Internal hematoma architecture predicts subdural hematoma responsiveness to standalone middle meningeal artery embolization.

Purpose: Subdural hematoma (SDH) is quickly becoming the most common neurosurgical pathology due to the aging population. Middle meningeal artery embolization (MMAE) has recently emerged as an effective adjunct to surgical SDH evacuation by decreasing recurrence risk. MMAE has also shown promise as a standalone SDH intervention, but clinical and radiographic predictors of successful MMAE remain ill-defined.

Methods: Retrospective chart review from 2020 to 2023 at a single center identified all MMAE cases performed as primary SDH treatment. Cases were classified by hematoma internal architecture as homogeneous, separated, laminar, or trabecular. SDH maximal thickness was assessed on all follow-up imaging and any recurrences or expansions requiring surgery were denoted as treatment failures.

Results: 164 standalone MMAE cases were reviewed. Most cases were in male patients (75.0%) with a mean age of 73.2 years. The overall MMAE treatment failure rate was 6.7% with a 4.9% periprocedural complication rate. The cases with trabecular and laminar collections were slightly larger than those with homogeneous and separated collections (16.2 mm vs. 14.2 mm, p = 0.008*), but other baseline characteristics were similar. The MMAE failure rate was significantly lower in the laminar and trabecular subgroup (1.2%) compared to the homogeneous and separated subgroup (12.4%) (p = 0.005*). Homogeneous and separated internal hematoma architecture was the only predictor of MMAE failure in multivariate analysis (OR 10.5, p = 0.027*) and was also associated with delayed SDH resorption (ANOVA: F = 4.8, p = 0.0025*).

Conclusions: Standalone MMAE is an effective, safe, and durable treatment for non-acute SDHs, and is especially effective for SDHs with more membranous internal architecture.