DEAR MAYO CLINIC:

One of my dearest friends has a grandmother who has 100 percent blockage in one of the arteries in her neck and 75 percent in the other. Her doctors have told her that there is nothing to be done for the 100 percent blocked artery. Is this true? What are her options?

ANSWER:

The two arteries in the neck that supply most of the blood to the brain are called the carotid arteries. The carotid arteries can be affected by atherosclerosis that can lead to progressive narrowing (stenosis) and, in some instances, complete blockage (occlusion). In most cases of complete carotid artery occlusion, attempting to reopen the blocked artery isn't beneficial. Treatment options typically are focused on carotid arteries that are only partially blocked.

Atherosclerosis of the carotid arteries -- also called carotid artery disease or atherosclerotic occlusive disease of the carotid arteries -- develops when fatty deposits (plaque) clog those arteries. The buildup of plaque blocks the blood supply to the brain and increases a person's risk of stroke.

In its early stages, carotid artery disease may not produce any signs or symptoms. As the disease progresses, however, it can deprive the brain of blood and lead to a transient ischemic attack (TIA). The signs and symptoms of TIA include sudden numbness or weakness involving the face, arm or leg, typically on one side of the body; slurred or garbled speech or difficulty understanding others; or sudden blindness in one eye. Although a TIA produces symptoms similar to a stroke, it usually lasts only a few minutes and causes no permanent damage. But, a TIA may warn of an impending stroke.

In mild to moderate cases, carotid artery disease often can be managed with a combination of lifestyle changes -- such as quitting smoking, losing weight, eating healthy foods and exercising regularly -- and medication. In more severe cases, such as the one you describe in which a carotid artery is more than 70 percent blocked, a procedure to remove the blockage and open the artery (revascularization) may be necessary to reduce the risk of TIA and stroke.

Carotid endarterectomy and carotid artery stenting are both safe, effective treatments for advanced carotid artery disease. During endarterectomy, a surgeon opens the affected carotid artery and removes the plaque. The artery is then repaired with either stitches or a graft. During carotid angioplasty and stenting, a tiny balloon is threaded by catheter to the area where the artery is clogged. The balloon is inflated to widen the artery, and a small wire-mesh coil (stent) is inserted to keep the artery from narrowing again. Clinical trials have shown that these procedures are low risk in most healthy people, have lasting benefit and help prevent strokes.

In most instances when a carotid artery is completely blocked, the risk of a revascularization procedure usually outweighs the benefit. Fortunately, the brain has great capacity to use alternative routes to provide blood to the area of the brain supplied by the blocked artery. A network of blood vessels at the base of the brain, called the circle of Willis, can often supply the necessary blood flow.

Many people function normally with one completely blocked carotid artery, provided they haven't had a disabling stroke. If narrowing hasn't caused complete blockage, then a revascularization procedure may be warranted. Both medical treatment and surgical procedures can prove effective for preventing TIA and stroke with carotid artery narrowing. Because individual circumstances are unique, however, the therapeutic options should be discussed in detail with a specialist, preferably a neurologist.

-- Kevin Barrett, M.D., Neurology, Mayo Clinic, Jacksonville, Fla.

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