Evaluation of Hemorrhage Risk and Predictors Following Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations: A Retrospective Single-center Study

<h2>Abstract</h2><h3>Objective</h3> Radiotherapy is a well-established treatment method for cerebral arteriovenous malformations (AVMs) used in combination with other treatment modalities or alone. This study evaluates the post-intervention bleeding risk of cerebral arteriovenous malformations (AVMs) treated with stereotactic radiosurgery (SRS) using a linear accelerator (LINAC) and identifies predictors of post-therapeutic hemorrhage. <h3>Methods</h3> A retrospective analysis was conducted on 134 consecutive patients with AVMs treated with LINAC-based SRS between 1983 and 2022 at <i>blinded</i>. Patients were followed for a median of 49 months. Statistical analysis was performed to assess the influence of variables such as AVM grade, prior treatment, SRS dose, and other clinical factors on post-SRS bleeding risk. <h3>Results</h3> Nine post-SRS hemorrhages occurred for a total of 816.6 patient-years, resulting in an overall bleeding rate of 6.7% and an annual rate of 1.1%. No bleeding-related fatalities were recorded. Higher Spetzler-Martin AVM grade (<i>p</i> = 0.013) and prior treatment, particularly embolization or the combination of surgery and embolization (<i>p</i> = 0.005), were associated with increased post-therapeutic hemorrhage risk. In contrast, factors such as age, sex, and SRS dose showed no significant influence. Two bleeding events occurred even after presumed angiographic obliteration. <h3>Conclusion</h3> LINAC-based SRS for AVMs goes along with a relatively low risk of post-treatment hemorrhage, with an annual bleeding rate lower than that of untreated AVMs and comparable to the risk found in previous studies. Higher AVM grades and prior treatments are key predictors of post-SRS hemorrhage. Given the possibility of hemorrhage even after angiographic obliteration, close long-term follow-up is recommended. Modern imaging techniques may enhance post-obliteration monitoring in high-risk cases.