Radiosurgery for Spetzler-Martin Grade III Arteriovenous Malformations of the Brain. Comparison of the Results of a Single Institution in Finland with a Systematic Literature Review.

Abstract

BackgroundSpetzler-Martin (SM) grade III arteriovenous malformations of the brain (bAVMs) represent a clinical gray area with no definitive treatment guidelines. It is not well established whether case volume and experience influence radiosurgical outcomes for SM III bAVMs.Material and methodsWe performed a systematic literature review of radiosurgical outcomes for SM III bAVMs according to the PRISMA guidelines, compared the results with our own, single institution (Kuopio University Hospital, KUH) clinical series and performed a statistical analysis with a binary random-effects model (DerSimonian-Laird).ResultsThe literature review consisted of 24 studies and a total of 3295 bAVMs. In the random effects model based on the literature review, radiosurgery was associated with an obliteration rate of 69% (CI 64.2-73.5%), morbidity of 8.8% (CI 4.6-13%) and mortality of 3.8% (CI 2.6-4.4%). A random-effects metaregression analysis did not find a statistically significant difference between institutional case volume and obliteration rate. Radiosurgery in KUH had an overall obliteration rate of 70% (16/23), achieved after a mean of 2.8 years. 17% (4/23) of patients experienced bAVM rupture within the latency period after radiosurgery. All four ruptures led to morbidity for a morbidity rate of 17% (4/23).ConclusionsRadiosurgical results for SM III bAVMs are generally favorable, and our results suggest that in a low volume center, a dedicated team with formal training can achieve results comparable to high-volume centers. Larger prospective studies on the influence of case volumes on radiosurgical outcomes and on radiosurgery´s role in downgrading bAVMs prior to resection are warranted.