Stroke is a leading cause of disability and the third leading cause of death for Americans. According to the American Heart Association (AHA), there are more than five million stroke survivors and about 500,000 new strokes occur each year. In general, women experience more strokes than men and African-Americans are at twice the risk than Caucasians.
Strokes are caused when there is a block (ischemic stroke) or bleed (hemorrhagic stroke) in an artery that supplies blood to the brain. The stroke event itself can last from minutes to hours (sometimes days) but the impairments that results are often long-lasting including spastic movements, lack of movement coordination and weakness on one side of the body.
Ischemic Strokes
Ischemic strokes are the most common type of stroke, accounting for almost 90 percent of all strokes. Ischemic strokes happen when there is a block in an artery supplying blood to the brain. Typical causes of a block are a blood clot or the break off of plaques that have lined the arterial, a marker of artherosclerosis (narrowing of the arteries).
The stroke is referred to as a thrombosis if the blood clot originates in the brain. The stroke is referred to as an embolism if the clot originated somewhere else in the body and traveled to an artery supplying blood to the brain. Embolisms can occur in other parts of the body. For example, a pulmonary embolism occurs when a blood clot that traveled from somewhere in the body to the lungs.
Hemorrhagic Strokes
Hemorrhagic stroke occurs when there is bleeding in the brain. They are far less common than ischemic strokes. But similar to inschemic stroke, there are two primary categories of hemorrhagic stroke, depending on where the bleeding occurs. If the bleeding occurs within the brain, it is termed intracerebral; intra- referring to inside and -cerebral referring to brain. If the bleeding occurs between the brain and the bone of the skull, it is termed subarachnoid, meaning beneath the arachnoid membrane. Brain aneurysms are a form of hemorrhagic stroke.
Risk Factors
Physiologically, a stroke occurs because of a block or bleed in an artery and the there is little warning of the event itself. However, the underlying cause of the block or bleed is often related to risk factors that can be controlled. High blood pressure, or hypertension, is a common in the American adult population and is a primary source for narrowing of the arteries. However, it can be treated with medication and lifestyle changes that include weight loss, increase in exercise, and stress management. Other risk factors for stroke that are controllable include smoking, diabetes, cholesterol and alcohol/substance abuse.
