Conditions InDepth: Stroke
En Español (Spanish Version)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
© 2009 Nucleus Medical Media, Inc.
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:
An ischemic stroke most often occurs when blood flow to the brain becomes blocked.
Stroke
© 2009 Nucleus Medical Media, Inc.
One of the following events may cause this blockage:
- The most common cause is a build-up of fatty substances 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.
This clot is called a thrombus.
- Blockage can also be caused by a blood clot from another part of the body (often the heart) that breaks free. The clot travels to and becomes lodged in an artery supplying the brain. This clot is called an embolus, and the process is called embolism.
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.
According the the Centers for Disease Control and Prevention, stroke has affected 6.5 million Americans. Along with heart disease and cancer, stroke is one of the leading causes of death. Ischemic type occurs more often—in about 87% of the cases—compared to hemorrhagic.
Kasper DL, Braunwald E, Fauci A, Hauser S, Longo D, Jameson JL.
Harrison's Principles of Internal Medicine.
16th ed. New York, NY: McGraw-Hill; 2004.
Last Reviewed February 2010