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: "Multiinfarct Dementia"
+docid: "3823c4d4-5e98-46da-a717-892fef54b382"
+breadcrumbs:
+  - "Nuclear Medicine"
+  - "Central Nervous System"
+  - "Neurodegeneration"
+  - "Multiinfarct Dementia"
+---
+# KEY FACTS
+
+- ## Terminology
+  
+  
+    - Impairments in cognition and behavior affecting functional status due to pathologic changes resulting from various vascular insults throughout brain
+- ## Imaging
+  
+  
+    - F-18 FDG PET may be used in differential diagnosis between vascular dementia and Alzheimer disease
+    - Glucose hypometabolism in multifocal (scattered) pattern of cortical with subcortical regions is indicative of vascular dementia
+          - Multifocal or unifocal hypometabolism involving cortical gray matter, subcortical white matter, and other structures
+          - Generally involves cerebral hemispheres, thalamus, basal ganglia, hippocampi
+    - Amyloid PET imaging does not demonstrate gray matter amyloid deposition in vascular dementia
+    - SPECT with Tc-99m HMPAO or Tc-99m ECD shows similar asymmetrically decreased perfusion
+- ## Pathology
+  
+  
+    - Vascular-related lesions leading to loss of brain function
+    - Chronic small vessel insults > large vessel infarcts
+- ## Clinical Issues
+  
+  
+    - Significant heterogeneity in clinical presentation depending on location, type, and size of vascular lesion
+    - Overt disease: Cognitive impairment due to clinically evident vascular event (i.e., stroke)
+    - Covert disease: Insidious process of vascular insults (clinically silent strokes)
+    - 2nd most common cause of dementia after Alzheimer disease
+
+# TERMINOLOGY
+
+- ## Definitions
+  
+  
+    - Impairments in cognition and behavior affecting functional status due to pathologic changes resulting from various vascular insults throughout brain
+    - Vascular cognitive impairment (VCI) is more comprehensive term incorporating vascular dementia (VaD) as well as other vascular-related cognitive impairment, including mild cognitive impairment due to vascular disease
+
+# IMAGING
+
+- ## General Features
+  
+  
+    - ### Best diagnostic clue
+      
+      
+          - Multifocal or unifocal infarcts involving cortical gray matter, subcortical white matter, and other structures
+                  - Especially when correlates with other clinical findings
+          - Generally involve cerebral hemispheres, thalamus, basal ganglia, hippocampi
+          - Generally significant white matter involvement
+          - Bilateral > unilateral
+          - Size: Decreased due to atrophy
+          - Morphology: Multiple small &/or large vessel with lacunar infarcts
+- ## Nuclear Medicine Findings
+  
+  
+    - F-18 FDG PET/CT
+          - Glucose hypometabolism in multifocal (scattered) pattern of cortical with subcortical regions
+                  - Altered pattern depending on subtype (i.e., multifocal small vessel infarcts vs. large territory infarcts)
+                  - Hypometabolism often in clinically affected areas: Correlates with other clinical findings
+          - May be used in differential diagnosis between VaD and Alzheimer disease (AD)
+                  - AD pattern: Hypometabolism in bilateral parietotemporal with posterior cingulate cortices: Extension to frontal/occipital
+                  - VaD may have hypometabolism in subcortical areas, which are spared in AD
+    - Amyloid PET without gray matter amyloid deposition
+          - May be used in differential diagnosis between VaD and AD
+    - SPECT with Tc-99m HMPAO or Tc-99m ECD shows similar asymmetric decreased perfusion
+- ## Imaging Recommendations
+  
+  
+    - ### Best imaging tool
+      
+      
+          - F-18 FDG PET may aid in differential diagnosis
+          - MR to see vascular insults and look for potential reversible causes of dementia
+    - ### Protocol advice
+      
+      
+          - 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: 5-15 mCi F-18 FDG
+                  - Dosimetry: Urinary bladder receives largest dose
+                  - Image acquisition: 30-60 min after injection
+
+# DIFFERENTIAL DIAGNOSIS
+
+- [Alzheimer Disease](/document/alzheimer-disease/2aad3ac4-44fd-43e5-8e50-a86987483af3)
+    - Early F-18 FDG hypometabolism in parietotemporal and posterior cingulate cortices
+          - Later changes include frontal lobe
+    - Positive amyloid PET
+    - Atrophy of medial temporal lobe structures on MR/CT
