Middle Meningeal Artery Embolization Versus Best Medical Treatment in Chronic Subdural Hematoma: A Meta-Analysis of Randomized Controlled Trials

Introductionː Embolization of middle meningeal artery (MMA) has become a minimally invasive alternative that can reduce the high rate of recurrence of chronic subdural hematoma (cSDH), but so far randomized evidence is scattered. To better explain its effectiveness and safety, we conducted a more recent meta-analysis of randomized controlled trials (RCTs). Evidence Acquisitionː A protocol in the PRISMA-2020 scheme was registered and PubMed, Embase, Cochrane CENTRAL, Scopus, ClinicalTrials.gov and WHO-ICTRP were searched via inception to 5 June 2025. RCTs focusing on adults alone with a comparison of MMA embolization (stand-alone, or adjunct to surgery) versus standard management were only eligible in this study. The pooled risk ratios (RRs) or standardized mean differences (SMDs) were created using random-effects models (DerSimonian–Laird) with Hartung–Knapp adjustment. The major endpoints were symptomatic recurrence (efficacy) and all-cause mortality (safety). Evidence Synthesisː Eight randomized controlled trials (RCTs) were included in this systematic review and quantitative synthesis (n = 1,862 patients). MMA embolization reduced symptomatic recurrence by approximately 47% compared to control (RR = 0.53; 95% CI: 0.39–0.73; I² = 0%; 95% prediction interval: 0.33–0.85; number needed to treat [NNT] = 14, 95% CI: 11–24). There was no significant benefit on good functional outcome (mRS ≤ 2) (RR = 1.01; 95% CI: 1.00–1.02; I² = 0%; 95% prediction interval: 0.93–1.10; three trials) or on independent functional outcome (mRS ≤ 3) (RR = 1.01; 95% CI: 1.01–1.02; I² = 0%; 95% prediction interval: 0.97–1.06; three trials) or on hematoma thickness reduction (SMD = –0.13; 95% CI: –0.35 to 0.09; I² = 42.4%; four trials, n = 1,467). All-cause mortality showed a non-significant trend toward reduction in the MMA embolization group (RR = 0.66; 95% CI: 0.38–1.16; I² = 23.4%; eight trials). Procedure-related complications were infrequent; the pooled complication rate across eight trials was approximately 1% (95% CI: 0–2%; I² = 23.6%; 95% prediction interval: 0–3%; 13 events in 964 patients), and no deaths were attributed to the embolization itself. The overall risk of bias across the included studies was low-to-moderate, and statistical heterogeneity was minimal across all key outcomes. Conclusionsː In summary, MMA embolization significantly reduces chronic subdural hematoma recurrence with a low complication rate, supporting its role as a safe adjunct to standard care. However, current evidence remains insufficient to confirm long-term functional, cognitive, or radiographic benefits, and further multicenter trials with standardized protocols and extended follow-up are essential.