Most strokes (also called “brain attacks”) are caused by a blockage in an artery that carries blood to the brain. This can cause that part of the brain to be damaged, and you may lose control of a function that is controlled by that part of the brain. For example, you could lose the use of an arm or leg, or the ability to speak. The damage can be temporary or permanent, partial or complete. Doctors have found that if you get treatment right away after symptoms start, there is a better chance of getting the blood moving to your brain, and less chance of damage.
If you have any of the following symptoms, call for emergency help immediately. The sooner you get help, the more doctors can do to prevent permanent damage.
- Sudden weakness or numbness of the face, arm or leg on one side of the body
- Sudden dimness or loss of vision, particularly in one eye
- Loss of speech, trouble talking or understanding what others are saying
- Sudden severe headache with no known cause
- Unexplained dizziness, unstable walking or falling, especially along with any of the other symptoms
Another warning sign of a stroke is called a TIA, or transient ischemic attack (also called a “mini-stroke”). A TIA can cause the symptoms listed above and may last only a few minutes, but should not be ignored. People who have a TIA are at greater risk of having a stroke later. Call your doctor immediately if you think you are having a TIA.
General symptoms of a stroke include sudden onset of:
- Numbness, weakness, or paralysis of the face, arm, or leg, typically on one side of the body.
- Vision problems in one or both eyes, such as dimness, blurring, double vision, or loss of vision.
- Confusion, trouble speaking or understanding.
- Trouble walking, dizziness, loss of balance or coordination
- Severe headache.
However, symptoms may vary depending on whether it is an ischemic or hemorrhagic stroke. Location of the blood clot or bleeding and the extent of brain damage can also affect symptoms.
- Symptoms of an ischemic stroke (caused by a clot blocking a blood vessel) usually occur in the side of the body opposite from the side of the brain where the clot occurred. For example, a stroke in the right side of the brain affects the left side of the body.
- Symptoms of a hemorrhagic stroke (caused by bleeding in the brain) can be similar to those of an ischemic stroke, but may be distinguished by symptoms relating to higher pressure in the brain, including severe headache, nausea and vomiting, neck stiffness, dizziness, seizures, irritability, confusion, and possibly unconsciousness.
Causes of ischemic stroke
An ischemic stroke is caused by blockage of a blood vessel that supplies blood to the brain. Blockage may develop from:
- A blood clot that has formed in an artery supplying the brain (thrombus). When atherosclerosis causes narrowing and hardening of an artery that supplies blood to brain tissue, a clot may form and reduce blood flow. A clot can also form in the carotid arteries. If one of the carotid arteries becomes blocked, the stroke often affects a large area of the brain.
- A blood clot that has traveled from another part of the body (embolus), usually the heart. The clot travels through the blood and lodges in a blood vessel supplying blood to the brain.
Blood clots are usually the result of other problems in the body that affect the normal flow of blood, such as:
- Hardening of the arteries (atherosclerosis).
- Atrial fibrillation or other irregular heart rhythms.
- Certain heart valve problems, including having an artificial heart valve, a repaired heart valve, heart valve disease such as mitral valve prolapse, or narrowing (stenosis) of a heart valve.
- Infection of the heart valves (endocarditis).
- A patent foramen ovale, a congenital heart defect.
- Blood-clotting disorders.
- Inflammation of blood vessels (vasculitis).
- Heart attack.
Low blood pressure (hypotension) is a less common cause of ischemic stroke. This usually occurs with narrowed or diseased arteries but may also result from a heart attack, a large loss of blood, or a severe infection.
In addition, surgery to correct narrowed carotid arteries, which is called a carotid endarterectomy, may sometimes cause a stroke.
Two types of uncontrolled bleeding (hemorrhage) cause most hemorrhagic strokes.
- A cerebral hemorrhage is sudden bleeding from a blood vessel inside the brain. The most common cause of bleeding inside the brain is high blood pressure.
- A subarachnoid hemorrhage is sudden bleeding from a blood vessel in the space surrounding the brain. Sudden bleeding may be caused by a ruptured aneurysm.
What Increases Your Risk
Risk factors for stroke include those you can change and those you can’t change.
Risk factors you cannot change include:
- Age. The risk for stroke increases with age. The risk doubles every decade you are over 55. At least 66% of all people who have a stroke are age 65 or older.
- Race. African-Americans and Hispanics have a higher risk than those of other races. Compared with whites, young African-Americans have 2 to 3 times the risk of ischemic stroke, and African-American men and women are more likely to die from stroke.
- Gender. Stroke is more common in men than women until age 75, when more women than men have strokes. At all ages, more women than men die of stroke.
- Family history. The risk for stroke is greater if a parent, brother, or sister has had a stroke or transient ischemic attack (TIA).
- History of stroke or TIA.
Having certain diseases increases your risk for stroke. If you can control the disease, you lower your risk.
Risk factors you can control include:
- High blood pressure (hypertension). High blood pressure is the second most important stroke risk factor after age.
- Diabetes. About one-quarter of people with diabetes die of stroke. Having diabetes doubles your risk for stroke because of the circulation problems associated with the disease.
- High cholesterol. High cholesterol can lead to coronary artery disease and heart attack, which can damage the heart muscle and increase your risk for stroke.
- Coronary artery disease, which can lead to heart attack and stroke.
- Other heart conditions, such as atrial fibrillation, endocarditis, heart valve conditions, patent foramen ovale, or cardiomyopathy.
- Smoking, including secondhand smoke.
- Physical inactivity.
- Obesity.
- Use of some medications, such as birth control pills – especially by women who smoke or have a history of blood-clotting problems – and anticoagulants or steroids. In postmenopausal women, hormone replacement therapy has been shown to slightly increase the risk of stroke.
- Heavy use of alcohol. People who drink alcohol excessively, especially people who binge drink, are more likely to have a stroke. Binge drinking is defined as drinking more than 5 drinks in a short period of time.
- Use of cocaine and other street drugs.
Other Organizations
National Stoke Association
http://www.stroke.org
800-STROKES (800-787-6537)
American Heart Association
http://www.americanheart.org
800-AHA-USA1 (800-242-8721)