Radiation-induced cavernous malformation arising within vestibular schwannoma manifesting as subarachnoid hemorrhage: Case report and literature review

Background: Radiation-induced cavernous malformation within a vestibular schwannoma is rare, with only four previous cases reported. Case Description: A 65-year-old female developed a radiation-induced cavernous malformation within a vestibular schwannoma 2 years after gamma knife radiosurgery, initially presenting with mild facial palsy. Six days later, she was admitted with an acute severe headache, trigeminal neuropathy, complete abducens palsy, complete facial palsy, and deafness. Computed tomography and magnetic resonance imaging revealed subarachnoid hemorrhage as well as an intratumoral hematoma. Three weeks after the hemorrhage, the tumor was gross totally removed to reduce the mass effect and prevent recurrent hemorrhage. However, her symptoms persisted after discharge. Conclusion: A review of reported cases suggests that radiation-induced cavernous malformation within vestibular schwannoma shows a higher rate of hemorrhagic transformation (80%) with multiple cranial nerve dysfunction compared with radiation-induced cavernous malformation in the brain (approximately 20%). Although radiation-induced cavernous malformation in vestibular schwannoma is rare, long-term follow-up is warranted.