For Doctors in a Hurry
- Researchers investigated if middle meningeal artery embolization reduces the high recurrence rates typically seen after surgical drainage of chronic subdural hematomas.
- This randomized trial enrolled 192 adults with symptomatic hematomas across nine centers to compare adjunctive embolization against surgical drainage alone.
- Symptomatic recurrence occurred in 4.3 percent of the embolization group versus 28 percent of controls (risk difference -23.7; P < .001).
- The authors concluded that adjunctive arterial embolization within 72 hours of surgery significantly lowers the risk of symptomatic hematoma recurrence.
- These findings suggest that adding endovascular embolization to standard surgical care may improve long term outcomes for patients with unilateral hematomas.
Mitigating Recurrence in Chronic Subdural Hematoma
Chronic subdural hematoma remains a persistent challenge in geriatric neurosurgery, characterized by a high incidence of recurrence following standard surgical evacuation [1, 2]. The pathophysiology involves a cycle of inflammation and angiogenesis within a neo-membrane, which is primarily irrigated by the middle meningeal artery [3, 4]. While surgical drainage provides immediate decompression, it often fails to address these underlying vascular drivers of fluid re-accumulation [5, 6]. Endovascular middle meningeal artery embolization has emerged as a potential strategy to interrupt this cycle by occluding the arterial supply to the hematoma cavity [7, 8]. A recent randomized clinical trial provides definitive data on whether this adjunctive intervention can effectively lower the risk of symptomatic recurrence in patients undergoing surgical drainage, offering clinicians a potential strategy to reduce repeat operations.
Trial Design and Patient Characteristics
The trial was designed as a randomized, open-label, blinded-end point study to evaluate the efficacy of middle meningeal artery embolization as an adjunct to standard surgical care. Conducted across nine tertiary care centers in Canada, the study period spanned from August 2021 to April 2025. The researchers utilized a blinded-end point design (a methodology where treating clinicians know the group assignments, but independent adjudicators assessing outcomes remain unaware to prevent observer bias). This rigorous framework was applied to a cohort of 192 randomized participants, of whom 186 completed the trial, resulting in 93 patients in the embolization group and 93 in the control group. Inclusion criteria focused on adults presenting with a unilateral, symptomatic chronic subdural hematoma measuring 10 millimeters or greater in maximum thickness on imaging. The study population reflected the typical demographic for this condition, with a mean age of 71.8 years and a notable male predominance (136 participants, or 73%, were male). Patients randomized to the intervention arm received embolization using a liquid embolic agent within 72 hours following surgical drainage. By comparing this combined approach against a control group receiving surgery alone, the trial aimed to determine if occluding the arterial supply could significantly alter the clinical trajectory of patients with large, symptomatic hematomas.
Adjunctive Embolization Protocol
The intervention group received adjunctive embolization of the middle meningeal artery, a procedure designed to devascularize the fragile neo-membranes that often lead to chronic fluid re-accumulation. This endovascular intervention utilized Onyx-18, a liquid embolic agent (a non-adhesive, biocompatible polymer that solidifies upon contact with blood to create a permanent vascular occlusion). To ensure the arterial supply was addressed during the critical early postoperative window, the protocol mandated that the embolization procedure be performed within 72 hours after surgical drainage. In contrast, the control group underwent surgical drainage alone, which currently serves as the standard of care for symptomatic chronic subdural hematoma. By isolating the middle meningeal artery as a primary driver of recurrence, the researchers aimed to determine if the addition of a liquid embolic agent could interrupt the cycle of chronic inflammation and micro-hemorrhage. This comparison between the combined surgical and endovascular approach versus traditional evacuation alone provided the basis for evaluating the subsequent reduction in symptomatic recurrence observed between the two cohorts.
