TRANSIENT ISCHEMIC ATTACKS - DIAGNOSIS, AND MEDICAL AND SURGICAL-MANAGEMENT

Patients experiencing transient ischemic attacks (TIAs) may have a 2-y ear stroke rate as high as 57%, and carotid endarterectomy has been sh own in prospective randomized studies to be highly effective in reduci ng this rate. Therefore, it is crucial to correctly identify patients with TIAs, treat underlying causes appropriately, and identify those m ost likely to benefit from endarterectomy. Whether in the anterior or posterior circulation, TIAs are focal neurologic events that usually l ast 5 to 30 minutes and are characterized by an abrupt onset followed by gradual resolution. They may be caused by artery-to-artery thromboe mbolism, cardiogenic embolism, or thrombosis of a small penetrating ce rebral vessel (threatened lacunar infarction). A number of contributin g disorders must be considered, including migraine, arterial dissectio n, vasculitis, thrombotic diatheses, blood dyscrasias, infections, and drug abuse. Carotid endarterectomy should be considered only for pati ents with hemispheric TIAs in whom lacunar events, cardiogenic embolis m, and other underlying causes of stroke have been excluded and ipsila teral carotid stenosis of greater than 70% has been demonstrated. The value of endarterectomy increases: if the patient is relatively willin g to take immediate risks in order to avoid future morbid events (low risk aversion) and believes stroke is a serious event, nearly tantamou nt to death; if the morbidity and mortality of the operation, as deter mined by institutional audits, is low; and if the degree of carotid st enosis is high. The value of endartectomy declines rapidly with time e lapsed from the TIA. Endarterectomy is of marginal value in patients w ith amaurosis fugax, of uncertain value in patients with stroke, and u nlikely to be of any value in patients with asymptomatic carotid steno sis. Long-term anticoagulation has been shown to be beneficial only in patients at risk for cardiogenic embolism. Others, including those un dergoing endarterectomy, should receive aspirin. In all patients, ther e should be an aggressive effort to control risk factors for cardiovas cular and cerebrovascular disease.