CT images of head if ventricular activity equivocal on planar imaging - -# DIFFERENTIAL DIAGNOSIS - -- [Alzheimer Dementia](/document/alzheimer-disease/2aad3ac4-44fd-43e5-8e50-a86987483af3) - - Ventriculomegaly with sulcal enlargement - - Small hippocampi - - Type II or IIIa CSF flow pattern on cisternography - - Dementia most pronounced clinical symptom -- ## Parkinson Disease - - - - Resting tremor (pill-rolling) - - Shuffling gate - - Cogwheel rigidity -- ## Normal Aging - - - - Type II CSF flow pattern on cisternography -- ## Noncommunicating Hydrocephalus - - - - Type I CSF flow pattern on cisternography - - Usually diagnosed on MR - -# PATHOLOGY - -- ## General Features - - - - ### Etiology - - - - Causes - - Idiopathic (50%) - - Secondary (50%) - - Subarachnoid hemorrhage or subdural hematoma - - Meningitis or encephalitis - - Leptomeningeal carcinomatosis - - Head trauma - - Brain radiation - - Neurosurgery - - Pathophysiology - - Impaired CSF resorption by arachnoid villi causes communicating hydrocephalus - - Traditional theory: Increased resistance to CSF outflow - - Newer theory: Increased pulsations in intracranial pressure has been suggested as potential mechanism - - Dysfunctional CSF dynamics without increase in intracranial pressure - -# CLINICAL ISSUES - -- ## Presentation - - - - ### Most common signs/symptoms - - - - Heterogeneous triad: Gait abnormality, urinary incontinence, dementia - - All 3 present in only 10% of patients - - Gait abnormality may manifest as magnetic gait, frontal ataxia, or gait apraxia (can be difficult to distinguish from shuffling gait or Parkinson disease) - - Urinary urgency usually precedes incontinence - - Dementia usually manifests with frontal lobe symptoms, such as apathy, lack of concentration and inattention, and psychomotor slowing - - Symptom severity is related to CSF levels of neurofilament protein, marker of neuronal degeneration - - ### Clinical profile - - - - Reversible cause of dementia -- ## Demographics - - - - ### Age - - - - Most common in patients > 60 years - - Idiopathic form of NPH tends to present in older adults - - Secondary NPH can present at earlier age - - ### Sex - - - - M = F -- ## Natural History & Prognosis - - - - Natural course: Continuing cognitive and motor decline, akinetic mutism, and eventual death - - Potentially reversible cause of dementia when shunted, although gait symptoms are usually most predominant - - Some patients worsen after shunting -- ## Treatment - - - - Ventricular shunt (most commonly VP) - - Predictors of positive response to shunting - - Patient < 75 years - - Early symptoms (mild gait abnormality and urinary urgency) - - Known history of intracranial infection or bleeding (nonidiopathic NPH) - - Gait abnormality as dominant clinical symptom - - Absence of central atrophy or ischemia - - Prominent CSF flow void - - Response to CSF removal trial - - Exclusion of comorbidities, such as concomitant Alzheimer dementia or Parkinson disease - - After shunt surgery - - Variable outcome amongst studies, likely due to differing patient selection criteria - - Early research may suggest role for amyloid, FDG, &/or DOPA PET in predicting outcomes to surgery - -# DIAGNOSTIC CHECKLIST - -- ## Consider - - - - Whether ventricular dilation is solely due to atrophy or another underlying neurodegenerative disease -- ## Image Interpretation Pearls - - - - Classic finding of NPH on radionuclide cisternography - - Prominent ventricular activity at 24 hours with absent activity over convexities - - d11495d3-e2da-4ebf-86d2-25c60a3ed963 diff --git a/docs_md/articles/parkinsonian-syndromes_app.statdx.com_document_content_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_dc973ded_20251014T193525Z.md b/docs_md/articles/parkinsonian-syndromes_2b99b31a-ec1a-4dce-bb63-2a101fe9f044.md similarity index 98% rename from docs_md/articles/parkinsonian-syndromes_app.statdx.com_document_content_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_dc973ded_20251014T193525Z.md rename to docs_md/articles/parkinsonian-syndromes_2b99b31a-ec1a-4dce-bb63-2a101fe9f044.md index 367ddd9..34b70c7 100644 --- a/docs_md/articles/parkinsonian-syndromes_app.statdx.com_document_content_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_dc973ded_20251014T193525Z.md +++ b/docs_md/articles/parkinsonian-syndromes_2b99b31a-ec1a-4dce-bb63-2a101fe9f044.md @@ -1,5 +1,12 @@ -# Parkinsonian Syndromes - +--- +title: "Parkinsonian Syndromes" +docid: "2b99b31a-ec1a-4dce-bb63-2a101fe9f044" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Neurodegeneration" + - "Parkinsonian Syndromes" +--- # KEY FACTS - ## Terminology @@ -240,4 +247,4 @@ - Abnormal grade 2: Abnormal (period shape) reduced putamen activity bilaterally - Abnormal grade 3: Markedly reduced uptake bilaterally - cc5405dd-1797-4f98-b1a1-127b9159f5f1 + cc5405dd-1797-4f98-b1a1-127b9159f5f1 \ No newline at end of file diff --git a/docs_md/articles/pituitary-anomalies_09ca9b54-a3d9-43fd-a9cc-4c0212b578a1.md b/docs_md/articles/pituitary-anomalies_09ca9b54-a3d9-43fd-a9cc-4c0212b578a1.md new file mode 100644 index 0000000..9ac9f37 --- /dev/null +++ b/docs_md/articles/pituitary-anomalies_09ca9b54-a3d9-43fd-a9cc-4c0212b578a1.md @@ -0,0 +1,309 @@ +--- +title: "Pituitary Anomalies" +docid: "09ca9b54-a3d9-43fd-a9cc-4c0212b578a1" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Congenital" + - "Pituitary Anomalies" +--- +# KEY FACTS + +- ## Terminology + + + - Congenital anomalies of pituitary stalk → potential hypothalamic/pituitary axis malfunction +- ## Imaging + + + - Posterior pituitary ectopia (PPE) + - No (or tiny) pituitary stalk, ectopic posterior pituitary (EPP) on midline sagittal T1WI MR + - Look for associated anomalies: Heterotopia, optic nerve hypoplasia, corpus callosum anomalies + - Duplicated pituitary gland/stalk (DP) + - 2 pituitary stalks on coronal view, thick tuber cinereum on midline sagittal view +- ## Top Differential Diagnoses + + + - PPE + - Surgical or traumatic stalk transection + - Central diabetes insipidus + - Hypothalamic lipoma (in tuber cinereum) + - DP + - Dilated infundibular recess of 3rd ventricle ("pseudoduplication") + - Tuber cinereum hamartoma +- ## Pathology + + + - PPE: Genetic mutation → defective neuronal migration during embryogenesis + - DP: Genetic mutation unknown; may constitute polytopic field defect due to splitting of notochord +- ## Clinical Issues + + + - PPE: Short stature + - DP: Unsuspected finding on craniofacial imaging for other indications +- ## Diagnostic Checklist + + + - PPE: Assess optic and olfactory nerves, frontal cortex + - DP: Oral tumors compromise airway patency + +# TERMINOLOGY + +- ## Synonyms + + + - Ectopic pituitary bright spot +- ## Definitions + + + - Congenital anomalies of pituitary stalk → potential hypothalamic/pituitary axis malfunction + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Posterior pituitary ectopia (PPE): No (or tiny) pituitary stalk, ectopic posterior pituitary (EPP) on midline sagittal T1WI MR + - Partial pituitary ectopia also reported + - Duplicated pituitary gland/stalk (DP): 2 pituitary stalks on coronal view, thick tuber cinereum on midline sagittal view + - Tuberomammillary fusion: Tuber cinereum/mammillary bodies fused into single mass + - Pituitary hypoplasia: Small sella turcica and adenohypophysis + - ### Location + + + - PPE: EPP located along median eminence of tuber cinereum or truncated pituitary stalk + - DP: Paired lateral stalks, pituitary glands, bony fossae + - ### Size + + + - PPE: Anterior pituitary (adenohypophysis) is small + - DP: Each pituitary gland is normal in size + - ### Morphology + + + - PPE: Small adenohypophysis and osseous sella + - DP: Each pituitary gland and osseous sella is normal in morphology but laterally located +- ## Radiographic Findings + + + - ### Radiography + + + - PPE: Small sella turcica on lateral view + - DP: Craniofacial/craniocervical anomalies common; may observe 2 fossae on AP view +- ## CT Findings + + + - ### NECT + + + - PPE: Narrow pituitary fossa and skull base structures and clivus, ± persistent sphenopharyngeal foramen + - DP: 2 widely separated pituitary fossae, ± midline basisphenoid cleft or frontonasal dysplasia + - ### CTA + + + - PPE: Medial deviation of juxtasellar/supraclinoid carotid arteries ("kissing" carotids) + - DP: Duplicated basilar artery (BA), ± widely separated juxtasellar/supraclinoid carotid arteries +- ## MR Findings + + + - ### T1WI + + + - PPE: Absent, truncated, or thread-like pituitary stalk; small adenohypophysis + - EPP located along truncated stalk or median eminence of tuber cinereum + - Usually ↑ signal on T1WI (phospholipids/secretory granules) + - Posterior pituitary may "dim" as patient outgrows available hormone levels + - Chiari 1 (20%), ± olfactory hypoplasia, frontal lobe dysgenesis/migration anomalies + - ± absent septum pellucidum, ocular dysgenesis, hypoplastic optic nerves/chiasm + - DP: Mass-like thickening of tuber cinereum on sagittal view portends duplicated pituitary axis + - Mammillary bodies fused with tuber cinereum into thickened 3rd ventricle floor + - 2 lateralized but otherwise normal pituitary glands/stalks + - Brain anomalies: Callosal dysgenesis, duplicated anterior 3rd ventricle, cleft brainstem, Dandy-Walker malformation + - Cranial nerve anomalies: Olfactory nerve and optic nerve hypoplasia + - Oral tumors: Epignathus (giant teratoma) or dermoid (mixed signal), lipoma (↑ T1WI) + - ### T2WI + + + - PPE: Variable signal of posterior pituitary + - DP: Normal signal of glands, stalk, tuberomammillary fusion mass + - ### T1WI C+ + + + - Both: Stalks and remnants enhance (absent blood-brain barrier) + - PPE: Hyperintensity absent if multiple endocrine anomalies/diabetes insipidus; contrast enhancement helps find neurohypophysis + - ### MRA + + + - PPE: Supraclinoid carotid arteries medially deviated, "kiss" in midline; rare absent carotid artery/canal + - DP: Fenestration (common) or total duplication (rare) of BA; widely separated juxtasellar carotid arteries + - ### MRV + + + - Used to characterize torcular and straight sinus anomalies if midline posterior fossa anomaly identified +- ## Angiographic Findings + + + - Conventional + - PPE: Variable deviation "kissing" carotids (37%) + - DP: Split/duplicated BA, ± lateral deviation carotids +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - Multiplanar T1WI MR + - ### Protocol advice + + + - Both: Sagittal and coronal T1WI ± T2WI of hypothalamic/pituitary axis + - PPE: Assess olfactory nerves, anterior frontal lobes with coronal T2WI + - 3D T1WI SPGR can identify small posterior pituitaries, occult on conventional 2D sagittal T1WI + - DP: 3D CT of skull base and face in selected patients + +# DIFFERENTIAL DIAGNOSIS + +- [Posterior Pituitary Ectopia](/document/pituitary-anomalies/556da02b-74c3-489a-8aed-ebbc97b620fa) + - **Central diabetes insipidus** + - Hyperintensity of posterior pituitary lobe is absent but normal location of stalk and gland + - **Surgical or traumatic stalk transection** + - Permits build-up of neurosecretory granules along stump + - [Hypothalamic lipoma (located at tuber cinereum)](/document/lipoma-brain/1bdb974e-8346-4730-9b1c-dea7b70b844d) + - Posterior pituitary is not suppressed by fat saturation; lipoma is suppressed +- ## Duplicated Pituitary Gland/Stalk + + + - **Dilated infundibular recess of 3rd ventricle ("pseudoduplication")** + - Simulates duplicated stalk but only 1 gland and 1 pituitary fossa + - [Tuber cinereum hamartoma](/document/hypothalamic-hamartoma/7f85487f-9497-44a9-b884-b98e50d41018) + - Round mass of 3rd ventricle floor but 1 midline pituitary stalk/gland + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - PPE: Genetic mutation → defective neuronal migration during embryogenesis + - Adenohypophysis (anterior pituitary) grows up from stomodeal ectoderm (Rathke pouch) + - Hypothalamic-releasing hormones reach adenohypophysis via infundibular portal system + - Anterior pituitary dysfunction thought to be related to absent infundibulum + - Neurohypophysis (posterior pituitary) grows down from diencephalic neuroectoderm, remains attached by stalk + - Antidiuretic hormone and oxytocin transported to neurohypophysis via neurosecretory cells along infundibulum + - DP: Congenital anomaly, presumed genetic duplication of stomodeal origin structures 2° to aberrant ventral induction + - Theory: Duplication prechordal plate and tip of rostral notochord leads to duplicated pituitary primordium + - ### Genetics + + + - PPE: Mutations in genes encoding developmental transcription factors allow maldevelopment + - *HESX1* (homeobox gene), *POU1F1* (PIT1), *PITX2*, *LHX3*, *LHX4*, *PROP1*, *SF1*, and *TBX19* (TPIT) + - DP: Gene mutation unknown; may constitute polytopic field defect due to splitting of notochord + - ### Associated abnormalities + + + - DP + - Midline tumors in oral, nasopharyngeal, palate + - Epignathus, hamartomas, teratomas, dermoids, lipomas + - Spinal anomalies include segmentation/fusion anomalies, schisms, hydromyelia, enteric cysts + - Rib and cardiac anomalies, Pierre-Robin anomaly + - **Both**: Common midline CNS anomalies + - PPE + - ± anomalies of structures formed at same time (anterior pituitary lobe, forebrain, eyes, olfactory bulbs) + - ± lobar holoprosencephaly, septo-optic dysplasia, Joubert syndrome + - DP + - Callosal dysgenesis, Dandy-Walker spectrum, frontonasal dysplasia + - Craniofacial clefting and duplication anomalies: Frontonasal dysplasia; clefts/duplication of skull base, face, mandible, nose, palate + - Pituitary hypoplasia associated with Kallmann syndrome +- ## Gross Pathologic & Surgical Features + + + - PPE: Hypoplastic anterior lobe, stalk truncation or aplasia + - Sella may be covered over with dura + - DP: Tuberomammillary fusion, 2 normal glands/stalks +- ## Microscopic Features + + + - PPE: Ectopic pituitary cells in stalk or sphenoid bone + - DP: Normal (but duplicated) pituitary glands, tuberomammillary fusion, incompletely migrated hypothalamic nuclear cells + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - PPE: Short stature + - DP: Unsuspected finding on craniofacial imaging for other indications + - ### Other signs/symptoms + + + - PPE: Multiple pituitary hormone deficiencies common + - DP: Rarely