Related terms: brain attack, ischemic stroke, hemmorhagic stroke, mini-stroke or TIA (transient ischemic attack), cerebrovascular disease
Stroke is a form of cerebrovascular disease, meaning it affects the vessels that supply blood to the brain. Stroke was first called "apoplexy," a Greek word that means "to strike down." Symptoms may appear slowly or suddenly, but the underlying conditions that lead to stroke are usually present for years before a stroke happens.
The American Heart Association estimates that about 795,000 Americans have a new or recurrent stroke each year. In people who survive a stroke, there may be paralysis, emotional problems, or trouble with speech, memory, or judgment. How bad the injury or impairment is depends on what artery was blocked and for how long.
Most strokes happen in people 65 years and older. Although many strokes happen without warning, there are physical symptoms that may signal you are having a stroke.
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What is a stroke?
A stroke is an injury to the brain that may also severely affect the body. A stroke happens when blood supply to part of the brain is cut off or when there is bleeding into or around the brain.
Your brain is a large, soft mass of tissue made up of billions of nerve cells. It is your body's main control center and helps you to see, hear, taste, smell, talk, and walk. It is also the control center for thought, emotion, memory, judgment, and awareness.
The brain's nerve cells need a constant supply of oxygen and sugar (glucose), which are carried by the blood. When blood fails to get through to parts of the brain, the oxygen supply to those areas is cut off. This is called ischemia. Without oxygen, brain cells die. The longer the brain is without blood, the more severe the damage will be. The area of tissue death that results from ischemia is known as an infarction.
Blood flow to the brain can be blocked in two ways:
- A clump of blood called a blood clot blocks an artery in the brain or neck.
- A weakened artery bursts in the brain.
Your brain cells control movement, so part of your body may become paralyzed after a stroke. If the right side of your brain is affected, the left side of your body may become paralyzed. If the left side of your brain is affected, the right side of your body may become paralyzed.
The effects of a stroke may be mild or severe, short-term or permanent. Some people have strokes and recover completely within a few days, while others may never recover. How severe a stroke is depends on
- What part of your brain is affected
- How much brain cell damage there is
- How quickly your body can restore blood to the injured parts of your brain
- How quickly the healthy parts of your brain can take over for the injured area
What causes a stroke?
A blood clot or a blocked artery leading to the brain causes about 87% of all strokes. This type of stroke is called an ischemic stroke. There are 2 kinds of ischemic stroke: cerebral thrombosis and cerebral embolism.
The other 13% of strokes are caused by ruptured or leaky blood vessels in or around the brain. This type of stroke is called a hemorrhagic stroke. There are 2 kinds of hemorrhagic strokes: cerebral and subarachnoid. Hemorrhagic strokes cause more deaths than ischemic strokes, but those who survive a hemorrhagic stroke recover more fully and have fewer long-lasting disabilities.
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How is stroke diagnosed?
Tests that show images of the brain (CT scan, MRI), measure the brain's electrical activity (EEG), and show blood flow to the brain (carotid duplex scan) are used to find out the type and severity of stroke.
See also on this site: Diagnosing Stroke
What are the treatments for stroke?
Advanced treatments and rehabilitation are helping many stroke patients return to their homes and families. Stroke treatments include anti-clotting drugs, hospital care, rehabilitation, and, rarely, surgery.
The best therapy for stroke is prevention. By knowing the warning symptoms and controlling risk factors such as cigarette or tobacco smoking, high blood pressure, diabetes, and heart disease, you can reduce your risk of stroke.
See also on this site: Stroke Treatment and Support
See on other sites:
Know Stroke: Know the Signs. Act in Time
National Institutes of Health (NIH) / National Institute of Neurological Disorders and Stroke
View the 8-minute video from NIH
National Stroke Association
May is National Stroke Awareness Month
American Stroke Association
Warning signs, life after stroke, learn about stroke
Updated May 2014