Clinicoepidemiological Features of Asymptomatic Moyamoya Disease in Adult Patients

OBJECTIVE The aim of this study was to document the natural course of asymptomatic adult moyamoya disease (MMD) and the factors related to disease progression to aid in treatment decisions. MATERIALS AND METHODS Among 459 adult MMD patients (aged ≥ 20 years), 42 patients were included in this retrospective cohort study. Clinical records of adult asymptomatic MMD patients (n = 42) and follow-up data from September 2013 were reviewed to determine the factors related to disease progression. RESULTS The mean age of patients at the time of diagnosis was 41.2 years (range, 23-64 years), and the mean follow-up period was 37.3 months (range, 7.4-108.7 months). Of the 42 patients and 75 hemispheres, there were 12 patients (28.6%) and 13 hemispheres (17.3%) with disease progression. There were four hemispheres (5.3%) with symptomatic progression (three hemorrhage, one transient ischemic attack) and nine hemispheres (12.0%) with asymptomatic radiographic progression. There were no relationships with sex, diabetes, hypertension, thyroid disease, family history of MMD, or family history of stroke. However, reduced initial cerebrovascular reserve capacity was observed in seven hemispheres (9.3%) in patients with disease progression. A relationship was found between disease progression and initial cerebrovascular reserve capacity (p = 0.05). None of the patients underwent bypass surgery during the follow-up period. CONCLUSION It appears that asymptomatic adult MMD is not a permanent stable disease. In particular, reduced cerebrovascular reserve capacity is an indication of MMD progression, so close regular observation is needed.