Add comprehensive articles on Vascular Dementia and Wallerian Degeneration

- Created a detailed article for Vascular Dementia covering key facts, terminology, imaging findings, differential diagnoses, pathology, clinical issues, and diagnostic checklist.
- Developed an extensive article on Wallerian Degeneration including key facts, terminology, imaging features, differential diagnoses, pathology, clinical issues, and diagnostic checklist.

docs_md/articles/lewy-body-dementia_f6a4382b-f0f7-4582-a703-7f695c65656f.md

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+---
+title: "Lewy Body Dementia"
+docid: "f6a4382b-f0f7-4582-a703-7f695c65656f"
+breadcrumbs:
+  - "Nuclear Medicine"
+  - "Central Nervous System"
+  - "Neurodegeneration"
+  - "Lewy Body Dementia"
+---
+# KEY FACTS
+
+- ## Terminology
+  
+  
+    - Progressive neurodegenerative disease characterized by parkinsonism, visual hallucinations, fluctuations in cognition (alertness/attention), and other cognitive impairments leading to functional decline
+- ## Imaging
+  
+  
+    - Low dopamine transporter uptake in basal ganglia on I-123 FP-CIT SPECT similar to parkinsonian syndromes
+          - Decreased tracer binding may be more symmetric and diffuse when compared to typical cases of Parkinson disease (PD)
+    - Cardiac sympathetic denervation on MIBG
+    - Significant occipital lobe glucose hypometabolism relative to Alzheimer disease (AD) with preservation of posterior cingulate gyrus
+- ## Top Differential Diagnoses
+  
+  
+    - PD and PD dementia (PDD)
+    - AD, including posterior cortical atrophy
+    - Frontotemporal dementia (FTD)
+- ## Pathology
+  
+  
+    - Intraneuronal aggregates of α-synuclein result in neurodegeneration
+    - Significant amount of Lewy body dementia (LBD) cases involve comorbid Alzheimer pathology, which can complicate decisions about amyloid-targeting therapies (ATTs)
+- ## Clinical Issues
+  
+  
+    - Parkinsonism
+    - Fluctuating cognition, especially in attention/alertness
+    - Recurrent visual hallucinations
+    - Progressive impairment of cognition with motor complications leading to loss of functional independence
+    - REM sleep behavioral disorders
+    - No current disease-modifying treatment for LBD
+
+# TERMINOLOGY
+
+- ## Abbreviations
+  
+  
+    - Lewy body dementia (LBD)
+- ## Synonyms
+  
+  
+    - Dementia with Lewy bodies
+- ## Definitions
+  
+  
+    - Progressive neurodegenerative disease of brain characterized by
+          - Visual hallucinations
+          - Parkinsonism (bradykinesia, rigidity, tremor)
+          - Fluctuations in cognition (alertness/attention)
+          - REM sleep behavioral disorder
+
+# IMAGING
+
+- ## General Features
+  
+  
+    - ### Best diagnostic clue
+      
+      
+          - Indicative imaging criteria
+                  - Abnormally low dopamine transporter (DaT) binding in basal ganglia on DaT SPECT study
+                  - Absent myocardial uptake on MIBG [sympathetic denervation can also be seen with primary heart disease and diabetic neuropathy as well as Parkinson disease (PD) dementia (PDD)]
+          - Supportive imaging criteria
+                  - Medial temporal lobe hypometabolism less severe than Alzheimer disease (AD) on FDG PET
+                  - Significant occipital lobe glucose hypometabolism relative to AD on FDG PET
+                  - Preservation of posterior cingulate gyrus on FDG PET (cingulate island sign)
+    - ### Location
+      
+      
+          - Cortical, subcortical, and brainstem structures; midbrain, basal ganglia, occipital lobe
+- ## Imaging Recommendations
+  
+  
+    - ### Best imaging tool
+      
+      
+          - DaT SPECT with I-123 ioflupane (FP-CIT)
+                  - Binds to DaT predominantly in presynaptic striata
+                  - Normal uptake in caudate and putamen
+                  - Abnormal DaT imaging indicative feature for LBD diagnosis
+                  - Compared to PD, DaT findings in LBD can be more uniformly decreased between caudate and putamen and less likely asymmetric
+                  - DaT imaging differentiates between LBD (abnormal DaT) and AD (normal DaT)
