Transient ischemic attack: Definitions and clinical presentations

The definition of transient ischemic attack has changed from a focal, neurologic event that lasts less than 24 hours to one that typically lasts less than 1 hour and is not associated with changes on neuroimaging. Transient ischemic attacks, using the older definition, carry a 10% risk of stroke within 90 days and are therefore considered a serious condition meriting urgent attention. The manifestations of transient ischemic attacks are varied and include events that involve the anterior and posterior cerebral circulations. Correct diagnosis depends on an accurate medical history and physical examination, combined with the appropriate neuroimaging. It is uncommon that syndromes such as syncope, isolated dizziness, drop attacks, or global amnesia are caused by cerebral ischemia or transient ischemic attack. With the careful evaluation of symptoms according to this definition of transient ischemic attack, a clinician can determine whether a transient ischemic attack has occurred and thus propose treatment that may decrease the likelihood of a subsequent stroke.