Stroke
Stroke is a 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 unde...