What is a stroke?

A stroke, sometimes called a "brain attack," is when blood is prevented from flowing through the brain. This can happen two ways:

  1. A blood clot. A clot can block blood from flowing through blood vessels in the brain. This is the most common type of stroke and is called an ischemic stroke.
  2. A hemorrhage. When a blood vessel breaks, blood drains into other areas of the brain and does not get to the places it needs to go. This type of stroke is called a hemorrhagic stroke. About 15% of strokes are hemorrhagic strokes.

A stroke is a very serious problem because the brain is the command center for the body. In both types of strokes, the brain cells don’t receive the blood they need to survive. Every minute of a stroke, two million brain cells die. Because of this, stroke is the third-leading cause of death in the U.S.

Most people who have a stroke will survive but it’s possible they will become disabled by their stroke. When brain cells die, the abilities controlled in that part of the brain can be lost. For example, the areas in the brain that control speech, memory, and movement can be affected. This is why stroke is the number-one cause of adult disability in the U.S.

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Recognize a Stroke

Recognizing and acting fast after a stroke can save a life and may prevent disabilities from becoming permanent. Most people have two or more symptoms of a stroke, but people can have just one symptom. The most common signs of a stroke are:

  • Sudden numbness or weakness of face, arm, or leg (mainly on one side of the body)
  • Sudden trouble seeing in one or both eyes
  • Sudden trouble walking, dizziness, or loss of balance
  • Sudden confusion or trouble talking or understanding speech
  • Sudden bad headache with no known cause

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What Causes a Stroke?

A stroke is caused when a blood vessel clogs or bursts, preventing blood flow to the brain. Without a way to get oxygen and nutrients from the blood vessel, brain cells die.

The majority of strokes, about 87%, are called ischemic strokes. These are strokes caused by clots. Clots typically form in an artery in the brain. Arteries in the brain are more likely to experience clots when they have been damaged by fatty buildups, called atherosclerosis. Clots also can happen when a clot forms somewhere else in the body, travels through the bloodstream and then gets stuck in a narrowed artery in or near the brain. Atrial fibrillation (an abnormal heart rhythm) is a condition which may cause blood clots in the heart, which can then travel up to the brain.

Ischemic strokes, strokes that are caused by blood clots, sometimes can be treated with drugs that dissolve clots, such as the drug TPA (tissue plasminogen activator.) TPA must be given within three hours of when the stroke started, and tests must be done before TPA can be given to ensure the patient is a good candidate for TPA. That’s why it is so important for you or your loved ones to call 911 and get to a hospital as fast as possible after you notice symptoms.

About 13% of strokes are called hemorrhagic strokes. These are strokes caused when an artery in the brain bursts. These strokes can be caused by severely high blood pressure, a head injury or by aneurysms (blood-filled pouches that balloon out from weak parts of the artery.) Aneurysms are often caused or made worse by high blood pressure.

This information has been adapted from American Stroke Association and National Stroke Association.