Abstract 443: Middle Meningeal Artery Embolization for Subacute Versus Chronic Subdural Hematoma: A Propensity Matched Study Using a Nationwide Database

Background Chronic subdural hematoma (SDH) is a common neurosurgical condition, with middle meningeal artery embolization (MMAE) emerging as a promising minimally invasive treatment. While MMAE has been extensively studied in SDH, limited data exist comparing its efficacy in subacute versus chronic SDH. This study aimed to evaluate outcomes of MMAE in patients with subacute and chronic SDH using a large, nationwide database. Methods We conducted a retrospective cohort study using the TriNetX US Collaborative Network. Adult patients diagnosed with nontraumatic subacute or chronic SDH who underwent MMAE within 21 days of diagnosis were identified. Propensity score matching (PSM) was applied to balance baseline characteristics between cohorts. The primary outcomes included rates of subsequent surgical intervention, inpatient readmission, emergency department utilization, headache, functional dependence, and mortality from 7 days to 6 months post‐MMAE. Subgroup analyses were performed to compare outcomes in patients undergoing MMAE alone and MMAE with concurrent surgical intervention. Results A total of 3,889 patients underwent MMAE, including 846 with subacute SDH and 3,043 with chronic SDH. After 1:1 PSM, 841 patients remained in each cohort with well‐balanced characteristics. No significant differences were observed between the subacute and chronic SDH groups in surgical intervention rates (7.7% vs. 7.4%, p = 0.782), readmission (27.9% vs. 26.3%, p = 0.443), emergency department visits (28.2% vs. 25.9%, p = 0.297), functional dependence (11.4% vs. 12.2%, p = 0.597), or mortality (6.1% vs. 6.3%, p = 0.840). In subgroup analyses, among 2,338 patients who underwent MMAE alone, outcomes did not differ significantly between subacute and chronic SDH groups after PSM. Similarly, in the 1,551 patients who underwent MMAE with surgery, the subacute cohort had a lower unadjusted mortality rate (3.1% vs. 6.5%, p = 0.011), but this difference was not significant after matching. Conclusion Outcomes were comparable between subacute and chronic SDH cohorts. These findings suggest that MMAE may be effective across different SDH stages, though further research is needed for confirmation.