Volume-Staged Stereotactic Radiosurgery in Pediatric Patients With Large Brain Arteriovenous Malformations: An International, Multicenter Study.

Abstract

Pediatric large-volume brain arteriovenous malformations (AVMs) carry a substantial lifelong hemorrhage risk, neurological symptoms, and treatment morbidity. Single-session stereotactic radiosurgery (SRS) is often unsuitable due to constraints on dose-volume toxicity. Volume-staged SRS (VS-SRS) enables sequential dosing of large nidus volumes, potentially enhancing safety while maintaining efficacy. Evidence in children remains limited. We aimed to evaluate outcomes of VS-SRS for large AVMs in pediatric patients. A multicenter retrospective cohort was assembled from 21 centers, including patients aged younger than 21 years treated with VS-SRS for AVMs >10 cm3. Clinical and radiological end points included obliteration, hemorrhage, and permanent symptomatic radiation-induced changes (RIC). A total of 103 patients were included (median age 14 years; IQR, 12-17). The median nidus volume at first stage was 18.2 cm3 (IQR, 12.3-25.6). Median prescription dose per stage was 17 Gy (IQR, 16-18). The median clinical follow-up from the first stage was 57.5 months (IQR, 25-138). Obliteration occurred in 42 of 103 patients (40.8%), with actuarial rates of 6.9% (95% CI: 2.8-14) at 3 years and 29% (95% CI: 20-39) at 5 years. Hemorrhage occurred in 17 of 103 patients (16.5%) during follow-up, and permanent RIC was observed in 9 of 103 patients (8.7%). VS-SRS is a reasonably safe, selected option for pediatric large-volume AVMs when microsurgical or endovascular cure is not feasible or prudent. Delivering ≥17 Gy per stage while limiting each treatment volume to <15 cm3 supports durable nidus control with acceptable toxicity. VS-SRS represents a key modality in multidisciplinary management of this historically difficult-to-treat population.