Association of First-Line Stand-Alone Middle Meningeal Artery Embolization for Nonacute Subdural Hematoma with In-Hospital Outcomes.

Background While randomized trials have demonstrated that middle meningeal artery embolization (MMAE) reduces subdural hematoma recurrence over several months, its effect on immediate hospitalization outcomes remains unclear. Purpose To evaluate the impact of first-line stand-alone MMAE on immediate hospitalization outcomes for patients admitted with nontraumatic nonacute subdural hematoma (NASDH). Materials and Methods In this retrospective cohort study of the Nationwide Readmissions Database (2019-2022), nonelectively hospitalized patients with NASDH with clinically significant mass effect who did not undergo urgent decompression within 3 days were included. Those with multicompartment hemorrhage, cerebrovascular malformations, intracranial tumors, or embolization performed after delayed surgery were excluded. First-line stand-alone MMAE was compared with conservative management (CM) alone, and 3:1 propensity score matching was used to balance groups according to baseline characteristics. The primary outcome was functional independence at discharge. The secondary outcome was in-hospital mortality. Patients were followed up through the end of their hospital stays. Results A total of 5829 patients were included (median age, 74 years [IQR, 65-83 years]; 3949 male patients); 896 (15.4%) underwent MMAE. After propensity score matching, 850 and 2257 patients remained in the MMAE and CM groups, respectively. MMAE was associated with a higher functional independence rate (52.8% vs 42.2%, P = .001), lower mortality (3.1% vs 8.3%, P < .001), lower rate of need for rescue surgery (12.9% vs 31.7%, P < .001), and lower respiratory complication rate (10.5% vs 15.5%, P < .001). In exploratory subgroup analysis, functional independence rates were higher for early MMAE (within 3 days) versus CM (59.0% vs 42.2%, P < .001) but not for late MMAE versus CM (41.3% vs 42.2%, P = .81). Conclusion First-line stand-alone MMAE for patients nonelectively hospitalized for NASDH who did not require urgent decompression was associated with a higher early functional independence rate and lower in-hospital mortality, rescue surgery, and in-hospital complication rates than CM, particularly when MMAE was performed early. © RSNA, 2026 Supplemental material is available for this article.