Abstract
A 2-year-old boy with unilateral moyamoya disease demonstrated progression to the bilateral condition 1 year later. Previous reports of progression from unilateral to bilateral moyamoya disease showed that all patients were children or relatively young, and developed ischemic symptoms as the initial manifestation. These findings suggest that a considerable proportion of unilateral pediatric cases are in the initial stage of moyamoya disease and will progress to the contralateral side in the future.
