Embolization for Arteriovenous Malformations: Significant Nidal Volume Reduction Prior to Radiosurgery

Introduction: Treatment for arteriovenous malformations (AVMs) includes embolization, microsurgery, or stereotactic radiosurgery (SRS). SRS is often used for deep or eloquent locations that may pose a high risk for surgery. Prior studies have shown that efficacy of SRS is highest in AVMs that are < 3 cm in diameter. Embolization prior to SRS has been suggested as a modality that could be used to reduce the size of the AVM nidus and the volume of treatment required for SRS. The aim of this study is to determine the AVM nidal volume reduction with the use of embolization prior to SRS.

Methods: We retrospectively reviewed patients within our study criteria treated with embolization prior to SRS for treatment of AVMs. Patient demographics, AVM characteristics, embolization details, and time between embolization and SRS were recorded. We then used contrast enhanced magnetic resonance imaging (MRI) to contour AVM volumes based on pre-embolization imaging and then compared to post embolization imaging. Planned AVM volume prior to embolization was then compared to actual treated AVM volume post embolization.

Results: We identified 10 patients treated with embolization prior to SRS from 2011-2023. Average age was 46.2 years. Prior to embolization there were 3 patients with Spetzler Martin (SM) grade 2 AVMs, 5 patients with SM grade 3 AVMs, and 2 patients with SM grade 4 AVMs. Mean time between last embolization and SRS was 3.5 months. Mean AVM nidal volume prior to embolization was 14.75cc and mean AVM volume post embolization was 5.88cc. The average percent reduction in AVM nidal volume was 55.3% with embolization prior to SRS, which was statistically significant (p=0.0128). There were no complications related to embolization or SRS in our case series.

Conclusion : In our cohort, embolization prior to SRS resulted in a statistically significant reduction in AVM nidal volume without a higher risk of complications. Therefore, embolization prior to SRS may improve dose reduction at time of SRS treatment allowing for decreased risk of SRS complications without higher embolization complication rates.