+                  - Cannot reliably distinguish between other disorders with parkinsonism
+          - I-123 MIBG cardiac exam
+                  - Norepinephrine analogue taken up by sympathetic cardiac nerves
+                  - Cardiac sympathetic denervation seen with PD, PDD, and LBD
+                  - Usually preserved with atypical parkinsonian syndromes, AD, and frontotemporal dementia (FTD)
+          - F-18 FDG PET
+                  - Generalized glucose hypometabolism with significant occipital lobe hypometabolism
+                            - Occipital lobe involvement may help distinguish from classic AD-like pattern of hypometabolism
+                            - Similar hypometabolic pattern seen in PD and PDD
+                  - Medial temporal lobe hypometabolism less severe than in AD
+          - F-18 amyloid PET
+                  - Can be positive in 50% or more of LBD patients, possibly reflecting AD-LBD copathology
+                  - Important to consider DaT scan in patients with positive amyloid and any clinical concern for LBD before starting amyloid-targeting therapy (ATTs)
+    - ### Protocol advice
+      
+      
+          - I-123 ioflupane
+                  - Patient preparation
+                            - Patient should be off all interfering dopaminergic medications
+                            - Pretreat with thyroid blocker (oral potassium solution, Lugol) 1 hour before tracer injection
+                            - Pregnancy category C: Unknown whether I-123 ioflupane can cause fetal damage or early termination of pregnancy
+                  - Radiopharmaceutical: I-123 ioflupane
+                  - Dose: 3-5 mCi (111-185 MBq)
+                  - Dosimetry: Striata receives highest radiation exposure, followed by bladder, bowel, and lungs (assuming thyroid is blocked)
+                  - Image acquisition: 3-6 hours after injection
+          - I-123 MIBG 
+                  - Patient preparation
+                            - Patient should be off all interfering medications
+                            - Pretreatment with Lugol (KI) solution
+                  - Dose: 3-10 mCi (111-370 MBq)
+                  - Dosimetry: Bladder (assuming thyroid is blocked)
+                  - Image acquisition: Anterior planar imaging early (15 min) after injection and delayed (4 hours) after injection; can perform SPECT as well
+                  - Heart:mediastinum ratio calculated on delayed anterior planar image (< 1.8 concerning for denervation)
+          - F-18 FDG PET
+                  - Patient preparation
+                            - Patient should fast, stop IV fluids containing dextrose, 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 for 30 min
+                  - Radiopharmaceutical: F-18 FDG
+                  - Dose: 5-20 mCi (185-740 MBq)
+                  - Dosimetry: Urinary bladder receives largest dose
+                  - Image acquisition: 30-60 min after injection
+
+# DIFFERENTIAL DIAGNOSIS
+
+- [Parkinson Disease and Parkinson Disease Dementia](/document/parkinsonian-syndromes/2b99b31a-ec1a-4dce-bb63-2a101fe9f044)
+    - Neurodegenerative disease that often presents with cogwheel rigidity, shuffled gate, pill-rolling tremor at rest, bradykinesia
+    - Shares similar Lewy body-related neuropathology with LBD
+    - Dementia may develop but generally 10 years after onset of motor symptoms
+          - PDD: PD cases where dementia is diagnosed 1 year after onset of motor symptoms
+- ## Posterior Cortical Atrophy (Visual Alzheimer Disease Variant)
+  
+  
+    - Most commonly resulting from amyloid-β and τ protein aggregates, similar to classic AD
+    - Visuospatial and visuoperception deficits most common, simultanagnosia
+    - FDG PET often shows hypometabolism in classic areas (precuneus, posterior cingulate, posterior temporal lobes) with atypical occipital involvement
+    - Unlike LBD, tends to involve posterior cingulate, typically more occipital asymmetric hypometabolism than LBD, negative DaT and MIBG
+- [Alzheimer Disease](/document/alzheimer-disease/2aad3ac4-44fd-43e5-8e50-a86987483af3)