symptomatic from pituitary causes + - ### Clinical profile + + + - PPE: Short stature (growth hormone deficiency), ± multiple endocrine deficiencies + - Peak growth hormone levels < 3 g/L more likely to have abnormal MR + - ± anosmia, poor vision, seizures (cortical malformations) + - Neonatal hypoglycemia or jaundice, micropenis, single central incisor + - DP: ± facial midline anomalies, oral or nasal mass (hamartoma or teratoma) + - Face: ± hypertelorism or frontonasal dysplasia + - Craniocervical segmentation and fusion anomalies + - Airway or oral obstruction from pharyngeal tumor +- ## Demographics + + + - ### Age + + + - PPE: Early growth failure apparent in childhood + - DP: Usually discovered in early infancy during imaging for complicated facial anomalies + - ### Sex + + + - PPE: M > F + - DP: M < F + - ### Ethnicity + + + - None identified in either diagnosis + - ### Epidemiology + + + - PPE: Prevalence 1:4,000 to 1:20,000 births + - DP: Extremely rare (reported in 20+ cases) +- ## Natural History & Prognosis + + + - PPE: Stable if no pituitary/hypothalamic crises; growth may be normal for a while + - Severity and number of hormone deficiencies predicted by degree of stalk and gland hypoplasia + - DP: Usually significant intracranial, upper airway, or craniocervical malformations (some lethal) + - Clinical outcome unrelated to pituitary function +- ## Treatment + + + - Assess/treat endocrine malfunction + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - PPE: Assess optic and olfactory nerves, frontal cortex + - DP: Oral tumors compromise airway patency +- ## Image Interpretation Pearls + + + - PPE/DP: Can miss findings/diagnosis if thick sections (MR) are used or osseous structures (bone CT) not evaluated + + 36b1a7e3-ae5c-4195-b627-5b6e09d38c5a \ No newline at end of file diff --git a/docs_md/articles/pituitary-hyperplasia_9696bc9e-f00b-4fa7-aa67-f039efd8fbed.md b/docs_md/articles/pituitary-hyperplasia_9696bc9e-f00b-4fa7-aa67-f039efd8fbed.md new file mode 100644 index 0000000..444e833 --- /dev/null +++ b/docs_md/articles/pituitary-hyperplasia_9696bc9e-f00b-4fa7-aa67-f039efd8fbed.md @@ -0,0 +1,206 @@ +--- +title: "Pituitary Hyperplasia" +docid: "9696bc9e-f00b-4fa7-aa67-f039efd8fbed" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Miscellaneous" + - "Pituitary Hyperplasia" +--- +# KEY FACTS + +- ## Terminology + + + - Normal maximal pituitary height varies with age, sex + - Pregnant/lactating females: 12 mm + - Young menstruating females: 10 mm + - Males, postmenopausal females: 8 mm + - Infants, children: 6 mm + - Nonphysiologic hyperplasia seen with + - Hypothyroidism, Addison disease, or other end-organ failure + - Some neuroendocrine neoplasms +- ## Imaging + + + - Enlarged homogeneously enhancing pituitary gland with convex superior margin + - Best technique: High-resolution MR + - Sagittal/coronal T1; coronal T2 + - Dynamic coronal T1WI + - Postcontrast T1 FS sagittal/coronal T1 + - 3- to 4-mm slice thickness +- ## Top Differential Diagnoses + + + - Pituitary macroadenoma + - Pituitary microadenoma + - Lymphocytic hypophysitis + - Venous congestion (intracranial hypotension, dural arteriovenous fistula) +- ## Pathology + + + - Normal: Physiologic hyperplasia in pregnancy, lactation + - Abnormal: Longstanding untreated primary hypothyroidism + - Loss of thyroxine feedback inhibition, overproduction of thyrotropin-releasing hormone + - Secondary pituitary hyperplasia + - Orthotopic or ectopic production of hypothalamic-releasing hormones + - Orthotopic: Response to end-organ failure + - Ectopic: Related to neuroendocrine tumors + +# TERMINOLOGY + +- ## Definitions + + + - Upper limit of normal pituitary height varies with age, sex + - Pregnant/lactating females: 12 mm + - Young menstruating females: 10 mm + - Males, postmenopausal females: 8 mm + - Infants, children: 6 mm + - Nonphysiologic pituitary hyperplasia seen with + - Longstanding untreated primary hypothyroidism + - Addison disease, end-organ failure, some neuroendocrine neoplasms + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Enlarged homogeneously enhancing pituitary gland with convex superior margin + - > 10 mm up to 15 mm + - May be nodular, mimic pituitary adenoma + - ### Location + + + - Sella; may extend into suprasellar region, compress adjacent structures +- ## CT Findings + + + - ### NECT + + + - Noncalcified pituitary gland enlargement + - ### CECT + + + - Homogeneous enhancement +- ## MR Findings + + + - ### T1WI + + + - Isointense with remainder of pituitary gland + - ### T2WI + + + - Isointense with remainder of pituitary gland + - ### T1WI C+ + + + - Diffusely enhancing gland is typical + - Rare = may cause focal nodular enlargement + - Dynamic MR: Enhances similar to remainder of gland +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR with 3- to 4-mm slices, small FOV + - ### Protocol advice + + + - Sagittal/coronal T1; coronal T2 + - Dynamic enhanced coronal T1WI + - Postcontrast T1 FS sagittal/coronal + +# DIFFERENTIAL DIAGNOSIS + +- [Pituitary Macroadenoma](/document/pituitary-microadenoma/283f3068-d369-4f79-bf01-0f2b82c6e49b) + - May be indistinguishable + - Rare: May occur secondary to primary hypothyroidism +- [Pituitary Microadenoma](/document/pituitary-microadenoma/283f3068-d369-4f79-bf01-0f2b82c6e49b) + - May be indistinguishable + - Enhances slower than normal gland on dynamic study +- [Lymphocytic Hypophysitis](/document/lymphocytic-hypophysitis/f30774c3-cbd0-4ab3-b3d1-e0574106db1f) + - Enlarged gland &/or stalk + - Pregnant or postpartum females +- ## Venous Congestion + + + - [Can occur with intracranial hypotension](/document/intracranial-hypotension/818a7972-1032-4d3e-a65a-97c494334aac) + - [Dural arteriovenous fistulas](/document/dural-av-fistula/628fd160-1e22-4b55-83f9-c25464d05bd6) + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Normal: Physiologic hyperplasia in pregnancy, lactation + - Longstanding untreated primary hypothyroidism + - Loss of thyroxine feedback inhibition, overproduction of thyrotropin-releasing hormone + - Secondary pituitary hyperplasia + - Orthotopic or ectopic production of hypothalamic-releasing hormones + - Orthotopic: Response to end-organ failure + - Ectopic: Related to neuroendocrine tumors +- ## Microscopic Features + + + - Nodular hyperplasia characterized by marked expansion of acini, architectural distortion + - Diffuse hyperplasia requires formal cell count + - Growth hormone cell hyperplasia usually diffuse, occurs with neuroendocrine tumors + - Pancreatic islet cell tumor, pheochromocytoma, and bronchial and thyroid carcinoid tumors + - Associated with McCune-Albright syndrome, multiple endocrine neoplasia syndrome, and Carney complex + - Prolactin cell hyperplasia: Diffuse > nodular + - May be seen with pregnancy and lactation, estrogen treatment, primary hypothyroidism, Cushing disease + - Corticotroph hyperplasia: Nodular or diffuse + - Associated with Cushing disease, neuroendocrine tumors, untreated Addison disease + - Thyrotroph hyperplasia + - Longstanding primary hypothyroidism, may have associated prolactin hyperplasia + - Gonadotroph hyperplasia (e.g., Turner, Klinefelter syndromes) + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Varies with cell type of hyperplasia +- ## Demographics + + + - ### Age + + + - Typically adults (rare in children) + - ### Sex + + + - No predilection +- ## Treatment + + + - If related to hypothyroidism, regression after thyroid hormone therapy common + - Treat end-organ failure or neuroendocrine tumor + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Hyperplasia may mimic adenoma + - Clinical information can help differentiate + - If imaging looks like adenoma in prepubescent male, consider end-organ failure + + f1e3a750-ebdd-439c-8134-0efe1099c891 \ No newline at end of file diff --git a/docs_md/articles/pkan_aa473236-a733-4f9b-8d92-267ab8d4bcd9.md b/docs_md/articles/pkan_aa473236-a733-4f9b-8d92-267ab8d4bcd9.md new file mode 100644 index 0000000..48b296b --- /dev/null +++ b/docs_md/articles/pkan_aa473236-a733-4f9b-8d92-267ab8d4bcd9.md @@ -0,0 +1,246 @@ +--- +title: "PKAN" +docid: "aa473236-a733-4f9b-8d92-267ab8d4bcd9" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Inherited Metabolic/Degenerative Disorders" + - "Miscellaneous" + - "PKAN" +--- +# KEY FACTS + +- ## Terminology + + + - Pantothenate kinase-associated neurodegeneration (PKAN) + - Pantothenate kinase 2 (*PANK2*) mutation + - Most common form of neurodegeneration with brain iron accumulation (NBIA) +- ## Imaging + + + - Best diagnostic clue: Eye of tiger sign = diffuse pallidal T2 hypointensity with medial foci ↑ T2 signal + - Highly suggestive of PKAN + - Hyperintense "eye" may predate surrounding pallidal hypointensity +- ## Top Differential Diagnoses + + + - Disorders with ↑ T2 signal globus pallidus (GP) + - Metabolic: Methylmalonic acidemia (MMA), Kearns-Sayre, L-2-hydroxyglutaric aciduria, Canavan, neuroferritinopathy + - Ischemic/toxic: Anoxic encephalopathy, carbon monoxide/cyanide poisoning, kernicterus +- ## Pathology + + + - *PANK2* gene encodes mitochondrial-targeted pantothenate kinase 2, key enzyme in biosynthesis of coenzyme A (CoA) + - Progressive, physiologic brain iron accumulation occurs in GP, substantia nigra (SN) > red and dentate nuclei + - Basal ganglia and retina vulnerable to oxidative damage secondary to high metabolic demand + - Autosomal recessive (50% sporadic) + - *PANK2* mutation → CoA deficiency → energy and lipid dyshomeostasis → production of oxygen free radicals → phospholipid membrane destruction + - Iron accumulation likely secondary phenomenon in PKAN +- ## Clinical Issues + + + - Classic PKAN: Dystonia, dysarthria, rigidity, choreoathetosis in young child + - Atypical PKAN: Psychiatric, speech, pyramidal/extrapyramidal disturbances in older child/teenager + - Epidemiology + - Rare; incidence unknown + - Prognosis + - Classic PKAN: Fatal; mean disease duration after symptom onset is 11 years + - Atypical PKAN: Eventual severe impairment/death + - No curative treatment +- ## Diagnostic Checklist + + + - Eye of tiger sign highly suggestive of PKAN + - Physiologic GP hypointensity difficult to distinguish from pathologic hypointensity in teenager/adult + +# TERMINOLOGY + +- ## Abbreviations + + + - Pantothenate kinase-associated neurodegeneration (PKAN) +- ## Synonyms + + + - Neurodegeneration with brain iron accumulation type 1 (NBIA-1) + - Hallervorden-Spatz syndrome (obsolete term) + - PKAN and NBIA-1 = preferred terms +- ## Definitions + + + - Neurodegeneration with brain iron accumulation (NBIA) = umbrella term for neurodegenerative disorders characterized by brain iron accumulation + - Known causes include PKAN (most common), aceruloplasminemia, neuroferritinopathy, and infantile neuroaxonal dystrophy + - PKAN caused by mutation pantothenate kinase 2 gene (*PANK2*) + +# IMAGING + +- ## General Features + + + - Best diagnostic clue: Eye of tiger sign = diffuse pallidal T2 hypointensity with medial foci ↑ T2 signal + - Highly suggestive of PKAN + - Hyperintense "eye" may predate surrounding pallidal hypointensity + - "Eye" caliber and intensity ↓ as disease progresses + - Pallidal hypointensity increases as disease progresses + - Eye of tiger sign has been described in neuroferritinopathy + - Variable ↓ T2 signal substantia nigra (SN) > > dentate nuclei (DN) + - Atrophy in advanced diseases + - Location: Globus pallidus (GP), SN, DN + - Morphology: Signal alteration of GP resembles tiger eyes + - Iron deposition (ferritin bound) responsible for T2-hypointense imaging appearance +- ## CT Findings + + + - NECT: Variable; hypodense, hyperdense, normal GP + - CECT: No abnormal enhancement +- ## MR Findings + + + - T1WI: Variable (ferritin-bound iron has > T1 shortening than hemosiderin bound) + - T2WI + - Eye of tiger sign = diffuse pallidal hypointensity with medial foci ↑ signal + - Variable ↓ signal SN; more common in older patients + - FLAIR: "Eye" persists + - T2* GRE: ↓ T2 signal GP, SN "blooms" due to paramagnetic effect iron + - Susceptibility-weighted imaging (SWI): Greater blooming artifact than T2* GRE + - T1WI C+: No abnormal enhancement + - MRS: ↓ NAA GP (neuronal loss) +- ## Nuclear Medicine Findings + + + - Tc-99m SPECT: ↑ activity in medial GP + - Possible chelation Tc-99m by pallidal cysteine +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - Multiplanar MR with SWI + - ### Protocol advice + + + - Consider SWI or T2* GRE sequence for mineralization + - T2 hypointensity more conspicuous on spin-echo (vs. fast spin-echo) and high-field strength magnets + +# DIFFERENTIAL DIAGNOSIS + +- ## Disorders With ↑ T2 Signal Globus Pallidus + + + - Metabolic + - Methylmalonic acidemia (MMA): ↑ T2 signal GP ± periventricular white matter (WM) + - Kearns-Sayre/L-2-hydroxyglutaric aciduria: ↑ T2 GP (> than other deep gray) and peripheral WM + - Canavan: ↑ T2 GP (> than other deep gray) and subcortical WM; macrocephaly; ↑ NAA + - Neuroferritinopathy: Variable-sized foci ↑ T2 signal GP, putamen, caudate heads with ↓ T2 SN, DN; disease of adults + - Guanidinoacetate methyltransferase deficiency (impairs creatine synthesis) + - Ischemic/toxic + - Anoxic encephalopathy: ↑ T2 GP (and other deep gray) and cortex + - Carbon monoxide poisoning: ↑ T2 GP (± other deep gray, cortex, WM) + - Cyanide poisoning: ↑ T2 basal ganglia followed by hemorrhagic necrosis + - Kernicterus: ↑ T2/T1 GP in neonate + +# PATHOLOGY + +- ## General Features + + + - Iron accumulation likely secondary phenomenon in PKAN + - Serial MRs in patients with PKAN show hyperintense foci in GP predating surrounding hypointensity + - Embryology, anatomy + - Progressive, physiologic brain iron accumulation occurs in GP, SN > red and DN + - ↓ T2 signal GP identified in majority of normal patients by age ≥ 25, but never before age 10 + - Genetics + - Autosomal recessive (50% sporadic) + - > 100 *PANK2* mutations Chr 20p12.3-p13 identified + - MR eye of tiger sign highly correlative with *PANK2* mutation + - *PANK2* gene encodes mitochondrial-targeted pantothenate kinase 2, key enzyme in biosynthesis of coenzyme A (CoA) + - CoA essential to energy and fatty acid metabolism, among other functions + - Null mutations are more common in early onset, rapidly progressive disease + - Missense mutations