Factors associated with treatment failure after primary middle meningeal artery embolization for chronic subdural hematoma: a retrospective cohort study

Objectives Chronic subdural hematoma (cSDH) is increasingly managed with middle meningeal artery embolization (MMAE). Identifying factors associated with treatment failure is important for patient selection and postprocedural management. We evaluated clinical and radiographic factors associated with failure following primary MMAE for cSDH.Design Retrospective cohort study.Setting Single academic tertiary care center.Participants 56 patients undergoing primary MMAE for cSDH between 2018 and 2024, representing 79 embolized hematoma sides.Interventions MMAE performed as primary treatment without planned surgical drainage.Main outcome measures Treatment failure was defined as need for surgical drainage or mortality due to cSDH. Associations between hematoma thickness, hematoma volume, percentage of subdural hematoma relative to intracranial volume (% SDH of ICV), and treatment failure were assessed.Results Of 56 patients, 13 (23%) required subsequent drainage. Baseline age, admission Glasgow Coma Scale score, Markwalder score, anticoagulation status, and platelet count did not differ significantly between treatment success and treatment failure groups. Hematoma thickness was not associated with treatment failure (p=0.66). Sides in the treatment failure group had larger initial hematoma volumes than sides in the treatment success group (79±31 mL vs 55±37 mL, p=0.003) and higher % SDH of ICV (5.2%±1.9% vs 3.7%±2.3%, p=0.006). 30-day readmission was more common with treatment failure (69% vs 14%, p<0.001).Conclusions Larger hematoma volume and higher % SDH of ICV, but not hematoma thickness, were significantly associated with failure following primary MMAE for cSDH. These findings support further evaluation of volumetric measures as candidate factors for risk stratification.