Transient ischemic attacks: Part I. Diagnosis and evaluation.

Transient ischemic attack is no longer considered a benign event but, rather, a critical harbinger of impending stroke. Failure to quickly recognize and evaluate this warning sign could mean missing an opportunity to prevent permanent disability or death. The 90-day risk of stroke after a transient ischemic attack has been estimated to be approximately 10 percent, with one half of strokes occurring within the first two days of the attack. The 90-day stroke risk is even higher when a transient ischemic attack results from internal carotid artery stenosis. Most patients reporting symptoms of transient ischemic attack should be sent to an emergency department. Patients who arrive at the emergency department within 180 minutes of symptom onset should undergo an expedited history and physical examination, as well as selected laboratory tests, to determine if they are candidates for thrombolytic therapy. Initial testing should include complete blood count with platelet count, prothrombin time, International Normalized Ratio, partial thromboplastin time, and electrolyte and glucose levels. Computed tomographic scanning of the head should be performed immediately to ensure that there is no evidence of brain hemorrhage or mass. A transient ischemic attack can be misdiagnosed as migraine, seizure, peripheral neuropathy, or anxiety.