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/vascular-dementia_f59dab57-c511-4369-8fcc-592421a4b8d1.md

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+---
+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
+  
+  
+    - Vascular dementia (VaD), multiinfarct dementia (MID), vascular cognitive impairment (VCI)
+    - Stepwise progressive ↓ in cognitive function
+    - Heterogeneous group of disorders with varying etiologies, pathologic subtypes
+          - VaD often mixed etiology
+          - Can occur alone or in association with Alzheimer disease
+          - MID secondary to repeated cerebral infarctions
+    - VaD: Dementia caused by cerebrovascular disease or ↓ cerebral blood flow
+    - VCI: Cognitive impairment caused by or associated with vascular factors
+    - Can occur alone or in association with Alzheimer disease (AD)
+- ## Imaging
+  
+  
+    - General features
+          - Multifocal infarcts [cortical gray matter (GM), subcortical white matter (WM)]
+          - Basal ganglia (BG), pons
+          - Territorial as well as lacunar lesions
+          - Coexisting microvascular WM disease common
+          - Multiple remote microhemorrhages
+    - CT
+          - Multifocal infarcts
+          - Single or multiple, lacunar to territorial
+          - WM hypointensities (discrete to confluent)
+    - FDG PET
+          - Multifocal regions ↓ metabolism in cortex, WM
+- ## Top Differential Diagnoses
+  
+  
+    - AD
+    - Frontotemporal lobar degeneration
+    - CADASIL
+    - Dementia with Lewy bodies
+- ## Clinical Issues
+  
+  
+    - 2nd most common dementia (after AD)
+    - Mood & behavioral changes more typical than memory loss
+- ## Diagnostic Checklist
+  
+  
+    - Report strategically placed infarcts
+    - Look for hemorrhage, DWI abnormalities
+
+# TERMINOLOGY
+
+- ## Abbreviations
+  
+  
+    - Vascular dementia (VaD)
+- ## Synonyms
+  
+  
+    - Multiinfarct dementia (MID)
+    - Vascular cognitive disorder (VCD)
+    - Vascular cognitive impairment (VCI)
+    - Subcortical ischemic VaD
+    - Poststroke dementia
+- ## Definitions
+  
+  
+    - Dementia caused by cerebrovascular disease or ↓ cerebral blood flow (CBF)
+    - VCI: Cognitive impairment caused by or associated with vascular factors
+    - Secondary to repeated cerebral infarctions
+    - Can occur alone or in association with Alzheimer disease (AD)
+    - 2nd most common cause of dementia next to AD
+
+# IMAGING
+
+- ## General Features
+  
+  
+    - ### Best diagnostic clue
+      
+      
+          - Multifocal infarcts
+                  - Cortical gray matter (GM), subcortical white matter (WM)
+                  - Basal ganglia (BG), pons
+                  - Territorial as well as lacunar infarcts
+                  - Changes of microvascular WM ischemia common
+    - ### Location
+      
+      
+          - Typically involves cerebral hemispheres & BG
+          - Usually bilateral but may be unilateral
+    - ### Size
+      
+      
+          - Vary from single to multiple, punctate to large/confluent
+    - ### Morphology
+      
+      
+          - Small infarcts are rounded or oval; large confluent abnormalities are ill defined
+- ## CT Findings
+  
+  
+    - ### NECT
+      
+      
+          - Hypodensity in periventricular WM
+          - Cortical, subcortical, BG infarcts
+          - Generalized atrophy with focal cortical infarcts typical
+- ## MR Findings
+  
+  
+    - ### T1WI
+      
+      
+          - Generally have hypointense BG lacunar infarcts
+          - Atrophy with enlargement of ventricles & sulci
+    - ### T2WI
+      
+      
+          - Punctate or confluent regions of hyperintense WM
+          - Central pontine infarcts
+          - Large areas of volume loss with widened sulci
+    - ### FLAIR
+      
+      
+          - Hyperintense foci within BG
