Effect of treatment period on outcomes after stereotactic radiosurgery for brain arteriovenous malformations: an international multicenter study

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The role of and technique for stereotactic radiosurgery (SRS) in the management of arteriovenous malformations (AVMs) have evolved over the past four decades. The aim of this multicenter, retrospective cohort study was to compare the SRS outcomes of AVMs treated during different time periods.


The authors selected patients with AVMs who underwent single-session SRS at 8 different centers from 1988 to 2014 with follow-up ≥ 6 months. The SRS eras were categorized as early (1988–2000) or modern (2001–2014). Statistical analyses were performed to compare the baseline characteristics and outcomes of the early versus modern SRS eras. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RICs).


The study cohort comprised 2248 patients with AVMs, including 1584 in the early and 664 in the modern SRS eras. AVMs in the early SRS era were significantly smaller (p < 0.001 for maximum diameter and volume), and they were treated with a significantly higher radiosurgical margin dose (p < 0.001). The obliteration rate was significantly higher in the early SRS era (65% vs 51%, p < 0.001), and earlier SRS treatment period was an independent predictor of obliteration in the multivariate analysis (p < 0.001). The rates of post-SRS hemorrhage and radiological, symptomatic, and permanent RICs were not significantly different between the two groups. Favorable outcome was achieved in a significantly higher proportion of patients in the early SRS era (61% vs 45%, p < 0.001), but the earlier SRS era was not statistically significant in the multivariate analysis (p = 0.470) with favorable outcome.


Despite considerable advances in SRS technology, refinement of AVM selection, and contemporary multimodality AVM treatment, the study failed to observe substantial improvements in SRS favorable outcomes or obliteration for patients with AVMs over time. Differences in baseline AVM characteristics and SRS treatment parameters may partially account for the significantly lower obliteration rates in the modern SRS era. However, improvements in patient selection and dose planning are necessary to optimize the utility of SRS in the contemporary management of AVMs.

ABBREVIATIONS AVM = arteriovenous malformation; EBRT = external beam radiation therapy; GKRS = Gamma Knife radiosurgery; IGKRF = International Gamma Knife Research Foundation; RIC = radiation-induced change; SM = Spetzler-Martin; SRS = stereotactic radiosurgery; VRAS = Virginia Radiosurgery AVM Scale.

Article Information

Correspondence Jason Sheehan: University of Virginia, Charlottesville, VA. jps2f@virginia.edu.

INCLUDE WHEN CITING Published online February 2, 2018; DOI: 10.3171/2017.8.JNS171336.

Disclosures Dr. Grills reports having stock ownership and serving on the Board of Directors in a company called Greater Michigan Gamma Knife, and Dr. Grills reports receiving funding for non–study-related research from Elekta through her institution. Dr. Lunsford reports owning stock in Elekta and being a consultant for Insightec and DSMB.

© AANS, except where prohibited by US copyright law.



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    Box-and-whiskers plot showing the linear decreasing trend of marginal dose to the year of SRS treatment. Figure is available in color online only.

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    Box-and-whiskers plot showing the linear increasing trend of AVM volume to the year of SRS treatment. Figure is available in color online only.





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