• Bengt Karlsson, Hidefumi Jokura, Huai-Che Yang, Masaaki Yamamoto, Roberto Martinez-Alvarez, Jun Kawagishi, Wan-Yuo Guo, Wen-Yuh Chung, Michael Söderman, Tseng Tsai Yeo, and Ingmar Lax.
• Division of Neurosurgery, Department of Surgery, National University Hospital, Singapore, Singapore.
• Neurosurgery. 2022 Dec 1; 91 (6): 920927920-927.

BackgroundKnowledge about the natural course of brain arteriovenous malformations (AVMs) have increased during the past 20 years, as has the number of AVMs treated, especially larger ones. It is thus timely to again analyze the risk for hemorrhage after Gamma Knife Surgery (GKS).ObjectiveTo confirm or contradict conclusions drawn 20 years ago regarding factors that affect the risk for post-GKS hemorrhage.MethodsThe outcome after GKS was studied in 5037 AVM patients followed for up to 2 years. The relation between post-treatment hemorrhage rate and a number of patient, AVM, and treatment parameters was analyzed. The results were also compared with the results from our earlier study.ResultsThe annual post-treatment hemorrhage rate was 2.4% the first 2 years after GKS. Large size, low treatment dose, and old age were independent risk factors for AVM hemorrhage. After having compensated for the factors above, peripheral AVM location and female sex, at least during their child bearing ages, were factors associated with a lower post-GKS hemorrhage rate.ConclusionLarge AVMs (>5 cm 3 ) treated with low doses (≤16 Gy) had higher and small AVMs treated with high doses a lower risk for hemorrhage as compared with untreated AVMs. This was detectable within the first 6 months after GKS. No difference in hemorrhage rate could be detected for the other AVMs. Based on our findings, it is advisable to prescribe >16 Gy to larger AVMs, assuming that the risk for radiation-induced complications can be kept at an acceptable level.Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Congress of Neurological Surgeons.

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