To identify prognostic factors with emphasis on chronic subdural hematoma (CSDH) architecture that determines short-term outcome of middle meningeal artery embolization (MMAE).

• Internal architecture of chronic subdural hematoma influences the radiological endpoint of successful therapy (≥50% of hematoma volume reduction) after middle meningeal artery embolization.
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• Out of the four architectural types: homogeneous, laminar, separated, and trabecular types, separated type of hematoma has the least likelihood of reaching the endpoint following middle meningeal artery embolization.

Consecutive CSDH patients treated by MMAE (November 2019 and March 2022) were retrospectively analyzed. Four architectures were analyzed: homogeneous, laminar, separated, and trabecular types. Predictor variables from baseline CT were correlated with radiological endpoint (≥50% of hematoma volume reduction), time to reach the endpoint and rate of volume reduction.

Study included 50 patients with 56 CSDHs (median age [first quartile, Q1; third quartile, Q3]: 70.5 [60, 78.3] years; 36 were men). Separated type reached the endpoint at a lower rate on both bivariate (p=0.02) and multivariate Cox model (0.034). Kaplan-Meier curves demonstrated the median [Q1, Q3] time for 50% of the hematomas to reach the endpoint were 5 [4, 8], 4 [3, 5], 15 [15, 15], and 11 [4, 19] weeks for homogeneous, laminar, separated, and trabecular types, respectively. Linear mixed effects model demonstrated a significant variation in the slope of hematoma volume reduction that was -4.16 (95% confidence interval [CI]: -5.4, -2.9), -6.7 (95% CI: -8.35, -5.1), -2.03 (95% CI: -4.14, 0.08), and -5.06 (95% CI: -6.8, -3.32) milliliters per week for homogeneous, laminar, separated, and trabecular subtypes, respectively.