Early-onset Moyamoya syndrome in a patient with Down syndrome: case report and review of the literature.

Moyamoya disease is a chronic occlusive cerebrovascular disorder. It can occur as a primary disease or as a syndrome associated with a variety of conditions. Usually it takes 1 to 2 years to develop a classic moyamoya pattern. We report a 20-month-old girl with Down syndrome and moyamoya syndrome who presented with seizure and hemiparesis. To our knowledge, this is the youngest case reported with moyamoya syndrome and Down syndrome. The prognosis and current treatment of moyamoya syndrome and its relation to Down syndrome are reviewed. There is some reason to speculate that the abnormalities associated with Down syndrome might create a vulnerability for the development of moyamoya syndrome.