Middle Meningeal Artery Embolization for "Trial-Ineligible" Chronic Subdural Hematomas.

Background and objectives: The benefit of middle meningeal artery embolization (MMAE) in the treatment of chronic subdural hematoma (CSDH) has been recently demonstrated in a series of clinical trials. Whether MMAE benefits "trial-ineligible" patients remains elusive. We thus sought to explore the potential benefit of MMAE in neurologically stable (modified Rankin Scale ≤3) patients with "trial-ineligible" CSDHs because of large size: Thickness >15 mm and/or midline shift ≥5 mm.

Methods: A prospectively maintained database was reviewed to identify trial-ineligible CSDHs undergoing standalone MMAE. Surgical rescue rate, hematoma resolution, and neurological deterioration after hematoma progression were evaluated and compared with trial-eligible counterparts. Effect sizes were adjusted for demographic, clinical, and radiological features using multivariable regression.

Results: Of 150 standalone MMAE procedures, 92 (61%) were performed in "trial-ineligible" cases: 41% with CSDH thickness >15 mm, 21% with midline shift ≥5 mm, and 38% with both. The surgical rescue rate was 7.6% in the trial-ineligible cohort. Over a median follow-up of 62.5 days, 88.9% cases achieved satisfactory hematoma resolution (≥50% in thickness); 76% had satisfactory resolution at 90-day follow-up. Antithrombotic resumption was a risk factor for surgical rescue (adjusted odds ratio 9.64 [95% CI, 1.33-69.74]; P = .02). Surgical rescue and hematoma resolution did not significantly differ between trial-ineligible and trial-eligible cohorts (P = .87 for surgical rescue rate and P = .85 for hematoma resolution rate).

Conclusion: This study emphasizes the considerable prevalence of potentially "trial-ineligible" patients with CSDHs because of large size that may still benefit from standalone MMAE.