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What Is Stroke?
One in four strokes occurs in someone younger than 65. Find out more about stroke symptoms and diagnosis.

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picture of jumbled letters What Is Stroke?

Your brain needs a constant supply of oxygen and nutrient-rich blood to nourish its billions of nerve cells. When this supply is reduced or shut off completely, starving brain cells die within minutes. That is why stroke is sometimes called a "brain attack."

You may think that strokes happen only to older people, non-exercisers or men who have a lot of job stress. But nearly one in four of all strokes occur in people who are younger than 65. Both men and women are at risk. Stroke is the leading cause of long-term disability, but getting treatment quickly greatly improves the chance for recovery.

What are the types of stroke?
There are two main types of stroke:

Ischemic stroke is due to a reduced blood flow. The majority of strokes, about 85 percent, occur when a blood clot blocks the flow of blood in the brain. The blood clot may form in a blood vessel within the brain. Or, a blood clot can form elsewhere in the body, like the heart, then break loose and flow to the brain.

Hemorrhagic stroke is from bleeding. About 15 percent of all strokes are this type. In a hemorrhagic stroke, a weakened blood vessel in or around the brain ruptures and bleeds. Because the brain is confined within the skull, blood that collects pushes on and damages the surrounding brain tissue. Two types of problems cause most hemorrhagic strokes:

  • Brain aneurysm. This is a ballooning out of a weakened artery. The artery can tear open and cause serious bleeding.
  • Arteriovenous malformation (AVM). This is an abnormal collection of blood vessels that can rupture.

What are symptoms of stroke?
Symptoms of stroke come on suddenly. Call 9-1-1 right away if you have any of the following:

  • Sudden weakness or numbness of the face, arm or leg
  • Sudden trouble seeing in one or both eyes
  • Sudden confusion, difficulty speaking or trouble understanding speech
  • Sudden severe headache with no known cause
  • Sudden dizziness or unsteadiness
  • Sudden loss of balance or trouble with walking or coordination
  • Loss of consciousness
  • Seizure in a person who does not have epilepsy
  • Any concern that you or someone else may be having a stroke

How is stroke diagnosed?
Getting prompt medical help for stroke symptoms is critical. Your doctor will quickly gather information through a history and physical. He or she will ask you questions about symptoms and risk factors for stroke. Your doctor will do a neurological examination to test reflexes, muscle strength, sensation and other functions. Imaging tests may be needed to find the cause of symptoms or type of stroke. The two imaging tests commonly done are:

  • CT scan. A CT uses a series of x-ray images to produce cross-sectional views of the brain. It can show bleeding in and around the brain due to a hemorrhagic stroke as soon as it happens. However, it may not reveal swelling and more subtle changes from an ischemic stroke in the first few hours. A repeat CT scan may be needed to confirm an ischemic stroke.
    MRI scan. An MRI uses a strong magnet to make more detailed images than a CT scan. The MRI can show an ischemic stroke in less time than a CT scan. A special MRI called an "MRA" (magnetic resonance angiogram) shows blood flow to the brain and can show a blood clot or aneurysm in the blood vessels leading to the brain.

It is critical to determine the type of stroke before treatment is started.

  • If the stroke is hemorrhagic (due to bleeding), blood-thinning medicines are not used because they can increase bleeding.
  • If the stroke is ischemic (due to a blood clot), your doctor may use a clot-dissolving drug. But, this drug must be given within 3 to 4.5 hours of the first stroke symptoms to be effective.

If the doctor suspects a stroke is due to a blood clot coming from the heart or carotid arteries, other imaging tests may be done:

  • An echocardiogram uses ultrasound waves to take pictures of the heart and blood flow. This test can show a blood clot that has formed within the heart.
  • A carotid ultrasound also uses sound waves to make images of the carotid arteries in your neck as blood flows to the brain. The test can show if there is narrowing in the blood vessels due to atherosclerosis (cholesterol plaque).
By Louis Neipris, MD, Staff Writer
Created on 06/08/1999
Updated on 04/14/2010
  • Biller J, Love BB, Schneck MJ. Vascular diseases of the nervous system. Ischemic cerebrovascular disease. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Bradley: Neurology in Clinical Practice, 5th ed. Philadelphia, PA: Butterworth-Heinemann Elsevier; 2008.
  • del Zoppo GJ, Saver JL, Jauch EC, Adams Jr HP. Expansion of the time window for treatment of acute ischemic stroke with intravenous tissue plasminogen activator. Stroke. 2009;40(5):1687-1691.
  • Kase CS. Vascular diseases of the nervous system. Intracerebral hemorrhage. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Bradley: Neurology in Clinical Practice, 5th ed. Philadelphia, PA: Butterworth-Heinemann Elsevier; 2008.
  • American Stroke Association. Types of stroke.
  • Centers for Disease Control and Prevention. Stroke facts and statistics.
  • National Institutes of Neurological Disorders and Stroke. Know stroke: Know the signs. Act in time.
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