+- ## Dementia With Lewy Bodies
+  
+  
+    - Commonly presents with hallucinations, sleep disturbances, and parkinsonian motor features
+    - F-18 FDG PET hypometabolism in occipital cortex or striatal loss of dopamine transport
+- [Normal-Pressure Hydrocephalus](/document/normal-pressure-hydrocephalus/834ccc3e-2116-4295-8408-0ac9a06bd2ff)
+    - Dilated ventricles on CT or MR
+    - Metabolic or perfusion reductions in lateral cortex (frontal and parietal), separation of caudate heads
+    - Reduced activity in periventricular WM and ventricular regions > expected for age
+- ## Mixed Dementia
+  
+  
+    - Characteristic features of > 1 type of dementia
+    - Commonly includes AD and another pathology (such as VaD)
+- ## Frontotemporal Dementia
+  
+  
+    - Commonly presents with personality and behavioral changes
+    - Atroph of frontal and anterior temporal lobes
+    - F-18 FDG PET hypometabolism primarily in frontal and anterior temporal lobes
+- [Huntington Disease](/document/huntington-disease/4abd9bb7-7d47-4308-a71f-9985fdb23c2c)
+    - Major reduction in basal ganglia metabolism and perfusion (worse in caudate)
+    - Cortical reductions (late)
+- ## Posttraumatic Dementia
+  
+  
+    - Pattern of abnormality on functional imaging variable: Depends on severity, directional forces at injury
+    - Chronic subdural may cause significant asymmetry
+    - Deceleration injury may cause anterior frontal and temporal tip reductions
+    - Atrophic pattern may occur; worse with increasing severity of injury
+    - Focal reduction correlates with encephalomalacia and other cortical abnormalities on CT or MR
+    - Basal ganglia, thalamic abnormalities may be present
+- ## Drug-Related Dementia
+  
+  
+    - Cocaine and amphetamine abuse: Random small focal defects throughout brain
+          - Swiss cheese pattern on FDG PET and SPECT
+    - Alcohol abuse: May demonstrate frontal lobe decrease
+- ## Autoimmune Dementia
+  
+  
+    - Vasculitis pattern in systemic lupus; frontal watershed abnormalities
+    - Small cortical defects mainly frontal lobe
+- [Creutzfeldt-Jakob Disease](/document/creutzfeldt-jakob-disease-cjd/e1b27954-6591-4bb0-a659-b13790492620)
+    - Rapidly fatal, prion-related disease with impairments in cognition and behavioral changes
+    - Diffusion-weighted imaging hyperintensity in striatum, cingulum, and neocortex
+- ## Causes of Reversible Dementia
+  
+  
+    - Normal-pressure hydrocephalus, vitamin B12 deficiency, hypothyroidism, depression, mass lesions, infections (neurosyphilis, HIV), trauma (chronic subdurals)
+
+# PATHOLOGY
+
+- ## General Features
+  
+  
+    - Vascular-related lesions leading to loss of brain function
+    - Chronic small vessel insults > large vessel infarcts
+    - Areas of infarction (focal or multifocal) with associated atrophy
+- ## Risk Factors
+  
+  
+    - History of myocardial infarction/coronary artery disease, stroke/transient ischemic attack (TIA)
+    - Atherosclerosis, hypertension, hyperlipidemia, atrial fibrillation
+    - Diabetes, obesity, smoking, advanced age
+
+# CLINICAL ISSUES
+
+- ## Presentation
+  
+  
+    - Significant heterogeneity in clinical presentation depending on location, type, and size of vascular lesion
+    - Impairment in at least 1 cognitive domain leading to decline in functional status
+          - Executive function and attention more commonly initially affected than in AD
+          - Slow motor/information processing
+          - Language difficulties
+          - Changes in behavior and personality
+          - Depression and anxiety
+    - Other: Seizures, bladder incontinence, gait disturbance, and additional focal abnormalities
+    - Overt disease: Cognitive impairment due to clinically evident vascular event [large territory infarct(s)]
+          - > 60% of stroke patients (dementia in ~ 30% of cases)
+    - Covert disease: Insidious process of vascular insults (clinically silent with extensive lacunar infarcts)
+- ## Demographics
+  
+  
+    - 2nd most common cause of dementia after AD
+          - > 10% of dementia cases
+    - Age: Incidence increases with age
+    - Sex: M > F
+
+# DIAGNOSTIC CHECKLIST
+
+- ## Image Interpretation Pearls
+  
+  
+    - Heterogeneous F-18 FDG activity without any specific pattern suggests VaD
+    - Lesions can include basal ganglia and other areas typically spared in other diseases
+    - MR correlation helpful
+
+ 7855ad33-290d-4bb0-81a6-63126fea7e4f