[Fulminating midbrain irradiation injury of pediatric brain tumor]

Abstract

We report two children with post radiation midbrain damage causing severe neurological symptoms. A twelve-year-old boy with a four year history of hydrocephalus was diagnosed with tectal glioma, which endoscopic biopsy revealed to be low grade. He underwent gamma knife radiation surgery (central 24 Gy/peripheral 12 Gy). Two months later bilateral ptosis followed by total oculomotor palsy and drowsiness developed. Despite pulsed-steroid therapy the tumor size increased up to 4.6 times in volume. The tumor was totally removed and was diagnosed as an early delayed radiation reaction pathologically. His symptoms disappeared except for a slight upper gaze palsy. The second patient was a six-year-old girl with a medulloblastoma. Following total resection and a VP shunt she received conventional radiation therapy along with chemotherapy. After the final irradiation she became comatose (JCS II-2) and MRI revealed diffuse midbrain damage with acute aqueduct obstruction, which recovered in two weeks. Reports of irradiation injuries of the midbrain in childhood are rare but it should be considered as a possible cause of fulminant symptoms requiring emergency treatment. Because of midbrain anatomical complexity, midbrain radiation therapy requires great care, especially in children.