Embolization of middle meningeal artery (EMMA) for non-acute subdural hematoma: Insight from recent randomized trials and meta-analysis.

Embolization of the middle meningeal artery (EMMA) has emerged as a promising treatment for non-acute subdural hematoma (NASDH), either as an adjunct to surgical drainage or as a primary intervention in patients not undergoing surgery. Recent randomized controlled trials (RCTs) have investigated the efficacy of EMMA using dimethyl sulfoxide (DMSO)-based agents like ONYX and SQUID. The EMBOLISE trial demonstrated a significant reduction in hematoma recurrence with adjunctive EMMA, while the STEM trial showed similar benefits at 180 days. Conversely, the MAGIC MT trial found no significant difference in recurrence rates with EMMA. A meta-analysis of these trials confirmed EMMA's safety, with no significant increase in serious adverse events. The analysis indicated a modest overall benefit in reducing NASDH recurrence (risk difference -0.09, P = 0.02), though results were largely driven by the STEM trial. The benefit of adjunctive EMMA was less clear, with no significant effect found. Primary EMMA showed marginal benefit but with considerable variability. Factors such as primary outcome, trial design, patient demographics, and surgical biases complicate the interpretation of these findings. While the safety of EMMA is supported, its clinical efficacy remains inconclusive. Further trials, including patient-level meta-analyses, are needed to refine the role of EMMA in NASDH management and address existing gaps in the literature.