Transient ischemic attacks: an update.

This is a review of extant concepts of transient ischemic attacks (TIAs), their definitions, prognostic significance, pathogenesis, physiology, and management. The natural history of TIAs depends upon the risk factors of the population group studied, so that therapeutic trials should be controlled and randomized and not dependent upon published natural history data. A strong association between TIAs and coronary artery disease has now been established. It may be difficult to establish the cause or pathogenesis of TIAs in any given patient in view of the relatively poor correlation between the patient's symptoms and location of arterial plaques. Recent studies have suggested mechanisms aside from impaired perfusion or embolization from carotid plaques or vertebral basilar disease. There are no proven indications for carotid endarterectomy, a procedure which has been excessively used in the United States, but presently ongoing prospective, randomized, controlled multi-center studies will likely resolve this important issue. Neither is there scientific validation for the use of long-term anticoagulants, but data support the efficacy of ASA in reducing the incidence of stroke and myocardial infarction in patients with TIAs.