Transient ischemic attacks

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Abstract
Transient ischemic attacks (TIA) are common [in the USA]. Estimates of the percentage of major strokes preceded by TIA range from 4-75%. The aim of anticoagulant therapy (heparin and the coumarin and indandione derivatives) in TIA is to reduce the frequency of attacks and, more important, to prevent major stroke. Investigators disagree about the pathophysiology of TIA, implicating hemodynamic factors, or emboli of platelet-fibrin and atheromatous material, usually of carotid origin, but sometimes from the heart, including bacterial endocarditis. Some may be caused by repeated transient thrombotic occlusion of the internal carotid artery. The natural history of TIA has varied among reports. That anticoagulants may be of value in TIA remains an unproved hypothesis, with all studies to date lacking either randomized controls or statistical significance. Nonsignificance does not disprove a hypothesis, and many of the studies show trends that suggest that anticoagulants may be of benefit.