Stroke, or cerebrovascular accident (CVA), is the third leading cause of death (after heart disease and cancer) in the United States and the industrialized countries of the world. The term "stroke," which comes from subjects being suddenly "struck down" with neurological deficits, is commonly used by both professional and lay groups. Efforts are being made to replace the term with "brain attack" to dramatize its analogous effects to a "heart attack," the term used for myocardial infarction. The term "cerebrovascular accident" is used interchangeably with stroke ("accident" indicates the catastrophic nature of strokes, not a traumatic origin as the term implies). More than 600,000 strokes occur annually in the United States, according to the American Heart Association, and stroke prevalence (number of living stroke victims) is approximately 4.5 million with an annual cost in 1997, both direct and indirect, of over $40 billion.
Stroke refers to the usually sudden onset of a neurological deficit, such as hemiparesis (weakness on one side of the body), or aphasia (impairment of language comprehension and production), which can be attributed to either the occlusion or rupture of a cerebral vessel. Resulting specific neurological symptoms and signs are determined by the area of the brain that is affected, and since the complex functions of the brain are either localized in specialized areas or diffusely distributed, stroke symptoms may similarly be localized or generalized in nature. For example, the long pathway of motor fibers can be interrupted, with resulting hemiparesis involving various cerebral arteries or their branches, such as the anterior, middle, or vertebrobasilar arteries. Occlusion of smaller arterioles which feed smaller areas of brain may result in more isolated effects, such as pure sensory or motor hemiparesis. On the other hand, occlusion or rupture of vessels in "silent" areas of the brain, as in the frontal or parietal cortex, can lead to subtle nonfocal symptoms reflected in impaired cognition, executive function, or memory. Other symptoms of impaired specialized brain functions from strokes include apraxia (impairment in the execution of motor actions), and agnosia (loss of ability to recognize familiar objects). Leukoaraiosis, or increased T2-signal intensity, on magnetic resonance imaging (MRI) of brain white matter results predominantly from small-vessel disease, and this syndrome is associated with increased risks for strokes and dementia.
FRANK YATSU, The Gale Group Inc., Macmillan Reference USA, New York,