Comparison of Repeat Versus Initial Stereotactic Radiosurgery for Intracranial Arteriovenous Malformations: A Retrospective Multicenter Matched Cohort Study.

Background and Objectives: Studies comparing neurological and radiographic outcomes of repeat to initial stereotactic radiosurgery (SRS) intracranial arteriovenous malformations are scarce. Our aim was to perform a retrospective matched comparison of patients initially treated with SRS with those undergoing a second radiosurgical procedure.
Methods: We collected data from arteriovenous malformations managed in 21 centers that underwent initial and repeated radiosurgery from 1987 to 2022. Based on arteriovenous malformations volume, margin dose, deep venous drainage, deep, and critical location, we matched 1:1 patients who underwent an initial SRS for treatment-naive arteriovenous malformations and a group with repeated SRS treatment.
Results: After the selection process, our sample consisted of 328 patients in each group. Obliteration in the initial SRs group was 35.8% at 3 and 56.7% at 5 years post-SRS, while the repeat SRS group showed obliteration rates of 33.9% at 3 years and 58.6% at 5 years, without statistically significant differences (P = .75 and P = .88, respectively). There were no statistically significant differences between the 2 groups for obliteration rates (hazard ratio = 0.93; 95% CI, 0.77-1.13; P = .5), overall radiation-induced changes (RIC) (OR = 1.1; 95% CI, 0.75-1.6; P = .6), symptomatic RIC (OR = 0.78; 95% CI, 0.4-1.5; P = .4), and post-SRS hemorrhage (OR = 0.68; 95% CI; P = .3).
Conclusion: In matched cohort analysis, a second SRS provides comparable outcomes in obliteration and RIC compared with the initial SRS. Dose reduction on repeat SRS may not be warranted.
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