• Subdural

Neurointerventionalists are participating in a transformative moment in the field, from expanded thrombectomy indications,1 to the endovascular treatment of hydrocephalus,2 and endovascular brain–computer interfaces.3 Perhaps most consequential in recent years is the endovascular treatment of subacute or chronic subdural hematoma (cSDH) via middle meningeal artery embolization (MMAE). First reported in 20004 as salvage therapy in patients with high surgical comorbidities, this treatment has grown in popularity as its safety and efficacy have been studied.

cSDH carries a high morbidity, mortality, and healthcare resource burden.5 Existing medical and surgical treatments, while effective, are imperfect, with recurrence rates of up to 20%6 and reoperation rates of 12%.7 These high rates were considered acceptable given the limited alternatives; adjunct medical treatment is at best moderately helpful,8 and at worst, harmful.9 In this setting, MMAE for cSDH emerged as a promising alternative. Recent meta-analysis found reoperation rates falling to 4.6% in cSDH treated with surgery and adjunctive MMAE, and 6.8% in cSDH treated with MMAE alone.10 These results, while favorable, were based primarily on case series and retrospective data collection.

The results of three randomized, prospective trials of MMAE for the treatment of cSDH were simultaneously reported at the International Stroke Conference 2024 meeting. Embolization of the Middle Meningeal Artery With Onyx Liquid Embolic System in the Treatment of Subacute and Chronic Subdural Hematoma (EMBOLISE) is an investigator-initiated but industry-sponsored multicenter, prospective, randomized, interventional, controlled, open label, adaptive design clinical trial of MMAE for patients with symptomatic cSDH across 39 centers in the USA using Onyx (Medtronic Neurovascular, Irvine, CA). EMBOLISE targeted enrollment of up to 600 patients across two arms. Patients with mild cSDH (defined as midline shift <5 mm, hematoma thickness ≤15 …