Transient ischemic attack: a dangerous Harbinger and an opportunity to intervene.

Transient ischemic attack (TIA) and ischemic stroke are both characterized by sudden onset of neurological symptoms due to focal cerebral ischemia, but they are distinguished by the duration of neurological symptoms, with TIA traditionally defined by resolution of symptoms within 24 hours and stroke reserved for symptoms of longer duration. Because TIA and ischemic stroke share etiologies, it is not surprising that the recommended evaluations and secondary prophylaxis are identical. However, recent studies suggest that optimal management of TIA and stroke may differ more than previously recognized. The short-term risk of ischemic stroke after TIA is very high, which may be because rapid recovery from neurological symptoms is indicative of reversal of ischemia and tissue still at risk. Regardless of whether residual symptoms or infarction are present, rapid recovery appears to predict a greater short-term risk of subsequent ischemic stroke and is more likely to reflect a distinct, unstable pathophysiology. Therefore, it may be more useful to characterize acute ischemic cerebrovascular syndromes on the basis of the extent of rapid recovery (i.e., on the inferred reversal of ischemia) than on the completeness of recovery at 24 hours. Patients with substantial rapid recovery may be those for whom acute intervention is most warranted.