1141 Particles vs Onyx vs n-BCA in Middle Meningeal Artery Embolization for Chronic Subdural Hematomas: Multicenter Propensity Score Matched Analysis of 1070 Embolizations

INTRODUCTION: Multiple preferences exist in terms of embolic materials preferences in middle meningeal artery embolization (MMAE) for chronic subdural hematoma (cSDH) with limited comparative literature data. METHODS: Consecutive patients undergoing MMAE for cSDH at 14 North-American centers (2018-2023) were included. Patients were classified into 3 groups a) particles, b) Onyx, c) n-BCA. The endpoints were unplanned rescue surgery and radiographic success (=50% reduction in hematoma thickness at last imaging "minimum 2-weeks"). Initial unmatched analysis compared the 3 groups. Subsequent matched analysis via propensity score matching (PSM) compared particles versus liquid group (groups b & c combined; Onyx/n-BCA). Additional subgroup PSM analyses compared particles vs Onyx, particles vs n-BCA, Onyx vs n-BCA. All matched analyses controlled for: age, sex, concurrent surgery, prior surgery, hematoma thickness, midline shift, pre-treatment antithrombotics, baseline mRS. RESULTS: 872 patients (median-age 73 years, 72.9% males) underwent 1070 MMAE procedures (22.8% bilateral). Median cSDH thickness was 14 mm (IQR 10-18), with median midline shift 3mm (IQR 0–5.5). Onyx was the most utilized material (41.4%) followed by particles and n-BCA (40.3% and 15.5%, respectively). Retreatment rates were not different between particles, Onyx, n-BCA (9.8% vs 7% vs 11.7% respectively, p=0.14). Similarly, radiographic success rates were comparable (78.8% vs 79.3% vs 77.4% respectively, p=0.91). The PSM comparing particles vs liquid generated 128 matched-pairs; no significant differences in retreatment rates (11.7% vs 10.9%; p=0.84), or radiographic success (74.5% vs 74.5%; p=0.73). Concurrently, the PSM comparing Onyx vs n-BCA resulted in 42 matched pairs; without differences in radiographic improvement between the groups (67.7% vs 76.5%; p=0.42), or surgical rescue rates (11.9% vs 9.5%; p=0.72). No differences in procedural complications were noted between the groups across the previous analyses. CONCLUSIONS: We found no significant differences in clinical and radiographic efficacy between the particles and the liquid embolics in MMAE.