Prevalence and prognosis of coexistent asymptomatic intracranial stenosis.

BACKGROUND AND PURPOSE: There are limited data on the prevalence and prognosis of asymptomatic intracranial stenosis (AIS). METHODS: Baseline cerebral angiograms and MR angiograms were used to determine AIS (50% to 99%) coexistent to symptomatic intracranial stenosis for patients enrolled in the Warfarin-Aspirin Symptomatic Intracranial Disease study. RESULTS: Coexisting AIS were detected in 18.9% (n=14/74) of patients undergoing 4-vessel cerebral angiography and 27.3% (n=65/238) of patients undergoing MR angiogram. During a mean follow-up period of 1.8 years, no ischemic strokes were attributable to an AIS on cerebral angiography and 5 ischemic strokes (5.9%, 95% CI: 2.1% to 12.3%) occurred in the AIS territory on MR angiogram (risk at 1 year=3.5%, 95% CI: 0.8% to 9.0%). CONCLUSIONS: Whereas the prevalence of coexisting AIS (50% to 99%) in patients with symptomatic stenosis is high, the risk of stroke from these asymptomatic stenoses is low.