The nearly occluded internal carotid artery: a diagnostic trap.

Nine cases of nearly occluded internal carotid artery (ICA) origins, usually simulating total occlusion, are presented. Correct diagnosis is aided by an awareness of the possibility of near occlusion of the ICA origin and by careful study of selective common carotid angiography with a long imaging sequence and subtraction. Carotid endarterectomy is the operative procedure of choice, since there may be startling apparent increase in size of the arterial lumen distal to the surgical repair. Many cases reported previously as internal carotid artery occlusion with successful endarterectomy may actually have been severe stenoses.