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This article waslast modified on October 10, 2017.
What is a stroke?

Stroke occurs when the blood supply to a part of the brain is suddenly blocked or diminished, which alters the body function controlled by that area of the brain. If any part of the body, including the brain, is without a source of fresh blood and oxygen, the cells will be injured or may die. Although some cell injury is reversible, the death of brain cells is permanent, usually leaving lasting disability.

Strokes are the fifth leading cause of death in the U.S. Each year, about 795,000 Americans suffer a new or recurrent stroke while more than 129,000 people die as a result of stoke. Over 60% of stroke deaths occur in women. Strokes are also associated with long-term disability among survivors, and 25% of those who survive their first stroke will have another within 5 years.

There are two main types of stroke:

  1. Ischemic – caused by a blockage of arteries supplying blood to the brain; account for 87% of strokes; can occur from a blood clot in a narrow artery (thrombotic stroke) or a clot that breaks off in a blood vessel somewhere in the body and travels to the brain (embolic stroke)
  2. Hemorrhagic – caused by rupture of a blood vessel, resulting in bleeding in and around the brain; can occur from the inside by aneurysms or from the outside from head injury. Aneurysms are often caused by congenital defects or high blood pressure (hypertension). Hemorrhagic strokes are the most severe and are often fatal.
Accordion Title
About Strokes
  • Risk Factors

    There are many risk factors for stroke. These include:

    • High blood pressure (hypertension)
    • Coronary artery disease (CAD) and other heart problems, including atrial fibrillation and other heart disease
    • Diabetes mellitus
    • High cholesterol
    • Age - the risk of a stroke doubles for each decade of life after age 55
    • Family history of stroke
    • Race - Americans of African descent have a higher risk of death from stroke than Caucasians, resulting from higher risk of hypertension, diabetes and obesity
    • Sex - men have more strokes than women, although more women than men die from stroke


    Additional risk factors include:

  • Signs and Symptoms

    Most strokes are preceded by one or more mini-strokes called Transient Ischemic Attacks (TIAs) that should act as a warning to seek medical attention immediately.

    While symptoms of a stroke typically persist, symptoms of a TIA typically resolve on their own within a few hours. The five most common symptoms of a stroke or TIA are:

    • Sudden numbness, weakness, or paralysis of the face, arm, or leg, usually on one side of the body
    • Sudden loss of speech or trouble talking or understanding what is said
    • Sudden dizziness, loss of balance, coordination, or trouble walking
    • Sudden blurred vision or difficulty seeing in one or both eyes
    • Severe, unexplained headache
  • Tests

    Diagnosis of a stroke is currently based mostly on non-laboratory testing, including a physical and neurological exam and a variety of imaging tests. Researchers continue to try to find laboratory tests, such as stroke biomarkers, that could be used in stroke screening, diagnosis, treatment, and management.

    Possible biomarkers that could be helpful in risk assessment include Lp-PLA2, N-methyl-D-aspartate neuroreceptors (NMDAR), and NT-proBNP, while candidates for stroke diagnosis include antibodies to NR2A/2B and metalloproteinases (MMPs). It may be that a panel of biomarkers would be most effective as a diagnostic or risk assessment tool. These tests are not yet widely available, and their uses are mainly in research studies at present.

    Other laboratory tests may be ordered to evaluate a patient suspected of having had a stroke or to rule it out, including:


    Less commonly, one or more tests may be done in specific situations to identify conditions that contribute to risk of stroke. Some examples include:


    Non-laboratory tests may include a CT scan or MRI of the brain to look for any injury as well as tests of electrical activity and blood flow in the brain.

  • Treatment

    There are steps that can be taken to prevent a stroke and drugs that can be given in the event of a stroke.

    • Preventive measures involve identifying risk factors such as hypertension, atrial fibrillation, and diabetes so they can be treated and taking medications such as anticoagulants (e.g., warfarin) and antiplatelet agents (e.g., aspirin, clopidogrel) if someone is at risk or have had an ischemic stroke. Certain procedures may be performed to remove blockages from blood vessels.
    • If a person is having a stroke, immediate action is necessary. A drug called tissue plasminogen activator (tPA), a "clot-buster," can be given for ischemic stroke within 3 hours of the start of symptoms, which may reduce the chances of long-term disability.
    • Surgical procedures may be recommended for those who have had a hemorrhagic stroke to prevent known aneurysms from rupturing or to remove abnormal vessels.
    • For those who have disabilities as a result of a stroke, such as weakness or paralysis on one side of the body and speech or memory problems, rehabilitation can be helpful.


    It is important that anyone with sudden onset of symptoms suggestive of a stroke or Transient Ischemic Attack (TIA) seek medical attention as soon as possible.

View Sources

NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used. To access online sources, copy and paste the URL into your browser.

Sources Used in Current Review

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(2014 December 17). Heart Disease and Stroke Statistics – At-a-Glance. American Health Association [On-line information]. Available online at http://www.heart.org/idc/groups/ahamah-public/@wcm/@sop/@smd/documents/downloadable/ucm_470704.pdf. Accessed March 2016.

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