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Introduction Middle meningeal artery embolization (MMAe) is often performed as an adjunct to surgical evacuation for chronic subdural hematoma (cSDH). However, the optimal order and timing of MMAe relative to surgical evacuation remain poorly defined, ranging from preoperative (pre-op), postoperative (post-op), concurrent, and staged approaches. We sought to determine whether MMAe pre-op vs. post-op or concurrent with surgery vs. staged influences outcomes in cSDH.Methods We performed a PRISMAguided systematic review (January 2015-2025) using PubMed, Scopus, Ovid Embase (Elsevier), and the Web of Science. Studies comprising adults with nonacute subdural hematomas undergoing adjunct MMAe that directly compared pre-op vs. post-op or concurrent vs. staged embolization were included. The outcome of interest was the need for rescue treatment, defined as an unplanned additional surgical treatment for cSDH after MMAe due to persistence or re-accumulation of the hematoma. Random effects models were used to obtain pooled estimates for each outcome.Results A total of 8 studies comprising 2,950 patients (mean age 71.9 years, 24.8% female) met inclusion criteria. Particles were the most common embolic agent (50.5%) followed by liquid embolic (49.3%) with the remainder treated with coiling. There were 4 studies that compared pre-op vs. post-op MMAe (877 embolizations; 408 pre-op, 469 post-op). There was no difference in the odds of rescue treatment between pre-op and post-op MMAe (OR 0.86, 95% CI 0.34 - 2.23; I2 = 62%). There were 5 studies that compared concurrent vs. staged MMAe (2,210 embolizations; 632 concurrent, 1,578 staged). There was no difference in the odds of rescue treatment between concurrent and staged MMAe (OR 0.65, 95% CI 0.19 - 2.23; I2 = 75%).Conclusion This meta-analysis revealed no difference in rescue treatment rates based on when MMAe was performed relative to surgical evacuation, with similar rates observed between pre-op and post-op MMAe, as well as between concurrent and staged approaches. These findings suggest that the order and timing of adjunctive MMAe are less important, but the results may be limited by the small number of studies, lack of radiographic outcomes, and substantial heterogeneity across study designs.Disclosures N. Manalil: None. K. Sporn: None. T. Buddhavarapu: None. J. Collard de Beaufort: None. J. Lee: None. H. Polavarapu: None. N. Goyal: None. H. Hoffman: None.