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

## TL;DR

A rare brain condition called radiation-induced cavernous malformation can develop years after radiosurgery, requiring individualized treatment based on symptoms and location.

## Contribution

This paper reports a case of a brainstem cavernous malformation 19 years after radiosurgery and reviews 32 similar cases, highlighting long latency periods.

## Key findings

- Radiation-induced cavernous malformations can occur up to 19 years after stereotactic radiosurgery.
- Most cases (78%) underwent surgery, especially those with bleeding or worsening symptoms.
- Conservative management is an option for asymptomatic or mildly symptomatic cases.

## Abstract

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.

What are the clinical characteristics, management considerations, and outcomes of RICM following SRS?

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.

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.

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.

•Radiation-induced cavernous malformations (RICMs) have historically been associated with conventional fractionated radiotherapy or whole brain radiation in children.•32 cases of RICMs following stereotactic radiosurgery were identified in our literature review, and patients were treated for a range of different conditions.•We describe a brainstem RICM presenting 19 years after Gamma Knife® radiosurgery for vestibular schwannoma, emphasizing the potential for very long latency intervals.•RICMs after stereotactic radiosurgery are poorly documented in the literature.

Radiation-induced cavernous malformations (RICMs) have historically been associated with conventional fractionated radiotherapy or whole brain radiation in children.

32 cases of RICMs following stereotactic radiosurgery were identified in our literature review, and patients were treated for a range of different conditions.

We describe a brainstem RICM presenting 19 years after Gamma Knife® radiosurgery for vestibular schwannoma, emphasizing the potential for very long latency intervals.

RICMs after stereotactic radiosurgery are poorly documented in the literature.