Extracranial (brachiocephalic) atherosclerosis is hardening of the arteries that supply the head and neck (carotid and vertebral arteries), causing narrowing and blockage of these vessels. It is similar to hardening of the arteries elsewhere in the body such as the heart or legs. If a vessel becomes completely blocked or even severely narrowed, blood flow to part of the brain can be threatened and a stroke can occur.
The same risk factors that are associated with intracranial atherosclerosis are associated with atherosclerosis elsewhere (such as in the vessels of the heart, causing heart attacks). They include diabetes, high blood pressure, high cholesterol, and smoking. Atherosclerosis of the carotid arteries often causes transient ischemic attacks (TIAs or ministrokes) because pieces of the material that forms the blockage (plaque) and blood clots that form on the plaque break off and are carried into the head where they can block vessels supplying the brain. Typical symptoms include weakness or numbness on one side of the body, inability to speak or understand speech, and changes in vision. If the blockage produced by this material is small and breaks up quickly, a TIA occurs. If there is blockage of a larger vessel or the blockage doesn’t break up right away, a stroke follows.
Blockage of the vertebral arteries usually causes symptoms because of decreased blood flow to part of the brain, not because of pieces of plaque and clot breaking off. The symptoms of blockage of these vessels may get better and worse, or they may suddenly appear if a stroke occurs. These symptoms include dizziness, nausea, difficulty with balance or coordination, blurry or double vision, and changes in hearing.
If the carotid artery is minimally constricted due to blockage, medical treatment may be recommended. However, if significant blockage is present, surgery (endarterectomy) is usually performed. Designed to remove the plaque causing the constriction which in turn allows the blood to flow more freely, endarterectomy is becoming increasingly more common, and is often referred to as “the gold standard” treatment for carotid atherosclerosis. Endarterectomy is especially recommended for patients who have significant blockage.
In 2004, a minimally invasive treatment for carotid atherosclerosis called carotid stenting received FDA approval. This procedure is performed by opening the artery with a small tube and then inflating a balloon catheter to press the plaque into the sides of the artery wall. Similar to angioplasty, this procedure is also utilized in the heart. Subsequently, a stent, or supportive tube, is then placed in the artery to cover the plaque and help keep the vessel open.
In deciding between surgery and stenting to treat carotid atherosclerosis, doctors consider the patient’s overall health condition. In cases where a patient is symptomatic and at high risk for surgery (experiencing poor health in general, manifesting a heart condition or experiencing a previous stroke), angioplasty and stenting has been proven in a recent trial to be at least as effective as surgery. However, the same trial also proves that as stroke and death rates for carotid stenting range from 4.4% to over 12% at 30 days, with a one-year stroke and death rate of up to 12%, neither carotid stenting nor surgery may be a good option for patients with no symptoms from their stenosis.
In cases where a narrowing or stenosis is present in the vertebral artery, angioplasty and stenting are usually performed.