Neurology · Dementia
The facts most likely to be tested
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Vascular dementia presents with a stepwise decline in cognitive function corresponding to recurrent cerebrovascular events.
The clinical course is characterized by patchy cognitive deficits rather than the global, uniform decline seen in Alzheimer disease.
Neuroimaging via MRI is the diagnostic modality of choice, revealing multiple infarcts, lacunar infarcts, or white matter hyperintensities.
Patients frequently exhibit focal neurologic deficits such as hemiparesis, gait abnormalities, or pseudobulbar palsy.
The pathophysiology involves small vessel disease or large vessel atherosclerosis leading to cumulative cerebral infarction (and white matter ischemia).
Executive dysfunction is often the most prominent cognitive impairment, occurring earlier than the memory loss seen in Alzheimer disease.
Management focuses on secondary prevention of stroke through strict control of hypertension, diabetes mellitus, and hyperlipidemia.
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A 74-year-old male is brought to the clinic by his daughter, who reports that his memory has worsened in a 'stair-step' fashion over the past 18 months. The patient has a history of hypertension and type 2 diabetes. On examination, he demonstrates impaired executive function and slowed processing speed, but his memory is relatively preserved compared to his planning abilities. Physical exam reveals asymmetric hyperreflexia and an unsteady, shuffling gait. MRI of the brain shows periventricular white matter hyperintensities and evidence of prior lacunar infarcts.
What is the most likely diagnosis?
Vascular dementia
The patient's 'stepwise' decline, history of vascular risk factors, and MRI findings of white matter disease and lacunar infarcts are classic for vascular dementia, which is primarily driven by executive dysfunction.
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Etiology / Epidemiology
Second most common dementia caused by cerebrovascular disease and chronic hypertension.
Clinical Manifestations
Characterized by a stepwise decline in cognitive function with focal neurologic deficits.
Diagnosis
Diagnosis requires MRI brain showing evidence of infarction or white matter disease.
Treatment
Management focuses on blood pressure control and antiplatelet therapy to prevent further strokes.
Prognosis
Prognosis is poor, with substantially higher mortality than Alzheimer disease due to recurrent cardiovascular events.
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Epidemiology & Etiology
Vascular dementia is primarily driven by atherosclerosis and small vessel disease. Major risk factors include hypertension, diabetes mellitus, and atrial fibrillation. It is frequently seen in patients with a history of lacunar infarcts or strategic infarcts.
Pertinent Anatomy
Damage typically involves the subcortical white matter or the thalamus. Involvement of the frontal-subcortical circuits explains the executive dysfunction and psychomotor slowing observed in patients.
Pathophysiology
Chronic ischemia leads to leukoaraiosis and demyelination of white matter tracts. Repeated micro-infarctions result in cumulative cognitive impairment. Unlike Alzheimer's, the damage is often patchy and related to specific vascular territories.
Clinical Manifestations
Patients present with a stepwise decline in cognition, often following discrete stroke events. Executive dysfunction is typically more prominent than memory loss in early stages. Look for focal neurologic deficits such as hemiparesis, gait abnormalities, or pseudobulbar palsy.
Diagnosis
The MRI brain is the gold standard imaging modality to identify ischemic lesions. Diagnostic criteria require evidence of cerebrovascular disease on imaging and a temporal relationship between a stroke and cognitive decline. Hachinski Ischemic Score is often used to differentiate from Alzheimer's.
Treatment
Primary management is aggressive blood pressure control to prevent further vascular injury. Aspirin is the standard antiplatelet therapy for secondary prevention. Avoid anticoagulation unless there is a clear indication like atrial fibrillation. Cholinesterase inhibitors are not FDA-approved but may be used off-label.
Prognosis
The disease course is often punctuated by acute worsening. Recurrent stroke is the primary cause of morbidity. Patients require strict monitoring of lipid profiles and HbA1c to mitigate progression.
Differential Diagnosis
Alzheimer's: insidious onset with early memory loss
Lewy Body Dementia: visual hallucinations and parkinsonism
Frontotemporal Dementia: early personality and behavioral changes
Normal Pressure Hydrocephalus: wet, wobbly, and wacky triad
Delirium: acute, fluctuating consciousness with reversible cause