more common in late onset, more slowly progressive disease + - Suggests residual pantothenate kinase 2 activity in late-onset (less severe) disease + - HARP: **H**ypoprebetalipoproteinemia, **a**canthocytosis,**r**etinitis pigmentosa, and **p**allidal degeneration + - Allelic with PKAN + - Prominent orofacial dystonia; early-onset parkinsonism + - Etiology + - Leading theory + - *PANK2* mutation → CoA deficiency → energy and lipid dyshomeostasis → production of oxygen free radicals → phospholipid membrane destruction + - Basal ganglia and retina vulnerable to oxidative damage secondary to high metabolic demand + - Additional factors + - Cysteine accumulation in GP secondary to ↓ phosphopantothenate causes iron chelation and peroxidative cell membrane damage + - Axonal spheroids further compromise glial and neuronal function +- ## Gross Pathologic & Surgical Features + + + - Symmetric, rust-brown pigmentation GP (interna > externa), and pars reticulata SN + - In addition to iron, intra-/extraneuronal ceroid lipofuscin and melanin contribute to pigmentation + - Variable atrophy +- ## Microscopic Features + + + - Classic features + - ↑ iron GP interna and pars reticulata SN + - Iron located in astrocytes, microglial cells, neurons, and around vessels + - Neuronal loss, gliosis, and glial inclusions primarily involving GP interna and pars reticulata SN + - Round or oval, nonnucleated, axonal swellings ("spheroids") in GP, SN, cortex, and brainstem + - Loose tissue (consisting of reactive astrocytes, dystrophic axons, and vacuoles in anteromedial GP) corresponds to "eye" in eye of tiger sign on MR + - Variably present acanthocytes (on blood smear) + +# CLINICAL ISSUES + +- ## Presentation + + + - Clinical classification into classic and atypical disease + - Classic PKAN: Early onset, more rapidly progressive disease, uniform phenotype + - Atypical PKAN: Late onset, more slowly progressive disease, heterogeneous phenotype + - Most common signs/symptoms + - Classic PKAN: Dystonia + - Other extrapyramidal signs/symptoms: Dysarthria, rigidity, choreoathetosis + - Upper motor neuron signs/symptoms and cognitive decline are frequent + - Pigmentary retinopathy (66%) + - Atypical PKAN: Psychiatric and speech disturbances + - Other signs/symptoms: Pyramidal/extrapyramidal disturbances (including freezing), dementia + - Clinical profile + - Classic PKAN: Young child with gait, postural deficits + - Atypical PKAN: Teenager with speech, psychiatric disturbance + - Normal serum and CSF iron levels + - Confirmatory *PANK2* mutation analysis should be performed in all suspected cases of PKAN +- ## Demographics + + + - ### Age + + + - Classic PKAN: Majority present before 6 years of age + - Atypical PKAN: Mean age at presentation is 13 years + - Epidemiology: Rare; incidence unknown +- ## Natural History & Prognosis + + + - Natural History + - Classic PKAN: Rapid, nonuniform progression with periods of deterioration interspersed with stability, leading to early adulthood death + - Atypical PKAN: More slowly progressive with loss of ambulation 15-40 years after disease onset + - Prognosis + - Classic PKAN: Fatal; mean disease duration after symptom onset is 11 years + - Atypical PKAN: Eventual severe impairment, ± death, adulthood +- ## Treatment + + + - No curative treatment; iron chelation ineffective + - Palliative therapy + - Baclofen, trihexyphenidyl frequently ineffective + - Stereotactic pallidotomy + - Promising initial results with pallidal deep brain stimulation + +# DIAGNOSTIC CHECKLIST + +- ## Image Interpretation Pearls + + + - Eye of tiger sign highly suggestive of PKAN + - Physiologic GP hypointensity difficult to distinguish from pathologic hypointensity in teenager/adult + + 75a89de0-4391-4f70-bdeb-e30215e65031 \ No newline at end of file diff --git a/docs_md/articles/primary-progressive-aphasia_app.statdx.com_document_content_5dca11fe-b5ee-404c-b22e-4008b7571844_3b5d482e_20251014T193517Z.md b/docs_md/articles/primary-progressive-aphasia_5dca11fe-b5ee-404c-b22e-4008b7571844.md similarity index 97% rename from docs_md/articles/primary-progressive-aphasia_app.statdx.com_document_content_5dca11fe-b5ee-404c-b22e-4008b7571844_3b5d482e_20251014T193517Z.md rename to docs_md/articles/primary-progressive-aphasia_5dca11fe-b5ee-404c-b22e-4008b7571844.md index b15769b..2b96963 100644 --- a/docs_md/articles/primary-progressive-aphasia_app.statdx.com_document_content_5dca11fe-b5ee-404c-b22e-4008b7571844_3b5d482e_20251014T193517Z.md +++ b/docs_md/articles/primary-progressive-aphasia_5dca11fe-b5ee-404c-b22e-4008b7571844.md @@ -1,5 +1,12 @@ -# Primary Progressive Aphasia - +--- +title: "Primary Progressive Aphasia" +docid: "5dca11fe-b5ee-404c-b22e-4008b7571844" +breadcrumbs: + - "Nuclear Medicine" + - "Central Nervous System" + - "Neurodegeneration" + - "Primary Progressive Aphasia" +--- # KEY FACTS - ## Terminology @@ -207,4 +214,4 @@ - Exclude alternative etiologies and identify normal areas of metabolism on F-18 FDG PET - Consider additional imaging, such as amyloid PET, for suspected lvPPA, which would be beneficial for assessing candidacy for amyloid-targeting therapies - 92b83333-bc7b-40b2-b629-dd77297359fc + 92b83333-bc7b-40b2-b629-dd77297359fc \ No newline at end of file diff --git a/docs_md/articles/progressive-supranuclear-palsy_840ed321-c0ab-4069-a07e-ad416232f916.md b/docs_md/articles/progressive-supranuclear-palsy_840ed321-c0ab-4069-a07e-ad416232f916.md new file mode 100644 index 0000000..c8ded8d --- /dev/null +++ b/docs_md/articles/progressive-supranuclear-palsy_840ed321-c0ab-4069-a07e-ad416232f916.md @@ -0,0 +1,288 @@ +--- +title: "Progressive Supranuclear Palsy" +docid: "840ed321-c0ab-4069-a07e-ad416232f916" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Progressive Supranuclear Palsy" +--- +# KEY FACTS + +- ## Terminology + + + - Neurodegenerative disease characterized by vertical supranuclear gaze palsy, postural instability, mild dementia +- ## Imaging + + + - Midbrain atrophy (penguin or hummingbird sign) + - Sagittal T1WI shows concave/flat upper border of midbrain (normally convex) + - Axial T1WIs show abnormal concavity of lateral margins of midbrain tegmentum (morning glory or Mickey Mouse sign) + - Thinning of superior colliculus + - Midsagittal 3D-MPRAGE or FSPGR images + - Voxel-based morphometry used to calculate ratio of midbrain area:pons area + - Midbrain area < 70 mm² (50% of normal) + - Midbrain:pons ratio < 0.15 strongly suggests PSP + - MR parkinsonism index: Allows discrimination of PSP from MSA-P, PD, and control + - New MRPI 2.0 more powerful than MRPI for differentiating PSP from PD +- ## Top Differential Diagnoses + + + - Multiple system atrophy, parkinsonian type + - Corticobasal degeneration + - Dementia with Lewy bodies + - Parkinson disease +- ## Pathology + + + - Neurofibrillary tangles and neuropil threads in globus pallidus, subthalamic nucleus, substantia nigra; cerebral cortex relatively preserved except for perirolandic cortex + - Neuronal loss, tufted astrocytes (hallmark of PSP), and coiled bodies of oligodendrocyte +- ## Clinical Issues + + + - PSP-RS (Richardson syndrome) + - Lurching gait, axial dystonia, vertical supranuclear palsy + - PSP-P (parkinsonian type) + - Bradykinesia, rigidity, normal eye movements + - 2nd most common neurodegenerative cause of parkinsonism overall + +# TERMINOLOGY + +- ## Abbreviations + + + - Progressive supranuclear palsy (PSP) +- ## Synonyms + + + - Steele-Richardson-Olszewski syndrome +- ## Definitions + + + - Atypical parkinsonian syndrome and neurodegenerative disease characterized by vertical supranuclear gaze palsy, postural instability with unexplained falls, akinesia, and cognitive dysfunction + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Midbrain tegmentum atrophy (penguin or hummingbird sign) + - Most accurate: Calculation of midbrain area:pons area ratio + - Distinguishes PSP from other conditions + - PSP vs. parkinsonian form of multisystem atrophy (MSA-P) + - ### Location + + + - Midbrain + - Tegmentum + - Tectum (superior colliculus) + - ### Morphology + + + - Prominent midbrain volume loss + - Pons normal +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR + - PET + - ### Protocol advice + + + - Midsagittal T1WI + - 3D MPRAGE or FSPGR images + - Use voxel-based morphometry to calculate ratio of midbrain area:pons area +- ## CT Findings + + + - ### NECT + + + - Atrophy of midbrain with prominent mesencephalic cisterns and enlarged 3rd ventricle +- ## MR Findings + + + - ### T1WI + + + - Sagittal T1WI helpful in detecting midbrain tectal atrophy (penguin or hummingbird sign) + - Concave or flat profile of cephalad surface of midbrain (as opposed to normal convex superior profile) + - Thinning of superior colliculus + - Axial T1WIs show abnormal concavity of lateral margins of midbrain tegmentum (morning glory or Mickey Mouse sign) + - Superior cerebellar peduncle atrophy (correlates with disease duration) + - Midbrain area ~ 1/2 that of normal individuals + - Ratio of midbrain area:pons area in PSP (0.124) was significantly smaller than in Parkinson disease (PD) (0.208), MSA-P (0.266), and normal control (0.237) + - Sagittal midbrain area < 70 mm², ratio of midbrain tegmentum:pons area < 0.15 → diagnostic of PSP + - Sensitivity: 100%; specificity: 91-100% + - MR parkinsonism index (MRPI) = (pons area/midbrain area x middle cerebellar peduncle width/superior cerebellar peduncle width) + - Allows discrimination of patients with PSP from MSA-P, PD, and control with 100% sensitivity, 100% specificity, and 100% PPV + - MRPI 2.0 + - MRPI 2.0 = MRPI x (3rd ventricle width/frontal horns width) + - Higher sensitivity (100%) and similar specificity (94.3%) of MRPI 2.0 in differentiating patients with PSP-P from those with PD when compared to previous MRPI (sensitivity and specificity of 73.5% and 98.1%, respectively) + - More powerful than MRPI in differentiating PSP patients in early stage of disease with slowness of vertical saccades from patients with PD + - Help clinicians to consolidate diagnosis based on clinical features + - AP midbrain diameter < 17 mm + - ### T2WI + + + - ↓ AP diameter of midbrain on axial T2WI < 17 mm, 75% positive predictive value in differentiating PSP from MSA + - Hyperintense signal in midbrain tegmentum = periaqueductal + - Prominent mesencephalic cisterns and enlarged 3rd ventricle + - Occasionally abnormal hypointense signal in striatum + - ### DWI + + + - ↑ ADC in putamen might discriminate PSP from PD + - ↑ ADC in decussation of superior cerebellar peduncles + - DTI + - ↑ mean diffusivity in decussation of superior cerebellar peduncle + - DTI indices (fractional anisotropy, mean diffusivity) demonstrate widespread white matter abnormalities + - ↑ mean diffusivity in midbrain of PSP patients compared with PD and MSA +- ## Nuclear Medicine Findings + + + - ### PET + + + - 18 F-FDG ↓ in putamen, thalamus, medial frontal cortex, and midbrain + - 11C-raclopride PET ↓ striatal dopamine receptor binding + - Fluorodopa-PET: Reduction of F-dopa uptake in caudate, putamen (more severe than in PD) + - SPECT + - I-123-IBZM SPECT: Reduced dopamine receptor binding in striatum + +# DIFFERENTIAL DIAGNOSIS + +- [Multiple System Atrophy, Parkinsonian Type](/document/multiple-system-atrophy/4fb9af00-e0bd-4164-8f61-4011ddc8bf9e) + - T2 hypointensity in putamen without prominent midbrain atrophy + - Cerebellar and pontine atrophy + - Prominent cerebellar symptoms, autonomic dysfunction, parkinsonism +- [Corticobasal Degeneration](/document/corticobasal-degeneration/23f97d4e-8724-4229-b9f8-08f63906ebd8) + - Severe frontoparietal atrophy in asymmetric pattern + - Unilateral parkinsonism + - "Alien limb" phenomenon, cortical sensory deficit +- [Dementia With Lewy Bodies](/document/dementia-with-lewy-bodies/e8e46d1d-46d2-4e5a-880f-f025a84c5871) + - Cortical atrophy without prominent midbrain atrophy + - Hallucinations, cortical dementia with aphasia, parkinsonism +- [Parkinson Disease](/document/parkinson-disease/0bc3188a-935b-416d-b1a0-25b2d52c6399) + - No prominent midbrain atrophy + - Tremor-dominant clinical symptoms, good response to levodopa + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - PSP is tauopathy + - Abnormal accumulation of phosphorylated tau protein in brain + - Pallidum, subthalamic nucleus, red nucleus, substantia nigra, pontine tegmentum, striatum, oculomotor nucleus, medulla, dentate nucleus + - ### Genetics + + + - Associated with tau, *MTAP* on chromosome 17 + - Tau haplotype H1 associated with both PSP and corticobasal degeneration + - Suggests that gene on chromosome 17 for tau abnormality causes both diseases +- ## Gross Pathologic & Surgical Features + + + - Atrophy of subthalamic nucleus and brainstem (midbrain tectum and superior cerebellar peduncle) + - Loss of pigmentation in substantia nigra → nigrostriatal dopaminergic degeneration +- ## Microscopic Features + + + - Neuronal loss, astrocytic plaques, and tufts of abnormal fibers are highly characteristic of typical PSP + - Neurofibrillary tangles and neuropil threads in globus pallidus, subthalamic nucleus, substantia nigra; cerebral cortex relatively preserved except for perirolandic cortex + - Tau pathology is also noted in glia: Tufted astrocytes (hallmark of PSP), coiled bodies of oligodendrocyte + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - PSP-RS (Richardson syndrome): More common classic type + - Classic, more common presentation of lurching gait, axial dystonia, vertical supranuclear palsy + - PSP-P (parkinsonian type) 1/3 patients + - Bradykinesia, rigidity, normal eye movements, and transient response to levodopa + - Postural instability and frequent falls, oculomotor findings, cognitive and behavioral change, memory problems, sleep disturbance, apathy + - Most common cause of atypical parkinsonian syndrome + - 2nd most common neurodegenerative cause of parkinsonism overall + - Clinical criteria for "probable" PSP + - Probable PSP is diagnosed when clinical features with high specificity are present + - Gradually progressive bradykinetic/akinetic disorder + - Vertical gaze palsy and slowing of vertical saccades + - Prominent postural instability with falls in 1st year + - Cognitive dysfunction + - Sporadic occurrence, onset at age 40 or later + - No evidence for