Determining the Number of Chronic Subdural Hematoma Potentially Eligible for Middle Meningeal Artery Embolization: A Population-Based Study

BACKGROUND: Middle meningeal artery embolization (MMAE) was recently proven to be an evidence-based adjunct to burr-hole drainage for chronic subdural hematoma (CSDH). Population-level estimates of patients with CSDH potentially eligible for MMAE are lacking, limiting rational service development and health-system planning. We aimed to determine the proportion of patients with CSDH who meet restrictive and permissive criteria for MMAE in a contemporary Australian population sample. METHODS: Patients with CSDH were stratified via a prespecified eligibility algorithm derived from recent MMAE trials comprising maximal hematoma thickness, presence of midline shift or mass effect, and neurological symptoms attributable to CSDH. Recognizing that institutions may interpret recent MMAE trial data either rigidly or loosely, 2 separate eligibility algorithms were applied: restrictive (modified Rankin Scale <4 and burr-hole drainage) and permissive. RESULTS: In a population of 493 972 people, 530 patients admitted with subdural hematoma were identified during the 1-year study period. Of these, 210 of 530 (39.2%) had subacute or chronic subdural hematoma. Seventy-seven of 210 (36.7%) met restrictive eligibility criteria. Using permissive criteria, 105 of 210 (50.0%) patients were eligible. The permissive algorithm identified an additional 28 potential candidates beyond the restrictive group. Using the restrictive algorithm, there were 15.6 (95% CI, 12.4–19.5) potential MMAE eligible patients per 100 000 person-years, and 21.3 (95% CI, 17.4–25.7) using the permissive algorithm. CONCLUSIONS: In this population-based cohort, ≈36.7% of patients with CSDH were eligible for MMAE, while 50.0% met permissive criteria. The permissive criteria predict that ≤21.3 CSDH per 100 000 person-years may be eligible.