Transient Ischemic Attacks

– Recurrent, focal neurologic disturbances of sudden onset and brief duration characterized by loss of sensory, motor, or visual function.

Causes and Incidence

Most transient ischemic attacks (TIAs) are caused by cerebral emboli that break off from atherosclerotic plaques in the carotid or vertebral arteries in the neck. Hypertension, atherosclerosis, heart disease, diabetes mellitus, and polycythemia serve as predisposing factors. The attacks are most common in adults past middle age and often presage a stroke. Occasionally TIAs are seen in children with severe cardiovascular disease and an elevated hematocrit.

Disease Process

An atherosclerotic plaque breaks off from an artery in the neck and travels to the brain, where it temporarily impedes the blood flow in the carotid-middle or vertebral basilar artery in the circle of Willis.

Symptoms

TIAs appear suddenly, usually last 2 to 30 minutes, and then subside with no neurologic sequelae. They may occur daily or two or three times a year. The manifestations are specific to the artery occluded.

Carotid
Ipsilateral blindness described as a shade being pulled down over the eye; contralateral hemiparesis; paresthesias; slurred speech

Vertebrobasilar
Confusion; vertigo; diplopia or binocular blindness; unilateral or bilateral muscular weakness and paresthesias; drop attacks with buckling of the legs; slurred speech

Potential Complications

TIAs may precede a stroke.

Diagnostic Tests

The diagnosis is made on the clinical history with an ultrasound scan or arteriography, which confirms the presence of stenosis and atherosclerosis of the carotid or vertebral arteries.

Treatments

Surgery
Endarterectomy to remove atherosclerotic plaque from the artery is considered if the artery is at least 70% occluded; intracranial anastomosis to revascularize the brain.

Drugs
Antiplatelet agents and anticoagulants for 2 to 3 weeks to interfere with clot formation; aspirin therapy long term to interfere with platelet aggregation.

General
Monitor for bleeding; long-term follow-up.