Stroke is the nation's No. 3 killer and the leading cause of long-term disability in the U. S. More than 700,000 Americans will suffer a stroke this year, yet many Americans do not know the symptoms or what to do when they witness someone having a stroke. The following information is provided by the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.

"Stroke is an unmistakable event. Few other medical conditions come on so suddenly or are so noticeable to a bystander," said John Marler, M.D., associate director for clinical trials at the institute.

A stroke occurs when blood flow to the brain is interrupted. Brain cells die when deprived of oxygen and nutrients provided by blood. Because stroke injures the brain, if you are having a stroke, you may not realize what is happening. But to a bystander, the signs of a stroke are distinct:

+Sudden numbness or weakness of the face, arm or leg (especially on one side of the body)

+Sudden confusion, trouble speaking or understanding speech

+Sudden trouble seeing in one or both eyes

+Sudden trouble walking, dizziness, or loss of balance or coordination

+Sudden severe headache with no known cause In treating a stroke, every minute counts. New treatments are available that greatly reduce the damage caused by a stroke. But you need to arrive at the hospital as soon as possible after symptoms start. Knowing the symptoms of a stroke and getting to the hospital quickly can help you act in time to save yourself-or someone you know- from serious long-term disability.

And making changes in your lifestyle can help prevent stroke. The institute is dedicated to research and education on the causes and treatments and prevention of stroke. Risk factors include family history, high blood pressure, smoking, diabetes, physical inactivity, heavy alcohol consumption and being overweight. Talk to your doctor. Find out your risks and take action.

More information and free materials on stroke is available by calling (800) 352-9424 or by visiting www.ninds.nih.gov/stroke.