A stroke is a brain injury that occurs because the brain's blood supply is interrupted. Because the brain's blood supply can be disrupted for different reasons, doctors generally classify strokes into three categories:

• Hemorrhagic stroke � Bleeding (hemorrhage) causes this type of stroke. Bleeding can occur within the brain or between the brain and the skull. When bleeding occurs, small blood vessels that are near to the hemorrhage react by tightening in a spasm. This means that some brain areas get too little blood flow. A hemorrhagic stroke that occurs within the brain is called an intracerebral hemorrhage. It often is linked to high blood pressure (hypertension), old age, heavy alcohol use, or the use of cocaine or methamphetamines. A stroke that occurs between the brain and the skull is called a subarachnoid hemorrhage. Hemorrhagic strokes account for about 10% to 15% of all cases of stroke.



• Thrombotic stroke � A blood clot (thrombus) forms inside one of the brain's arteries and blocks blood flow. This usually happens inside an artery that already has been narrowed by atherosclerosis, a condition in which fatty deposits (plaques) build up along the walls of blood vessels. Thrombotic strokes are the most common type of stroke, accounting for almost 40% to 50% of cases. Thrombotic strokes can affect large or small arteries in the brain. When a thrombotic stroke occurs in a small artery that is deep within the brain (in the thalamus, the basal ganglia or pons) the stroke is more specifically named a lacunar stroke.



• Embolic strokes � To cause this stroke type, a blood clot or other solid mass of debris travels to the brain, where it blocks a brain artery. In many cases a floating blood clot, called an embolus, originates inside the heart as a result of sluggish blood flow. This can occur in the setting of a type of irregular heart rhythm (atrial fibrillation) or in severe heart failure. In one type of embolic stroke, the floating debris is not a blood clot but is a clump of bacteria and inflammatory cells. This type of embolus can form if there is a bacterial infection on the valves of the heart, known as endocarditis. Embolic strokes account for about 20% of all stroke cases.

In 15% to 20% of cases, the type of stroke cannot be clearly determined.

Because different areas of the brain are responsible for different functions (sensation, movement, sight, speech, balance, coordination, etc.), the symptoms of stroke vary depending on which area of the brain is damaged.

Symptoms can include any of the following:

• Headache, with or without vomiting
• Dizziness or confusion
• Weakness or paralysis on one side of the body
• Sudden, severe numbness in any part of the body
• Visual disturbance, including sudden loss of vision
• Difficulty walking, including staggering or veering
• Coordination problems in the arms and hands
• Slurred speech or inability to speak
• Sudden deviation of the eyes toward one direction
• Seizures
• Irregular breathing
• Stupor
• Coma

The sudden appearance of one or more of these symptoms is a warning sign that a stroke may be in progress.

In some cases, strokes are preceded by one or more transient ischemic attacks (TIAs). TIAs are brief episodes of stroke-like symptoms that last less than 24 hours, most commonly 5 to 20 minutes.

Your doctor will review your medical history and your risk factors for stroke (high blood pressure, smoking, diabetes, certain types of heart disease, family history of stroke). Your doctor will examine you, paying specific attention to your blood pressure and your heart. The doctor will do a neurological examination to check for changes in your brain function.

To diagnose and classify your stroke, your doctor will need an imaging test of the brain. Tests can include a computed tomography (CT) scan or magnetic resonance imaging (MRI) scan of the brain. Depending on the type of stroke suspected, your doctor may do a lumbar puncture spinal tap that checks your cerebrospinal fluid for blood, or use tests such as Doppler ultrasonography or MRI angiography to evaluate blood flow to your brain.

If it is clear that you are having a stroke, your evaluation will include tests to check for a cause, such as atherosclerosis or other causes of blood clotting in the heart or large arteries. You may have a chest X-ray and a test called an electrocardiogram (EKG). Blood tests evaluate your blood cell counts and the ability of your blood to clot. Some people may undergo ultrasound testing of the arteries in the neck (carotid Doppler) or of the heart (echocardiogram).

If circulation to the brain is restored quickly, symptoms can improve within a few days. If the blood supply is interrupted for longer periods, brain injury can be more severe, symptoms can last for many months and you may need physical rehabilitation. Permanent brain damage can cause permanent disability. Some people, especially those who have a large hemorrhagic stroke, die of their stroke.

You can help to prevent stroke by controlling risk factors, including high blood pressure, smoking, an abnormal heart rhythm (atrial fibrillation), high cholesterol atherosclerosis and diabetes. A healthy lifestyle and taking an aspirin once a day can also help to prevent stroke.

