Institutional Experience of Linear Accelerator-Based Stereotactic Radiosurgery For Brain Arteriovenous Malformations

Summary: The annual bleeding risk for an intracranial arteriovenous malformation (AVM) is 2-8%, but obliterating the nidus reduces the risk to near population levels. We evaluate the outcomes of linear accelerator (LINAC) based stereotactic radiosurgery (SRS) in an institutional AVM cohort. Intracranial AVMs receiving LINAC SRS with follow-up care greater than 1 month from 2014-2021 were included. Baseline characteristics were compared between pediatric and adults. Multiple statistical methods were used for comparisons. Time-to-event analyses were conducted using the Kaplan-Meier survival method. Statistical significance (P< 0.05) involved two-tailed tests and simple/multiple logistic regression. Among the 29 qualifying patients with SRS-treated AVMs, mean nidus volume was 6.26cm3 (Range=0.13-40.2) and nidus max diameter was 24.8mm (Range=2-60). Mean target dose was 18.72 Gy (Range=13.5-22) for single- fraction (86.7%) and 19Gy (Range=18-20) for two fractions. Median time to follow-up was 23.6 months. Obliteration occurred in 53.33% of patients (median time to obliteration=27.1 months). Between adults and pediatric patients diagnosed with AVMs, significant factors affecting likelihood of SRS delivery were sex (p=0.05), race (p=0.0089), nidus max diameter (p=0.033), pre- treatment SRS (p=0.027) and neurological deficits at presentation (p=0.0169). Likelihood of obliteration decreased with increasing nidus volume with an estimated 10% for each additional cm3 (OR=0.90, 95% CI=0.82-0.99, p=0.027). Adverse events (AE) were observed in 55.2% of patients with a median time to AE of 11.4 months. Nidus max diameter significantly affected rate of AE (HR=1.36, 95% CI=1.03-1.8, p=0.031). LINAC SRS resulted in 53.3% of our cohort achieving obliteration (mean follow-up: 23.6 months). Adverse events occurred in 55.2% of patients, but most were mild and resolved. Forrest Kwong, MD (Presenting Author) - MD Anderson Cancer Center, Department of Radiation Oncology; Jerry Jaboin, MD, PhD, MBA, FACRO, FASTRO (Co-Author) - University of Oklahoma Health Sciences Center; Shearwood McClelland III, drwood@post.harvard.edu (Co-Author) - University Hospitals Seidman Cancer Center, Case Western Reserve University School of Medicine; Louisa Onyewadume, MD (Co-Author) - Duke Department of Radiation Oncology; Daphne Scarpelli, BS (Co-Author) - Oregon Health and Science University Medical School