BACKGROUND AND PURPOSE - To describe baseline clinical features and outcomes of adults with moyamoya phenomenon treated at a single North American institution. METHODS - We identified 34 adults with moyamoya phenomenon by review of angiographic records. Clinical presentation and baseline stroke risk factors were obtained by chart review. Follow-up was obtained prospectively. A 5-year Kaplan-Meier stroke risk was calculated. RESULTS - The median age was 42 (range 20 to 79) years. Twenty-five were women. The initial symptom was ischemia, hemorrhage, or asymptomatic in 24, 7, and 3 patients, respectively. Twenty-two had bilateral involvement and 12 had unilateral moyamoya vessels. Baseline stroke risk factors were similar between groups. The median follow-up in 31 living patients was 5.1 (range 0.2 to 19.6) years. Fourteen patients were treated with surgical revascularization (20 total hemispheres). In medically treated symptomatic hemispheres, the 5-year risk of recurrent ipsilateral stroke was 65% after the initial symptom and 27% after angiographic diagnosis. Patients with bilateral involvement presenting with ischemic symptoms were at the highest risk of subsequent stroke (n=17, 5-year risk of stroke with medical treatment after first symptom of 82%). In surgically treated hemispheres, the 5-year risk of perioperative or subsequent ipsilateral stroke or death was 17%. This was significantly different compared with medical treatment after first symptom (P=0.02) but not after angiographic diagnosis. CONCLUSION - Moyamoya phenomenon in North American adults is associated with a high risk of recurrent stroke, particularly those with bilateral involvement and ischemic symptoms. These data suggest a potential benefit with surgery if diagnosis could be made earlier.

Original languageEnglish
Pages (from-to)1490-1496
Number of pages7
Issue number6
StatePublished - Jun 2006


  • Cerebral hemorrhage
  • Cerebral infarction
  • Cerebral revascularization
  • Moyamoya disease
  • Retrospective studies


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