Stroke

A stroke occurs when the flow of blood to a part of the brain is cut off. This can be due to something (usually a blood clot) blocking the flow of blood to the brain (ischemic stroke). It can also be caused by a burst blood vessel bleeding into the brain (hemorrhagic stroke). About 80% of strokes are ischemic and 20% are hemorrhagic. Without a blood supply, the brain cells in the affected area start to die.

The effects of a stroke depend on which part of the brain is affected and how severe the damage is. A stroke may affect your ability to move, your ability to speak and understand speech, your memory and problem-solving abilities, your emotions, and your senses of touch, hearing, sight, smell, and taste. In some cases, a stroke can be fatal.

It's important to recognize the warning signs of stroke, because quick treatment can reduce the risk of brain injury and death. A stroke usually comes on suddenly, over a few minutes or hours.

The warning signs of stroke include:

• sudden weakness, numbness, or tingling of the face, arm, or leg (often on only one side of the body)
• sudden confusion, trouble speaking, or trouble understanding speech
• sudden vision loss (often in one eye only) or double vision
• sudden trouble walking, dizziness, loss of balance or coordination, or falls
• sudden severe headache (often described as "the worst headache of my life") with no known cause

If you notice these symptoms, call 9-1-1 (or your emergency medical number if you do not have 9-1-1 service) immediately. Stroke is a medical emergency.