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Stroke is the fifth leading cause of death in the United States (after heart disease, cancer, chronic lung disease, and injuries and accidents) and the most common disabling neurologic disorder. Approximately 800,000 new strokes occur and approximately 130,000 people die from stroke in the United States each year.
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The incidence of stroke increases with age; approximately two-thirds of all strokes occur in those older than 65 years. Modifiable risk factors for stroke include systolic or diastolic hypertension, atrial fibrillation, diabetes, dyslipidemia, physical inactivity, and obstructive sleep apnea (Table 13-1). Genetic, usually polygenic, factors also contribute to stroke risk. The incidence of stroke has decreased in recent decades, largely because of improved treatment of hypertension, dyslipidemia, and diabetes and reduction in smoking.
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Stroke is a syndrome with four key features:
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Sudden onset—The sudden onset of symptoms is documented by the history.
Focal involvement of the central nervous system—The site of involvement is suggested by symptoms and signs, pinpointed more precisely by neurologic examination, and confirmed by imaging studies (computed tomography [CT] or magnetic resonance imaging [MRI]).
Lack of rapid resolution—The duration of neurologic deficits is documented by the history. The classic definition of stroke requires that deficits persist for at least 24 hours (to distinguish stroke from transient ischemic attack, discussed later). However, any such time point is arbitrary, and transient ischemic attacks usually resolve within 1 hour.
Vascular cause—A vascular cause may be inferred from the acute onset of symptoms and often from the patient’s age, the presence of risk factors for stroke, and the occurrence of symptoms and signs referable to the territory of a particular cerebral blood vessel. Investigative studies can often identify a more specific etiology, such as arterial thrombosis, cardiogenic embolus, or clotting disorder.
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Strokes begin abruptly. Neurologic deficits may be maximal at onset or may progress over seconds to hours (or occasionally days).
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