Transient ischemic attacks (TIA) are caused by temporary disturbance of blood supply to a restricted area of brain and cause recurrent and brief (less than 24 hours) neurologic dysfunctions. If the neurologic dysfunction due to lack of blood supply lasts more than 24 hours, it is named as stroke.

A transient ischemic attack is a medical emergency.

Symptoms depend on the involved area of the brain and frequent symptoms are temporary loss of vision, difficulty speaking, hemiparesis, numbness usually on one side of the body and loss of consciousness. TIA is a warning for an approaching stroke. If the time period of blood supply impairment lasts more than a few minutes, the nerve cells of the brain die permanently and cause permanent neurologic deficit. One third of the people with TIA later have recurrent TIAs and one third has a stroke due to permanent nerve cell loss. The cause of reduced blood flow is most frequently emboli (a small blood clot) that occludes a brain vessel. Other reasons are excessive narrowing of large vessels due to an atherosclerotic plaque and increased blood viscosity due to some blood diseases. TIA is related with other medical conditions like hypertension, heart disease, migraine, cigarette smoking and diabetes mellitus. For treatment, underlying causes like heart diseases, diabetes mellitus should be treated and cigarette smoking should be stopped. Anticoagulant medications such as aspirin, dipyridamole, heparin and coumadin may be used. For people with more than 70% stenosis within the carotid artery, removal of atherosclerotic plaque by surgery (carotid endarterectomy) may be recommended.