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Conditions InDepth: Stroke by Ricker Polsdorfer, MD

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. Tissue loss in the brain causes a sudden loss of function. Another term for stroke is cerebrovascular accident (CVA).

Blood Supply to the Brain

Like a heart attack, the early emergency treatment is given the better the recovery. Acute treatment is beginning to positive results if done within 4½ to 6 hours of the start of stroke.

The types of stroke include:

Ischemic Stroke

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

Stroke

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.

Hemorrhagic Stroke

A stroke may also occur if a blood vessel breaks and bleeds into or around the brain. Hemorrhagic stroke is most common in young people. The leading causes of this type of stroke are:

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 to the Centers for Disease Control and Prevention, stroke has affected 6.2 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.

References:

About stroke. American Stroke Association website. Available at: http://www.strokeassociation.org/STROKEORG/AboutStroke/About-Stroke_UCM_308529_SubHomePage.jsp . Accessed September 4, 2012.
Cerebrovascular disease or stroke. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/nchs/FASTATS/stroke.htm . Updated May 2010. Accessed September 4, 2012.
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.
Stroke (acute management). EBSCO Publishing DynaMed website. Available at: http://www.ebscohost.com/dynamed . Updated August 30, 2012. Accessed September 4, 2012.
Types of stroke. American Stroke Association website. Available at: http://www.strokeassociation.org/STROKEORG/AboutStroke/TypesofStroke/Types-of-Stroke_UCM_308531_SubHomePage.jsp . Accessed September 4, 2012.

Last reviewed September 2012 by Rimas Lukas, MD

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