Makindo Medical Notes

Related Subjects: |Neurological History taking |Causes of Stroke |Ischaemic Stroke |Hypertension |Small Vessel Disease |CADASIL |CARASIL

Introduction

Leukoaraiosis refers to changes in the cerebral white matter, visible as hypodense areas on CT scans or hyperintense areas on MRI. It is commonly associated with small vessel disease, particularly due to chronic hypertension leading to lipohyalinosis of small penetrating arteries. Leukoaraiosis is a significant radiological marker for chronic ischemic damage and is associated with increased risk of stroke and vascular dementia.

About

• Leukoaraiosis involves changes in the subcortical white matter, frequently seen as a complication of hypertension.
• Microvascular disease contributes to the risk of stroke and vascular cognitive impairment.
• There is an increased risk of symptomatic intracerebral hemorrhage (sICH), especially after thrombolytic therapy with tissue plasminogen activator (tPA).
• Patients may have a higher risk of basal ganglia and lobar hemorrhages.

Aetiology

• Caused by damage to the cerebral microcirculation, particularly small perforating arteries.
• Leukoaraiosis is a radiological marker indicating chronic ischemic damage in the white matter.
• Associated with a greater risk of symptomatic intracerebral hemorrhage after tPA administration.

Risk Factors for Small Vessel Disease

• Chronic hypertension
• Diabetes mellitus
• Coronary artery disease
• Obesity (body mass index ≥ 30)
• Elevated homocysteine levels
• Physical inactivity
• Advancing age (men over 45, women over 55)
• Smoking
• Dyslipidemia

Pathology

• Myelin Degeneration: Loss of myelin sheath around nerve fibers in white matter.
• Astrogliosis: Proliferation of astrocytes in response to injury.
• Vessel Wall Changes: Thickening with hyaline changes and fibrosis of small deep vessels due to lipohyalinosis.
• Lacunar Infarcts: Presence of small cavities (lacunes) due to infarction of deep brain structures.

Clinical Features

• Stroke: Increased incidence of lacunar infarcts and subcortical hemorrhages.
• Vascular Dementia: Cognitive impairment due to chronic ischaemia, historically referred to as Binswanger's disease.
• Motor Symptoms: May present with gait disturbances and parkinsonism.
• Negative Association: Less commonly associated with atrial fibrillation and carotid artery disease compared to other stroke types.
• Asymptomatic: Many patients remain asymptomatic until late stages.

Other Causes of Leukoaraiosis

• Cerebral Amyloid Angiopathy (CAA): Deposition of amyloid β-peptide in cerebral vessels leading to vessel fragility.
• CADASIL: Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy; a genetic condition causing similar white matter changes.
• Multiple Sclerosis: Demyelinating disease that can cause white matter lesions.
• Radiation Therapy: Exposure can lead to white matter changes resembling leukoaraiosis.

Investigations

• Computed Tomography (CT): Shows periventricular hypodensities and may reveal lacunar infarcts.
• Magnetic Resonance Imaging (MRI): Preferred modality using high-resolution T2-weighted and FLAIR sequences.
• MRI findings include bilateral and symmetrical hyperintensities in periventricular white matter and corona radiata.
• Lesions are described as caps (adjacent to ventricles), rims, halos, or patchy areas.
• Gradient-echo T2-weighted MRI may detect silent cerebral microbleeds.
• Scoring Severity: The Fazekas scale is commonly used to grade white matter changes.

Fazekas Scale for White Matter Lesions

The Fazekas scale grades periventricular and deep white matter lesions separately:

• Periventricular White Matter Lesions:
• 0: No lesions
• 1: Caps or a pencil-thin lining
• 2: Smooth halo
• 3: Irregular lesions extending into deep white matter
• Deep White Matter Lesions:
• 0: No lesions
• 1: Punctate foci
• 2: Beginning confluence of foci
• 3: Large confluent areas

Management

• Blood Pressure Control: Aggressive management of hypertension to the lowest tolerated levels.
• Risk Factor Modification: Control diabetes, manage cholesterol, encourage smoking cessation, and promote physical activity.
• Antiplatelet Therapy: May reduce the risk of stroke in patients with small vessel disease.
• Cognitive Assessment: Regular monitoring for signs of cognitive decline or dementia.
• Patient Education: Inform about the importance of adherence to medication and lifestyle changes.

Prognosis

• Leukoaraiosis is associated with an increased risk of stroke, cognitive decline, and functional impairment.
• Early detection and management of risk factors can slow progression.

References

• Inzitari D. Leukoaraiosis: An Independent Risk Factor for Stroke? Stroke. 2003;34(8):2067-2071.
• Wardlaw JM, Smith C, Dichgans M. Mechanisms of sporadic cerebral small vessel disease: insights from neuroimaging. Lancet Neurol. 2013;12(5):483-497.
• Fazekas F, Chawluk JB, Alavi A, et al. MR signal abnormalities at 1.5 T in Alzheimer's dementia and normal aging. AJR Am J Roentgenol. 1987;149(2):351-356.