Vascular dementia (Multi-infarct dementia…)

Vascular dementia (VD) describes gradual cognitive decline caused by small or large vessel disease. Important risk factors include hypertension, diabetes mellitus, hyperlipidemia, and advanced age. Large vessel changes primarily lead to thrombotic and/or embolic vascular occlusion, resulting in localized infarctions. In contrast, small vessel changes generally lead to more diffuse lesions. Common symptoms are cognitive impairment, motor disorders and changes in behavior. The severity of symptoms and the mode of onset (insidious or sudden) depend on the number of vascular events and the extent of cerebral damage. Vascular dementia is primarily a clinical diagnosis that is supported by evidence of cerebrovascular lesions on imaging. Management consists of treating underlying conditions (e.g., hypertension) and, in some cases, antiplatelet drugs.

• Second most common type of dementia (10–20% of cases).
• Prevalence increases with age (∼ 1–4% in patients ≥ 65 years)

References:^[1]

Epidemiological data refers to the US, unless otherwise specified.

• VD may occur as a result of a prolonged and severe cerebral ischemia of any etiology; primarily
  • Large artery occlusion (usually cortical ischemia)
  • Lacunar stroke (small vessel occlusion resulting in subcortical ischemia)
  • Chronic subcortical ischemia
• Risk factors
  • Advanced age
  • History of stroke
  • Underlying conditions associated with cardiovascular disease; : chronic hypertension; , hyperglycemia, hypercholesterolemia and hypertriglyceridemia, obesity
  • Traumatic brain injury with intracranial or intracerebral hemorrhage

References:^[1]

Lesions of the smaller (microangiopathy) and larger (macroangiopathy) cerebral arteries share common risk factors and pathological features but produce distinct clinical entities.

Small vessel disease

• Predominantly caused by lipohyalinosis, microatheroma, and/or amyloid beta deposition ) of cerebral vessels → thickening of the intima and/or the vessel wall, inflammation, thromboembolisms → vessel stenosis, occlusion or rupture → cerebral ischemia → VD
• Mainly causes infarcts or chronic ischemia in subcortical white matter; (e.g., internal capsule) and/or in small penetrating arteries (lacunes) → diffuse white matter disease (infarctions or chronic ischemia), subcortical lacunar infarct, or the combination of both (known as Binswanger's disease, which has multiple synonyms)

Large vessel disease

• Primarily caused by atherosclerosis (risk factors include hypertension, diabetes, and hyperlipidemia)
• Usually in the form of repeated cortical ischemic events → progressive damage to neural networks (multi-infarct dementia).
• If the affected area is large and/or significant enough (strategic infarctions ), a single ischemic event may suffice to bring on VD (single-infarct dementia)

References:^[1][2][3][4]

Symptoms depend on the location of ischemic events and therefore vary widely between individuals, but a progressive impairment of daily life is common. Because of the diverse clinical picture, the term “vascular cognitive impairment” is gaining popularity over VD .

Dementia due to small vessel disease

• Symptoms tend to progress gradually or stepwise and comparatively slower than in multi-infarct dementia
• Generally associated with signs of subcortical pathology
  • Early symptoms
    • Impaired memory
    • Reduced executive functioning
    • Loss of visuospatial abilities
    • Confusion
    • Apathy
    • Motor disorders (e.g., gait disturbance, urinary incontinence)
  • Later symptoms:
    • Further cognitive decline: loss of judgement, disorientation
    • Mood disorders (e.g., euphoria, depression)
    • Behavioral changes (e.g., aggressiveness)
  • Advanced stages:
    • Further motor deterioration: dysphagia, dysarthria

Dementia due to large vessel disease

• Usually sudden onset
• Multi-infarct dementia: typically, stepwise deterioration
• Generally associated with signs of cortical pathology
  • Cognitive impairment in combination with asymmetric or focal deficits (e.g., unilateral visual field defects, hemiparesis, Babinski reflex present)
  • Symptoms depend on the affected cerebral region(s): see “Clinical features” of stroke

References:^[1][4][5][6]

VD is a clinical diagnosis (as with all dementias; see the Mini-mental state examination) based on medical history and clinical features, which is supported by imaging findings.

• Ultrasound
  • Doppler examination of critical vessels (particularly the carotid arteries) for signs of cerebrovascular risk (e.g., atherosclerosis)
  • Echocardiography to evaluate the risk of cardioembolic events
• Cranial CT: microangiopathic lesions located in white matter, multiple lacunar lesions
• Functional imaging (PET-CT): may be helpful in distinguishing between VD and Alzheimer's disease (AD).
  • VD: hypoperfusion and hypometabolism more pronounced in the frontal lobe
  • AD: hypoperfusion and hypometabolism more pronounced in the parietal and temporal lobes
• Cranial MRI: : multiple lacunar and white matter lesions (periventricular and in the semioval center)
• Conduct laboratory tests to rule out other potential causes or comorbidities (e.g., glucose levels, TSH)

References:^[1][5]

• The clinical findings of vascular dementia are often similar to other types of dementia, e.g. Alzheimer's disease. However, there are some distinguishing features (see differential diagnosis of dementia subtypes)
• Metabolic and endocrine disorders (e.g., vitamin B12 deficiency, hypothyroidism)
• Infections (e.g., neurosyphilis)
• Multiple sclerosis
• Space-occupying lesions (e.g., brain tumors or chronic subdural hematoma)
• Depression

The differential diagnoses listed here are not exhaustive.