Radiation-induced meningiomas, cerebral aneurysm, and multiple cavernomas 2 decades after radiotherapy for medulloblastoma: illustrative case.

backgroundRadiation therapy is a mainstay in the management of medulloblastoma. However, it carries long-term side effects including radiation-induced tumors and vasculopathies. The authors report the first case of the occurrence of radiation-induced meningiomas, an intracranial aneurysm, and multiple cavernomas in a patient with a remote history of medulloblastoma. In addition, this is only the seventh reported radiation-associated superior cerebellar artery (SCA) aneurysm, the first such aneurysm to be associated with external beam RT and the first such aneurysm to be treated with microsurgery. OBSERVATIONS: The patient was diagnosed with medulloblastoma when he was 4 years old and underwent surgery, craniospinal irradiation, and chemotherapy. He was well until 25 years later, when he presented with headache and left-sided weakness. Cranial imaging revealed multiple meningiomas and cavernomas. He underwent surgery to excise the largest meningioma in the right frontotemporal area. Two years later, he underwent another operation for a left frontal meningioma that increased in size. Two months postexcision, he presented with a subarachnoid hemorrhage from a ruptured right SCA aneurysm and underwent clipping. He was discharged well. LESSONS: This case highlights the importance of long-term surveillance for patients treated with radiotherapy. However, the ideal follow-up duration and frequency of screening tests have yet to be determined. https://thejns.org/doi/10.3171/CASE25898.