EMBOLISE randomized surgical trial for subdural hematoma: clinical benefits beyond reoperation with middle meningeal artery embolization

Background Randomized clinical trials have demonstrated that middle meningeal artery embolization (MMAe) reduces reoperation rates in surgically treated patients with subacute/chronic subdural hematoma (SDH). The effect of embolization on outcomes beyond reoperation remains to be determined. We analyzed the impact of reoperation and healthcare encounters among patients enrolled in the EMBOLISE trial. Methods Symptomatic subacute/chronic SDH patients were randomized to surgical evacuation alone (control) or surgical evacuation plus Onyx MMAe (treatment). Changes in modified Rankin Scale (mRS) scores, frequency of unscheduled follow-up visits, and radiographic evolution of hematomas in patients with versus without reoperation were analyzed. Results A total of 197 patients were randomly assigned to the treatment group and 203 to the control group. Patients who required reoperation compared with those who did not exhibited a ~threefold higher incidence of mRS >2 (37.0% vs 12.9%, P=0.0025) and an ~2.5fold increase in mRS worsening (22.2% vs 9.5%, P=0.0503) at 180 days. In patients who did not receive MMAe, there was a ~threefoldfold increase in rate of SDH recurrence/progression even among those who did not require reoperation (14.3% vs 5.3%, P=0.0045) and a ~twofoldincrease in unscheduled physician follow-up visits (27.1% vs 14.7%, P=0.0031). Conclusion Among patients with symptomatic subacute/chronic SDH, reoperation was associated with increased rates of mRS worsening and higher mRS scores at follow-up. Adjunctive Onyx MMAe resulted in lower rates of hematoma recurrence/progression and fewer unscheduled physician follow-up visits. Thus, in addition to reducing surgical reoperation rates, adjunctive MMAe led to improved clinical outcomes and reduced healthcare encounters.