+          - Multifocal diffuse & confluent WM hyperintensities
+    - ### T2* GRE
+      
+      
+          - Multiple blooming hypointensities in cortex & along pial surface
+    - ### DWI
+      
+      
+          - ↓ fractional anisotropy & ↑ ADC within lesions, normal-appearing WM (NAWM)
+          - ↑ in mean diffusivity of NAWM correlates with disability found on tests of executive function
+    - ### MRA
+      
+      
+          - Most abnormalities in small arteries, generally not well seen on MRA
+    - ### MRS
+      
+      
+          - ↓ NAA in both cortical & WM regions
+          - Frontal cortex NAA negatively correlated with volume of WM signal hyperintensity
+- ## Ultrasonographic Findings
+  
+  
+    - Transcranial Doppler sonography: Pulsatility indices in large arteries ↑ compared to AD
+- ## Nuclear Medicine Findings
+  
+  
+    - FDG PET
+          - Multiple areas of hypometabolism without specific lobar predominance
+          - Severity of MID neuropsychiatric symptoms correlates with extent of ↓ metabolism in cortex & WM
+    - SPECT
+          - Iodine-123-iodoamphetamine: ↓ frontal & BG CBF, which correlates with low cognitive scores
+          - Tc-99m hexamethyl propyleneamine oxime: CBF heterogeneity more prominent in anterior portion of brain
+                  - Unlike pattern in AD, in which posterior abnormalities predominate
+- ## Imaging Recommendations
+  
+  
+    - ### Best imaging tool
+      
+      
+          - MR
+          - PET/SPECT may also provide specificity
+    - ### Protocol advice
+      
+      
+          - Axial FLAIR to detect WM infarcts
+          - Axial & coronal T2WI to assess regions of atrophy
+          - T2* GRE/SWI to identify hemorrhage
+
+# DIFFERENTIAL DIAGNOSIS
+
+- [Alzheimer Disease](/document/alzheimer-disease/f71f5cf5-b1af-4c6d-b145-b4c10eec7b58)
+    - Striking hippocampus & amygdala atrophy
+    - PET: Bilateral temporoparietal hypoperfusion/hypometabolism (BG spared)
+    - Often coexists with VaD
+- [Frontotemporal Lobar Degeneration](/document/frontotemporal-lobar-degeneration/49510d0e-acf7-45cb-9eb1-53f8193b0b6d)
+    - Characterized by early onset of behavioral changes with intact visual, spatial skills
+    - Frontal, temporal lobe atrophy
+    - Marked atrophy → knife-like gyri
+- [Alcoholic Encephalopathy](/document/alcoholic-encephalopathy/88021852-b73d-4cdf-a719-dd4ae3231e45)
+    - 3rd most common cause of dementia
+    - Generalized > focal atrophy; superior vermis atrophy
+- [CADASIL](/document/cadasil/6b5a24c8-afd7-4106-bb4b-11421ed1592c)
+    - Most common heritable cause of stroke, VaD in adults
+    - Earlier age of onset
+    - Imaging looks like small vessel disease
+- [Dementia With Lewy Bodies](/document/dementia-with-lewy-bodies/e8e46d1d-46d2-4e5a-880f-f025a84c5871)
+    - Hypometabolism of entire brain
+    - Without infarcts or significant atrophy
+
+# PATHOLOGY
+
+- ## General Features
+  
+  
+    - ### Etiology
+      
+      
+          - MID is usually due to multiple small infarctions
+                  - Infarcts involving entire major vessel territories are usually absent
+                  - Minority may be secondary to single or few large infarctions
+          - ~ 75% of all MID patients exhibit small vessel disease rather than thromboembolism
+          - Growing evidence exists for involvement of cholinergic system in VaD
+                  - Cholinergic deficits well documented in VaD, independent of concomitant AD pathology
+                  - Cholinergic neuron loss in 70% of AD, 40% of VaD
+    - ### Genetics
+      
+      
+          - Apolipoprotein E (*APOE*)
+                  - Serum protein involved in lipid metabolism
+                  - Encoded at single gene locus on chromosome 19 by 3 alleles: ε2, ε3, ε4
+                  - Frequency of ε4 allele significantly higher among patients with AD & VaD compared to controls
