Transient ischemic attack: an evidence-based update.

Transient ischemic attack represents a medical emergency and warns of an impending stroke in roughly one-third of patients who experience it. The risk of stroke is highest in the first 48 hours following a transient ischemic attack, and the initial evaluation in the emergency department is the best opportunity to identify those at highest risk of stroke recurrence. The focus should be on differentiating transient ischemic attack from stroke and common mimics. Accurate diagnosis is achieved by obtaining a history of abrupt onset of negative symptoms of ischemic origin fitting a vascular territory, accompanied by a normal examination and the absence of neuroimaging evidence of infarction. Transient ischemic attacks rarely last longer than 1 hour, and the classic 24-hour time-based definition is no longer relevant. Once the diagnosis has been made, clinical risk criteria may augment imaging findings to identify patients at highest and lowest risk of early recurrence. Early etiologic evaluation, including neurovascular and cardiac investigations, allows for catered secondary prevention strategies. Specialized transient ischemic attack clinics and emergency department observation units are safe and efficient alternatives to hospital admission for many transient ischemic attack patients.