transient ischemic attack

ABBR: TIA A neurological deficit that appears suddenly and resolves quickly. Refinements in imaging technologies and blood testing suggest that all syndromes previously known as TIAs may in fact occur because of small cerebral infarctions.

INCIDENCE
The American Heart Association estimates that between 200,000 and 500,000 people in the U.S. have a TIA each year. The risk for TIA increases with aging. About 1 in 15 people over the age of 65 has survived a TIA.

CAUSES
TIAs usually occur in patients with underlying atherosclerosis, esp. of the carotid arteries, intracranial arteries, or the aorta. Emboli to the brain caused by atrial fibrillation, cerebrovascular vasospasm, transient episodes of hypotension, cerebral vasculitis, polycythemia vera, and other illnesses may occasionally produce TIAs.

SYMPTOMS AND SIGNS
TIAs and strokes have similar symptoms. These vary depending on the blood vessel affected but may include weakness of one half of the face or half of the body, confusion, dizziness, aphasia, monocular visual loss, hemibody sensory loss, sudden trouble walking, loss of balance, or severe headache with no known cause. A person who develops any of these symptoms should seek emergency medical assistance immediately. He or she should not attempt to drive to the emergency center but should call or have a family member call 911 for help.

Most TIAs resolve within an hour of onset. Patients who have suffered a TIA have an increased risk of peripheral and coronary artery atherosclerosis and an increased risk of subsequent heart attack and stroke. The risk for a completed stroke is greatest in the first week after a TIA (it occurs in more than 4% of patients). Patients with paralysis or aphasia during TIA are at the greatest risk.

DIAGNOSIS
Patients who experience a TIA should undergo neuroimaging and carotid artery ultrasonography promptly. Blood tests (complete blood count, serum chemistries, and glucose levels) and blood pressure measurements are also standard elements in the diagnostic evaluation.

TREATMENT
Studies involving large numbers of patients have shown that the risk of subsequent stroke in those who have suffered TIAs can be substantially reduced with antiplatelet or anticoagulant drugs (such as aspirin, clopidogrel, or warfarin) and with drugs that control blood pressure and lipids. Carotid endarterectomy or balloon angioplasty and stenting are better options than medical therapy for stroke prevention in TIA patients with extensive carotid artery blockages, provided that their surgeons have an operative mortality rate of less than 5%.

PATIENT CARE
Because symptoms of TIA may resolve by the time the patient reaches the emergency care center, an accurate history of the event should be obtained, questioning not only the patient but also the family, first-responders, and any other witnesses. Carotid arteries are assessed for bruits, the heart for evidence of atrial fibrillation, and the cranial nerves, speech and motor strength for signs of functional loss. The patient should undergo brain imaging studies (such as CT or MRI) to identify lacunar strokes, larger ischemic strokes or other intracerebral disorders. Baseline laboratory studies including serum chemistries, glucose level and coagulation factors are obtained. The health care professional supports the patient and family during diagnostic procedures by explaining the procedures and expected reactions and by encouraging verbalization of feelings and concerns. Therapeutic interventions are provided, and the patient is instructed about desired effects and adverse reactions of prescribed drugs.

The patient also is encouraged to follow preventive measures: stopping smoking and avoiding second-hand smoke, exercising regularly (walking at a moderate pace for 30 min daily), losing weight if obesity is a concern, eating a heart-healthy diet, drinking no more than one (women) or two (men) alcoholic drinks daily, seeking medical management for elevated cholesterol or blood pressure, and more tightly controlling glucose levels if diabetes mellitus is present.
SEE: stroke