Intracranial stenosis refers to a condition where arteries within the brain become narrowed. This narrowing can significantly impede blood flow to various brain regions, potentially leading to serious health consequences.
Understanding Intracranial Stenosis
Intracranial stenosis involves the narrowing of arteries located inside the skull. The term “stenosis” itself means a constriction or narrowing of a passage. This condition typically affects major arteries that supply blood to the brain, such as the middle cerebral artery, anterior cerebral artery, posterior cerebral artery, and basilar artery, as well as the internal carotid artery (ICA). When these arteries narrow, the flow of oxygen and nutrients to brain tissue is reduced. Adequate blood flow is necessary for brain cells to function properly, and any significant reduction can impair neurological processes.
Causes and Contributing Factors
The most common cause of intracranial stenosis is atherosclerosis, a buildup of fatty deposits, known as plaque, within the artery walls. Over time, this plaque hardens and narrows the arterial lumen, restricting blood flow. Plaque can also rupture, leading to the formation of blood clots that further obstruct the artery or travel downstream to block smaller vessels.
Several factors increase the risk of developing atherosclerosis and, consequently, intracranial stenosis. High blood pressure, high cholesterol, and diabetes are significant modifiable risk factors. Smoking and obesity also contribute to the development of this condition. Less common causes include vasculitis, which is inflammation of blood vessels, arterial dissection (a tear in the artery wall), fibromuscular dysplasia, and radiation-induced changes to the vessels.
Identifying the Symptoms
Symptoms of intracranial stenosis arise from the reduced blood flow to specific areas of the brain. The primary manifestations are transient ischemic attacks (TIAs) and ischemic strokes. A TIA, often called a “mini-stroke,” occurs when blood flow to the brain is temporarily interrupted, leading to stroke-like symptoms that usually last a few minutes to hours.
Symptoms of a TIA or stroke can include sudden numbness or weakness on one side of the body, difficulty speaking or understanding speech, vision changes, or problems with balance and coordination. A sudden, severe headache with no known cause can also occur. These symptoms are warnings that blood flow to the brain is compromised and should prompt immediate medical attention, as they can progress to a full stroke if the arterial narrowing is severe or a clot completely blocks the vessel.
Diagnosis and Management
Diagnosing intracranial stenosis typically begins with a medical history review and a neurological examination. Imaging tests are then used to confirm the presence and severity of arterial narrowing. Magnetic Resonance Angiography (MRA) and Computed Tomography Angiography (CTA) are non-invasive tests that provide detailed images of the brain’s blood vessels, often utilizing a contrast agent to enhance visibility. Digital Subtraction Angiography (DSA) is another diagnostic method that offers highly detailed views of the arteries, often considered the gold standard for visualizing vascular structures.
Management of intracranial stenosis focuses on reducing the risk of stroke and preserving brain function. Medical therapy is typically the first line of treatment. Antiplatelet medications, such as aspirin and clopidogrel, are commonly prescribed to prevent blood clots from forming in the narrowed arteries. Dual antiplatelet therapy (DAPT), combining agents like aspirin and clopidogrel, may be used for a period to further reduce stroke risk.
Controlling risk factors is also a major component of medical management. Statins are used to manage high cholesterol levels and can help stabilize plaque within the arteries. Medications to control high blood pressure and diabetes are also prescribed to reduce the progression of atherosclerosis. Lifestyle modifications, including a healthy diet, regular exercise, and smoking cessation, are strongly encouraged to complement medical treatments.
For more severe cases, or when medical therapy does not adequately control symptoms, endovascular procedures may be considered. Angioplasty involves inserting a catheter with a balloon into the narrowed artery and inflating the balloon to widen the vessel. Stenting often accompanies angioplasty, where a mesh tube is placed within the artery to help keep it open and maintain blood flow. While these procedures can improve blood flow, they carry their own risks, including the potential for stroke or vessel damage. The decision to pursue endovascular interventions is carefully weighed against the patient’s individual risk factors and the severity of their condition.