Silent stroke and carotid stenosis.

BACKGROUND AND PURPOSE: Silent cerebral infarction is often found on computed tomographic scan in patients with asymptomatic carotid stenosis, but its relation to the arterial stenosis is uncertain. METHODS: We compared computed tomographic scans and carotid Doppler in 115 patients with asymptomatic carotid stenosis, 203 with carotid transient ischemic attacks and carotid stenosis, and 63 with transient ischemic attacks but without carotid stenosis. There was no group with normal carotid arteries for comparison. RESULTS: Lesions seen on CT scan were most common in the transient ischemic attack with carotid stenosis group (47%) compared with the other groups (30%, 19%) (p less than 0.001). Cerebral infarcts ipsilateral to the carotid stenosis were found in 10% of patients with mild (35-50%) stenosis, 17% in moderate (50-75%) stenosis, and 30% with severe (greater than 75%) carotid stenosis (p less than 0.001). In patients with asymptomatic carotid stenosis, 68% of infarcts were ipsilateral to the stenosis; in those with transient ischemic attacks and carotid stenosis, 86% of infarcts were ipsilateral to the stenosis. CONCLUSIONS: The more severe the carotid stenosis, the higher the incidence of cerebral infarction ipsilateral to the stenosis. This finding applied to central infarcts as well as to peripheral infarcts in both symptomatic and asymptomatic patients. Silent cerebral infarction may be an indication for carotid endarterectomy in asymptomatic patients.