EPIDEMIOLOGY

Stroke is the leading cause of long-term disability and is the third leading cause of mortality in the United States. Each year, approximately 700,000 people have a stroke, approximately 200,000 of which are recurrent. Of all stroke cases, 87% are ischemic and 12% are hemorrhagic. Approximately 14% of those who have an ischemic stroke or transient ischemic attack (TIA) will have another event within 1 year (see Figures 13.1 and 13.2). Approximately 22% of men and 25% of women with stroke will die within a year and this percentage is higher among people aged 65 years and older. In addition, the prevalence of TIA is estimated to be approximately 240,000 cases annually and the prevalence of silent ischemic stroke between the ages of 55 and 64 years is approximately 11%, 22% between the ages of 65 and 69 years, 28% between the ages of 70 and 74 years, 32% between the ages of 75 and 79 years, 40% between the ages of 80 and 85 years, and 43% by the age of 85 years and older. Thus, age is a risk factor for stroke.

STROKE SUBTYPE

Ischemic stroke can be classified based on the presumed mechanism into the modified Trial of Org 10172 in Acute Stroke Treatment or TOAST criteria: 1) large-artery atherosclerosis, 2) cardioembolism, 3) small-vessel occlusion, 4) stroke of other determined etiology (such as arterial dissection or hypercoagulable states), and 5) stroke of undetermined etiology.