What is chronic microangiopathy of the brain?

Chronic Microangiopathy of the Brain: Understanding Small Vessel Disease

Chronic microangiopathy of the brain refers to pathological processes affecting the small blood vessels in the brain, leading to various neurological symptoms and cognitive impairment. This condition is a key component of cerebral small vessel disease (cSVD) and represents one of the leading causes of stroke, cognitive decline, and vascular dementia 1.

Pathophysiology

Cerebral microangiopathy involves several pathological changes in small brain vessels:

• Endothelial dysfunction: Blood-brain barrier (BBB) failure is pivotal in the pathophysiology of cerebral microangiopathy 1
• Arteriosclerosis (lipohyalinosis): Thickening and hardening of small arterial walls, often associated with aging and hypertension 1
• Microvascular changes: Including fibroid necrosis, microaneurysm formation, and perivascular hemosiderin deposition 1

Types of Cerebral Microangiopathy

1. Age-related and hypertension-related small vessel disease: Most common form 2
2. Cerebral amyloid angiopathy (CAA): Characterized by amyloid deposition in vessel walls, predisposing to lobar hemorrhages 1
3. Hereditary forms:
   • CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) 1, 3
   • CARASIL (Cerebral Autosomal Recessive Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) 1
   • HERNS (Hereditary Endotheliopathy with Retinopathy, Nephropathy, and Stroke) 1
4. Other rare forms: Including vasculitides, mitochondrial cytopathies, and Fabry's disease 3

Clinical Manifestations

Cerebral microangiopathy presents with various neurological symptoms depending on the location and severity of vascular damage:

• Progressive cognitive decline (38.1% of patients) 4
• Gait apraxia (27.8%) 4
• Stroke-related symptoms and seizures (24.2%) 4
• Transient ischemic attack (TIA) symptoms (22%) 4
• Vertigo (17%) 4
• Urinary incontinence 4

The location of lesions correlates with specific symptoms:

• Frontal lobe lesions: Associated with cognitive decline, seizures, and gait problems
• Parietooccipital lesions: Related to TIA, seizures, and incontinence
• Basal ganglia lesions: Associated with gait apraxia, vertigo, and incontinence 4

Neuroimaging Findings

Cerebral microangiopathy is characterized by several imaging findings:

• White matter hyperintensities (WMH): Visible on T2-weighted MRI 1, 5
• Lacunar infarcts: Small subcortical infarcts typically less than 1 cm in size 1
• Enlarged perivascular spaces 1
• Cerebral microbleeds: Small hemorrhages visible on susceptibility-weighted MRI 1
• Blood-brain barrier leakage: Detectable with dynamic contrast-enhanced MRI 1

Risk Factors

Major risk factors for cerebral microangiopathy include:

• Age: Strong positive correlation with lesion load 4
• Arterial hypertension: Most important modifiable risk factor 4, 2
• Obesity: Positively related to cerebral lesion load 4
• Diabetes mellitus 2
• Hypercholesterolemia 2
• Smoking 2

Clinical Implications and Management

Cerebral microangiopathy has significant clinical implications:

• Increased stroke risk: Both through small vessel occlusion and hemorrhagic events 5
• Cognitive impairment: Progressive decline that may lead to vascular dementia 2
• Reduced cerebrovascular reactivity: Impaired capacity to adapt to changes in perfusion pressure 5

Management focuses on:

1. Control of vascular risk factors:

   • Aggressive blood pressure management (though optimal targets remain debated) 2
   • Treatment of diabetes, hyperlipidemia, and obesity
   • Smoking cessation

2. Pharmacological interventions:

   • Antihypertensive medications may help prevent cognitive decline 2
   • Acetylcholinesterase inhibitors may provide therapeutic benefit for cognitive symptoms 3

Important Caveats

• The relationship between microangiopathy and cognitive decline is complex, with both high and low blood pressure potentially contributing to cognitive impairment 2
• Cerebral microangiopathy often coexists with large vessel disease, with potentially additive negative effects on brain perfusion 5
• Diagnosis requires careful neuroimaging interpretation, as artifacts and normal variants can mimic pathological findings 1

Cerebral microangiopathy represents an increasingly recognized cause of neurological disability, and its early identification and management of risk factors are essential to prevent progression and improve outcomes.