Cerebral Small Vessel Disease and Vascular Cognitive Impairment: An Overview

Introduction

Cerebral small vessel disease is a leading cause of stroke (reduced blood flow to the brain). Patients suffering from cerebral small vessel disease are at an increased risk of developing a stroke. The small blood vessels of the brain, such as small arteries, arterioles, venules, and capillaries, are crucial for maintaining blood supply throughout the brain. Inadequate blood supply to the brain due to pathology in these blood vessels gives rise to other systemic problems. This disease is also associated with several neurological issues.

What Are Cerebral Small Vessels?

They are the small, minute blood vessels of the brain. Cerebral small vessels are of two types -

1. They are present on the convex surface of the brain and subarachnoid space (a part of the meninges that are layers covering the brain and separating the brain from the skull).

2. They are perforating arteries that arise from the anterior (front), middle, and posterior (back) cerebral arteries. These arteries supply blood to the subcortical parenchyma (functional brain tissue).

The diameter of these small blood vessels ranges from 50 to 400 micrometers. These small vessels supply blood to the brain tissue. Obstructions in these small blood vessels lead to restricted blood supply to the brain.

What Causes Cerebral Small Vessel Disease?

There are various etiological factors involved in the progression of this disease. Pathologies associated with the blood vessels are the leading causes of this condition including -

Arteriolosclerosis -

• Arteriolosclerosis is the build-up of fat and cholesterol in the walls of the arteries causing the narrowing of the arteries. The arteries are small pipe-like structures that consist of a lumen (space). The fatty deposition takes place in the lumen which increases blood pressure.

• This causes severe degenerative changes in the arteries. The arteries lose their elasticity and become inflexible. This directly affects the flowing of blood. An adequate amount of blood fails to reach the brain tissue.

• The occlusion produced by the fatty deposition in the lumen causes restricted or no blood flow through the artery. This leads to ischemia (reduced oxygen levels) due to decreased blood flow in the blood vessel.

• Patients with diabetes and hypertension are more prone to develop arteriolosclerosis. Advancing age, smoking, and obesity are also conventional risk factors.

Cerebral Amyloid Angiopathy -

Amyloid is a protein deposited in the lumen of the arteries of the brain, causing acute ischemia and leading to stroke. Cerebral amyloid angiopathy is commonly seen in older individuals (above 55 years). The amyloid protein deposits in the lumen of the arteries cause bleeding into the brain. This bleeding causes harm to the brain tissue. The following symptoms of this disorder are -

• Headache.

• Drowsiness and weakness.

• Vomiting.

• Problems with vision, such as double vision and blurred vision.

• Mental confusion.

• Seizures are also known as amyloid spells (rapid involuntary movements of the body accompanied by loss of consciousness).

• Coma (a state of prolonged unconsciousness with no response to external stimuli).

• Severe uncontrolled bleeding can lead to loss of mental function and memory loss.

What Is the Relation Between Cerebral Small Vessel Disease and Vascular Cognitive Impairment?

Cerebral small vessel diseases are the main cause of vascular cognitive impairment. It is the leading cause of stroke and dementia (memory loss). Patients with arteriosclerosis suffer from neurological problems mainly due to reduced blood supply to the brain.

Vascular dementia is a condition caused when the blood flow through an artery gets blocked. Restricted blood flow through an artery leads to acute ischemia, causing a stroke. Reduction in blood supply will deprive the brain of its essential nutrients leading to neurological symptoms.

The following symptoms are observed in patients with vascular cognitive impairment -

• Mental confusion.

• Thinking disabilities, lack of attention and focus.

• Problems with memory and difficulty in planning or organizing tasks.

• Urinary incontinence (it is a sudden or frequent urge to pass urine and inability to control it).

• Unsteady gait (walk), problems with balance and coordination.

• Patients suffer from depression and mood changes.

How to Diagnose Cerebral Small Vessel Disease?

The various diagnostic approaches for cerebral small vessel disease are as listed:

Physical Examination: The doctor will conduct a thorough physical examination. Medical and medication history may also be accounted for.

Imaging Studies: Brain imaging scans such as MRI (magnetic resonance imaging), CT scan (computed tomography), and PET scan (positron emission tomography) help identify diseases or injuries in the brain. The MRI scan will show the following characteristics -

• Small Subcortical Infarcts - These infarcts are obstructions in blood circulated caused due to deposition of fats in the arteries. They are in the cerebral cortex, composed of the frontal, temporal, parietal, and occipital lobes.

• Lacunar Infarcts - They are a type of subcortical infarcts.

• Microbleeds in the Brain - These are small circular areas of micro hemorrhages in the brain. They occur due to the chronic accumulation of blood products in the brain tissue.

• Enlarged Perivascular Spaces - These spaces surround the penetrating arteries in the brain.

• Brain Atrophy - A loss of brain tissue, including the neurons and the connections between them. The shrunken appearance of the brain with loss of function is characteristic of this condition.

How Are the Neurological Symptoms Treated?

• The treatment involves providing symptomatic relief.

• The patients are advised to physical therapy to improve motor function. Exercise will help regain muscle strength and reduce weakness.

• Medications are prescribed to help improve memory.

• Anti-epileptic medications are used to control seizures.

• Antiplatelet medications are given to patients with ischemic stroke.

• Antihypertensive medications are given to patients with increased blood pressure.

• Preventive measures such as abstaining from smoking and consuming alcohol, exercising regularly, and maintaining a healthy diet to keep weight in check are to be adopted by the patient to prevent further complications.

Conclusion:

Cerebral small vessel disease is a serious condition that can adversely affect brain function. Preventive and therapeutic procedures are proven to help treat this condition. The prognosis of this disease is good if a prompt diagnosis is made and the physician adopts effective treatment modalities. Medications and lifestyle modifications by the patient will help control neurological symptoms.