competing diagnostic possibilities + - Exclusion criteria + - Recent encephalitis, alien limb syndrome, cortical sensory defects or temporoparietal atrophy, psychosis unrelated to dopaminergic treatment, important cerebellar signs, severe asymmetric parkinsonian signs, relevant structural abnormality of basal ganglia on neuroimaging + - Severe cerebral leukoencephalopathy, relevant structural abnormality (e.g., NPH; basal ganglia, diencephalic, mesencephalic, pontine or medullary infarctions, hemorrhages, hypoxic-ischemic lesions, tumors, or malformations) +- ## Demographics + + + - ### Age + + + - Generally 45-75 years + - Peak onset: 65 years + - ### Sex + + + - No sex predominance + - ### Epidemiology + + + - Prevalence: 3-7 cases per 100,000 +- ## Natural History & Prognosis + + + - Most common atypical parkinsonian syndrome with variable disease course + - Survival from time of symptom onset in PSP ranges from 5.3-9.7 years + - Neuropsychiatric symptoms develop > 50% patients within 2 years of disease onset +- ## Treatment + + + - Symptomatic + - Levodopa may help rigidity and bradykinesia of PSP + - Mitochondrial nutrient coenzyme Q10 can give modest benefit +- ## Variant PSP Syndrome + + + - PSP with Richardson syndrome (PSP-RS), + - PSP with predominant parkinsonism (PSP-P) + - PSP with predominant oculomotor dysfunction (PSP-OM) + - PSP with predominant postural instability (PSP-PI) + - PSP with progressive gait freezing (PSP-PGF) + - PSP with predominant frontal presentation (PSP-F) + - PSP with predominant speech/language disorder (PSP-SL) + - PSP with predominant corticobasal syndrome (PSP-CBS) + - PSP with predominant cerebellar ataxia (PSP-C) + - PSP with predominant primary lateral sclerosis (PSP-PLS) + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Consider PSP when MR shows marked midbrain atrophy in patients with atypical parkinsonism, vertical gaze palsy, and cognitive dysfunction +- ## Image Interpretation Pearls + + + - Sagittal images helpful in identifying penguin silhouette sign + - Minimal or no lobar atrophy + + fff14e0c-5958-4336-93e1-26ef6cac9c30 \ No newline at end of file diff --git a/docs_md/articles/rathke-cleft-cyst_8f1561f7-92a7-485c-a0ae-2e2d5c8c1628.md b/docs_md/articles/rathke-cleft-cyst_8f1561f7-92a7-485c-a0ae-2e2d5c8c1628.md new file mode 100644 index 0000000..43afacc --- /dev/null +++ b/docs_md/articles/rathke-cleft-cyst_8f1561f7-92a7-485c-a0ae-2e2d5c8c1628.md @@ -0,0 +1,310 @@ +--- +title: "Rathke Cleft Cyst" +docid: "8f1561f7-92a7-485c-a0ae-2e2d5c8c1628" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Anatomy-Based Diagnoses" + - "Sella and Pituitary" + - "Congenital" + - "Rathke Cleft Cyst" +--- +# KEY FACTS + +- ## Terminology + + + - Nonneoplastic cyst arising from remnants of embryonic Rathke cleft + - Benign, sellar region endodermal cyst lined by ciliated, mucus-producing epithelium +- ## Imaging + + + - Nonenhancing, noncalcified, intrasellar &/or suprasellar cyst with intracystic nodule + - Completely intrasellar (40%), suprasellar extension (60%) + - Density/signal intensity varies with cyst content (serous vs. mucoid) + - Most symptomatic RCCs: 5-15 mm in diameter + - Occasionally RCCs can become very large + - Claw sign = enhancing rim of compressed pituitary surrounding nonenhancing cyst + - No internal enhancement +- ## Top Differential Diagnoses + + + - Craniopharyngioma + - Cystic pituitary adenoma + - Arachnoid cyst + - Other nonneoplastic cyst (pars intermedia, colloid cyst) +- ## Clinical Issues + + + - Most are asymptomatic, found incidentally at imaging or autopsy + - Common presenting features when symptomatic: Headache, pituitary dysfunction, visual changes + - Rare but important: Apoplexy, cavernous sinus syndrome + - Can be indistinguishable from pituitary apoplexy + - Conservative management if asymptomatic + - Have been reported to resolve without therapy + - Surgical aspiration, partial excision, or resection if symptomatic + - Recurrence rates in up to 18% of patients + +# TERMINOLOGY + +- ## Abbreviations + + + - Rathke cleft cyst (RCC) +- ## Definitions + + + - Nonneoplastic cyst arising from remnants of embryonic Rathke cleft + - Benign, sellar region endodermal cyst lined by ciliated, mucus-producing epithelium + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Nonenhancing, noncalcified, intrasellar &/or suprasellar cyst with intracystic nodule + - Uncommon but pathognomonic = posterior ledge sign + - Upward extension through diaphragma sellae + - Ledge of tissue overlies posterior lobe + - ### Location + + + - Completely intrasellar (40%), suprasellar extension (60%) + - Most Rathke cleft cysts are limited to sella + - Between anterior, intermediate lobes + - Symptomatic Rathke clef cysts involve suprasellar location + - ### Size + + + - Most symptomatic Rathke cleft cysts 5-15 mm in diameter + - Occasionally become very large + - May cause expansile, intrasellar/suprasellar mass + - Rare: Erosion of skull base + - Size usually constant, does not enlarge + - Transient decrease reported in response to glucocorticoids + - ### Morphology + + + - Well defined, round/ovoid +- ## CT Findings + + + - ### NECT + + + - Well-delineated, round/lobulated, intra-/suprasellar mass + - Hypodense (75%), mixed iso-/hypodense (20%) + - Hyperdense (5-10%) + - Ca⁺⁺ (10-15%), curvilinear, in cyst wall + - Rare: May cause sphenoid sinusitis + - ### CECT + + + - Does not enhance + - Occasionally see claw sign with normal pituitary gland surrounding cyst +- ## MR Findings + + + - ### T1WI + + + - Varies with cyst content (serous vs. mucoid) + - Hyperintense (50%), hypointense (50%) + - Hyperintense, intracystic nodule (75%) + - Mixed (5-10%), may have fluid-fluid level + - ### T2WI + + + - Varies with cyst content + - Hyperintense (70%), iso-/hypointense (30%) + - Hypointense, intracystic nodule (75%) + - ### FLAIR + + + - Hyperintense + - ### T2* GRE + + + - Rarely see susceptibility artifact + - ### T1WI C+ + + + - No internal enhancement + - Claw sign = enhancing rim of compressed pituitary surrounding nonenhancing cyst + - Small, nonenhancing, intracystic nodule (75%) + - If enhancing nodule present, likely craniopharyngioma +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR + - ### Protocol advice + + + - Thin-section, high-resolution imaging of sellar region + - Sagittal, coronal precontrast T1/T2 MR + - "Dynamic" coronal T1 C+ MR through sella + - Sagittal, coronal thin-section T1 C+ MR + +# DIFFERENTIAL DIAGNOSIS + +- [Craniopharyngioma](/document/craniopharyngioma/00e66680-6731-4287-b5a1-3f0b3f09053b) + - Histologic continuum between Rathke cleft cyst, craniopharyngioma + - Floccular Ca⁺⁺ common in craniopharyngioma, rare in Rathke cleft cyst + - Noncalcified RCC can be indistinguishable from craniopharyngioma on imaging + - Rim or nodular enhancement (90%) + - Cytokeratin profile helps distinguish from Rathke cleft cyst + - RCCs express cytokeratins 8, 20 +- [Cystic Pituitary Adenoma](/document/pituitary-microadenoma/283f3068-d369-4f79-bf01-0f2b82c6e49b) + - Ca⁺⁺ rare + - Signal intensity often heterogeneous + - Rim or rim with nodular enhancement common +- [Arachnoid Cyst](/document/arachnoid-cyst/d25aaeb3-5b3c-4483-99dc-2757468eedb9) + - Follows CSF signal intensity + - Does not occur within pituitary gland + - No intracystic nodule +- ## Other Nonneoplastic Cyst + + + - [Dermoid cyst](/document/dermoid-cyst/9b7aeb04-2cb3-405d-8c51-dd13297dd67c) + - May have short T1 signal related to fat or Ca⁺⁺ + - Look for evidence of rupture + - [Epidermoid cyst](/document/epidermoid-cyst/704c5ddf-e1f7-4a5d-a1b8-5b0e603170d9) + - Mild irregular enhancement, Ca⁺⁺ (25%) + - DWI hyperintensity, FLAIR lack of suppression + - Otherwise follow CSF signal + - [Miscellaneous intrasellar cyst](/document/dermoid-cyst/9b7aeb04-2cb3-405d-8c51-dd13297dd67c) + - Pars intermedia, colloid cysts + - [Rare: Sellar/hypophyseal neurocysticercosis (NCC)](/document/neurocysticercosis/6a45835f-6d7c-443e-874a-f33131d3def1) + - May see racemose NCC in sellar/suprasellar region + - May rarely see scolex + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - One of spectrum of midline sellar/juxtasellar endodermal cysts + - Arises from embryonic remnants of fetal Rathke pouch + - Rathke cleft normally regresses by 12th gestational week + - ### Genetics + + + - No known heritable conditions + - ### Associated abnormalities + + + - Sphenoid sinusitis (rare) + - Compression of optic chiasm, pituitary gland, hypothalamus + - May cause hyperintensity on T2WI/FLAIR along optic chiasm, tracts + - Embryology + - Persistence of Rathke pouch + - Stomodeum (primitive oral cavity) invaginates + - Extends dorsally, forms craniopharyngeal duct + - Meets infundibulum (outgrowth of 3rd ventricle) by 11th fetal week, gives rise to hypophysis + - Anterior wall of pouch forms anterior lobe, pars tuberalis + - Posterior wall forms pars intermedia + - Lumen forms narrow cleft (Rathke cleft) that normally regresses by 12th week of gestation + - Persistence, expansion gives rise to RCC +- ## Gross Pathologic & Surgical Features + + + - Smoothly lobulated, well-delineated, intrasellar/suprasellar cystic mass + - Content varies from clear CSF-like fluid to thick mucoid material +- ## Microscopic Features + + + - Wall = single layer of ciliated cuboidal/columnar epithelium ± goblet cells + - Changes of mixed acute, chronic inflammation may be present + - May see squamous metaplasia (associated with increased rates of recurrent cysts) + - Variable cyst content + - Clear or serous + - ± hemorrhage, hemosiderin + - Amorphous, inspissated, eosinophilic, mucicarmine (+) colloid ± cholesterol clefts + - Firm, waxy, yellow, inspissated material + - Rare: Hemorrhage (cyst apoplexy) + - Immunohistochemical stains positive for cytokeratin + - Express cytokeratins 8, 20 + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Most are asymptomatic, found incidentally at imaging or autopsy + - Found in up to ~ 20% of autopsy cases + - Symptomatic Rathke cleft cyst + - Larger lesions, typically > 1 cm + - Pituitary dysfunction (70%) + - Amenorrhea/galactorrhea, diabetes insipidus, panhypopituitarism, hyperprolactinemia + - Visual disturbances (45-55%) + - Headache (50%) + - Other signs/symptoms + - Head pain, visual disturbance + - Hypopituitarism + - Central diabetes insipidus + - Rare but important: Apoplexy, cavernous sinus syndrome + - Cyst apoplexy + - Can occur ± intracystic hemorrhage + - Can be indistinguishable from pituitary apoplexy + - Cavernous sinus syndrome + - Caused by lateral extension of Rathke cleft cyst into cavernous sinus + - ### Clinical profile + + + - Asymptomatic most commonly +- ## Demographics + + + - ### Age + + + - Mean: 45 years + - ### Sex + + + - Slight female predominance + - ### Epidemiology + + + - Common, intrasellar/suprasellar, nonneoplastic cyst + - Usually incidental, found in up to 20% of all autopsies +- ## Natural History & Prognosis + + + - Most are stable, do not change in size/signal intensity + - Some cysts may shrink/disappear spontaneously + - Iso-/hyperintense cysts on T1 MR more often cause symptoms + - Rathke cleft cysts do not undergo neoplastic degeneration + - Some authors propose continuum from RCC to craniopharyngioma +- ## Treatment + + + - Conservative if asymptomatic + - Surgical aspiration/partial excision/resection if symptomatic + - Persistent/recurrent cyst formation occurs in ~ 15-18% of patients + - May occur many years after surgery + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Obtaining endocrine profile +- ## Image Interpretation Pearls + + + - Look for hypointense, intracystic nodule on T2 MR + + 7627570e-5f61-4f2f-9e4d-fb044c354667 \ No newline at end of file diff --git a/docs_md/articles/solitary-cystic-parenchymal-mass-general_8bfa943b-c158-4a3b-9d43-e6ef057f45d4.md b/docs_md/articles/solitary-cystic-parenchymal-mass-general_8bfa943b-c158-4a3b-9d43-e6ef057f45d4.md new file mode 100644 index 0000000..42218c5 --- /dev/null +++ b/docs_md/articles/solitary-cystic-parenchymal-mass-general_8bfa943b-c158-4a3b-9d43-e6ef057f45d4.md @@ -0,0 +1,147 @@ +--- +title: "Solitary Cystic Parenchymal Mass, General" +docid: "8bfa943b-c158-4a3b-9d43-e6ef057f45d4" +breadcrumbs: + - "Brain" + - "Differential Diagnosis" + - "Brain Parenchyma, General" + - "Generic Imaging Patterns" + - "Solitary Cystic Parenchymal Mass, General" +--- +# ESSENTIAL INFORMATION + +- ## Key Differential Diagnosis Issues + + + - Definition + - Includes cystic or cyst-like parenchymal masses + - Excludes extraaxial cysts + - Cisternal (arachnoid cyst), intraventricular (ependymal or choroid plexus cyst), or choroid fissure cysts + - Includes "pseudoparenchymal" lesions that invaginate into brain, mimic cystic parenchymal/intraaxial mass + - Cystic meningioma, epidermoid/dermoid cyst + - Key clinical issue: Effect of age on diagnosis + - More common in children + - Porencephaly, encephalomalacia, infection (abscess, parasite), neoplasm (primary > > metastatic) + - More common in adults + - Enlarged perivascular space (PVS), encephalomalacia, neoplasm (glioblastoma, metastasis), infection (abscess, parasite) + - Key imaging issues + - Does cystic mass follow CSF**exactly** in density/signal intensity? + - Enlarged PVS, encephalomalacia, porencephalic or neuroglial cyst, some parasitic cysts + - Does cystic mass **not**follow CSF exactly? + - Cystic neoplasm, abscess, tumefactive demyelination, epidermoid or neurenteric cyst, some parasitic cysts + - Is density/signal intensity of surrounding brain abnormal? + - Encephalomalacia, infection, neoplasm + - Does lesion enhance (focal nodule or ring)? + - Yes: Neoplasm, abscess, resolving (subacute) hematoma, tumefactive demyelination + - No: Enlarged PVS, encephalomalacia, porencephalic or neuroglial cyst + - Does cyst have mural nodule or scolex? + - Neoplasm; neurocysticercosis or other parasites +- ## Helpful Clues for Common Diagnoses + + + - **Enlarged Perivascular Space** + - Usually multiple but can be solitary + - Well-delineated, round/ovoid, isodense/isointense to CSF cyst; may see central/traversing vessel + - Large/giant PVS may show surrounding FLAIR hyperintensity due to chronic gliosis + - **Cystic Encephalomalacia** + - Prior injury, including trauma, ischemia/infarction + - Cystic areas isodense/isointense to CSF + - Adjacent parenchyma often hyperintense on FLAIR due to gliosis without cavitation + - **Neurocysticercosis** + - Parenchymal cysts often multiple but may be solitary ± visible scolex, usually ≤ 2 cm + - Cyst fluid may be proteinaceous, not exactly follow CSF + - Variable enhancement/edema depending on stage + - Parenchymal calcifications often present + - **Porencephalic Cyst** + - CSF-containing cyst contiguous with ventricle + - Most commonly seen in children: In utero or perinatal periventricular white matter (WM) injury + - **Metastasis** + - 30% are solitary + - Ring enhancement is common, but center typically does not restrict diffusion; helps to distinguish from pyogenic abscess, which shows central ↓diffusion + - **Glioblastoma, IDH-Wildtype** + - Most common malignant primary brain tumor + - Cyst formation is common; also necrosis, hemorrhage, neovascularity, vasogenic edema + - Thick, irregular rim or nodular enhancement + - Supratentorial WM most common location + - **Abscess** + - Appearance depends on stage: Rim enhancement typical in late cerebritis, early and late capsular stages + - Central restricted diffusion due to pus: Bright on DWI + - Dual rim sign may be seen on T2/FLAIR/SWI (hypointense outside, hyperintense inside) + - **Pilocytic Astrocytoma** + - Usually seen in children, young adults + - Cyst with mural nodule is most common pattern; often centered on cerebellar vermis or hemisphere + - Cyst contents variably isodense/isointense to CSF +- ## Helpful Clues for Less Common Diagnoses + + + - **Intracerebral Hematoma (Resolving)** + - Center slightly hyperdense to CSF on NECT + - Cystic portion usually hyperintense on T1 and T2WI + - Low signal intensity rim (hemosiderin) on GRE/SWI + - Rim enhancement common + - **Demyelinating Lesion** + - True cyst formation is uncommon + - Tissue destruction may → cyst formation with large, tumefactive lesions (> 2 cm) + - Incomplete ring of enhancement ± restricted diffusion + - Relative lack of edema, mass effect for size + - **Ganglioglioma** + - Cortically based cyst(s) with enhancing nodule + - Variable Ca⁺⁺; may remodel skull if large enough + - **Dysembryoplastic Neuroepithelial Tumor** + - Cortically based mass, common in temporal lobe + - Solitary cyst or cluster of multiple cysts ± enhancing nodule(s); may be indistinguishable from ganglioglioma + - Calcification in ~ 30%; little or no associated edema + - **Pleomorphic Xanthoastrocytoma** + - Cortically based cyst + nodule + - Infiltration of dura/dural tail has been described + - Typically larger, more aggressive appearing than ganglioglioma or DNET; + vasogenic edema + - **Hemangioblastoma** + - Young to middle-aged adults + - May be multiple, familial (von Hippel-Lindau disease) + - Typical: Posterior fossa cyst + enhancing nodule that abuts pial surface; may lack cyst, especially if small + - Hypervascular; macroscopic vessels seen with larger lesions; hyperperfusion is typical + - **Meningioma, Cystic** + - Most common intracranial extraaxial tumor + - May push deeply into parenchyma; rarely 1° intraaxial + - Enhancing mass with ≥ 1 peripheral or intralesional cysts + - **Epidermoid Cyst** + - Irregular, cauliflower-like margins + - Typically extraaxial, but can insinuate deeply into brain parenchyma; rarely 1° intraaxial + - CT: Similar to CSF; not typically calcified + - MR: Does not suppress on FLAIR; marked ↓ diffusion + - DWI very helpful to detect postoperative residual + - **Dermoid Cyst** + - Congenital ectodermal inclusion cyst, like epidermoid + - Variable fat content, fat-fluid level(s), calcification + - Ruptured dermoid → fat droplets in subarachnoid space + - **Neuroglial Cyst** + - a.k.a. glioependymal cyst + - Frontal lobe most common site + - Unilocular, well-delineated cyst with thin wall; usually suppresses on FLAIR; no diffusion restriction, no enhancement, and no edema + - Minimal/no surrounding signal abnormality + - **Ependymoma, Supratentorial** + - 1/3 of ependymomas + - 80% parenchymal, not arising within or contacting ventricular surface + - Often large, heterogeneous with cyst formation, hemorrhage, calcification (50%) + - Variable enhancement of cyst wall, solid component +- ## Helpful Clues for Rare Diagnoses + + + - **Parasites, Miscellaneous** + - Solitary or conglomerate cyst(s) + - Some (e.g., hydatid cyst) characteristically very large + - Eccentric nodule may suggest toxoplasmosis + - **Schwannoma, Cystic** + - Only 1-2% of schwannomas arise in brain parenchyma + - Nonspecific peripheral cyst and enhancing nodule + - **Neurenteric Cyst** + - Most are extraaxial in posterior fossa/spinal canal + - Rarely occur in supratentorial brain + - Well-delineated cyst with variable density/signal intensity + - **Desmoplastic Infantile Ganglioglioma** + - Cystic tumor of infants variably involving superficial cerebral cortex, leptomeninges, dura + - Large cyst and peripheral tumor nodule + - Enhancement of adjacent meninges + - **Encephaloclastic Cyst** + - Uncommon complication of catheter-based intraventricular chemotherapy or deep brain stimulating electrode placement + - Cystic dilatation of brain parenchyma around catheter or electrode, surrounding edema \ No newline at end of file diff --git a/docs_md/articles/spinocerbellar-ataxia_df64565a-5c8c-4387-879b-b341b655e478.md b/docs_md/articles/spinocerbellar-ataxia_df64565a-5c8c-4387-879b-b341b655e478.md new file mode 100644 index 0000000..19f57f2 --- /dev/null +++ b/docs_md/articles/spinocerbellar-ataxia_df64565a-5c8c-4387-879b-b341b655e478.md @@ -0,0 +1,320 @@ +--- +title: "Spinocerbellar Ataxia" +docid: "df64565a-5c8c-4387-879b-b341b655e478" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Spinocerbellar Ataxia" +--- +# KEY FACTS + +- ## Terminology + + + - Spinocerebellar ataxia (SCA) +- ## Imaging + + + - Cerebellum atrophy always, brainstem often + - Supratentorial atrophy variably in volumetric analysis + - Cerebellum & pontine tegmentum (dorsal pons) atrophy in SCA1, SCA3 [Machado-Joseph disease (MJD)], DRPLA + - Cerebellum & pontine base (ventral pons) atrophy in SCA2 + - Pontine base:tegmentum distance ratio (BT-ratio) useful + - Cerebellum atrophy purely/predominantly in SCA5, SCA6, SCA11, SCA26, SCA30, SCA31, SCA37 + - Superior cerebellar peduncle atrophy in MJD, SCA6, SCA8, DRPLA; severe cerebral atrophy in juvenile-onset DRPLA + - Medulla & upper cervical cord atrophy in SCA3 (MJD); relative lack of cord involvement in SCA6 + - Hot cross bun sign in pons in SCA2 & rarely MJD + - Anteroposteriorly oriented pontine midline linear T2-hyperintensity (PMH) in SCA1, SCA2, SCA3 (MJD), DRPLA + - Bilateral bright middle cerebellar peduncle (MCP) sign rarely in SCA2, SCA3 (MJD), SCA6, DRPLA + - Cerebral white matter (WM), brainstem, & thalamic hyperintensities in adult-onset DRPLA + - Cerebral WM signal abnormalities usually absent in juvenile-onset DRPLA + - Periventricular WM changes may be seen in very late stage +- ## Top Differential Diagnoses + + + - Multiple system atrophy-cerebellar (MSA-C) + - Friedrich ataxia + - Ataxia with oculomotor apraxia types 1 & 2 + - Ataxia telangiectasia + - Fragile X-associated tremor/ataxia syndrome (FXTAS) + - Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) +- ## Pathology + + + - Autosomal dominant ataxia; many SCAs due to PolyQ expansion of coding CAG repeats + - Various other gene loci & proteins in remaining SCAs + - Commonest mutant genes: *ATXN1* (SCA1), *ATXN2* (SCA2), *ATXN3* (SCA3/MJD),*CACNA1A* (SCA6), *ATN1* (DRPLA) +- ## Clinical Issues + + + - Young to middle-aged patient with slowly progressing cerebellar ataxia & other typical associated symptoms +- ## Diagnostic Checklist + + + - Atrophy of cerebellum ± brainstem + - Evaluate axial T2WI for characteristic hyperintense signal in SCA types, especially pons, MCP, periventricular WM + +# TERMINOLOGY + +- ## Abbreviations + + + - Spinocerebellar ataxia (SCA) + - Polyglutamine repeats (PolyQ) + - Cytosine-adenine-guanine (CAG) + - Machado-Joseph disease (MJD) + - Dentatorubropallidoluysian atrophy (DRPLA) + - Distance ratio of pontine base:tegmentum (BT-ratio) +- ## Synonyms + + + - MJD = Spinocerebellar ataxia type 3 (SCA3) +- ## Definitions + + + - Slowly progressive cerebellum and cerebellar interconnection neurodegenerative diseases + - Autosomal dominant ataxia; many SCAs [SCA1, SCA2, SCA3 (MJD), SCA6, SCA7, SCA12, SCA17] due to PolyQ expansion of coding CAG repeats, similar to Huntington disease + - SCA8 shows CTG expansion and complementary CAG repeat + - Various other gene loci and proteins in remaining SCAs + - SCA type number as per order in which disease identified (by linkage analysis initially and gene discovery lately) + - SCA types now 1-40 and beyond; but SCA9, SCA33, and SCA39 not been assigned to specific clinical disorders + - SCA1, SCA2, SCA3, SCA6 relatively common types with SCA3 (MJD) being most common among these worldwide + - DRPLA, CAG repeat PolyQ expansion disorder that resembles SCA, usually discussed along with SCA + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Atrophy of cerebellum ± brainstem + - Atrophy difficult to detect in early stage, careful MR analysis needed + - ### Location + + + - Cerebellum always, brainstem often, supratentorial structures variably on volumetric analysis + - Early stages of any SCA may show pure cerebellar atrophy and later show brainstem atrophy + - ### Size + + + - Atrophy of involved structures + - Cerebellum and **pontine tegmentum (dorsal pons)** atrophy: SCA1, SCA3 (MJD), DRPLA + - Cerebellum and **basal pons (ventral pons)** atrophy: SCA2 + - Cerebellum atrophy purely/predominantly: SCA5, SCA6, SCA11, SCA26, SCA30, SCA31, SCA37 + - Superior cerebellar peduncle (SCP) atrophy mainly in SCA3 (MJD), SCA6, SCA8, DRPLA + - Medulla and upper cervical cord atrophy in SCA3 (MJD); relative lack of cord involvement in SCA6 + - Severe cerebral atrophy in juvenile-onset DRPLA + - Pontine **BT-ratio** useful in diagnostic decision tree + - Distance from ventral edge of pons to medial lemniscus (ML): Distance from ML to its dorsal edge + - ### Morphology + + + - Variable abnormal T2/FLAIR hyperintense signal + - **Hot cross bun sign** (**HCBS**; cruciform ↑ T2 in pons) + - 8.7% overall prevalence in SCA; 25.7% SCA2, 1.3% SCA3 (MJD); extremely rare SCA7, SCA8 + - Anteroposteriorly oriented **pontine midline** linear T2-**hyperintensity** (**PMH**) in SCA1, SCA3 (MJD), DRPLA + - Bilateral **bright middle cerebellar peduncle (MCP) sign** rarely in SCA2, SCA3 (MJD), SCA6, DRPLA + - Cerebral white matter (WM), brainstem, and thalamic hyperintensities in adult-onset DRPLA + - Cerebral WM usually normal in juvenile-onset DRPLA + - Periventricular WM changes may occur very late +- ## CT Findings + + + - Atrophy of involved structures +- ## MR Findings + + + - **SCA types 1 and 3 (SCA1 and SCA3/MJD)** + - Pontine tegmentum (dorsal pons) atrophy in early stage + - In contrast to multiple system atrophy with predominant cerebellar ataxia (MSA-C) + - Important, more common differential diagnosis + - MSA-C mainly pontine base (ventral pons) atrophy + - Cerebellum and brainstem atrophy prominent later + - PMH in later stage on axial T2WI MR; HCBS in 1.3% MJD + - In contrast to pontine HCBS in MSA-C commonly + - Slightly shrunken neurons of pontine nuclei with preserved cell architecture + - Relatively preserves myelinated transverse pontocerebellar fibers + - Fiber loss seen only in pontine midline where fibers from right and left pontine nuclei cross + - Considered early change of HCBS + - Volumetric MR: Caudate/putamen and temporal lobe atrophy in SCA1 + - Volumetric MR: Temporofrontoparietooccipital, limbic, SCP, basal ganglia, thalamus atrophy in MJD + - Medulla/upper cervical cord atrophy, bright MCP in MJD + - Progressive linear ↑ T2 just outside ICs (inner segments of globi pallidi) in SCA3 (MJD) + - **SCA2** + - MR findings **mimicking MSA-C in young** ataxic patient + - Prominent cerebellum and brainstem atrophy, more severe than SCA1 and SCA3 + - Pontine atrophy more prominent in pontine base (ventral pons) than tegmentum (dorsal pons) + - Characteristic pontine HCBS in 25%; PMH earlier + - Inconsistently, T2 hyperintensities of basal ganglia + - Rarely, bilateral MCP focal hyperintensities + - Volumetric data shows no cerebral gray matter (GM) or WM atrophy + - **SCA5, SCA6, SCA11, SCA26, SCA30, SCA31, SCA37** + - Pure/predominantly cerebellar atrophy + - **DRPLA** + - Cerebellum, brainstem, SCP atrophy + - Pontine atrophy is more prominent in pontine tegmentum (dorsal pons) than base (ventral pons) + - Rarely, PMH and/or bilateral MCP focal hyperintensities + - **Adult-onset DRPLA**: ↑ T2 cerebral WM, brainstem, thalamus + - **Juvenile-onset DRPLA**: Cerebral WM usually normal + - ↑ T2 periventricular WM in very late stage + - Severe cerebral atrophy in juvenile-onset DRPLA + - **MRS** + - Significantly lower NAA/Cr, Cho/Cr, and NAA/Cho in cerebellar hemispheres/vermis in SCAs, especially SCA2 + - MSA-C also shows similar findings +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR + - ### Protocol advice + + + - Volumetric 3D T1 MR sequences, such as MPRAGE or SPGR + - Axial T2WI and FLAIR to evaluate ↑ T2 like PMH, HCBS + +# DIFFERENTIAL DIAGNOSIS + +- [Multiple System Atrophy - Cerebellar](/document/multiple-system-atrophy/4fb9af00-e0bd-4164-8f61-4011ddc8bf9e) + - Most cases sporadic; 6th decade + - Atrophy of pons, cerebellum, and inferior olives + - Pontine atrophy predominantly at its**base (ventral pons)** + - PMH or HCBS in pons on axial T2; bright MCP sometimes + - Due to loss of myelinated transverse pontocerebellar fibers + - MR mimics SCA2 (consider SCA2 in younger patient) + - **SCP spared in MSA-C**; SCP may atrophy in MSA-P, PSP, SCA3/MJD, SCA6, SCA8, DRPLA, Friedrich ataxia, ARSACS +- ## Friedrich Ataxia + + + - Autosomal recessive ataxic disorder + - Severe spinal cord atrophy with flat posterior aspect + - May show ↑ T2 in spinal cord posterior (fasciculus gracilis and cuneatus) and lateral (pyramidal tracts) columns + - Atrophic dorsal medulla, rostral vermis (culmen, declive), inferomedial cerebellar hemisphere, and SCP + - Conventionally, cerebellar involvement considered rare, but nowadays volumetric MR shows atrophy + - Scoliosis, cardiomyopathy, and stroke due to atrial fibrillation or mural thrombus +- ## Ataxia With Oculomotor Apraxia Types 1 and 2 + + + - **Type 1**: Autosomal recessive, mutation in *APTX* gene + - MR shows cerebellar atrophy, mild brainstem atrophy + - Cortical atrophy in advanced stages + - **Type 2**: Autosomal recessive, mutation in *SETX* gene + - Peripheral neuropathy and ↑ serum α-fetoprotein + - MR shows cerebellar atrophy +- ## Ataxia Telangiectasia + + + - Autosomal recessive ataxic disorder + - Normal pons; initially cerebellum may also be normal + - MR between 3 and 7 years of age usually shows superior vermian and lateral cerebellar hemispheric atrophy + - Later, diffuse cerebellovermian atrophy, including dentate nuclei and cerebellar peduncles + - Subtle ↑ FLAIR signal of cerebellar cortex after atrophy + - Telangiectasias evident by late childhood and early adult stage using T2*/SWI/postcontrast MR + - Supratentorial WM hyperintensities due to spongiosis surrounding telangiectasias +- ## Fragile X-Associated Tremor/Ataxia Syndrome + + + - Late-onset X-linked dominant neurodegeneration + - Variable penetrance; males between 50 and 80 years of age + - *FMR1* gene mutation affecting CGG trinucleotide repeats + - Generalized cerebral, cerebellar, and brainstem atrophy + - Periventricular, deep WM and corpus callosum ↑ T2 + - Characteristic bilateral MCP focal hyperintensities in 60% +- ## Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay + + + - Atrophy of anterior cerebellar vermis and SCP 1st + - Cerebellar hemisphere, medulla, and cervical cord later + - Bulky pons and MCP; subtle ↑ T2 in lateral pons and MCP + - Characteristic ↓ T2/FLAIR transverse striations (pontine tigroid hypointensities) in pontine base and tegmentum + - DTI shows interruption of thin pyramidal tracts by these hyperplastic pontocerebellar fibers + - Rim of T2 hyperintensity around thalami + - Straightened spine in radiographs + +# PATHOLOGY + +- ## General Features + + + - Autosomal dominant ataxia; many SCAs due to PolyQ expansion of coding CAG repeats + - Various other gene loci and proteins in remaining SCAs + - 60-75% SCA patients only have mutations in known loci + - Expansion of CAG repeats produce toxic gain of function + - PolyQ SCAs, such as other PolyQ disorders, symptoms manifest above particular CAG repeat threshold + - Threshold for symptoms variable for different genes + - Threshold in most SCA types > 36, for SCA3 (MJD) > 50 + - Commonest mutant genes: *ATXN1* (SCA1), *ATXN2*(SCA2), *ATXN3* (SCA3/MJD), *CACNA1A* (SCA6), *ATN1* (DRPLA) +- ## Staging, Grading, & Classification + + + - SCA types currently numbered 1-40 and beyond + - Genetic anticipation: Earlier onset and progressive worsening of phenotype in successive generations +- ## Gross Pathologic & Surgical Features + + + - Cerebellar atrophy, variable brainstem atrophy, flattening of facial colliculus in MJD + - Neuronal dysfunction and neuronal loss in 10-20 years + - Neurodegeneration of pontine reticulotegmental nucleus in SCA1, SCA2, SCA3 + - Nucleus involved in horizontal smooth pursuit eye movements and accuracy of horizontal saccades + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - Cerebellar ataxia in all SCAs + - ### Other signs/symptoms + + + - SCA1: Pyramidal signs, peripheral neuropathy + - SCA2: Slow saccades, myoclonus, areflexia + - SCA3/MJD: Slow saccades, persistent stare, extrapyramidal signs, peripheral neuropathy + - SCA6: Nystagmus; mild, can be very late onset + - Juvenile-onset DRPLA: Myoclonus, seizures, behavioral changes, and intellectual deterioration + - Adult-onset DRPLA: Choreoathetosis, delusions, dementia +- ## Demographics + + + - **SCA3 (MJD)****:**Portuguese Azorean, William **Machado** family in New England 1st to be diagnosed with MJD + - Azorean Californian **Joseph** family also had MJD + - SCAs usually present in middle age + - SCA1, 37 years (range: 5-65); SCA2, 35 years (range: 7-66); SCA3, 37 years (range: 5-66); SCA6, 55 years (range: 31-77) + - Earlier age of onset and more severe disease with increasing number of CAG repeats on expanded alleles +- ## Natural History & Prognosis + + + - Average SCA disability progression over 1-2 decades + - Wheelchair bound by 10-15 years after symptom onset + - Higher baseline scores on Scale for the Assessment and Rating of Ataxia (SARA) associated with shorter survival + - SCA1 (mean age of death 56 years) more rapid disease progression and shorter survival than SCA2, SCA3, SCA6 +- ## Treatment + + + - No effective or curative treatment + - Zolpidem: Transient improvement in cerebellar symptoms + - Varenicline (partial nicotine agonist): Improvement in some measures of cerebellar dysfunction + - Polyglutamine neurotoxicity suppressed by overexpression of heat shock proteins in animal studies + - Gene silencing with RNA interference promising in SCA mouse model + +# DIAGNOSTIC CHECKLIST + +- ## Consider + + + - Young to middle-aged patient with slowly progressing cerebellar ataxia and other typical associated symptoms +- ## Image Interpretation Pearls + + + - Atrophy of cerebellum ± brainstem + - Evaluate axial T2WI for characteristic hyperintense signal in SCA types, especially pons, MCP, periventricular WM + + 55908b7f-4f89-444c-8107-f53412fe2751 \ No newline at end of file diff --git a/docs_md/articles/vascular-dementia_app.statdx.com_document_content_f59dab57-c511-4369-8fcc-592421a4b8d1_05e6592c_20251014T185346Z.md b/docs_md/articles/vascular-dementia_f59dab57-c511-4369-8fcc-592421a4b8d1.md similarity index 97% rename from docs_md/articles/vascular-dementia_app.statdx.com_document_content_f59dab57-c511-4369-8fcc-592421a4b8d1_05e6592c_20251014T185346Z.md rename to docs_md/articles/vascular-dementia_f59dab57-c511-4369-8fcc-592421a4b8d1.md index 92aa9be..f46d614 100644 --- a/docs_md/articles/vascular-dementia_app.statdx.com_document_content_f59dab57-c511-4369-8fcc-592421a4b8d1_05e6592c_20251014T185346Z.md +++ b/docs_md/articles/vascular-dementia_f59dab57-c511-4369-8fcc-592421a4b8d1.md @@ -1,5 +1,14 @@ -# Vascular Dementia - +--- +title: "Vascular Dementia" +docid: "f59dab57-c511-4369-8fcc-592421a4b8d1" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Vascular Dementia" +--- # KEY FACTS - ## Terminology @@ -305,4 +314,4 @@ - Report strategically placed infarcts, hemorrhagic components, DWI abnormalities, pattern of cortical volume loss if present - 6999ad9a-6bd9-47dd-8707-b571f32301e3 + 6999ad9a-6bd9-47dd-8707-b571f32301e3 \ No newline at end of file diff --git a/docs_md/articles/wallerian-degeneration_e4bb682d-6534-4176-9d39-34c1a42f3771.md b/docs_md/articles/wallerian-degeneration_e4bb682d-6534-4176-9d39-34c1a42f3771.md new file mode 100644 index 0000000..81da235 --- /dev/null +++ b/docs_md/articles/wallerian-degeneration_e4bb682d-6534-4176-9d39-34c1a42f3771.md @@ -0,0 +1,306 @@ +--- +title: "Wallerian Degeneration" +docid: "e4bb682d-6534-4176-9d39-34c1a42f3771" +breadcrumbs: + - "Brain" + - "Diagnosis" + - "Pathology-Based Diagnoses" + - "Acquired Toxic/Metabolic/Degenerative Disorders" + - "Dementias and Degenerative Disorders" + - "Wallerian Degeneration" +--- +# KEY FACTS + +- ## Terminology + + + - Wallerian degeneration (WaD) + - Progressive secondary anterograde degeneration of axons and their myelin sheaths caused by interruption of axonal integrity or damage to neuron +- ## Imaging + + + - Primary lesion is cortical or subcortical with WaD in descending white matter (WM) tracts ipsilateral to neuronal injury + - WaD can be seen in fibers crossing corpus callosum, fibers of optic radiations, fornices, and cerebellar peduncles + - CT is not sensitive for WaD in acute-subacute stages + - Detects atrophy of corticospinal tracts (CSTs) in chronic stage + - Time-dependent changes in CSTs on MR + - Strong correlation between WaD detected on T2WI and DWI and long-term morbidity + - DWI findings precede development of WaD assessed by conventional MR + - DTI may distinguish between primary lesion and associated WaD + - Reduced fractional anisotropy (FA) with ↑ mean diffusivity (MD) in infarct + - Reduced FA with preserved MD in CST +- ## Top Differential Diagnoses + + + - Normal CST can appear T2/FLAIR hyperintense on high-field-strength MR + - Neurodegenerative diseases + - Brainstem glioma + - Demyelinating and inflammatory diseases + - Hypertrophic olivary degeneration + - Metabolic diseases + - Intoxication (heroin inhalation) + +# TERMINOLOGY + +- ## Abbreviations + + + - Wallerian degeneration (WaD) +- ## Definitions + + + - Progressive secondary anterograde degeneration of axons and their myelin sheaths caused by interruption of axonal integrity or damage to neuron + +# IMAGING + +- ## General Features + + + - ### Best diagnostic clue + + + - Contiguous T2 hyperintensity along topographic distribution of corticospinal tract (CST) in internal capsule (IC) and brainstem in patients with various cerebral pathologies + - ### Location + + + - Primary lesion: Cortical or subcortical + - WaD: Descending white matter (WM) tracts ipsilateral to neuronal injury + - CST, corticobulbar, corticopontocerebellar tracts + - Corpus callosum, posterior column of spinal cord, limbic circuit, and optic pathway + - Center of cerebral peduncle may reveal WaD of CST + - Lateral side of cerebral peduncle may show WaD of corticopontine tract + - WaD can be seen in corpus callosum, optic radiations, fornices, and cerebellar peduncles + - WaD in distal optic radiations after infarction at their root + - Pontine infarct can cause WaD in middle cerebellar peduncle + - Corpus callosum has been shown to be susceptible to atrophy in Alzheimer disease mainly as correlate of WaD of commissural nerve fibers of neocortex + - Callosal atrophy is present predominantly in latest stage of Alzheimer disease + - Seizure-induced damage may cause secondary WM degeneration along tapetum and through splenium of corpus callosum + - ### Size + + + - Acute stage: Normal size + - Chronic stage: ↓ (atrophy) + - ### Morphology + + + - Signal changes conforming to WM tract shape + - Oval regions in posterior limb of IC and cerebral peduncle; thin curvilinear regions in pons +- ## CT Findings + + + - ### NECT + + + - Not sensitive for WaD in acute-subacute stages + - Detects atrophy of CSTs in chronic stage + - ↓ size of corresponding aspect of brainstem +- ## MR Findings + + + - ### T1WI + + + - Time-dependent changes in descending WM tracts + - Stage 1: No changes + - Stage 2: T1 hyperintense + - Stage 3: T1 hypointense + - Stage 4: Ipsilateral brainstem atrophy ± hypointensity + - ### T2WI + + + - Time-dependent changes in descending WM tracts + - Stage 1: No changes in adult CNS + - Stage 2: T2 hypointense + - Stage 3: T2 hyperintense + - Stage 4: Atrophy, best seen in brainstem + - Sometimes, T2 hyperintense signal may persist + - Neonates and infants: Identification of WaD by T2WI complicated by high water content and lack of myelination in immature WM + - Adults: Strong correlation between T2WI-detected WaD and long-term morbidity + - ### FLAIR + + + - Same as T2WI + - ### DWI + + + - Can demonstrate acute injury to descending WM tracts < 10 days after primary injury such as infarction + - Neonates and infants: Indicates acute WM injury + - DWI findings precede development of WaD assessed by conventional MR + - May portend poor clinical outcome + - Adults: Correlation of DW changes in descending motor pathways at presentation with long-term neurologic disability + - ↑ signal intensity in descending WM tract ipsilateral to territorial infarct at level of IC or cerebral peduncle or both + - ↓ ADC values in involved WM tract compared with normal WM + - Extent and severity of territorial ischemia is related to development of descending WM tract injury detectable by DWI + - Hyperintense DW signal intensity and ↓ ADC values within territorial infarct and ipsilateral CST + - DW and ADC time courses in region of territorial injury and CST injury may be different + - Relatively delayed development of diffusion abnormality in descending WM tracts + - Subacute period after territorial infarction in adults + - Within infarct, WM ADC reduction > that in GM + - DW signal intensity abnormality in descending WM tracts may persist, even as DW hyperintensity in ipsilateral cerebral hemisphere fades + - WaD of inferior cerebellar peduncle (after lateral medullary infarction) depicted by thin slice DWI has been reported + - ### T1WI C+ + + + - No contrast enhancement of degenerated tracts + - ### MRS + + + - ¹H-MRS enables in vivo assessment of axonal injury based on signal intensity of N-acetyl aspartate (NAA) + - ↓ NAA concentration in normal-appearing WM in pons and cerebellar peduncles in early stages of relapsing-remitting multiple sclerosis (MS) + - Evidence of early WaD outside MS plaques + - Correlates best with disability, MS duration, and relapse rate + - DTI + - Myelin breakdown leads to ↓ diffusion anisotropy + - DTI may distinguish between primary lesion and associated WaD + - Difference in diffusion properties between primary lesion and degenerated tract + - Fractional anisotropy (FA) = measure of directionality of water diffusion + - Mean diffusivity (MD) = measure of amount of water diffusion + - Reduced FA with ↑ MD in infarct + - Reduced FA with preserved MD in CST + - In patients with motor pathway infarction, diffusion indices in degenerated CST stabilize within 3 months and early changes in CST FA may predict long-term clinical outcomes +- ## Imaging Recommendations + + + - ### Best imaging tool + + + - MR + - ### Protocol advice + + + - DWI allows early detection (stage 1) + - T2WI detects changes after 4 weeks + +# DIFFERENTIAL DIAGNOSIS + +- ## Normal CST + + + - CST can appear T2/FLAIR hyperintense on 3T MR (normal fully myelinated brain) +- ## Neurodegenerative Diseases + + + - [Amyotrophic lateral sclerosis (upper &/or lower motor neuron involvement)](/document/amyotrophic-lateral-sclerosis-als/23de52b7-d9bd-441c-a18c-95c8afccb470) + - Bilateral hyperintensities along CST extending from corona radiata to brainstem on T2WI/PD/FLAIR + - Primary lateral sclerosis and infantile-onset hereditary spastic paraplegia + - Upper motor neuron degeneration only +- [Brainstem Glioma](/document/brainstem-tumors/657b37eb-c286-42bf-b8e6-55b5c20e5e50) + - T2 hyperintense