%0 Journal Article
%T Long-Term Outcome of Time-Staged Gamma Knife Radiosurgery for Large Arteriovenous Malformations.
%A Myeong HS
%A Jeong SS
%A Kim JH
%A Lee JM
%A Park KH
%A Park K
%A Park HJ
%A Park HR
%A Yoon BW
%A Hahn S
%A Lee EJ
%A Kim JW
%A Chung HT
%A Kim DG
%A Paek SH
%J J Korean Med Sci
%V 39
%N 29
%D 2024 Jul 29
%M 39079685
%F 5.354
%R 10.3346/jkms.2024.39.e217
%X <B>BACKGROUND: </B>Treatment for large (> 10 mL) arteriovenous malformations (AVMs) remains highly challenging. This study evaluated long-term effect of time-staged gamma knife radiosurgery (GKS) for large AVMs.<BR><B>METHODS: </B>For patients with large AVMs treated by time-staged GKS over 10 years, time-staged GKS was repeated every three years targeting the entire nidus if total obliteration was not achieved. Obliteration rate and post-GKS complications were assessed based on 10 mL volume interval of AVMs. Prognostic factors for these outcomes were evaluated using Cox regression analysis.<BR><B>RESULTS: </B>Ninety-six patients were analyzed. For AVMs in the 10-20 mL subgroup, a dose ≥ 13.5Gy yielded higher obliteration rate in the first GKS. In the 20-30 mL subgroup, a second GKS significantly boosted obliteration. AVMs > 30 mL did not achieve any obliteration with the first GKS. Among 35 (36.4%) cases lost to follow-up, 7 (7.2%) were lost due to GKS complications. Kaplan-Meier analysis showed that each subgroup needed different time for achieving 50% favorable obliteration outcome rate: 3.5, 6.5, and 8.2 years for 10-20 mL, 20-30 mL, and > 30 mL subgroup, respectively. Total obliteration rate calculated by intention-to-treat method: 73%, 51.7%, 35.7%, respectively, 61.5% overall. Post-GKS hemorrhage and chronic encapsulated expanding hematoma (CEEH) occurred in 13.5% and 8.3% of cases, respectively. Two patients died. Dose and volume were significant prognostic factors for obliteration. Initial AVM volume was a significant prognostic factor of post-GKS hemorrhage and CEEH.<BR><B>CONCLUSIONS: </B>Time-staged GKS for large AVMs less than 30 mL has highly favorable long-term outcome and a tolerable complication rate.