Extracranial carotid artery. Current concepts of diagnosis and management.

Extracranial carotid artery disease is a frequent cause of transient ischemic attack (about 50%), but a much less common cause of cerebral infarction (about 15%). Transient ischemic attack almost invariably precedes strokes caused by extracranial carotid stenosis, but rarely heralds strokes that result from cardiogenic embolism or intracranial vascular disease. When extracranial carotid stenosis produces a transient ischemic attack or stroke, artery-to-artery embolism is the predominant mechanism. Asymptomatic significant (>50%) carotid stenosis poses special clinical questions in patients scheduled to undergo general surgical or major cardiovascular operations. With general surgical procedures, there is no increased risk of stroke. With cardiovascular operations, however, there may be an increased risk of stroke in patients with critical (>90%) carotid stenosis or occlusion. When perioperative stroke occurs, the most common cause is embolism rather than focal hemodynamic change. For symptomatic high-grade (>70%) extracranial carotid stenosis, carotid endarterectomy is the treatment of choice in patients who are not high-risk surgical candidates. Alternatively, for high-risk patients, new drugs such as ticlopidine appear quite promising, and percutaneous angioplasty may also prove effective. Prevention of stroke must continue to be a major goal of national medical policy. Because cigarette smoking is the most important risk factor for extracranial carotid disease, more strenuous efforts must be directed toward eliminating this health risk.