Stroke ranks as the fourth leading killer in the United States. A stroke can be devastating to individuals and their families, robbing them of their independence. It is the most common cause of adult disability. Each year approximately 795,000 Americans have a stroke, with about 160,000 dying from stroke-related causes.
What is a Stroke?
A stroke, or “brain attack,” occurs when blood circulation to the brain fails. Brain cells can die from decreased blood flow and the resulting lack of oxygen. There are two broad categories of stroke: those caused by a blockage of blood flow and those caused by bleeding into the brain.
A blockage of a blood vessel in the brain or neck called an ischemic stroke, is the most frequent cause of stroke and is responsible for about 80 percent of strokes. These blockages stem from three conditions: the formation of a clot within a blood vessel of the brain or neck, called thrombosis; the movement of a clot from another part of the body such as the heart to the brain, called embolism; or a severe narrowing of an artery in or leading to the brain, called stenosis. Bleeding into the brain or the spaces surrounding the brain causes the second type of stroke, called hemorrhagic stroke.
The Warning Signs of a Stroke
Warning signs are clues your body sends that your brain is not receiving enough oxygen. If you observe one or more of these signs of a stroke or “brain attack,” don’t wait, call a doctor or 911 right away!
- Sudden numbness or weakness of face, arm, or leg, especially on one side of the body
- Sudden confusion, or trouble talking or understanding speech
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking, dizziness, or loss of balance or coordination
- Sudden severe headache with no known cause
Other danger signs that may occur include double vision, drowsiness, and nausea or vomiting. Sometimes the warning signs may last only a few moments and then disappear. These brief episodes, known as transient ischemic attacks or TIAs, are sometimes called “mini-strokes.” Although brief, they identify an underlying serious condition that isn’t going away without medical help. Unfortunately, since they clear up, many people ignore them. Don’t. Paying attention to them can save your life.
What are Risk Factors for a Stroke?
A risk factor is a condition or behavior that occurs more frequently in those who have, or are at greater risk of getting, a disease than in those who don’t. Having a risk factor for stroke doesn’t mean you’ll have a stroke. On the other hand, not having a risk factor doesn’t mean you’ll avoid a stroke. But your risk of stroke grows as the number and severity of risk factors increases.
Some factors for stroke can’t be modified by medical treatment or lifestyle changes.
- Age. Stroke occurs in all age groups. Studies show the risk of stroke doubles for each decade between the ages of 55 and 85. But strokes also can occur in childhood or adolescence. Although stroke is often considered a disease of aging, the risk of stroke in childhood is actually highest during the perinatal period, which encompasses the last few months of fetal life and the first few weeks after birth.
- Gender. Men have a higher risk for stroke in young and middle age, but rates even out at older ages, and more women die from stroke. Men generally do not live as long as women, so men are usually younger when they have their strokes and therefore have a higher rate of survival.
- Race. People from certain ethnic groups have a higher risk of stroke. For African Americans, stroke is more common and more deadly—even in young and middle-aged adults—than for any ethnic or other racial group in the United States. Studies show that the age-adjusted incidence of stroke is about twice as high in African Americans and Hispanic Americans as in Caucasians, and while stroke incidence has declined for whites since the 1990s, there has not been a decline for Hispanics or black Americans. An important risk factor for African-Americans is sickle cell disease, which can cause a narrowing of arteries and disrupt blood flow. The incidence of the various stroke subtypes also varies considerably in different ethnic groups.
- Family history of stroke. Stroke seems to run in some families. Several factors may contribute to familial stroke. Members of a family might have a genetic tendency for stroke risk factors, such as an inherited predisposition for high blood pressure (hypertension) or diabetes. The influence of a common lifestyle among family members also could contribute to familial stroke.
Which Risk Factors can be treated?
Some of the most important treatable risk factors for stroke are:
- High blood pressure, or hypertension.
Hypertension is by far the most potent risk factor for stroke. Hypertension causes a two-to four-fold increase in the risk of stroke before age 80. If your blood pressure is high, you and your doctor need to work out an individual strategy to bring it down to the normal range. Some ways that work: Maintain proper weight. Avoid drugs known to raise blood pressure. Eat right: cut down on salt and eat fruits and vegetables to increase potassium in your diet. Exercise more. Your doctor may prescribe medicines that help lower blood pressure. Controlling blood pressure will also help you avoid heart disease, diabetes, and kidney failure.
- Cigarette smoking.
