Damage to brain tissue caused by a disruption in blood flow to the brain. Strokes can be fatal and can result in temporary or permanent disability. Common aftereffects of a stroke include paralysis, weakness, muscular contractions, loss of sensation, and speech difficulties. Stroke is the third largest cause of death in the United States, and it is estimated to affect as many as 700,000 Americans each year.
There are two types of strokes: ischemic and hemorrhagic. Ischemic strokes, which account for 70% to 80% of all strokes, occur when fatty material or a blood clot blocks one of the blood vessels in the brain. Without the oxygen and nutrients carried in blood, brain cells can die within minutes. Hemorrhagic strokes occur when arterial blood leaks into the brain. This not only deprives some areas of the brain of blood and oxygen, but the accumulated blood may also exert pressure on surrounding tissue and cause further brain damage.
Some risk factors for stroke cannot be controlled. These include age (risk increases with age), gender (men are at greater risk than women), race (African-Americans are at greatest risk), and a family history of stroke. Other risk factors, including the following, can be avoided or managed:
- High blood pressure is the most important controllable factor. It makes a person four to six times more likely to have a stroke. Controlling blood pressure by losing excess weight, exercising more, reducing sodium intake, drinking less alcohol, and eating more fruits and vegetables or by taking medicines can significantly reduce your risk of stroke.
- Smoking doubles a person’s risk of having a stroke. You can significantly reduce your risk of stroke and many other health problems by quitting smoking.
- Atrial fibrillation, a condition in which the upper chambers of the heart (or atria) beat unpredictably, can cause blood clots that may lead to strokes. People with chronic atrial fibrillation often take anticoagulants (blood-thinning drugs), which inhibit the clumping of blood platelets.
- High cholesterol levels can speed up atherosclerosis (narrowing of the arteries) and increase the risk of stroke. You can lower your blood cholesterol by exercising more, eating less saturated fat, and taking cholesterol-lowering drugs.
- Alcohol in excessive amounts can also increase the risk of stroke. The American Heart Association recommends no more than two drinks a day for men and one drink a day for women for a healthy cardiovascular system.
- Diabetes can make a person two to three times more prone to stroke. People with Type 1 diabetes can decrease their risk by tightly controlling their blood glucose levels. In some cases, people with Type 2 diabetes can reduce their risk by improving blood glucose control and losing weight.
Until recently, strokes were viewed fatalistically: Doctors thought that once a stroke was in progress, there was nothing they could do to prevent the destruction of brain cells. Now, clot-dissolving drugs such as tissue plasminogen activator (tPA) are used to reduce the brain damage associated with ischemic strokes. However, these drugs must be taken within three hours of the onset of symptoms to be effective. Obviously, then, it is important to recognize the early symptoms of a stroke. However, studies suggest that only about 57% of people can correctly identify at least one of the five warning signs of a stroke, listed below:
- Weakness, numbness, or paralysis of the face, arms, or legs, especially on one side of the body
- Sudden blurred or decreased vision in one or both eyes
- Difficulty in speaking or understanding simple statements
- Loss of balance or coordination
- Sudden unexplained, severe headache