Clinical features of moyamoya disease in the United States.
BACKGROUND AND PURPOSE: We report the clinical features and longitudinal outcome of the largest cohort of patients with moyamoya disease described from a single institution in the western hemisphere. Moyamoya disease in Asia usually presents with ischemic stroke in children and intracranial hemorrhage in adults. METHODS: Our study population included all patients with moyamoya disease evaluated at a university hospital in Houston, Texas from 1985 through 1995 (n = 35). We used Kaplan-Meier methods to estimate individual and hemispheric stroke risk by treatment status (medical versus surgical). Predictors of neurological outcome were assessed. RESULTS: The ethnic background of our patients was representative of the general population in Texas. The mean age at diagnosis was 32 years (range, 6 to 59 years). Ischemic stroke or transient ischemic attack was the predominant initial symptom in both adults and children. Of the 6 patients with intracranial hemorrhage, 5 had an intraventricular site of hemorrhage. The crude stroke recurrence rate was 10.3% per year in 116 patient-years of follow-up. Twenty patients underwent surgical revascularization, the most common procedure being encephaloduroarteriosynangiosis. The 5-year risk of ipsilateral stroke after synangiosis was 15%, compared with 20% for medical treatment and 22% overall for surgery. CONCLUSIONS: Our observations indicate that moyamoya disease may have a different clinical expression in the United States than in Asia, and may demonstrate a trend toward a lower stroke recurrence rate and better functional outcome after synangiosis.