Stroke Health Article

Definitions

A stroke (also known as a cerebrovascular accident ) is an event characterized by either the sudden interruption of the blood supply to part of the brain or by the rupture of a blood vessel in the brain. Some of the disabilities that can result from a stroke include paralysis, cognitive deficits, speech problems, emotional difficulties, problems with activities of daily living, and pain.

The 2 forms of stroke are ischemic stroke and hemorrhagic stroke. .

An ischemic stroke occurs when an artery supplying the brain with blood becomes blocked, suddenly decreasing or stopping blood flow and ultimately causing a brain infarction. This type of stroke accounts for approximately 80% of all strokes. Blood clots are the most common cause of artery blockage and brain infarction and can cause damage in 2 ways. A clot that forms in a different part of the body can travel through blood vessels and become lodged in a cerebral artery. This free-roaming clot or embolus often forms in the heart. A stroke caused by an embolus is called an embolic stroke. The second type of ischemic stroke, called a thrombotic stroke, is caused by the formation of a blood clot in one of the cerebral arteries that adheres to the arterial wall until it grows large enough to obstruct blood flow.

During a hemorrhagic stroke, an artery in the brain bursts open, spewing blood into the surrounding tissue, disrupting not only the blood supply but also the delicate chemical balance neurons require to function. Such strokes account for approximately 20% of all strokes. Hemorrhage can occur in several ways. One common cause is a bleeding aneurysm. Another common cause is the imbalance that occurs when increased arterial pressure is applied to brittle, plaque-encrusted arterial walls. Hemorrhagic stroke can also occur in a person with an arteriovenous malformation, a condition characterized by a tangle of thin-walled, defective blood vessels and capillaries within the brain. Blood from ruptured cerebral arteries can flow into either the brain tissue (ie, intracerebral hemorrhage ) or into the various spaces surrounding the brain (ie, subarachnoid hemorrhage ). Subarachnoid hemorrhage is the most deadly of all strokes because it involves blood contamination of the cerebrospinal fluid.

A transient ischemic attack (TIA), or mini-stroke, differs from a stroke because its effects usually resolve within 24 hours and leave no residual deficits. A TIA is considered a warning that a person is at risk for a more serious stroke.

Scope

About 700,000 strokes occur in the United States each year. About 500,000 of these are first strokes. Over 160,000 persons die from stroke each year in the United States. Stroke is also a leading cause of serious long-term disability.

Stroke death rates are higher for black persons than for white persons, even at younger ages.

Nearly 75% of all strokes occur in persons older than 65 years, but strokes can occur at any age. The risk of having a stroke more than doubles each decade after age 55.

About 25% of persons who recover from their first stroke will have another stroke within 5 years. Recurrent stroke is a major contributor to stroke disability and death, with the risk of severe disability or death from stroke increasing with each stroke recurrence. The risk of a recurrent stroke is greatest immediately after a stroke, and the risk decreases with time.

The total cost of stroke to the United States is estimated at about $43 billion per year.