Volume-staged Versus Dose-Staged Stereotactic Radiosurgery, with or Without Embolization, in the Treatment of Large Brain Arteriovenous Malformations: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVE:While safe and effective modalities exist to treat small arteriovenous malformations (AVMs), large (>10 cm3) AVMs remain difficult to cure via surgical or endovascular means. Staged stereotactic radiosurgery (SRS), either volume-staged (VS) or dose-staged (DS), has been proposed for large AVMs. The relative efficacy of these two strategies, with or without endovascular embolization, is unclear. Accordingly, the goal of this study is to review existing literature on VS-SRS and DS-SRS for large brain AVMs to compare obliteration rates and complications, and determine the utility of neoadjuvant embolization. METHODS:MEDLINE, Scopus, and the Cochrane registry were searched for studies with at least five adult patients and an AVM volume of ≥10 cm3 prior to treatment. Meta-analyses of proportions were conducted and compared using a Wald-type test and the impact of prior embolization was investigated using weighted linear regression analysis. RESULTS:Eighteen studies (VS-SRS n = 235, DS-SRS n = 157) fit inclusion criteria, all of which were retrospective and none of which directly compared both treatment strategies. The average rate of complete AVM obliteration was significantly higher with VS-SRS (46.6 %; 39.7 % - 53.6 %) than DS-SRS (17.8 %; 7.0 % - 38.2 %, p = 0.027). Complication rates were comparable between VS-SRS (18.0 %; 9.2 % - 32.1 %) and DS-SRS (23.6 %; 12.2 % - 40.8 %, p = 0.544). Regression analysis demonstrated no significant relationship between prior embolization and complete obliteration for either VS-SRS (r = -0.36, p = 0.34) or DS-SRS (r = 0.58, p = 0.29). CONCLUSION:VS-SRS, without neoadjuvant embolization, appears to be the optimal approach when treating large AVMs with radiosurgery. Further prospective studies are warranted.