Stroke

The technical term for a stroke is a cerebrovascular accident (CVA). A stroke occurs when the blood supply to a part of the brain is interrupted. If the cells in the affected area of the brain do not receive the necessary supply of oxygen via blood, they die or become nonfunctional.

Two main causes of stroke can be identified: ischemic and intracranial hemorrhagic strokes. Ischemic strokes are caused by the blockage of an artery (blood vessel) that supplies blood to the brain. A temporary blockage that resolves itself, usually after a few seconds or minutes, is called a transient ischemic attack (TIA) or incomplete stroke. However, it is considered a serious signal of high probability for a complete stroke in the future.

Hemorrhagic strokes are less common than ischemic strokes. They are caused by sudden ruptures of blood vessels, leading to bleeding inside the brain. Hemorraghic strokes are frequently [Page 1072]caused by high blood pressure, causing arterial walls to rupture. Aneurysms are another cause for hemorrhages referring to arterial bulges caused by weaknesses in the tissue of the artery, which then breaks and causes bleeding in the brain and interruption of blood supply.

Strokes constitute one of the major disabling neurologic diseases in adult life. However, strokes can occur at any age, even in young children. Approximately 750,000 Americans have an initial or recurrent ischemic stroke. The health care cost exceeds $30 billion annually. Approximately 150,000 Americans will die from stroke annually. Stroke treatment has made considerable advances in the past two decades, in conjunction with advances in basic brain research, helping to significantly increase survival rates. It is estimated that in the United States, approximately 4 million stroke survivors reside at different levels of functioning and recovery.

Impairments from a stroke depend on the regions of the brain affected. If motor areas are affected by stroke, movement dysfunctions will be prominent; for example, by hemiparesis or weakness on one side of the body. Hemiparetic gait (walking) in stroke is characterized by weak muscle strength, short and slow steps, and reduced range of motions of joints on one side of the body, resulting in an uneven asymmetric walking pattern. Hemiparesis is also very common for arm function. If speech centers are affected by stroke, the result is often aphasia, a condition characterized by the inability to comprehend language or the inability to use expressive language, although the ability to comprehend is intact. A common perceptual deficit resulting from stroke is visual (sometimes including auditory) neglect in the left visual field. Persons with neglect do not process visual information properly on the neglect side, and act blind, although the visual system is not affected. Visual neglect is caused by strokes in the regions of the right hemisphere, which are responsible for spatial perception and orientation.