Brain Arteriovenous Malformations Treated With Linear Accelerator-Based Stereotactic Radiosurgery: A Single-Institution Retrospective Experience From Latin America

Background Stereotactic radiosurgery (SRS) is an established treatment option for selected patients with brain arteriovenous malformations (bAVMs), particularly for lesions not amenable to microsurgical resection or located in surgically high-risk areas. SRS can be delivered through different platforms, including Gamma Knife, CyberKnife, and linear accelerator (LINAC)-based systems. This retrospective single-institution study evaluated outcomes of patients with bAVMs treated with LINAC-based SRS at a quaternary care center in Bogotá, Colombia. Materials and methods We conducted a retrospective observational study of patients with bAVMs treated with LINAC-based SRS guided by triple-fusion imaging between 2011 and 2017. Clinical, treatment, and imaging data were collected from medical records. Telephone interviews were used only to supplement clinical follow-up and were not used to determine radiological obliteration. The primary outcome was radiological obliteration during the available follow-up period, assessed by follow-up imaging. Actuarial obliteration rates were estimated using Kaplan-Meier analysis and interpreted as exploratory because of limited follow-up and censoring. Univariable Cox proportional hazards analyses were performed as exploratory analyses to evaluate factors associated with obliteration. Results Eighty-two patients were included. At presentation, 36 patients (44.0%) had ruptured bAVMs, 61 (74.4%) had lesions in eloquent areas, and most had Spetzler-Martin grade III malformations. Prior embolization was performed in 47 patients (57.3%). Complete radiological obliteration was documented in 27 patients (33.0%) during available follow-up. The median follow-up was 16.3 months, and 46 patients (56.1%) were lost to follow-up before completing three years of institutional follow-up. Actuarial obliteration estimates at later time points should therefore be interpreted cautiously. In exploratory univariable Cox analysis, radiosurgery dose >20 Gy was associated with a shorter time to obliteration. Conclusions This single-institution retrospective study describes radiological and clinical outcomes after LINAC-based SRS for bAVMs in a Latin American quaternary care center. The findings suggest that LINAC-based SRS is a feasible treatment approach when appropriate technology, planning expertise, and quality assurance are available. However, the short median follow-up, substantial loss to follow-up, and lack of a comparator group limit conclusions regarding effectiveness. Future prospective studies with standardized long-term imaging follow-up are needed.