Defining Long-Term Clinical Outcomes and Risks of Stereotactic Radiosurgery for Brainstem Cavernous Malformations.

Background: We evaluated clinical outcomes in patients with symptomatic brainstem cavernous malformations (CMs) treated by stereotactic radiosurgery (SRS).

Methods: Between 1988 and 2016, Gamma Knife SRS was performed in 76 evaluable patients with solitary symptomatic brainstem CMs. Forty-nine (66%) were intrinsic (not reaching a pial or ependymal surface). Most patients (91%) had experienced 2 or more hemorrhages associated with new neurologic deficits. Fourteen patients (18%) underwent resection before radiosurgery. The median CM volume was 0.66 cm (range, 0.05-6.8), and the median margin dose was 15.0 Gy.

Results: After SRS, 15 patients (20%) had an imaging confirmed new hemorrhage at a median follow-up of 48 months. The hemorrhage-free survival after SRS for brainstem CMs was 92% at 1 year, 87% at 3 years, and 85% at 5 years. The annual hemorrhage rate was 31% before and 4% after SRS. In univariate analysis, CM volume, previous surgical resection, and increased number of hemorrhages before SRS were significantly associated with a higher rate of hemorrhage after SRS. In multivariate analysis, only number of previous hemorrhages was significant (P < 0.0005; hazard ratio, 1.51, 95% confidence interval, 1.23-1.85). Symptomatic adverse radiation effects developed in 7 patients (9%). The rate of symptom deterioration related to hemorrhage or symptomatic adverse radiation effects was 10% at 1 year, 18% at 3 years, and 20% at 5 years.

Conclusions: Patients with an increased rate of hemorrhage before SRS had an increased risk of repeat hemorrhage and symptom deterioration rate after SRS. Intrinsic CM location did not significantly affect rates of symptom deterioration or rebleeding.