mass ± enhancement +- ## Demyelinating and Inflammatory Diseases + + + - [MS: Periventricular T2 hyperintensity](/document/multiple-sclerosis/7892b2a2-f52a-4d7f-9858-a326f2b7ab04) + - [ADEM: Asymmetric T2 hyperintensity in WM and gray matter (GM) after viral prodrome](/document/adem/a3fafeb7-5861-4364-beb8-c0e30220564e) + - [Behçet disease: Enlarged T2 hyperintense brainstem ± thalamus](/document/behet-disease/4e447bb6-0f14-40e1-929a-4c1465feec0a) +- [Hypertrophic Olivary Degeneration](/document/hypertrophic-olivary-degeneration/78257543-6d52-4879-84b1-445f3611d996) + - Secondary degeneration of inferior olivary nucleus (ION), usually caused by primary lesions in dentato-rubro-olivary pathway + - Time-dependent T2 changes of ION + - Hyperintense signal without hypertrophy of ION: Within first 6 months of ictus + - Both ↑ signal and hypertrophy of ION: Between 6 months and 3-4 years after ictus + - Only ↑ signal in ION: Begins when hypertrophy resolves and can persist indefinitely +- ## Metabolic Diseases + + + - [X-linked adrenoleukodystrophy: Enhancing peritrigonal demyelination](/document/x-linked-adrenoleukodystrophy/0543abe3-8086-488b-85d2-483ce458f345) + - [Wilson disease: WM and GM lesions involving basal ganglia, dentate nucleus, brainstem](/document/wilson-disease/3d4d4876-4ce4-4af0-9e75-1a419bdd813c) + - [Hypoglycemic coma: Reversible CST changes](/document/adult-hypoglycemia/38e4de6e-07c4-485e-bac1-f4dd4815b3b8) +- [Heroin Inhalation](/document/drug-abuse/e4502a67-4b96-4d98-a167-6e90f6b65faf) + - Symmetric T2 hyperintensity in posterior WM, including posterior limb of IC + +# PATHOLOGY + +- ## General Features + + + - ### Etiology + + + - Infarction, hemorrhage, neoplasm, encephalitis + - Demyelinating disease, trauma, arteriovenous malformations + - Reported also in patients with movement disorder + - ### Genetics + + + - Process of axonal degeneration is genetically regulated + - ### Associated abnormalities + + + - Primary lesion/disorder that caused secondary WM tract degeneration +- ## Staging, Grading, & Classification + + + - Stage 1 (0-4 weeks) + - Degradation of axon; mild changes in myelin + - Stage 2 (4-14 weeks) + - Myelin protein breakdown; lipids remain intact + - Stage 3 (> 14 weeks) + - Myelin lipid breakdown, gliosis, changes in water content and structure + - Stage 4 (after months to years) + - Atrophy of ipsilateral brainstem +- ## Gross Pathologic & Surgical Features + + + - Brainstem asymmetry due to atrophy in chronic stage +- ## Microscopic Features + + + - Stage 1: Beginning of myelin and axon breakdown + - Myelin sheaths break up into ellipsoids and spheres but retain myelin-staining properties + - Stage 2: ↓ protein:lipid ratio + - Stage 3: ↑ edema and further lipid breakdown + - Stage 4: Atrophy due to volume loss; removal of axonal debris by microglia continues for 2 years (vs. completed in 3 weeks in peripheral nervous system) + - Expression of transcription factors *ATF3* and *JUN* by nonneuronal cells during WaD + - *ATF3*/*JUN* heterodimers may play role in regulating changes in gene expression necessary for preparing distal segments of injured peripheral nerves for axonal regeneration + - Absence of *ATF3* and *JUN* from CNS glia during WaD may limit their ability to support regeneration + - In CNS, astrocyte-dominated matrix fails to accommodate new axonal growth + +# CLINICAL ISSUES + +- ## Presentation + + + - ### Most common signs/symptoms + + + - WaD in CST is associated with persistent hemiparesis +- ## Demographics + + + - ### Age + + + - Reported in all ages + - ### Sex + + + - No preference + - ### Epidemiology + + + - WaD commonly follows CNS lesions + - WaD in pyramidal tract reported in 78.6% of cases of capsular infarct +- ## Natural History & Prognosis + + + - WaD may begin within 1 week of fiber tract damage + - Demyelination can continue during next 6 months + - Signifies irreversible loss of neuronal function + - Little evidence of axonal regeneration in CNS + - Presence or absence of WaD may influence clinical outcome after stroke + - Extent of WaD is related to severity of motor deficit + - Abnormal DWI signal in CST can be acute predictor of motor outcome in childhood infarction + - Contralesional CST abnormal DWI signal predicts severe hemiparesis +- ## Treatment + + + - No specific therapy + +# DIAGNOSTIC CHECKLIST + +- ## Image Interpretation Pearls + + + - In ischemic stroke: Important to differentiate DWI abnormality related to WaD from additional infarction + - Time-specific signal intensity changes of WaD → able to ascertain age of primary lesion + + b1941e68-6700-4295-b371-61c4b12e78ad \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_68d0cff6_20251014T195936Z.meta.md b/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_68d0cff6_20251014T195936Z.meta.md index bd1ab83..afd774b 100644 --- a/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_68d0cff6_20251014T195936Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_68d0cff6_20251014T195936Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/24559f7a-ed5a-4ab6-90ba-769f0b5c1197/media - +--- +title: "https://app.statdx.com/document/24559f7a-ed5a-4ab6-90ba-769f0b5c1197/media" +--- [ { "groupId": "e2f10f6a-0bef-498b-9eb3-1b9558473bfa", @@ -15,4 +16,4 @@ "documentId": "24559f7a-ed5a-4ab6-90ba-769f0b5c1197", "documentUrl": "/document/v2/24559f7a-ed5a-4ab6-90ba-769f0b5c1197", "imageTitle": "Enlarged Perivascular Spaces", - "thumbnailUrl": " + "thumbnailUrl": " \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_99132d9e_20251014T195833Z.meta.md b/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_99132d9e_20251014T195833Z.meta.md index bd1ab83..afd774b 100644 --- a/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_99132d9e_20251014T195833Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_99132d9e_20251014T195833Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/24559f7a-ed5a-4ab6-90ba-769f0b5c1197/media - +--- +title: "https://app.statdx.com/document/24559f7a-ed5a-4ab6-90ba-769f0b5c1197/media" +--- [ { "groupId": "e2f10f6a-0bef-498b-9eb3-1b9558473bfa", @@ -15,4 +16,4 @@ "documentId": "24559f7a-ed5a-4ab6-90ba-769f0b5c1197", "documentUrl": "/document/v2/24559f7a-ed5a-4ab6-90ba-769f0b5c1197", "imageTitle": "Enlarged Perivascular Spaces", - "thumbnailUrl": " + "thumbnailUrl": " \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_b5cae924_20251014T200033Z.meta.md b/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_b5cae924_20251014T200033Z.meta.md index bd1ab83..afd774b 100644 --- a/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_b5cae924_20251014T200033Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-24559f7a-ed5a-4ab6-90ba-769f0b5c1197-media_app.statdx.com_document_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_media_b5cae924_20251014T200033Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/24559f7a-ed5a-4ab6-90ba-769f0b5c1197/media - +--- +title: "https://app.statdx.com/document/24559f7a-ed5a-4ab6-90ba-769f0b5c1197/media" +--- [ { "groupId": "e2f10f6a-0bef-498b-9eb3-1b9558473bfa", @@ -15,4 +16,4 @@ "documentId": "24559f7a-ed5a-4ab6-90ba-769f0b5c1197", "documentUrl": "/document/v2/24559f7a-ed5a-4ab6-90ba-769f0b5c1197", "imageTitle": "Enlarged Perivascular Spaces", - "thumbnailUrl": " + "thumbnailUrl": " \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-2aad3ac4-44fd-43e5-8e50-a86987483af3-media_app.statdx.com_document_2aad3ac4-44fd-43e5-8e50-a86987483af3_media_93b3c006_20251014T193414Z.meta.md b/docs_md/external/https-appstatdxcom-document-2aad3ac4-44fd-43e5-8e50-a86987483af3-media_app.statdx.com_document_2aad3ac4-44fd-43e5-8e50-a86987483af3_media_93b3c006_20251014T193414Z.meta.md index 4620417..88f21c1 100644 --- a/docs_md/external/https-appstatdxcom-document-2aad3ac4-44fd-43e5-8e50-a86987483af3-media_app.statdx.com_document_2aad3ac4-44fd-43e5-8e50-a86987483af3_media_93b3c006_20251014T193414Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-2aad3ac4-44fd-43e5-8e50-a86987483af3-media_app.statdx.com_document_2aad3ac4-44fd-43e5-8e50-a86987483af3_media_93b3c006_20251014T193414Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/2aad3ac4-44fd-43e5-8e50-a86987483af3/media - +--- +title: "https://app.statdx.com/document/2aad3ac4-44fd-43e5-8e50-a86987483af3/media" +--- [ { "groupId": "a57ddf7c-7979-4f93-ace0-eb50c665527a", @@ -13,4 +14,4 @@ "annotated": true, "flanked": false, "documentId": "2aad3ac4-44fd-43e5-8e50-a86987483af3", - "documentUrl": "/document/v2/2aad3ac4-44fd-43e5-8e50-a86987483af3", + "documentUrl": "/document/v2/2aad3ac4-44fd-43e5-8e50-a86987483af3", \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-2b99b31a-ec1a-4dce-bb63-2a101fe9f044-media_app.statdx.com_document_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_media_c76d4e9f_20251014T193525Z.meta.md b/docs_md/external/https-appstatdxcom-document-2b99b31a-ec1a-4dce-bb63-2a101fe9f044-media_app.statdx.com_document_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_media_c76d4e9f_20251014T193525Z.meta.md index b149664..7a7e9c9 100644 --- a/docs_md/external/https-appstatdxcom-document-2b99b31a-ec1a-4dce-bb63-2a101fe9f044-media_app.statdx.com_document_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_media_c76d4e9f_20251014T193525Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-2b99b31a-ec1a-4dce-bb63-2a101fe9f044-media_app.statdx.com_document_2b99b31a-ec1a-4dce-bb63-2a101fe9f044_media_c76d4e9f_20251014T193525Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/2b99b31a-ec1a-4dce-bb63-2a101fe9f044/media - +--- +title: "https://app.statdx.com/document/2b99b31a-ec1a-4dce-bb63-2a101fe9f044/media" +--- [ { "groupId": "1b47e30c-5939-4904-9dcf-0b3f0b795a1c", @@ -18,4 +19,4 @@ "thumbnailUrl": "/image/thumbnail/17843f38-8102-416d-b40b-e43c4129deed?size=168&quality=85" }, { - "imageId": "e0ed92cb-b3a1-48fa- + "imageId": "e0ed92cb-b3a1-48fa- \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-media_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_media_6f4c1bc8_20251014T193509Z.meta.md b/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-media_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_media_6f4c1bc8_20251014T193509Z.meta.md index cebc3d9..167aed0 100644 --- a/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-media_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_media_6f4c1bc8_20251014T193509Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-media_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_media_6f4c1bc8_20251014T193509Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/49510d0e-acf7-45cb-9eb1-53f8193b0b6d/media - +--- +title: "https://app.statdx.com/document/49510d0e-acf7-45cb-9eb1-53f8193b0b6d/media" +--- [ { "groupId": "415b02cf-df4f-4cef-9c2b-866ef0618ec0", @@ -15,4 +16,4 @@ "documentId": "49510d0e-acf7-45cb-9eb1-53f8193b0b6d", "documentUrl": "/document/v2/49510d0e-acf7-45cb-9eb1-53f8193b0b6d", "imageTitle": "", - "thumbnailUrl": "/image/thumbnail/ccf3ab42-d18d-44f4-9b3f- + "thumbnailUrl": "/image/thumbnail/ccf3ab42-d18d-44f4-9b3f- \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-tables_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_tables_f2a7fa59_20251014T193509Z.meta.md b/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-tables_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_tables_f2a7fa59_20251014T193509Z.meta.md index 3e8ada3..1229489 100644 --- a/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-tables_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_tables_f2a7fa59_20251014T193509Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-49510d0e-acf7-45cb-9eb1-53f8193b0b6d-tables_app.statdx.com_document_49510d0e-acf7-45cb-9eb1-53f8193b0b6d_tables_f2a7fa59_20251014T193509Z.meta.md @@ -1,9 +1,10 @@ -# https://app.statdx.com/document/49510d0e-acf7-45cb-9eb1-53f8193b0b6d/tables - +--- +title: "https://app.statdx.com/document/49510d0e-acf7-45cb-9eb1-53f8193b0b6d/tables" +--- [ " # Imaging Features for Various Clinical Subtypes of Frontotemporal Dementia | Clinical Subtypes | Imaging Features | | --- | --- | -| bvFTD | MR: Atrophy of frontal & temporal lobes; asymmetric right frontal &/or temporal lobe atrophy may occur NM: Decreased perfusion & metabolism in frontal &/or te | +| bvFTD | MR: Atrophy of frontal & temporal lobes; asymmetric right frontal &/or temporal lobe atrophy may occur NM: Decreased perfusion & metabolism in frontal &/or te | \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-6cb71737-f574-4121-a8fb-02eeada9f9f7-media_app.statdx.com_document_6cb71737-f574-4121-a8fb-02eeada9f9f7_media_a7fbcf7b_20251014T195847Z.meta.md b/docs_md/external/https-appstatdxcom-document-6cb71737-f574-4121-a8fb-02eeada9f9f7-media_app.statdx.com_document_6cb71737-f574-4121-a8fb-02eeada9f9f7_media_a7fbcf7b_20251014T195847Z.meta.md index b54574c..f689471 100644 --- a/docs_md/external/https-appstatdxcom-document-6cb71737-f574-4121-a8fb-02eeada9f9f7-media_app.statdx.com_document_6cb71737-f574-4121-a8fb-02eeada9f9f7_media_a7fbcf7b_20251014T195847Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-6cb71737-f574-4121-a8fb-02eeada9f9f7-media_app.statdx.com_document_6cb71737-f574-4121-a8fb-02eeada9f9f7_media_a7fbcf7b_20251014T195847Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/6cb71737-f574-4121-a8fb-02eeada9f9f7/media - +--- +title: "https://app.statdx.com/document/6cb71737-f574-4121-a8fb-02eeada9f9f7/media" +--- [ { "groupId": "019f8155-d786-485b-95f5-4cf15b7bc150", @@ -14,4 +15,4 @@ "flanked": false, "documentId": "6cb71737-f574-4121-a8fb-02eeada9f9f7", "documentUrl": "/document/v2/6cb71737-f574-4121-a8fb-02eeada9f9f7", - "imageT + "imageT \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_23f69ac7_20251014T193351Z.meta.md b/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_23f69ac7_20251014T193351Z.meta.md index 185291d..841e383 100644 --- a/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_23f69ac7_20251014T193351Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_23f69ac7_20251014T193351Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/9f9eda8c-7e3c-4292-9861-4b8abc2c6474/media - +--- +title: "https://app.statdx.com/document/9f9eda8c-7e3c-4292-9861-4b8abc2c6474/media" +--- [ { "groupId": "fb01ca50-5af0-419d-ad89-6f4f2d980fd2", @@ -16,4 +17,4 @@ "documentUrl": "/document/v2/9f9eda8c-7e3c-4292-9861-4b8abc2c6474", "imageTitle": "", "thumbnailUrl": "/image/thumbnail/01274ce7-fce5-4f42-bd69-b5a99e6a4930?size=168&quality=85" - }, + }, \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_ed98dbd3_20251014T185356Z.meta.md b/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_ed98dbd3_20251014T185356Z.meta.md index 185291d..841e383 100644 --- a/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_ed98dbd3_20251014T185356Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-9f9eda8c-7e3c-4292-9861-4b8abc2c6474-media_app.statdx.com_document_9f9eda8c-7e3c-4292-9861-4b8abc2c6474_media_ed98dbd3_20251014T185356Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/9f9eda8c-7e3c-4292-9861-4b8abc2c6474/media - +--- +title: "https://app.statdx.com/document/9f9eda8c-7e3c-4292-9861-4b8abc2c6474/media" +--- [ { "groupId": "fb01ca50-5af0-419d-ad89-6f4f2d980fd2", @@ -16,4 +17,4 @@ "documentUrl": "/document/v2/9f9eda8c-7e3c-4292-9861-4b8abc2c6474", "imageTitle": "", "thumbnailUrl": "/image/thumbnail/01274ce7-fce5-4f42-bd69-b5a99e6a4930?size=168&quality=85" - }, + }, \ No newline at end of file diff --git a/docs_md/external/https-appstatdxcom-document-content-24559f7a-ed5a-4ab6-90ba-769f0b5c1197_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.meta.md b/docs_md/external/https-appstatdxcom-document-content-24559f7a-ed5a-4ab6-90ba-769f0b5c1197_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.meta.md index 8910ab4..8a77ba6 100644 --- a/docs_md/external/https-appstatdxcom-document-content-24559f7a-ed5a-4ab6-90ba-769f0b5c1197_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.meta.md +++ b/docs_md/external/https-appstatdxcom-document-content-24559f7a-ed5a-4ab6-90ba-769f0b5c1197_app.statdx.com_document_content_24559f7a-ed5a-4ab6-90ba-769f0b5c1197_0b5c5cd9_20251014T195936Z.meta.md @@ -1,5 +1,6 @@ -# https://app.statdx.com/document/content/24559f7a-ed5a-4ab6-90ba-769f0b5c1197 - +--- +title: "https://app.statdx.com/document/content/24559f7a-ed5a-4ab6-90ba-769f0b5c1197" +--- # ESSENTIAL INFORMATION - ## Key Differential Diagnosis Issues @@ -10,4 +11,4 @@ - Is there any associated mass effect? - Does lesion enhance? - str: @@ -279,31 +282,190 @@ def find_title_for_docid(docid: str, search_dir: str) -> str | None: """ if not docid: return None - pattern = os.path.join(search_dir, f"*{docid}*.json") - for path in sorted(glob.glob(pattern)): + + # Phase 1: scan all JSON files for breadcrumb/list-style captures and prefer + # their enhancedDocumentName/name when present. Breadcrumb captures often + # don't include the docid in their filename, so scan every JSON once. + all_paths = sorted(glob.glob(os.path.join(search_dir, "*.json"))) + for path in all_paths: try: with open(path, "r", encoding="utf-8") as f: data = json.load(f) except Exception: continue - # direct title + if isinstance(data, list): + for item in data: + try: + if isinstance(item, dict) and item.get("documentId") == docid: + ed = item.get("enhancedDocumentName") or item.get("name") + if isinstance(ed, str) and ed.strip(): + return html.unescape(ed.strip()) + except Exception: + continue + + # Phase 2: look only at files whose filename contains the docid for other + # title signals (top-level names, recursive title keys, searchResults). + pattern = os.path.join(search_dir, f"*{docid}*.json") + paths = sorted(glob.glob(pattern)) + for path in paths: + try: + with open(path, "r", encoding="utf-8") as f: + data = json.load(f) + except Exception: + continue + + # top-level keys commonly used + if isinstance(data, dict): + for key in ("enhancedDocumentName", "documentName", "name"): + if key in data: + v = data.get(key) + if isinstance(v, str) and v.strip(): + return html.unescape(v.strip()) + + # fallback: direct title anywhere in the JSON title = recursive_search_for_key(data, "title") - if title: - # some files include empty titles; skip blanks - if isinstance(title, str) and title.strip(): - return title.strip() + if title and isinstance(title, str) and title.strip(): + return html.unescape(title.strip()) + # sometimes summary objects contain results with titles - # try 'searchResults' -> 'results' list sr = data.get("searchResults") if isinstance(data, dict) else None if isinstance(sr, dict): results = sr.get("results") if isinstance(results, list): for r in results: if isinstance(r, dict) and r.get("id") == docid and r.get("title"): - return r.get("title") + return html.unescape(r.get("title")) + return None +def find_breadcrumbs_for_docid(docid: str, search_dir: str) -> list: + """Return a list of breadcrumb strings associated with docid by scanning + captured JSONs. Preserves discovery order and HTML-unescapes values. + """ + if not docid: + return [] + + def collect_names_from_breadcrumbs(bc_list): + names = [] + if isinstance(bc_list, list): + for item in bc_list: + if isinstance(item, dict) and item.get("name"): + names.append(html.unescape(item.get("name"))) + return names + + # First, prefer files whose filename contains the docid. These often + # include a structured `breadcrumbs` list (ordered parents) and may + # include a leaf node entry for the document. + candidates = [] + doc_paths = sorted(glob.glob(os.path.join(search_dir, f"*{docid}*.json"))) + for path in doc_paths: + try: + with open(path, "r", encoding="utf-8") as f: + data = json.load(f) + except Exception: + continue + + # look for a breadcrumbs list anywhere in this JSON + # and prefer the first full list we find + def recurse_find_breadcrumb_lists(obj): + out = [] + if isinstance(obj, dict): + for k, v in obj.items(): + if k == "breadcrumbs" and isinstance(v, list): + names = collect_names_from_breadcrumbs(v) + if names: + out.append(names) + out.extend(recurse_find_breadcrumb_lists(v)) + elif isinstance(obj, list): + for item in obj: + out.extend(recurse_find_breadcrumb_lists(item)) + return out + + bc_lists = recurse_find_breadcrumb_lists(data) + if bc_lists: + # take the first breadcrumbs list as base path + base = bc_lists[0].copy() + # try to find a leaf name for this doc within the JSON + leaf = None + def recurse_find_leaf(obj): + nonlocal leaf + if leaf: + return + if isinstance(obj, dict): + # node that references the document directly + if obj.get("documentId") == docid and obj.get("name"): + leaf = html.unescape(obj.get("name")) + return + # some files use enhancedDocumentName/documentName + for k in ("enhancedDocumentName", "documentName", "name", "title"): + if k in obj and isinstance(obj[k], str) and obj.get("documentId") == docid: + leaf = html.unescape(obj.get(k)) + return + for v in obj.values(): + recurse_find_leaf(v) + elif isinstance(obj, list): + for item in obj: + recurse_find_leaf(item) + + recurse_find_leaf(data) + if leaf and (not base or base[-1] != leaf): + base.append(leaf) + if base and base not in candidates: + candidates.append(base) + + # If we found candidate breadcrumb paths from docid-matching files, return the first + if candidates: + return candidates[0] + + # Otherwise, scan all JSONs for entries that explicitly list the docid and + # attempt to reconstruct a breadcrumb path by combining any nearby breadcrumbs + all_paths = sorted(glob.glob(os.path.join(search_dir, "*.json"))) + for path in all_paths: + try: + with open(path, "r", encoding="utf-8") as f: + data = json.load(f) + except Exception: + continue + + # list-of-dicts captures where an item references the documentId + if isinstance(data, list): + for item in data: + if isinstance(item, dict) and item.get("documentId") == docid: + # if this file also contains a breadcrumbs list elsewhere, use it + bc_lists = [] + if isinstance(data, dict): + bc_lists = [] + # try to locate breadcrumbs within same file by re-loading + def find_bcs(obj): + if isinstance(obj, dict): + if obj.get("breadcrumbs") and isinstance(obj.get("breadcrumbs"), list): + return collect_names_from_breadcrumbs(obj.get("breadcrumbs")) + for v in obj.values(): + res = find_bcs(v) + if res: + return res + elif isinstance(obj, list): + for it in obj: + res = find_bcs(it) + if res: + return res + return None + + bcs = find_bcs(data) + path_names = bcs or [] + # append the item's own enhancedDocumentName/name if present + leaf = item.get("enhancedDocumentName") or item.get("name") + if isinstance(leaf, str) and leaf.strip(): + leaf = html.unescape(leaf.strip()) + if not path_names or path_names[-1] != leaf: + path_names = path_names + [leaf] + if path_names: + return path_names + + return [] + + def find_title_in_capture_index(docid: str, base_dir: str) -> str | None: """Look for a title for docid inside a capture_index.jsonl file in base_dir. @@ -354,6 +516,9 @@ def process_file(path: str, out_dir: str, overwrite: bool = False) -> tuple[bool except Exception: data_peek = None + # deterministic doc id (if present in filename) + docid = None + article_name = None if isinstance(data_peek, dict): article_name = find_article_name_in_json(data_peek) @@ -363,13 +528,16 @@ def process_file(path: str, out_dir: str, overwrite: bool = False) -> tuple[bool # try to parse a uuid-like docid from filename m = re.search(r"([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})", base) if m: - docid = m.group(1) - # first consult capture_index.jsonl if present - title_from_index = find_title_in_capture_index(docid, os.path.dirname(path) or ".") - if not title_from_index: - title_from_index = find_title_for_docid(docid, os.path.dirname(path) or ".") - if title_from_index: - article_name = title_from_index + docid = m.group(1) + # Prefer nearby breadcrumb/document captures (which include + # enhancedDocumentName/name) over titles that appear in + # capture_index.jsonl. This makes section-level names + # like "Brain Tumor in Newborn/Infant" the canonical title. + title_from_nearby = find_title_for_docid(docid, os.path.dirname(path) or ".") + if not title_from_nearby: + title_from_nearby = find_title_in_capture_index(docid, os.path.dirname(path) or ".") + if title_from_nearby: + article_name = title_from_nearby # if still not found, try to extract from inline HTML if not article_name and isinstance(data_peek, dict): @@ -381,11 +549,15 @@ def process_file(path: str, out_dir: str, overwrite: bool = False) -> tuple[bool if article_name: slug = slugify(article_name) - out_base = f"{slug}_{name}" if slug else name + # prefer deterministic filename based on docid when available to avoid duplicates + if docid: + out_base = f"{slug}_{docid}" if slug else docid + else: + out_base = f"{slug}_{name}" if slug else name # place titled articles into an articles/ subfolder target_dir = os.path.join(out_dir, "articles") - if article_name.startswith("https"): + if isinstance(article_name, str) and article_name.startswith("https"): target_dir = os.path.join(out_dir, "external") else: # per request: only save files that have titles @@ -416,15 +588,79 @@ def process_file(path: str, out_dir: str, overwrite: bool = False) -> tuple[bool normalized_first = re.sub(r"[#\s]+", "", first_line).strip().lower() normalized_title = re.sub(r"[^a-z0-9]+", "", article_name.lower()) if not normalized_first or normalized_title not in normalized_first: - md = "# " + article_name.strip() + "\n\n" + md + # Build YAML frontmatter with title and breadcrumbs (and docid) + front_lines = ["---"] + # use JSON quoting to safely escape strings in YAML + front_lines.append(f"title: {json.dumps(article_name.strip())}") + if docid: + front_lines.append(f"docid: {json.dumps(docid)}") + # collect breadcrumbs and render as YAML list if present + crumbs = [] + if docid: + crumbs = find_breadcrumbs_for_docid(docid, os.path.dirname(path) or ".") + if crumbs: + front_lines.append("breadcrumbs:") + for c in crumbs: + front_lines.append(f" - {json.dumps(c)}") + front_lines.append("---\n") + front = "\n".join(front_lines) + + # Avoid duplicating an H1 that matches the title in the body + md_lines = md.lstrip().splitlines() + if md_lines: + first = md_lines[0].strip() + normalized_first = re.sub(r"[#\s]+", "", first).strip().lower() + normalized_title = re.sub(r"[^a-z0-9]+", "", article_name.lower()) + if first.startswith("#") and normalized_title in normalized_first: + # drop the first line (existing H1) + md_lines = md_lines[1:] + + md = front + "\n".join(md_lines).lstrip() except Exception: # be conservative: if anything goes wrong, keep the original md pass + # Before writing, compute a normalized content hash to detect duplicates + def normalize_for_hash(s: str) -> str: + # remove ISO8601-like timestamps and common date patterns, collapse whitespace + s2 = re.sub(r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:Z|[+-]\d{2}:?\d{2})?", "", s) + s2 = re.sub(r"\b\d{1,2}/\d{1,2}/\d{2,4}\b", "", s2) + # remove lines that are just timestamps or contain 'Last updated' + s2 = "\n".join([ln for ln in s2.splitlines() if not re.match(r"^\s*(Last updated|LastVisited|LastVisitedAsDate|Updated).*$", ln, re.I)]) + s2 = re.sub(r"\s+", " ", s2).strip() + return s2 + + def content_hash(s: str) -> str: + nh = normalize_for_hash(s) + return hashlib.sha256(nh.encode("utf-8")).hexdigest() + + # index stored at top-level out_dir to dedupe across articles/external + index_path = os.path.join(out_dir, "_content_index.json") + index = {} + try: + if os.path.exists(index_path): + with open(index_path, "r", encoding="utf-8") as ix: + index = json.load(ix) + except Exception: + index = {} + + ch = content_hash(md) + existing = index.get(ch) + if existing and os.path.exists(existing) and not overwrite: + # content already saved elsewhere — skip writing + return False, f"duplicate: {existing}" + try: os.makedirs(target_dir, exist_ok=True) with open(out_path, "w", encoding="utf-8") as f: f.write(md) + # update index + try: + index[ch] = out_path + with open(index_path, "w", encoding="utf-8") as ix: + json.dump(index, ix, indent=2, ensure_ascii=False) + except Exception: + pass # log saved file path with timestamp try: log_path = os.path.join(target_dir, "_saved_files.log") @@ -455,12 +691,8 @@ def main(argv: Iterable[str] | None = None) -> int: if args.clear and os.path.exists(output_dir): # remove all .md files in output_dir - for f in glob.glob(os.path.join(output_dir, "*.md")): - try: - os.remove(f) - except Exception: - pass - + shutil.rmtree(output_dir, ignore_errors=True) + files = sorted(glob.glob(os.path.join(input_dir, args.pattern))) if not files: print(f"No files found in {input_dir} matching {args.pattern}")