Middle Meningeal Artery Embolization with Small Polyvinyl Alcohol Particles (45-150 µm) for Chronic Subdural Hematoma: Safety, Efficacy, and Imaging Predictors.

PURPOSE: To evaluate the safety and efficacy of middle meningeal artery embolization (MMAE) using small polyvinyl alcohol (PVA) particles (45-150 µm) with or without coils for chronic subdural hematoma (cSDH) and to assess peri-interventional imaging predictors and survival outcomes. MATERIALS AND METHODS: This retrospective single-center observational study included patients (≥18 years) undergoing MMAE for cSDH between June 2019 and March 2024 at a tertiary neurovascular center. Inclusion criteria required pre-, post-interventional imaging and clinical follow-up; exclusions were acute traumatic hematomas, embolization with liquid embolics or coils alone, and insufficient imaging quality. Embolization was performed using PVA particles between 45-150 µm in size with or without coils. Primary endpoint: need for retreatment. Secondary endpoints: radiological hematoma evolution, modified Rankin Scale (mRS) score, procedure-related complications, and mortality. Statistical analysis included Cochran's Q test, Friedman ANOVA, χ² tests, Fisher's exact and Mann-Whitney U tests Kaplan-Meier, time-to-event analyses including sensitivity analyses accounting for bilateral hematomas and heterogeneous follow‑up. RESULTS: Eighty-nine patients (117 hematomas; mean age 80.9±9.1 years; 80.9% male) were included. PVA alone was used in 29 hematomas (24.8%) and PVA with coils in 88 hematomas (75.2%). Retreatment was not required in 90.6 % of hematomas. Radiological success (complete resorption or residual thickness <10 mm) was achieved in 71.0%. Mean baseline hematoma width was 19.2 ± 6.7 mm. Across all hematomas, the median individual reduction in width from baseline to last follow-up was 77.3 % (p < 0.001). The proportion of patients with mRS<3 improved significantly from 52.8% pre-intervention to 76.4% at last follow-up (p<0.001). Dyna-CT fluid level was associated with secondary radiological outcome in unadjusted analysis (p=0.002). PVA alone versus PVA with coils showed no difference in primary outcome or secondary outcomes. Procedure-related clinical complications occurred in 1.7% of embolizations (2/117). CONCLUSION: MMAE with small PVA particles (45-150 µm), with or without coils, is safe and effective for cSDH patients. The low clinical complication rate and absence of procedure-related mortality, combined with favorable survival, support small PVA particles as an effective embolic agent for MMAE in routine clinical practice. KEY POINTS: · Small PVA particles (45-150 µm): 90.6% primary success, 77.3% median hematoma reduction. mRS<3 improved significantly from 52.8% to 76.4% post-MMAE (p<0.001). Dyna-CT fluid level was associated with secondary radiological outcome. Small particles feasible and associated with favorable outcomes in this cohort. Procedure-related clinical complications 1.7%; mortality 6.7% (unrelated to procedure).. CITATION FORMAT: · Zaki MZG, Berlis A, Behrens L et al. Middle Meningeal Artery Embolization with Small Polyvinyl Alcohol Particles (45-150 µm) for Chronic Subdural Hematoma: Safety, Efficacy, and Imaging Predictors. Rofo 2026; DOI 10.1055/a-2933-2186.