Unoperated, asymptomatic significant internal carotid artery stenosis: a review of 182 instances.

One hundred and sixty-eight asymptomatic patients with a carotid artery stenosis of more than 50% were observed over a period of up to 12 years. During this time, 136 patients remained asymptomatic, two patients developed atypical neurologic symptoms that spontaneously disappeared, 26 patients developed transient ischemic attacks and successfully underwent carotid endarterectomy, three patients developed transient ischemic attacks that were ignored and they subsequently suffered a completed stroke, and one patient suffered a completed stroke without a warning transient attack. These data suggest that surgery is not required in the patient with an asymptomatic carotid stenosis until a transient ischemic attack occurs.