Cigarette smoking causes about a two-fold increase in the risk of ischemic stroke and up to a four-fold increase in the risk of hemorrhagic stroke. It has been linked to the buildup of fatty substances (atherosclerosis) in the carotid artery, the main neck artery supplying blood to the brain. Blockage of this artery is the leading cause of stroke in Americans. Also, nicotine raises blood pressure; carbon monoxide from smoking reduces the amount of oxygen your blood can carry to the brain; and cigarette smoke makes your blood thicker and more likely to clot. Smoking also promotes aneurysm formation. Your doctor can recommend programs and medications that may help you quit smoking. By quitting, at any age, you also reduce your risk of lung disease, heart disease, and a number of cancers including lung cancer.
- Heart disease.
Common heart disorders such as coronary artery disease, valve defects, irregular heart beat (atrial fibrillation), and enlargement of one of the heart’s chambers can result in blood clots that may break loose and block vessels in or leading to the brain. Atrial fibrillation—which is more prevalent in older people—is responsible for one in four strokes after age 80, and is associated with higher mortality and disability. The most common blood vessel disease is atherosclerosis. Hypertension promotes atherosclerosis and causes mechanical damage to the walls of blood vessels. Your doctor will treat your heart disease and may also prescribe medication, such as aspirin, to help prevent the formation of clots. Your doctor may recommend surgery to clean out a clogged neck artery if you match a particular risk profile. If you are over 50, NINDS scientists believe you and your doctor should make a decision about aspirin therapy. A doctor can evaluate your risk factors and help you decide if you will benefit from aspirin or other blood-thinning therapy.
- Warning signs or history of TIA or stroke.
If you experience a TIA, get help at once. If you’ve previously had a TIA or stroke, your risk of having a stroke is many times greater than someone who has never had one. Many communities encourage those with stroke’s warning signs to dial 911 for emergency medical assistance. If you have had a stroke in the past, it’s important to reduce your risk of a second stroke. Your brain helps you recover from a stroke by asking the unaffected brain regions to do double duty. That means a second stroke can be twice as bad.
In terms of stroke and cardiovascular disease, having diabetes is the equivalent of aging 15 years. You may think this disorder affects only the body’s ability to use sugar, or glucose. But it also causes destructive changes in the blood vessels throughout the body, including the brain. Also, if blood glucose levels are high at the time of a stroke, then brain damage is usually more severe and extensive than when blood glucose is well-controlled. Hypertension is common among diabetics and accounts for much of their increased stroke risk. Treating diabetes can delay the onset of complications that increase the risk of stroke.
- Cholesterol imbalance.
Low-density lipoprotein cholesterol (LDL) carries cholesterol (a fatty substance) through the blood and delivers it to cells. Excess LDL can cause cholesterol to build up in blood vessels, leading to atherosclerosis. Atherosclerosis is the major cause of blood vessel narrowing, leading to both heart attack and stroke.
- Physical inactivity and obesity.
Obesity and inactivity are associated with hypertension, diabetes, and heart disease. Waist circumference to hip circumference ratio equal to or above the mid-value for the population increases the risk of ischemic stroke three-fold.
Treatment for Stroke Victims
Generally there are three treatment stages for stroke: prevention, therapy immediately after the stroke, and post-stroke rehabilitation. Therapies to prevent a first or recurrent stroke are based on treating an individual’s underlying risk factors for stroke, such as hypertension, atrial fibrillation, and diabetes.
Acute stroke therapies try to stop a stroke while it is happening by quickly dissolving or removing the blood clot causing an ischemic stroke or by stopping the bleeding of a hemorrhagic stroke.
Post-stroke rehabilitation helps individuals overcome disabilities that result from stroke damage. Medication or drug therapy is the most common treatment for stroke. The most popular classes of drugs used to prevent or treat stroke are antithrombotics (antiplatelet agents and anticoagulants) and drugs that break up or dissolve blood clots, called thrombolytics.
Although stroke is a disease of the brain, it can affect the entire body. A common disability that results from stroke is complete paralysis on one side of the body, called hemiplegia. A related disability that is not as debilitating as paralysis is one-sided weakness or hemiparesis. Stroke may cause problems with thinking, awareness, attention, learning, judgment, and memory. Stroke survivors often have problems understanding or forming speech.
A stroke can lead to emotional problems. Stroke patients may have difficulty controlling their emotions or may express inappropriate emotions. Many stroke patients experience depression. Stroke survivors may also have numbness or strange sensations. The pain is often worse in the hands and feet and is made worse by movement and temperature changes, especially cold temperatures.
Recurrent stroke is frequent; about 25 percent of people who recover from their first stroke will have another stroke within 5 years.