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.