Introduction Middle meningeal artery (MMA) embolization is an emerging treatment for the management of chronic subdural hematomas (cSDHs) and can be performed alone or in combination with surgical evacuation. While several randomized trials are currently in progress to elucidate the efficacy of MMA embolization, the benefit of this procedure and appropriate patient selection criteria have not yet been definitively established. We sought to review our own experience with this procedure to investigate the differences in outcomes between MMA embolization for recurrent cSDH and untreated cSDH and the impact of comorbidities on the efficacy of MMA embolization for cSDH.

Methods We performed a retrospective chart review of patients who underwent MMA embolization at our institution between 1/1/2018 and 12/31/2022. Patients were divided into two groups: recurrent cSDHs, defined as treatment with surgery prior to MMA embolization, and untreated cSDHs. Data collected included patient demographics, Charleston Comorbidity Index (CCI) score, use of anticoagulants, and follow-up imaging outcomes at 2, 4, 6, and 12 weeks of treatment and at last imaging follow-up. Mortality was also recorded.

Results Ninety MMA embolization procedures were identified with at least one radiographic follow-up, of whom 40 (44.4%) had recurrent cSDH and 50 (55.6%) had untreated cSDH at time of MMA embolization. The groups were comparable in terms of age (67.3 vs. 72.4, p=0.05), sex (27.6% female vs. 24.0% female, p=0.81), CCI (3.3 vs. 3.5, p=0.43), and length of follow-up (7.5 months vs. 5.5 months, p=0.18). Reduction in the maximal thickness of the cSDH of >50% was observed in 71.1% of patients by last follow-up with no difference between groups (p=0.49). Reduction was greatest at last follow-up for recurrent cSDH (35.0%) and at week 12 for untreated cSDH (34.0%), with no differences in cumulative reduction at any time points. Resolution was observed in 34.4% of patients by last follow-up with no difference between groups (p=0.66). Resolution was greatest at last follow-up for both recurrent cSDH (25.0%) and untreated cSDH (20.0%). Increased cSDH size was noted in 17.8%, of which 62.5% had overall improvement at time of last follow-up. Only 3.3% had worsening size of cSDH at last follow-up. Overall mortality was 12.2%, with no difference between groups (12.5% vs. 10.0%, p=0.91).

CCI was associated with a decreased likelihood of resolution at last follow-up (p=0.029) but was not associated with mortality (p=0.48) or <50% reduction by last follow-up (p=0.35). Neither the recurrent cSDHs (p=0.13) or the untreated cSDHs (p=0.12) independently had CCI score associated with cSDH resolution. Anticoagulation use was not associated with cSDH resolution (p=0.18), mortality (p=0.22) or >50% reduction (p=0.80).

Conclusion Patients with SDH undergoing an MMA embolization show a high degree of interval improvement in size, with 50% of patients achieving >50% reduction in SDH size within 12-weeks of surgery. However, complete resolution was only seen in 10% by 12-week follow-up and 34.4% of patients at last follow-up. Higher CCI scores are associated with decreased interval resolution by last follow-up. There are no significant differences in outcomes between MMA embolization for recurrent cSDHs and untreated cSDHs.

Disclosures R. Chaliparambil: None. M. Potts: None.