Radiation-induced cavernous malformation in the brainstem after Gamma Knife radiosurgery for vestibular schwannoma: A case report and literature review.

Introduction: Radiation-induced cavernous malformation (RICM) is an uncommon late complication of radiation therapy. There are even fewer cases reported after stereotactic radiosurgery (SRS). In this study, we investigated the clinical characteristics, management considerations, and outcomes of RICM following SRS. Research question: What are the clinical characteristics, management considerations, and outcomes of RICM following SRS? Material and methods: We describe a case of a 50-year-old woman previously treated with Gamma Knife® radiosurgery for a vestibular schwannoma. Almost two decades later, brain magnetic resonance imaging revealed a brainstem cavernous malformation in the brainstem, in the dose fall-off region adjacent to the target volume. A literature review was subsequently conducted to identify comparable cases, associated therapeutic strategies, and clinical outcomes. Results: We identified 32 reported cases of RICM following SRS in the literature. The mean age at SRS was 65 years, with 57% being female. Mean latency to RICM development was 7.3 years. Our case demonstrated one of the longest latency periods reported for this complication. The patient had mild symptoms and was managed conservatively with surveillance imaging. Literature review revealed that 78% of cases underwent surgical management, predominantly those presenting with hemorrhage or progressive neurological symptoms. Conclusion: RICM represents a rare but clinically significant late complication of SRS that can occur after extended latency periods, even in adults. Management should be individualized based on symptoms, hemorrhage history, and lesion location. Further research is needed to develop more evidence-based management of RICM, and to better define the true incidence through long-term follow-up studies.