Several medicines to treat high blood pressure have been shown to have an especially strong benefit in preventing stroke. These include ACE inhibitors, including enalapril (Vasotec), ramipril (Altace), captopril (Capoten) or lisinopril (Prinivil, Zestril) and medicines called thiazide diuretics, including thiazide or chlorthalidone (Hygroton, Thalitone).

If you have atrial fibrillation, or if you have had it in the past, you can greatly reduce your risk of stroke by taking the blood-thinning medication warfarin (Coumadin). Most people who have atrial fibrillation can take this medication safely. Warfarin prevents clots from forming inside the left atrium of the heart that might later dislodge and cause a stroke.

People with diabetes can reduce their risk of atherosclerosis by controlling their blood sugar levels with aggressive treatment.

High cholesterol also should be treated aggressively. Cholesterol-lowering medications called statins can help to prevent strokes. If you do not have cholesterol problems, you should have your cholesterol checked every five years.

To help prevent stroke, you should exercise regularly and eat a healthy diet, one that is rich in fruits and vegetables and low in saturated fats, trans fats (hydrogenated or partially hydrogenated oils) and cholesterol. Recent research has shown that eating two to four servings of fish weekly can lower the risk of stroke. One study showed that people who eat fish frequently have about half the risk of stroke compared with people who eat fish one to three times a month. Also, avoid excessive use of alcohol and never take cocaine or amphetamines.

Talk to your doctor about the potential benefits of taking an aspirin daily. Aspirin in doses as low as 80 milligrams per day can reduce the risk of stroke overall, although one type of stroke, hemorrhagic stroke, occurs slightly more often when aspirin is taken regularly. Other medications that help to prevent clots from forming include ticlopidine (Ticlid) and clopidogrel (Plavix). Aspirin and these clot-preventing medicines are not safe for everyone.

The most effective treatment for stroke must be given immediately � within three hours after symptoms begin. For this reason, the medical community has been educating the public about stroke symptoms and the need for immediate emergency care. A clot-dissolving medication called tissue plasminogen activator (t-PA) can restore blood flow and oxygen to brain tissue affected by a stroke. People who receive this medication have less long-term disability following a stroke. In treating thrombotic stroke, clot-prevention medications, such as heparin, are used in later hours after a stroke, to prevent existing blood clots from getting bigger and to prevent new clots from forming. After a stroke has stabilized, aspirin or another mild blood-thinning agent (such as ticlopidine or clopidogrel) is usually prescribed daily to prevent another stroke.

However, t-PA is not helpful to treat hemorrhagic stroke. Sometimes, the hemorrhaged blood may have to be removed through surgery to relieve pressure on the brain. Occasionally, testing reveals an abnormality of a blood vessel (such as a ballooning blood vessel wall, known as an aneurysm). If a blood vessel abnormality is identified, it may require treatment with surgery in order to prevent another stroke.

A person who has experienced a significant stroke of any type usually is hospitalized for observation in case the symptoms worsen. A severe stroke can affect breathing, and some people may need a mechanical ventilator to help them breathe. People who have had a stroke may need help with self-care or feeding. Early intervention by an occupational therapist and physical therapist is helpful. These therapists can help a person work around a new disability and regain strength after brain injury. Commonly, hospitalization is followed by a period of residence at a rehabilitation center, where additional therapy may be provided intensively. The goal of rehabilitation is to maximize recovery.

If you or someone you are with develops any of the symptoms of stroke, call a doctor right away, call an ambulance or go to an emergency room. It is important to be evaluated even if your symptoms last only a few minutes. Remember, a transient ischemic attack (TIA) can be a warning sign of a coming stroke � about 1 of 10 people who experience a TIA have a stroke during the next 3 months. People who see a doctor immediately after having a TIA can receive treatment for high blood pressure, treat high cholesterol and review an aspirin plan. If these risks are addressed quickly, you can lower risk for stroke in the next 90 days by as much as 80%.

If the brain's blood supply is restored quickly and completely, the person may recover with little or no disability. In people with thrombotic strokes, early treatment with the clot-dissolving drug t-PA may reduce disability significantly. In people with hemorrhagic strokes caused by blood vessel abnormalities in the brain, there is about a 2% to 3% chance for re-bleeding if the abnormality is not treated.

National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
Phone: 301-496-5751
Toll-Free: 1-800-352-9424
TTY: 301-468-5981
http://www.ninds.nih.gov/

National Stroke Association
9707 E. Easter Lane
Englewood, CO 80112
Phone: 303-649-9299
Toll-Free: 1-800-787-6537
Fax: 303-649-1328
http://www.stroke.org/

American Heart Association (AHA)
7272 Greenville Ave.
Dallas, TX 75231
Toll-Free: 1-800-242-8721
http://www.americanheart.org/