Treatment of Subcortical Brain Arteriovenous Malformations. a Propensity Score Matched Comparison of Microsurgical Resection and Stereotactic Radiosurgery. a Secondary Analysis of the MISTA Consortium

Introduction: The treatment of subcortical AVMs is complex and becomes even more nuanced the deeper the origin of the lesion due to the increased chance of involvement with the core structures of the brain. Using propensity score matching we seek to compare microsurgical resection and stereotactic radiosurgery for the treatment of these complex lesions.

Methods: The authors performed a subgroup analysis of the international multicenter MISTA consortium including patients treated between January 2010 and December 2023. Only subcortical AVMs treated with either microsurgical resection or stereotactic radiosurgery that had at least 3 years or more of follow-up unless they had completely occluded earlier were included. PSM was used to control potential confounders, especially the location of AVM, “subcortical” or “deep”.

Results: A total of 245 patients with subcortical bAVMs, with a median age of 39, were included in this study: 118 were treated with microsurgery, and 127 with stereotactic radiosurgery. After 1:1 PSM 19 matched pairs were obtained. 84.2% of AVMs treated with SRS were Spetzler Martin grades 3 and above compared to 52.6% treated with microsurgery (p = .04). 94.7% of those treated with SRS and 73.7% of patients treated with microsurgery had an mRS ≤ 2 at the last follow-up (p = .08). There was no difference in overall outcome (difference between presentation mRS and follow-up mRS) between the two groups (p = .42). Patients that underwent microsurgery had longer lengths of stays (p < .001). 94.7% of microsurgery patients experiencee complete obliteration compared to 58.5% of the SRS group (p = .01). There was no difference between the groups in terms of complication rates (p = .37), post-procedure rupture (p = 1), and mortality (0%).

Conclusion : While overall functional outcomes between the two treatment modalities do not significantly differ SRS patients have shorter lengths of stay, usually returning home the same day as their procedure. However, microsurgery is significantly more likely to result in complete obliteration of the AVM, effectively reducing the rupture risk to zero directly following resection.