Long-term outcomes of Spetzler-Martin grade IV and V arteriovenous malformations: a single-center experience

Objective: This study aimed to explore whether intervention can benefit Spetzler-Martin (SM) grade IV-V arteriovenous malformations (AVMs).

Methods: Eighty-two patients with SM grade IV-V AVMs were retrospectively reviewed from 2015 to 2018. Patients were divided into two groups: those who received conservative management (22 cases [26.8%]) and intervention (60 cases [73.2%], including 21 cases of microsurgery, 19 embolization, and 20 hybrid surgery). Neurofunctional outcomes were assessed with the modified Rankin Scale (mRS). The primary outcome was long-term neurofunctional status, and the secondary outcomes were short-term neurofunctional status, long-term obliteration rate, seizure control, and risk of subsequent hemorrhage.

Results: Regarding the primary outcome, after an average of 4.7 years of clinical follow-up, long-term neurofunctional outcomes were similar after conservative management or intervention (absolute difference -0.4 [95% CI -1.5 to 0.7], OR 0.709 [95% CI 0.461-1.090], p = 0.106), whereas intervention had an advantage over conservative management for avoidance of severe disability (defined as mRS score > 3) (1.7% vs 18.2%, absolute difference 16.5% [95% CI -23.6% to 56.6%], OR 0.076 [95% CI 0.008-0.727], p = 0.025). Regarding the secondary outcomes, intervention was conducive to better seizure control (Engel class I-II) (70.0% vs 0.0%, absolute difference 70.0% [95% CI 8.6%-131.4%], p = 0.010) and avoidance of subsequent hemorrhage (1.4% vs 6.0%, absolute difference 4.6% [95% CI -0.4% to 9.6%], p = 0.030). In the subgroup analysis based on different intervention modalities, microsurgery and hybrid surgery achieved higher complete obliteration rates than embolization (p < 0.001), and hybrid surgery resulted in significantly less intraoperative blood loss than microsurgery (p = 0.041).

Conclusions: Intervention is reasonable for properly indicated SM grade IV-V AVMs because it provides satisfactory seizure control with decreased risks of severe disability and subsequent hemorrhage than conservative management. Clinical trial registration no.: NCT04572568 (ClinicalTrials.gov).