Aging & Health A to Z
Basic Facts & Information
What is a Stroke?
A “stroke” happens when normal blood flow is interrupted in some area of your brain. This can happen either because a blood vessel (a tube carrying blood) has become blocked, or as a result of a blood vessel breaking or bursting. Your brain cells need a constant supply of fresh blood carrying oxygen and nutrients to survive. Therefore, if blood stops getting to the cells, (even for a very short time) the cells start to die very quickly. Because of this, you may suffer brain damage in the affected area. For this reason, stroke is sometimes called a “brain attack”. Another term for stroke is “cerebrovascular accident” or CVA.
Depending on the location of the stroke, you may end up with a disability because the affected part of the brain can no longer send signals to your body. For example, if the cells die in an area of your brain that controls or interprets speech, you may have trouble speaking or understanding speech afterwards. In other cases, you may have trouble moving certain parts of your body, or your memory may be affected.
The Most Common Types of Stroke
Most strokes are categorized as either one of two types:
- Ischemic stroke
- Hemorrhagic stroke.
Ischemic stroke is the most common type of stroke. This kind of stroke occurs if a blood vessel gets blocked by a blood clot (thrombus) or by fat deposits (plaque). A stroke caused by a blood clot that forms along the wall of a blood vessel or blockage of fat deposits is also known as a thrombotic stroke. Often the blood vessel is already damaged from high blood pressure. An embolic stroke or cerebral embolism happens when a clot (an embolus) from another part of your body travels into the brain and blocks a blood vessel there. Most commonly, those blood clots come from the heart after a heart attack or when someone has irregular heartbeats, like with atrial fibrillation.
A hemorrhagic stroke, which is much less common than an ischemic stroke, occurs when a blood vessel carrying blood to part of the brain hemorrhages (breaks or bursts). This allows blood to leak into the brain. The two main types of hemorrhagic strokes are:
- Intracerebral hemorrhage
- Subarachnoid hemorrhage.
In an intracerebral hemorrhagic stroke, blood from a broken blood vessel leaks into the brain and damages brain cells. Also cells beyond the broken blood vessel die because they have been deprived of their normal blood supply.
Subarachnoid hemorrhagic stroke occurs when a blood vessel near the surface of the brain breaks, causing blood to collect between your skull and the surface of your brain. This causes irritation to the lining of your brain and is often painful.
Transient Ischemic Attack (TIA)
A TIA, also known as a “mini” stroke, is an ischemic stroke that goes away quickly because the blockage breaks up. Symptoms may last for only a few minutes or one or two hours. Since the blockage passes quickly, brain cells do not die. However, a TIA is often a warning sign of a full-blown ischemic stroke—possibly the same day or in the very near future. Therefore, if you have a TIA but symptoms go away, you still need an immediate and thorough medical evaluation.
How Common is Stroke?
Almost 800,000 people have strokes each year in the United States. Of these, about 140,000 people die annually from their strokes, making it the third most common cause of death in this country. Among older people, while men tend to have more strokes than women, women are more likely to die from strokes than men. Also, African Americans have twice the risk of a first stroke compared to Caucasians. The likelihood of suffering a TIA also increases with age. Up to 40 percent of all people who suffer a TIA will go on to have a full-blown stroke later on.
Although just over one out of 10 strokes are the hemorrhagic type, they account for 3 of 10 deaths from stroke each year.
Updated: March 2012
Posted: March 2012