Middle meningeal artery embolization for non-acute subdural hematoma: a meta-analysis of large randomized controlled trials

Middle meningeal artery embolization (MMAE) has emerged as a novel treatment for non-acute subdural hematoma (SDH), particularly for reducing the risk of SDH recurrence. Recently, five randomized controlled trials (RCT) of MMAE as an adjunct to conventional management (surgical or observant) have concluded their investigation and reported their outcomes. To synthesize trial results to provide more definitive guidance on the role of MMAE in the management of non-acute SDH. MEDLINE database from inception up to November 23, 2024. English-language clinical articles reporting large randomized controlled trials (n=100 or more) investigating the efficacy and safety of MMAE for non-acute subdural hematoma patients were identified. Five trials were identified - EMBOLISE, STEM, MAGIC-MT, EMPROTECT, and MEMBRANE. The primary efficacy endpoint was SDH treatment failure (broadly defined as SDH recurrence or requirement of surgical rescue) within 3 to 6 months. Safety endpoints include death and stroke. There was significant heterogeneity in terms of patient populations as well as reported outcomes. Overall, MMAE was associated with significantly lower odds of SDH treatment failure (OR 0.51 [95%CI 0.39 to 0.67], p<0.001), with minimal inter-study heterogeneity. Compared to conventional management, MMAE was not significantly associated with different odds of death (OR 1.03 [95%CI 0.36 to 2.99], p=0.95) or stroke (OR 1.10 [95%CI 0.36 to 3.39], p=0.86). Our meta-analysis is limited by selection bias and high heterogeneity in study design and reported outcomes. This study provides high-level evidence that, for patients with non-acute SDH, MMAE is safe and effective an adjunct to conventional management for preventing treatment failure. SDH = subdural hematoma; MMAE = middle meningeal artery embolization; RCT = randomized controlled trial.