Abstract
Objective: The purpose of this study is to investigate the efficacy of gamma knife radiosurgery for brainstem CMs in preventing bleeding, as well as, assess safety with regards to radiation-induced complications. Additionally, we aimed to evaluate the feasibility and safety of volumestaged gamma knife radiosurgery for larger CMs in the brainstem. Patients and methods: Between September 2007 and August 2017, 32 patients with brainstem cavernous malformations (CMs) were treated by gamma knife. A total of 33 lesions were treated (one patient had two brainstem CMs) There were 16 males and 16 females. The mean age at the time of treatment was 25 years (3-51 years). Twenty-eight patients had at least one hemorrhagic event before radiosurgery. The patients underwent 40 gamma knife sessions. These included 28 single sessions (including two sessions for same patient for 2 different lesions in pons). Five patients had volumestaged gamma knife treatments due to the large size of the CM. The mean total CM volume/lesion was 2.2 cc (0.1-30.4 cc), while the mean target volume/session was 1.8 cc (0.1-11.5 cc). The mean prescription dose was 12 Gy (10-14 Gy) and the mean 12 Gy volume was 1.2 cc (0.1-10.8 cc). Results: The mean follow up after treatment was 44 months (12-134 months). One patient died during follow up. The annual hemorrhage rate (AHR) before gamma knife radiosurgery was 25.5%. After treatment there were a total of 5 hemorrhagic events with an overall AHR of 3.8%. Three hemorrhagic events occurred in the first 2 years after treatment with an AHR of 5.2% and 2 events more than 2 years after treatment with an AHR of 1.7%. No hemorrhagic events occurred among the patients treated by volume-staged radiosurgery. Clinical improvement was observed in 15 (46.9%) patients, was stable in 16 (50%) and worsened in 1 (3.1%). Temporary adverse radiation events developed in 3 patients (9%). Conclusion: GKS for brainstem cavernomas has an acceptable safety profile. The annual hemorrhage rate after GKS appears to be reduced. Nonetheless, to better assess efficacy of GKS for brainstem cavernomas, prospective trials are needed. Volume-staged gamma knife radiosurgery for large brainstem CM appears to be a viable treatment option. |
