Introduction The incidence of chronic subdural hematoma (cSDH) has been increasing, while recurrence after surgery reaches up to 30%. Middle meningeal artery embolization (MMAE) is an increasingly popular treatment option for cSDH. We aimed to assess the safety and efficacy of liquid embolic agents in MMAE for cSDH and compare them with particle embolization.

Methods We systematically reviewed all the studies describing MMAE for cSDH with liquid embolic agents. Additionally, we included our institutional experience with liquid and particle embolic agents. We analyzed data with random-effects proportions, conducted a comparison meta-analysis, and assessed statistical heterogeneity.

Results A total of 18 studies with 507 cases of MMAE with liquid embolic agents (including our institutional experience) were included in the analysis. In our institution, 90 patients (117 hemispheres) underwent MMAE, with a mean age of 71.6±10.4 years, 21.1% were females, 62.4% were standalone MMAEs, and liquids were used in 32.5% of cases. On average, the included studies were of good quality. Publication bias was found in the proportion analysis but not in the comparison analysis. The success rate was 99% (95% CI 98-100%), all complications rate was 1% (95% CI 0-5%), major complications rate was 0% (95%CI 0-0%), and mortality rate was 1% (95% CI 0-6%). The rate of hematoma size reduction was 97% (95% CI 73-100%), complete resolution 64% (95% CI 33-87%), radiographic recurrence 3% (95% CI 1-7%), and reoperation 3% (95% CI 1-7%). No statistically significant differences were found between liquid embolic agents and particles regarding success (RR 1.01, 95% CI 0.99-1.02), all complications (RR 0.51, 95% CI 0.10-2.46), mortality (RR 0.47, 95% CI 0.13-1.67), improvement in SDH size (RR 1.02, 95% CI 0.89-1.17), recurrence (RR 0.75, 95% CI 0.30-1.85), and reoperation (RR 0.49, 95% CI 0.21-1.13). Sensitivity comparison analyses revealed that liquid embolic agents were associated with lower reoperation rates in upfront MMAE (RR 0.13, 95% CI 0.02-0.95).

Conclusion MMAE with liquid embolic agents is both safe and effective for the treatment of cSDH. Outcomes are comparable to particles, but liquids may be associated with a decreased risk of reoperation in upfront MMAE. Further well-designed clinical trials are needed to validate our findings and reveal any potential difference between embolic agents.

Disclosures G. Sioutas: None. J. Vivanco-Suarez: None. O. Shekhtman: None. I. Matache: None. M. Salem: None. J. Burkhardt: None. V. Srinivasan: None. B. Jankowitz: None.