Transient ischemic attack: a neurologic emergency.

Classically, a transient ischemic attack (TIA) has been defined as an acute episode of neurologic symptoms lasting less than 24 hours attributed to focal ischemia in a vascular distribution of the brain or retina. Stroke and TIA share similar risk factors, evaluation, and secondary prevention. However, evaluation of patients with TIA has traditionally lacked the same urgency that has been directed to acute stroke, probably because patients with TIA are at baseline neurologically when the diagnosis is made. Recently, several studies have found a high risk of stroke shortly after TIA. Furthermore, recent evidence suggests that early recovery from ischemia actually is associated with greater instability. Identifying patients with the highest risk of recurrent ischemic events for urgent evaluation and intervention is key in secondary stroke prevention. This article reviews the current literature on new concepts about TIA, subsequent risk of stroke, and guidelines on evaluation and treatment.