J. Gauri Shankar, Susan Alcock, Nima Kashani, Tim Darsaut, Bill Wang, Marlise P. dos Santos, Geneviève Milot, C J O’Kelly, Michael E Kelly, Daniela Iancu, Adela Cora, Tom Marotta, Brian van Adel, Kislay Kishore, Brian Drake, Howard Lesiuk, Sylvine Carrondo-Cottin, Jeremy Rempel, U Ahmed, Chiraz Chaalala, Joseph Silvaggio, Zul Kaderali, J McEachern, Mohammed Suheel Abdul Salam, Namita Sinha, Roman Marin, Yan Sin Leung, R Balshaw, Ian Fleetwood, Depeng Jiang, Bijoy K. Menon, Nishita Singh, Frederick A Zeiler, EMMA-Can investigators, Patrick McDonald, Annie Drapeau, Colin Kazina, Neil Berrington, Anthony Kaufmann, Jason Beiko, Alysa Almojuela, Perry Dhaliwal, Santhosh Annayappa, Josh Dian, Alwyn Gomez, Beili Huang, Benjamin Blackwood, Reva Trivedi, Marco Ayroso, Ira Shankar, Almunder Algird, Ramiro Larrazabal, Maksim Son, Amanda Martyniuk, Kowsiya Jeganathan, Robert Fahed, Gil Zur, Areej Fageeh, A Diouf, Rajiv Hira, Steven Cooper, Stephanie Shenassa, Betty Anne Schwarz, Nicole Mikhael, Kelly Villeneuve, Romika Mehta, Sandra Chanthavisouk, Michael Chow, Sudeshna Bhattacharya, Sylvia Gaucher, Lissa Peeling, Nima Kashani, Gary Hunter, U Ahmed, Aaron Gardner, Nicole Sylvain, Cassandra Tyson, Jessica Grosskleg, Kaitlyn Foster, Sydney Targerson, Roland Jabre, Sara Chakir, Guylaine Gévry, Adrienne Weeks, Gwenydd Pickett, Julia MacMillan, Vitor Mendes Pereira, Julian Spears, Eileen Liu, C R Stalker
Importance: Chronic subdural hematomas commonly recur after surgical drainage. The effect of adjunctive embolization of the middle meningeal artery (EMMA) on recurrence risk remains unclear. Objective: To evaluate whether EMMA as an adjunct to surgical drainage reduces chronic subdural hematoma recurrence compared with surgery alone. Design, Setting, and Participants: This trial was a randomized, open-label, blinded-end point trial involving adults with unilateral, symptomatic chronic subdural hematoma (≥10 mm) undergoing surgical drainage across 9 tertiary care centers in Canada between August 2021 and April 2025. Intervention: EMMA using a liquid embolic agent (Onyx-18) within 72 hours after surgical drainage vs a control group that did not receive EMMA after surgical drainage. Main Outcomes and Measures: Primary outcome was symptomatic recurrence of chronic subdural hematoma detected on computed tomographic (CT) scan at 90 days (range, 60 to 120 days). Secondary outcomes included radiographic recurrence of chronic subdural hematoma, 90-day mortality, and serious adverse events. The last date of follow-up was July 27, 2025. Results: Of 192 randomized participants, 186 (mean age, 71.8 years; 136 male [73%]) completed the trial (93 per group). The primary outcome of symptomatic recurrence of chronic subdural hematoma detected on CT scan occurred in 4 participants (4.3%) in the EMMA group vs 26 patients (28%) in the control group (risk difference, -23.7; 95% CI, -34.1 to -13.9; P < .001). Radiographic recurrence occurred in 13 participants (14%) in the EMMA group vs 46 patients (49.5%) in the control group. Mortality was 4.3% vs 1.1%; serious adverse events occurred in 8.6% vs 5.4%, respectively. Conclusions and Relevance: Adjunctive EMMA after surgical drainage significantly reduced symptomatic recurrence on CT scan of unilateral chronic subdural hematoma at 90 days compared with surgery alone. Trial Registration: ClinicalTrials.gov Identifier: NCT04750200.