1061. CyberKnife radiosurgery provides acceptable longterm control with low risk of rebleeding in high-grade arteriovenous malformations

Authors: Franziska Loebel, MD; Carolin Senger, MD; Gueliz Acker, MD; Markus Kufeld; Volker Budach; Peter Vajkoczy; Alfredo Conti (Berlin, Germany)

Introduction: Cerebral arteriovenous malformations (AVMs) are rare vascular lesions associated with a high risk of bleeding, leading to substantial neurological morbidity and mortality. Radiosurgery presents a valid therapeutic option for small intracerebral lesions, but reports on longterm control and rebleeding rates after CyberKnife radiosurgery for high-grade intracranial AVMs are rare. Methods: We retrospectively analyzed 35 patients with high-grade AVMs (Spetzler-Martin-grades 3-6), treated with single-fraction CyberKnife radiosurgery at our institution, in order to examine longterm radiographic outcome, incidence of toxicity and rebleeding rates. Results: Median age of the population was 39.8 yrs (range 9 -47 yrs). Median follow-up was 41 months (range 3 -74 months). Single-fraction doses between 14 – 21 Gy (median 17 Gy) were applied to the 85% isodose line. Complete obliteration was achieved in 10 (28.7%), near-complete obliteration in 4 ((11.4%)), partial remission in 18 cases (51.4%)), while minimal response or no change were observed in 4 cases (11.4%). Treatment induced toxicity (radiation necrosis and/or edema) was observed in only 6 cases (17.1%), while 29 patients (82.8%) remained symptom-free. Epileptic seizures occurred in 4 cases (11.4%). Two patients died during follow-up (5.2%), with only one death associated to rebleeding from the previously radiated AVM (2.8%). Conclusion: CyberKnife radiosurgery presents a valid therapeutic approach in the Treatment of high-grade AVMs with acceptable obliteration rates, low toxicity and rare incidence of rebleeding.