Comparison of Stroke Risk Factors between Symptomatic and Asymptomatic Patients in a North American Moyamoya Disease Cohort

Background: Risk factors for stroke in symptomatic and asymptomatic moyamoya disease (MMD) patients have recently been reported in a Japanese cohort. Such information in a North American population is lacking. Objective: We sought to elucidate the prevalence of stroke risk factors among North American patients with ischemic, hemorrhagic, and asymptomatic MMD. Methods: We retrospectively reviewed our institution’s database between 1990 and 2021. We excluded cases of moyamoya syndrome. We divided 119 patients into 3 groups based on the onset pattern; ischemic, hemorrhagic, and asymptomatic. We compared the prevalence of well-known stroke risk factors (diabetes, hypertension, etc.) between these three groups of patients. In the asymptomatic group, we analyzed the prevalence of cerebrovascular events on follow-up from the time of diagnosis. Results: Overall, 119 patients with MMD were available with predominately White ethnicity (80.7%). The mean age was 39 years, and 73.9% were female. Patients presented with ischemic stroke (82%) and hemorrhagic stroke (11%); 7% of patients were asymptomatic. The prevalence of stroke risk factors did not differ among ischemic, hemorrhagic, or asymptomatic MMD patients. In 8 asymptomatic patients, there was 81.8 months (SD ±51.0) of follow-up, and none of them developed any cerebrovascular events. Conclusions: No significant differences in the prevalence of stroke risk factors between MMD cohorts were found, corroborating evidence provided in a recent Japanese-based study. There were no apparent associations between stroke risk factors and interval cerebrovascular events in an asymptomatic group of MMD patients.