Moyamoya disease beyond Japan and East Asia

BACKGROUND: Moyamoya disease (MMD) was first described in Japan and is primarily recognized in East Asia. Although rare, it is increasingly diagnosed in Western countries. A Western phenotype - characterized by a lower risk of hemorrhage - has been proposed in a previous review article in this journal. OBJECTIVES: This narrative review explores MMD from a Western perspective. RESULTS: Drawing partly on studies from a Danish MMD cohort, the author suggests that MMD exhibits similar features across different regions. Nordic national registries and well-maintained clinical records provide valuable data for gaining a deeper understanding of this disease. CONCLUSIONS: In our data, the overall Kaplan-Meier 5-year stroke risk was 10%. We observed a trend toward higher stroke risk in females and in those with angiographic progression.