Strokes, or brain attacks, are a major cause of death and permanent disability. They occur when blood flow to a region of the brain is obstructed and may result in death of brain tissue.
There are two main types of stroke: ischemic and hemorrhagic. Ischemic stroke is caused by blockage in an artery that supplies blood to the brain, resulting in a deficiency in blood flow (ischemia). Hemorrhagic stroke is caused by the bleeding of ruptured blood vessels (hemorrhage) in the brain.
During ischemic stroke, diminished blood flow initiates a series of events (called ischemic cascade) that may result in additional, delayed damage to brain cells. Early medical intervention can halt this process and reduce the risk for irreversible complications.
Stroke is the third leading cause of death and the leading cause of disability in the United States. Approximately 600,000 strokes, or brain attacks, occur in the United States each year and of these, approximately 150,000 (25 percent) are fatal. The incidence of stroke is higher in African Americans than Caucasians.
Stroke occurs at an equal rate in men and women, but women are more likely to die from stroke. Ischemic stroke occurs more frequently in people over age 65 and hemorrhagic stroke is more common in younger people.