Stroke

Definition

A stroke is an interruption of the blood supply to any part of the brain. A stroke is sometimes called a "brain attack."

Alternative Names

Cerebrovascular disease; CVA; Cerebral infarction; Cerebral hemorrhage; Ischemic stroke; Stroke - ischemic

Causes

Every 45 seconds, someone in the United States has a stroke. A stroke can happen when:

• A blood vessel carrying blood to the brain is blocked by a blood clot. This is called an ischemic stroke.
• A blood vessel breaks open, causing blood to leak into the brain. This is a hemorrhagic stroke.

If blood flow is stopped for longer than a few seconds, the brain cannot get blood and oxygen. Brain cells can die, causing permanent damage.

ISCHEMIC STROKE

This is the most common type of stroke. Usually this type of stroke results from clogged arteries, a condition called atherosclerosis. (See stroke secondary to atherosclerosis.) Fatty deposits collect on the wall of the arteries, forming a sticky substance called plaque. Over time, the plaque builds up. Often, the plaque causes the blood to flow abnormally, which can cause the blood to clot. There are two types of clots:

• A clot that stays in place in the brain is called a cerebral thrombus.
• A clot that breaks loose and moves through the bloodstream to the brain is called a cerebral embolism.

Another important cause of cerebral embolisms is a type of arrhythmia called atrial fibrillation. Other causes of ischemic stroke include endocarditis, an abnormal heart valve, and having a mechanical heart valve. A clot can form on a heart valve, break off, and travel to the brain. For this reason, those with mechanical or abnormal heart valves often must take blood thinners.

HEMORRHAGIC STROKE

A second major cause of stroke is bleeding in the brain hemorrhagic stroke. This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells.

STROKE RISKS

High blood pressure is the number one reason that you might have a stroke. The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, high cholesterol, and heart disease.

Certain medications increase the chances of clot formation, and therefore your chances for a stroke. Birth control pills can cause blood clots, especially in woman who smoke and who are older than 35.

Men have more strokes than women. But, women have a risk of stroke during pregnancy and the weeks immediately after pregnancy.

Cocaine use, alcohol abuse, head injury, and bleeding disorders increase the risk of bleeding into the brain.

See also:

• Stroke secondary to carotid dissection (bleeding from the carotid arteries)
• Stroke secondary to carotid stenosis (narrowing of the carotid arteries)
• Stroke secondary to cocaine use
• Stroke secondary to FMD (fibromuscular dysplasia)
• Stroke secondary to syphilis
• Hemorrhagic stroke
• Arteriovenous malformation (AVM)

References

American Heart Association. Heart Disease and Stroke Statistics -- 2005 Update. Dallas, Texas: American Heart Association; 2005.

Goldman L, Ausiello D, eds. Cecil Textbook of Medicine, 22nd ed. Philadelphia, Pa: Saunders; 2004.

Marx JA, Hockberger RS, Walls RM, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002.

Mosca L, Banka CL, Benjamin EJ, et al. Evidence-Based Guidelines for Cardiovascular Disease Prevention in Women: 2007 Update. Circulation. 2007; Published online before print February 19, 2007.

Wolff T, Miller T. Evidence for the reaffirmation of the U.S. Preventive Services Task Force recommendation on screening for high blood pressure. Ann Intern Med. 2007;147(11): 787-91.