Accelerated Volume-Staged Stereotactic Radiosurgery for Large Cerebral Arteriovenous Malformations: A Single Institutional Experience.

PURPOSE: Large cerebral arteriovenous malformations (AVMs) pose significant management challenges, particularly in achieving complete nidus obliteration without increasing the risk of symptomatic necrosis. Stereotactic radiosurgery (SRS) is an established, noninvasive treatment for inoperable AVMs. However, for large AVMs, single-stage SRS is complicated by larger volumes of irradiated normal brain and increased radiation-induced toxicity. Here, we describe our institution's accelerated volume-staged SRS (AVS-SRS) strategy for large cerebral AVMs and report long-term clinical outcomes. METHODS AND MATERIALS: A retrospective analysis was performed on 19 patients with cerebral AVMs (≥6 cm3) treated with AVS-SRS at the University of Kansas Medical Center between 2009 and 2024. AVMs were divided into 2 to 3 subtargets, which were treated sequentially using an AVS-SRS approach at 2- to 3-week intervals. The prescription dose to the entire nidus ranged from 16 Gy to 24 Gy. Treatments were delivered on a stereotactic-dedicated linear accelerator platform. Annual follow-up included magnetic resonance imaging/magnetic resonance angiography (MRA) and a confirmatory cerebral arteriogram if MRA showed resolution of the nidus. One patient was excluded from outcome analysis due to a lack of follow-up evaluation. Outcomes included nidus obliteration, symptomatic radiation necrosis, posttreatment hemorrhage, and permanent neurological deficits. RESULTS: The median patient age was 38.5 years, with a median follow-up of 44.5 months. The median treated AVM volume was 9.6 ± 8.4 cm3. Angiographic- and MRA-confirmed complete resolution was achieved in 5 patients (27.7%), MRA-confirmed resolution was achieved in 2 patients (11.1%), and a partial response was achieved in 11 (61.1%) patients; 1 patient was not evaluated after treatment due to comorbidities. Three patients developed symptomatic radiation necrosis (16.6%); 1 developed acute neurological symptoms after the first stage, and 2 had radiographic necrosis, both resolving completely with corticosteroids. There were no post-AVS-SRS hemorrhage sequelae. CONCLUSIONS: AVS-SRS with a 2- to 3-week interstage interval represents a novel treatment approach for large cerebral AVMs. It demonstrated feasible obliteration outcomes with acceptable toxicity, including a low risk of symptomatic necrosis and no post-AVS-SRS hemorrhage, in this small retrospective cohort.