Supplementary Material for: Long-Term Natural History of Intracranial Arterial Stenosis: An MRA Follow-Up Study

Background: Intracranial arterial stenosis (ICAS) is a major cause of ischemic stroke in Asians. Despite the clinical importance of ICAS, the literature on the natural history of ICAS has been less enlightening. The aims of our study were to evaluate a long-term natural course of symptomatic and asymptomatic ICAS. Methods: 102 subjects (37 symptomatic and 65 asymptomatic) underwent follow-up MR angiography (MRA) with a median time interval between initial and follow-up MRA of 5.7 years (range 3.6-8.5 years). For each patient, the extent of stenosis of five arteries (both middle cerebral arteries, both intracranial internal carotid arteries, and basilar artery) was classified according to five grades, by consensus: normal, mild (signal reduction Results: Mean (Standard deviation) age at initial MRA was 63.5 (9.6) and 54% were men. The progression rate of ICAS differed significantly between symptomatic and asymptomatic patients (22 vs. 8%, p Conclusion: We found a greater risk of progression for symptomatic stenosis compared with asymptomatic stenosis.