Abstract 495: Middle Meningeal Artery Embolization for the Treatment of Chronic Subdural Hematoma: A Meta‐analysis of Randomized Controlled Trials.

Middle meningeal artery (MMA) embolization to treat chronic subdural hematomas (cSDH) involves embolising the MMA with liquid glue embolic agents, particles or cauterization to reduce blood flow to the dural membranes. MMAe is thought to reduce the recurrence rate of cSDH compared to standard of care (SOC) approaches, which include surgery such as burr‐hole drainage or craniotomy, non‐surgical management (NSMM) or any conservative management (ACM) incorporating surgery and/or NSMM. This meta‐analysis aims to compare the occurrence of primary efficacy outcome events between MMAe and standard of care (SOC) alone among recent randomized control trials (RCTs). In addition, we aim to assess the impact of MMAe adjunctive to surgery alone, ACM alone or NSMM alone. A systematic literature review and meta‐analysis of adjunctive MMAe versus SOC alone was conducted using PubMed, Cochrane, and OVID databases on the Nested Knowledge platform including only RCTs. Studies were required to include both an intervention arm incorporating adjunctive MMAe plus SOC and a control arm for comparison that could include NSMM, surgical management alone or ACM. Data were extracted on individual efficacy outcomes and compared across different interventions. The primary outcome was the occurrence of a combined primary efficacy event, with results compared using odds ratio (OR) and 95% confidence intervals. Our search yielded 768 articles, of which 11 met inclusion criteria for analysis. The RCTs assessed a wide range of primary outcomes, timepoints, and embolic agents. The primary efficacy outcomes varied and included outcomes such as cSDH recurrence, progression and resolution. The timepoints evaluated for primary efficacy outcomes across studies included 1 year, 180, 150 and 90 days. Embolic agents used included SQUID, Onyx, PHIL, nBCA, Embosphere (TAGM) and polyvinyl alcohol microparticles. One article assessed MMA cauterization. Evaluating all primary effectiveness outcomes together regardless of definition and timepoint, there was a reduction in the odds of primary outcome events in favour of adjunctive MMAe compared to SOC for the surgical arms (OR: 0.58 0.43, 0.78, 9 RCTs), ACM arms (OR: 0.60 0.43, 0.83, 5 RCTs) and the NSMM arms (OR: 0.32 0.19, 0.55, 4 RCTs). Overall, when examining all RCT data collectively, MMAe is associated with more favourable efficacy outcomes compared to surgery alone, NSMM alone, or either of the two (ACM). However, the considerable variation in primary outcomes and timepoints across the studies highlights the need for standardization in future research to facilitate more consistent interpretation of findings.