Conditions InDepth: Stroke

Stroke is a brain injury that occurs when the brain's blood supply is interrupted. Without oxygen and nutrients from blood, brain tissue starts to die within minutes, resulting in a sudden loss of function. Another term for stroke is cerebrovascular accident (CVA).

Blood Supply to the Brain

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In order to change people’s perception of stroke as untreatable, there has been a national effort over the past decade or so to call it a "brain attack," acquiring some of the urgency popularly associated with heart attacks. The acute treatment of "brain attacks" has not reached the level of success now achieved with heart attacks. Nevertheless, acute treatment is beginning to show results if done within three hours of onset.

The types of stroke include:

Ischemic Stroke

An ischemic stroke most often occurs when blood flow to the brain becomes blocked.


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One of the following events may cause this blockage:

  • The most common cause is a build-up of fatty substances (atherosclerotic plaque) along an artery's inner lining that causes it to narrow, reduces its elasticity, and decreases its blood flow.
  • A clot forms in an artery supplying the brain, usually one affected by atherosclerosis .
  • A clot forms somewhere in the body (often the heart) and breaks free, traveling to and becoming lodged in an artery supplying the brain. This clot is called an embolus, and the process is called embolism.

Hemorrhagic Stroke

A stroke may also occur if a blood vessel breaks and bleeds into or around the brain; this is called hemorrhagic stroke. Trauma, cocaine abuse, and high blood pressure are the leading causes of hemorrhagic strokes, which occur more commonly in younger people. Aneurysms predispose you to hemorrhagic stroke. An aneurysm is a weak spot in an artery that balloons out under pressure and can rupture, causing bleeding into the brain.

In the United States, cerebrovascular disease is the third leading cause of death and disability, striking about 700,000 people each year, and causing about 163,000 deaths per year. Of these, 85% to 90% are due to ischemic stroke and the remainder to hemorrhagic stroke. Asians and African Americans have a higher incidence of hemorrhagic stroke than whites.

What are the risk factors for stroke?
What are the symptoms of stroke?
How is stroke diagnosed?
What are the treatments for stroke?
Are there screening tests for stroke?
How can I reduce my risk of stroke?
What questions should I ask my healthcare provider?
What is it like to live with stroke?
Where can I get more information about stroke?


Kasper DL, Braunwald E, Fauci A, Hauser S, Longo D, Jameson JL. Harrison's Principles of Internal Medicine. 16th ed. New York: McGraw-Hill; 2004.

Last reviewed May 2007 by J. Thomas Megerian, MD, PhD, FAAP

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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