+    - Most common cause of dementia
+    - Impairments in episodic memory and other cognitive domains
+    - Preservation of motor functions
+    - Early F-18 FDG hypometabolism in parietotemporal and posterior cingulate cortices
+          - F-18 FDG PET hypometabolism spares occipital visual cortex
+    - Related to aggregation of amyloid-β and τ proteins
+          - Positive on amyloid PET
+- [Frontotemporal Dementia](/document/frontotemporal-dementia/9f9eda8c-7e3c-4292-9861-4b8abc2c6474)
+    - Commonly presents with personality and behavioral changes
+    - Atrophy of frontal and anterior temporal lobes
+    - F-18 FDG PET hypometabolism primarily in frontal/anterior temporal lobes
+
+# PATHOLOGY
+
+- ## General Features
+  
+  
+    - ### Etiology
+      
+      
+          - Abnormal aggregates of α-synuclein protein within neurons
+          - More diffusely seen than in PD
+    - ### Associated abnormalities
+      
+      
+          - Significant amount of LBD cases involve comorbid Alzheimer pathology, which can complicate decisions about ATTs
+                  - LBD is diagnosed when dementia is present before or concurrently with parkinsonian features
+- ## Gross Pathologic & Surgical Features
+  
+  
+    - Relative preservation of total brain volume relative to other dementias
+    - Increased volume of lateral ventricles relative to healthy controls
+    - Decreased pigmentation within substantia nigra (midbrain) and loci cerulei (pons)
+
+# CLINICAL ISSUES
+
+- ## Presentation
+  
+  
+    - ### Most common signs/symptoms
+      
+      
+          - Parkinsonism
+          - Fluctuating cognition, especially in attention/alertness
+          - Recurrent visual hallucinations
+          - REM sleep behavioral disorder
+    - ### Other signs/symptoms
+      
+      
+          - Severe neuroleptic sensitivity
+          - Hallucinations (other than visual)
+          - Depression
+          - Severe autonomic dysfunction
+    - ### Clinical profile
+      
+      
+          - 3 main types of dementia related to continuum of Lewy body clinicopathology
+                  - Diffuse LBD (isolated)
+                            - Dementia with diffuse cortical LB pathology
+                            - No other significant pathology (minimal plaques/tangles)
+                  - PDD
+                            - PD patients diagnosed with dementia 1 year after onset of motor symptoms
+                            - Onset of dementia in PD is generally 10 years after onset of motor symptoms
+                  - LBD-AD copathology
+                            - Pathology consistent with cortical LB (α-synuclein) and AD-like pathologic changes (amyloid plaques/neurofibrillary tangles)
+                            - Most common presentation, occurring in ~ 70% of LBD cases
+- ## Natural History & Prognosis
+  
+  
+    - Progressive impairment of cognition with motor complications leading to loss of functional independence
+          - Core features include fluctuating cognition with impact on alertness/attention, visual hallucinations, and features of parkinsonism
+    - Memory loss is less prominent early symptom in LBD but may develop with progression of disease
+          - Significant distinction from AD, where memory is common early symptom
+- ## Treatment
+  
+  
+    - No current disease-modifying treatment for LBD
+    - Several therapies may help alleviate common symptoms
+    - Levodopa can be used for some motor symptoms
+    - Cholinesterase inhibitors may be used for some cognitive symptoms
+    - Can have neuroleptic malignant syndrome if given some antipsychotic medications that interact with dopamine
+
+# DIAGNOSTIC CHECKLIST
+
+- ## Image Interpretation Pearls
+  
+  
+    - I-123 ioflupane
+          - Abnormally low DaT binding in basal ganglia on DaT SPECT study
+    - I-123 MIBG
+          - Sympathetic cardiac denervation
+    - F-18 FDG PET/CT
+          - Occipital lobe hypometabolism and normal posterior cingulate gyrus (cingulate island sign) to distinguish LBD from AD
+    - 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