Encyclopedia / S / Stroke


What Is Stroke?

A stroke is a medical emergency caused either by obstruction of an artery carrying blood to the brain or by rupture of one of the cerebral arteries. Because brain cells cannot regenerate, lack of oxygen from blockage of the blood supply may quickly lead to cell death and permanent brain damage.

Strokes are more likely to occur when arteries have been substantially narrowed by atherosclerosis (a buildup of plaques in the walls of the arteries). Blood flow through narrow arteries is reduced, and blood clots are more likely to form along the uneven surface of the plaque. A clot formed in a carotid artery in the neck or a cerebral (brain) artery can block the artery at the site. Clots may also form elsewhere, become detached, and ultimately block a cerebral artery, causing a stroke.

About 87 percent of strokes are ischemic strokes—caused by a blockage in either an artery in the brain or in one of the carotid arteries in the neck. The remaining 13 percent—called hemorrhagic strokes—result from a rupture of a brain artery. This type of stroke generally is most immediately life threatening, primarily because of the sudden excessive pressure the hemorrhage exerts on brain tissue.

Although incidence is highest among those over age 65, a stroke may afflict anyone at any age. Symptoms vary depending on the portion of the brain affected, but they often come on suddenly. Some patients will have temporary stroke-like episodes called transient ischemic attacks (TIAs) prior to a stroke, which may resolve in minutes to a few hours.

Strokes are the fourth leading cause of death in the United States, but the leading cause of disability. About 130,000 people die of stroke each year. Prevention is key.

Who Gets Stroke?

About 795,000 in the U.S. have a stroke each year—610,000 of these are first attacks and 185,000 are recurrent strokes. The risk of stroke increases with age: After age 55, the risk doubles with each decade. Less than 30 percent of people who suffer a stroke are younger than age 65. Women are more likely to have a stroke than men, in part because women live longer.


The symptoms of an ischemic stroke or hemorrhagic stroke can be the same. TIA symptoms are also the same, but often last only minutes to hours. As with a heart attack, the presence of stroke symptoms is an emergency—symptoms usually come on suddenly,

and getting to the hospital as soon as symptoms appear is essential.

  • Sudden weakness or paralysis in the face, arm, or leg on one side of the body.
  • Sudden loss or blurring of vision, double vision, dilated pupils, or crossed eyes due to partial inability to move the eye.
  • Slurred, loss of speech, or problems understanding other people.
  • Sudden, severe headache with no apparent cause.
  • Nausea and vomiting.
  • Unexplained dizziness, mental confusion, or loss of coordination, or falls.


  • Blood clots that obstruct a carotid or cerebral artery are the most common cause of stroke.
  • An embolus (a fragment of plaque, tissue, or blood clot) may develop in the heart and travel to the brain to cause a stroke. Emboli are most likely to develop in association with cardiac arrhythmias (especially atrial fibrillation), valvular heart disease, heart attack, or cardiomyopathy (see these disorders for more information).
  • An aneurysm (a balloonlike weak spot in an arterial wall) in a cerebral artery may burst or leak, resulting in a stroke.
  • Hypertension is a significant risk factor for stroke.
  • Severely narrowed arteries due to atherosclerosis increase the risk of stroke.
  • Use of cocaine or amphetamines may boost blood pressure dangerously high and cause a stroke.
  • Risk is high among those who have experienced one or more transient ischemic attacks (TIAs)—a temporary blockage in an artery that lasts for less than 24 hours (usually only a few minutes) and causes no brain damage.
  • A family history of stroke, early or premature heart attacks, atherosclerosis, or high blood pressure increases the risk of stroke.
  • Smoking, alcohol abuse, high blood cholesterol levels, a diet high in fat (especially animal fat), obesity, lack of exercise, diabetes mellitus, and oral contraceptive use all increase the risk of stroke.
  • Risk increases with age.
  • Some blood clotting disorders increase the risk of stroke.


  • Diagnosis is often made immediately upon examination by a doctor or emergency rescue technician.
  • Blood tests are taken.
  • CT (computed tomography) scans or MRI (magnetic resonance imaging) may be used to locate an abnormal blood vessel or an area of brain damage.
  • Ultrasound scans of carotid arteries reveal narrowing due to atherosclerotic plaque.
  • Cerebral angiography may be performed to locate the arterial blockage or aneurysm. Angiography is more commonly done by CT scan or MRI. However, in some cases, it may be necessary to insert a tiny catheter into an artery in the groin (the femoral artery) and thread it up to the carotid artery in the neck. A contrast material is injected to produce a clear x-ray image of the carotid and cerebral arteries.
  • An electrocardiogram (ECG) is performed to detect a cardiac arrhythmia or heart damage from a myocardial infarction (heart attack).
  • A cardiac ultrasound (echocardiography) may locate a source of blood clots in the heart.


  • Emergency treatment and immediate hospitalization is necessary in the event of a stroke. Life support measures may be required.
  • If a stroke is caused by arterial blockage due to a blood clot, thrombolytic (clot-dissolving) intravenous tPA should be initiated promptly—optimally within an hour of the onset of symptoms. It can be used in select patients up to 4.5 hours from onset of symptoms. The faster tPA is given, the more effective it is.
  • In some patients, the clot can be removed with a catheter inserted into the blocked vessel.
  • If the stroke is the result of a cerebral hemorrhage, physicians will immediately take measures to reduce blood pressure of hypertensive patients in order to minimize flow of blood from the ruptured artery.
  • Long-term therapy following a stroke may include antiplatelet medications, such as aspirin, or blood thinners, such as warfarin, to prevent future clots.
  • Special railings, braces, canes, wheelchairs, or other devices may be necessary to help increase mobility for those with partial paralysis.
  • Physical, speech, occupational, and emotional therapy helps patients and their families cope.
  • Those with extensive disabilities may need a period of in-hospital rehabilitation or professional in-home medical care.


  • Don’t smoke.
  • Eat a diet low in fat, cholesterol, and salt.
  • Engage in moderate, regular exercise. Check with a doctor before beginning an exercise program.
  • Hypertension must be treated aggressively.
  • Lose weight if you are more than 20 percent overweight.
  • If you have diabetes, take steps to ensure good glucose control.
  • Have no more than two alcoholic drinks a day.
  • Low daily doses of aspirin or other antiplatelet drugs (such as clopidogrel, ticlopidine, and dipyridamole) may be prescribed to reduce the chances of blood clot formation in those who have had a TIA or are otherwise at high risk for stroke.
  • Anticoagulant therapy with warfarin or one of several newer anticoagulants such as dabigitran (Pradaxa), rivaroxaban (Xarelto), or edoxaban (Eliquis) may be prescribed for those with atrial fibrillation and some other conditions to prevent blood clot formation.
  • Patients who show evidence of substantial atherosclerotic narrowing in the carotid arteries (the two main blood vessels in the neck supplying the brain) may be good candidates for carotid endarterectomy, a surgical procedure to clear away plaque deposits in these arteries.

When To Call Your Doctor

Emergency: Call an ambulance immediately if you or someone in your presence exhibits stroke symptoms.

Reviewed by Joseph V. Campellone, M.D., Division of Neurology, Cooper University Hospital, Camden, NJ. Review provided by VeriMed Healthcare Network.