Significant Hemorrhage Rate Reduction after Gamma Knife Radiosurgery in Symptomatic Cavernous Malformations: Long-Term Outcome in 95 Case Series and Literature Review.

BACKGROUND: The natural history of cavernous malformations (CMs) has remained unclear. This lack of knowledge has made treatment decisions difficult. Indeed, the use of stereotactic radiosurgery is nowadays controversial. The purpose of this paper is to throw light on the effectiveness of Gamma Knife radiosurgery (GKRS) therapy.

METHODS: The authors reviewed data collected from a prospectively maintained database. A total of 95 patients (57 female and 38 male) underwent GKRS for high-surgical-risk CMs. A total of 76 cavernomas were deeply located (64 lesions in the brainstem and 12 lesions in the thalamus). All of them were located in eloquent regions. The median malformation volume was 1,570 mm3. The median tumor margin dose was 11.87 Gy, and the mean tumor maximum dose was 19.56 Gy.

RESULTS: Ninety-five cavernous CMs were managed from 1994 to 2014. All patients had experienced at least 1 symptomatic bleeding incident before treatment (only 1 hemorrhage event in 81%). The median length of follow-up review was 78 months. The pretreatment annual hemorrhage rate was 3.06% compared with 1.4% during the first 3-year latency interval, and 0.16% thereafter (p = 0.004). Four patients developed new location-dependent neurological deficits, and 3 patients had edema-related headache after radiosurgery. All of them presented full recovery.

CONCLUSIONS: The best dosage range for preventing bleeding was identified as between 11 and 12 Gy in our series. Although the efficacy of radiosurgery in CMs remains impossible to quantify, a very significant reduction in the bleeding rate occurs after a 3-year latency interval. No permanent neurological morbidity is reported in our series. These results defend the safety of GKRS in surgical high-risk CM from the first bleeding event.