Incidence and long‐term outcome of postradiotherapy moyamoya syndrome in pediatric patients with primary brain tumors: a single institute experience in Taiwan

We aimed to investigate the incidence and long-term outcome of moyamoya syndrome in pediatric patients with primary brain tumors after receiving cranial radiotherapy (RT) in a single institute in Taiwan. The complete medical records, medical images, and RT notes of 391 pediatric patients with primary brain tumors treated with cranial RT between January 1975 and December 2005 in Taipei Veterans General Hospital (TVGH), Taiwan, were entered into an electronic registry and reviewed. Eight (2%) cases of post-RT moyamoya syndrome were identified in the sample of 391 patients. The median latency was 3 years post-RT. Among the eight patients, three had craniopharyngioma, two had optic glioma, two had medulloblastoma, and one had a suprasellar astrocytoma. The prescribed physical doses of RT were in the range of 40-54 Gy. The incidence was highest in those with optic glioma (0.039/person-year), followed by craniopharyngioma (0.013/person-year), astrocytoma (0.003/person-year), and medulloblastoma (0.002/person-year). No patients died of vasculopathy. No difference in crude incidence was found between our results and those of other series. The incidence of moyamoya syndrome was diagnosis dependent, with the highest incidence among patients with optic glioma. No regional difference in incidence was found. Long-term, stable neurological function may be achieved following timely surgical intervention.