A stroke, sometimes called a "brain attack," occurs when blood flow to the brain is interrupted. When a stroke occurs, brain cells in the immediate area begin to die because they stop getting the oxygen and nutrients they need to function.
There are two major kinds of stroke.
The first, called an ischemic stroke, is caused by a blood clot that blocks or plugs a blood vessel or artery in the brain. About 80 percent of all strokes are ischemic. The second, known as a hemorrhagic stroke, is caused by a blood vessel in the brain that breaks and bleeds into the brain. About 20 percent of strokes are hemorrhagic.
Although stroke is a disease of the brain, it can affect the entire body. The effects of a stroke range from mild to severe and can include paralysis, problems with thinking, problems with speaking, and emotional problems. Patients may also experience pain or numbness after a stroke.
Because stroke injures the brain, you may not realize that you are having a stroke. To a bystander, someone having a stroke may just look unaware or confused. Stroke victims have the best chance if someone around them recognizes the symptoms and acts quickly.
The symptoms of stroke are distinct because they happen quickly:
If you believe someone is having a stroke – if he or she suddenly loses the ability to speak, or move an arm or leg on one side, or experiences facial paralysis on one side – call 911 immediately.
Stroke is a medical emergency. Every minute counts when someone is having a stroke. The longer blood flow is cut off to the
brain, the greater the damage. Immediate treatment can save people's lives and enhance their chances for successful recovery.
Ischemic strokes, the most common type of strokes, can be treated with a drug called t-PA, that dissolves blood clots obstructing blood flow to the brain. The window of opportunity to start treating stroke patients is three hours, but to be evaluated and receive treatment, patients need to get to the hospital within 60 minutes.
A five-year study by the National Institute of Neurological Disorders and Stroke (NINDS) found that some stroke patients who received t-PA within three hours of the start of stroke symptoms were at least 30 percent more likely to recover with little or no disability after three months.
If you smoke – quit. If you have high blood pressure, heart disease, diabetes, or high cholesterol, getting them under control – and keeping them under control – will greatly reduce your chances of having a stroke.
"Know Stroke. Know the Signs. Act in Time.", NINDS.
NIH Publication No. 08-4872
Back to Stroke Information Page.
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NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.
All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.Last updated June 19, 2013