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.
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+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
+
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