+                  - Odds of developing AD or VaD are 4.4x & 3.7x higher (respectively) in presence of even single ε4 allele
+          - Paraoxonase (*PON1*)
+                  - Component of high-density lipoproteins with antioxidative potential
+                  - 2 *PON1* polymorphisms (Gln192Arg associated with enzyme activity & T-107C associated with enzyme concentration) are independent risk factors for VaD, particularly in *APOE* (ε4)
+- ## Staging, Grading, & Classification
+  
+  
+    - 8 subtypes of VaD
+          - MIDs: Due to large cerebral emboli, usually readily identifiable
+          - Strategically placed infarctions causing dementia
+          - Multiple subcortical lacunar lesions: Develop VaD 5-25x more frequently than age-matched controls
+          - Binswanger disease: Small vessel disease → widespread incomplete infarction of WM
+          - Mixtures of 2 or more VaD subtypes
+          - Hemorrhagic lesions causing dementia
+          - Subcortical dementias due to other causes [e.g., cerebral autosomal dominant arteriopathy with subcortical infarcts & leukoencephalopathy (CADASIL)]
+          - Hybrid forms of AD & VaD
+- ## Gross Pathologic & Surgical Features
+  
+  
+    - Multifocal infarctions with atrophy
+- ## Microscopic Features
+  
+  
+    - Arteriosclerosis & amyloid angiopathy major underlying pathologies in small vessel vascular disease
+    - Vessels display atheromata, lipohyalinosis, subintimal thickening, fibrinoid necrosis
+    - Infarcted tissue undergoes necrosis → gliotic wall surrounding CSF cavity
+    - Myelin & axonal loss with astrocytosis
+
+# CLINICAL ISSUES
+
+- ## Presentation
+  
+  
+    - ### Most common signs/symptoms
+      
+      
+          - Infarcts with transient focal neurologic deficits
+                  - Most deficits persist
+          - Mood & behavioral changes
+          - Deterioration of executive function & attention, changes in personality (rather than memory loss) predominate
+          - Severe depression is more common in VaD than AD
+    - ### Clinical profile
+      
+      
+          - Main risk factors
+                  - Advanced age, HTN, diabetes, smoking
+                  - Hypercholesterolemia, hypercoagulable states
+- ## Demographics
+  
+  
+    - ### Age
+      
+      
+          - Generally earlier age than AD
+          - Incidence ↑ with age
+    - ### Sex
+      
+      
+          - M > F
+    - ### Epidemiology
+      
+      
+          - 10% of dementias
+          - 2nd most common dementia (after AD)
+          - ~ 25% of elderly stroke patients meet VaD criteria
+          - Cerebral small vessel disease accounted for 33% of dementia risk
+- ## Natural History & Prognosis
+  
+  
+    - Poststroke dementia: Progressive, episodic, stepwise cognitive decline following stroke
+    - VaD without recent stroke: Progressive or stepwise cognitive decline without concurrent history of symptomatic stroke but with imaging evidence of clinically unrecognized cerebrovascular disease
+    - Neuropsychiatric & motor signs: VaD accompanied by neuropsychiatric signs, such as depression, abulia, apathy, & psychosis with delusions or hallucinations
+    - Intervals of clinical stabilization ± limited recovery
+    - 5-year survival with VaD ~ 50% of age-matched controls
+- ## Treatment
+  
+  
+    - Prevent further vascular insult
+          - Control precipitating factors (e.g., HTN, diabetes)
+
+# DIAGNOSTIC CHECKLIST
+
+- ## Image Interpretation Pearls
+  
+  
+    - Not single entity but large group of conditions with variable clinical & imaging findings
+- ## Reporting Tips
+  
+  
+    - Report strategically placed infarcts, hemorrhagic components, DWI abnormalities, pattern of cortical volume loss if present
+
+ 6999ad9a-6bd9-47dd-8707-b571f32301e3