Significant Reduction in Symptomatic Recurrence
The primary outcome of the trial was the symptomatic recurrence of chronic subdural hematoma detected on computed tomographic (CT) scan at 90 days, with the assessment window extending from 60 to 120 days post-procedure. Among the participants in the intervention group who received adjunctive middle meningeal artery embolization, symptomatic recurrence occurred in only 4 participants (4.3%). This rate was markedly lower than that observed in the control group, where symptomatic recurrence occurred in 26 participants (28%) among those who underwent surgical drainage alone. Statistical analysis of these findings revealed a risk difference for symptomatic recurrence of -23.7 (95% CI, -34.1 to -13.9; P < .001). This result demonstrates that the addition of embolization to the surgical management of unilateral, symptomatic chronic subdural hematomas significantly reduces the likelihood of a patient requiring further intervention or experiencing a return of neurological deficits. By achieving a nearly sevenfold reduction in the incidence of symptomatic recurrence, the adjunctive use of a liquid embolic agent directly addresses the high failure rate traditionally associated with surgical evacuation in this vulnerable geriatric population.
Radiographic Outcomes and Safety Profile
Beyond the reduction in symptomatic events, the researchers evaluated radiographic recurrence (the re-accumulation of blood visible on imaging, regardless of whether the patient exhibits new neurological deficits). In the group receiving adjunctive middle meningeal artery embolization, radiographic recurrence occurred in 13 participants (14%). This stands in stark contrast to the control group, where radiographic recurrence occurred in 46 participants (49.5%). This substantial difference suggests that the embolization procedure effectively addresses the underlying pathophysiology of chronic subdural hematoma by occluding the arterial supply to the fragile, leaky neo-membranes that characterize this condition. However, the safety profile of the intervention requires careful clinical consideration. At the 90-day follow-up, mortality was 4.3% in the embolization group compared to 1.1% in the control group. Additionally, serious adverse events occurred in 8.6% of the embolization group versus 5.4% in the control group. While the trial demonstrated a significant reduction in hematoma recurrence, these safety data points indicate that the procedure carries a risk of complications that clinicians must weigh against the benefit of preventing re-operation. The higher incidence of serious adverse events and mortality in the intervention group underscores the importance of careful patient selection and procedural expertise. For the practicing physician, these data suggest that while embolization provides a robust mechanism for preventing hematoma re-accumulation, its application should be carefully balanced against the baseline surgical risks and the specific cardiovascular or neurological comorbidities of the individual patient.
References
1. Elfil M, Ghaith HS, Elmashad A, et al. Adjunctive middle meningeal artery embolization for chronic subdural hematoma: A systematic review and meta-analysis of clinical trials.. Journal of the neurological sciences. 2025. doi:10.1016/j.jns.2025.123469
2. Fakhry R, Yeşildal C, Bártek J, et al. Updated systematic review of current randomised controlled trials in chronic subdural haematoma. Acta Neurochirurgica. 2025. doi:10.1007/s00701-025-06683-5
3. Kabir N, Kabir N, Owais B, Trifan G, Testai F. Efficacy and Safety of Middle Meningeal Artery Embolization for Patients with Chronic Subdural Hematoma: A Systematic Review and Meta-Analysis.. Cerebrovascular diseases (Basel, Switzerland). 2025. doi:10.1159/000543041
4. Scerrati A, Visani J, Ricciardi L, et al. To drill or not to drill, that is the question: nonsurgical treatment of chronic subdural hematoma in the elderly. A systematic review. Neurosurgical FOCUS. 2020. doi:10.3171/2020.7.focus20237
5. Wang AP, Shakil H, Ragulojan M, et al. Middle Meningeal Artery Embolization for Subdural Hematoma: Systematic Review and Meta-Analysis of Randomized Trials.. The Canadian journal of neurological sciences. Le journal canadien des sciences neurologiques. 2025. doi:10.1017/cjn.2025.10467
6. Zhang Z, Lim JX, Wen D, Wong CP, Lim WEH, Chia GS. Adjunct Middle Meningeal Artery Embolization Versus Surgery for Chronic Subdural Hematoma: A Systematic Review and Meta-Analysis.. Neurosurgical review. 2024. doi:10.1007/s10143-024-03107-3
7. Monteiro GDA, Mutarelli A, Gonçalves OR, et al. Middle meningeal artery embolization for chronic subdural hematoma: a meta-analysis of randomized controlled trials with trial sequential analysis.. Neurosurgical review. 2025. doi:10.1007/s10143-025-03464-7
8. Mortezaei A, Al-Saidi N, Yahyaei K, et al. Middle meningeal artery embolization versus standard of care for chronic subdural hematoma: Meta-analysis of randomized controlled trials.. The neuroradiology journal. 2025. doi:10.1177/19714009251389579
