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

Abstract

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.

Surveillance imaging for high‐grade childhood brain tumors: What to do 10 years after completion of treatment?

“…These patients are at increased risk for moyamoya independent of radiotherapy and separate guidelines for surveillance imaging exist. After excluding these patients from otherwise eligible studies, the number of patients without moyamoya is far less than 10 . Both studies showed that radiation to the circle of Willisi or the supratentorial region is a risk factor for moyamoya.…”

Moyamoya Syndrome after Radiation Therapy: a Clinical Report

“…Despite familial occurrence in approximately 10–15% of cases, the aetiology of MMD remains unknown [2] . The Japanese term “moyamoya” means “puff of smoke” and is a reference to the pathognomonic arteriographic appearance of MMD, corresponding to compensatory development of prominent arterial collateral circulation [3] .…”

“…Traditionally, patients with these characteristic features and no known associated risk factors are considered to have MMD, while those having one of the well-recognized predisposing conditions are classified as having MMS [4] . There are numerous reported links between MMS and a wide variety of diseases, the most frequent and strongly associated conditions being neuro-fibromatosis type 1, cranial therapeutic radiation, Down syndrome and sickle cell disease [2, 4] .…”

“…A younger age at radiation exposure seems to increase the risk of developing vasculopathy, with over half of all cases occurring in children under 5 years of age [3, 5] . Not surprisingly, a parasellar tumour location, such as with craniopharyngiomas, is another risk factor, likely due to the close relationship to the circle of Willis of the tumour [2–5] . To prevent it, some authors suggest reduced radiation doses in children with parasellar tumours [5] .…”

Neuroimaging of Pediatric Arteriopathies

“…The occurrence of MMS after radiation therapy in children with primary brain tumors reported to be mostly found with high doses (>5,000 cGy) of radiation to the circle of Willis. The most common primary neoplasms include optic nerve glioma in NF1, and craniopharyngiomas and medulloblastomas in most case series . The onset of development of MMS after radiation therapy is especially rapid in NF1 patients .…”