I.

Introduction

Stroke, brain damage caused by a lack of blood flow to part of the brain. In order to perform its many functions and direct activities throughout the body—from walking to seeing to reasoning—the brain requires a constant supply of energy, provided by the oxygen and nutrients that are delivered by the flowing blood. If blood flow is restricted or cut off at any point between the heart and the brain, portions of the brain relying on blood from the obstructed blood vessel become deprived of oxygen. Brain cells are extremely sensitive to such oxygen deprivation, and if they are deprived of oxygen and nutrients for more than several minutes, they, in effect, starve to death. A stroke results in permanent damage to the brain tissue—and in many cases, permanent disability for the patient. For example, a patient who has had a stroke may develop paralysis on one or both sides of the body; have difficulty with walking, eating, or other daily activities; or lose the ability to speak or understand speech.

Stroke is the third leading cause of death and a leading cause of serious, long-term disability in the United States. According to the American Heart Association, approximately 700,000 Americans suffer a stroke each year; about 25 percent of these strokes are fatal. Someone suffers a stroke every 45 seconds, and every 3.1 minutes someone dies of a stroke. Stroke is responsible for an estimated $40 billion in health-care costs and lost productivity each year.