Selection of an embolic agent for middle meningeal artery embolization (MMAE) in a chronic subdural hematoma (cSDH) is a subject of debate and is limited to observational data. We report the first meta-analysis that exclusively assessed randomized controlled trials (RCTs) to address this gap.

A systematic review and meta-analysis was conducted, incorporating all available RCTs that compared MMAE plus standard of care (SOC) versus SOC alone for cSDH usingeither Onyx, n-BCA, and Squid as embolic agent for embolization. Primary outcomes were the rate of hematoma recurrence/progression and the need for reoperation. Secondary outcomes included serious adverse events (SAE), all-cause mortality, functional independence (defined as a Modified Rankin Scale (mRS) score of 0–2), and the rate of successful embolization. To assess heterogeneity, a fixed-effect or random-effects model was applied, depending on statistical significance (I²>50%, P < 0.1).

Four RCTs, with 894 patients in the MMAE plus SOC group and 914 patients in the SOC alone group, were identified and met our standard for analysis. Results revealed significant superiority of n-BCA compared to Onyx and Squid in lower all-cause mortality at last follow-up. There was no significant difference in using Onyx, Squid, and n-BCA in recurrence at the last follow-up (P = 0.36), reoperation at the last follow-up (P = 0.55), and successful embolization (P = 0.52), and 90-day functional independence (P = 0.076) between trials. Additionally, further analysis on safety outcomes showed no significant difference between embolic agents in SAE at last follow-up (P = 0.78), embolization-related complications (P = 0.087), new onset ischemic stroke (P = 0.98), and deep venous thrombosis (P = 0.94).

This meta-analysis of RCTs suggests that while n-BCA is associated with lower all-cause mortality compared to Onyx and Squid in MMAE for cSDH, all three embolic agents demonstrate comparable efficacy and safety.