Transient ischemic attack

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 there are neurological symptoms persisting for more than 24 hours, it is classified as a cerebrovascular accident (stroke).

A transient ischemic attack is a medical emergency.

Symptoms vary widely from person to person depending on the area of the brain involved. The most frequent symptoms include temporary loss of vision, difficulty speaking, hemiparesis, numbness usually on one side of the body and loss of consciousness.

Patients diagnosed with a TIA are sometimes said to have had a warning for an approaching cerebrovascular accident. If the time period of blood supply impairment lasts more than a few minutes, the nerve cells of that area of the brain die permanently and cause permanent neurologic deficit. One third of the people with TIA later have recurrent TIAs and one third have a stroke due to permanent nerve cell loss.

Causes

The most common cause of a TIA is an embolus (a small blood clot) that occludes an artery in the brain. This most frequently arises from a atherosclerotic plaque in one of the carotid arteries or from a thrombus in the heart due to atrial fibrillation.

Other reasons include 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 (especially atrial fibrillation), migraine, cigarette smoking, hypercholesterolemia and diabetes mellitus.

Treatment

In managing a TIA, it may be necessary to undergo a brain scan (CT or MRI) to exclude an ongoing intracerebral hemorrhage which will need urgent neurosurgical intervention.

The mainstay of treatment following acute recovery from a TIA should be to diagnose and treat the underlying cause. Anticoagulant medications such as aspirin, dipyridamole, heparin and coumadin may be used. For people with a greater than 70% stenosis within the carotid artery, removal of atherosclerotic plaque by surgery (carotid endarterectomy) may be recommended.