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EMBOLISE

Adjunctive Middle Meningeal Artery Embolization for Subdural Hematoma

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Year of Publication: 2024

Authors: J.M. Davies, J. Knopman, M. Mokin, ..., for the EMBOLISE Investigators

Journal: New England Journal of Medicine

Citation: N Engl J Med 2024;391:1890–1900

Link: https://doi.org/10.1056/NEJMoa2313472

Clinical Question

Does adjunctive middle meningeal artery embolization reduce the need for reoperation in patients with subacute or chronic subdural hematoma undergoing surgical evacuation?

Bottom Line

Adjunctive middle meningeal artery embolization significantly reduced the risk of reoperation for hematoma recurrence or progression at 90 days. Neurologic outcomes and mortality were similar between groups, and embolization was associated with a 2% risk of serious adverse events.

Major Points

  • 400 patients with symptomatic subacute/chronic subdural hematoma were randomized to surgery alone vs. surgery + middle meningeal artery embolization (MMAE)
  • Primary endpoint (reoperation for recurrence/progression at 90 days) occurred in 4.1% of MMAE group vs. 11.3% of controls (RR 0.36; 95% CI 0.11–0.80; p=0.008)
  • Functional deterioration at 90 days was non-inferior: 11.9% (MMAE) vs. 9.8% (control); risk difference 2.1 percentage points (95% CI −4.8 to 8.9)
  • 90-day mortality was 5.1% (MMAE) vs. 3.0% (control); not statistically significant
  • MMAE-related serious adverse events occurred in 2.0%, including 2 disabling strokes
  • NNT to prevent one reoperation: 14

Design

Study Type: Multicenter, randomized, open-label, blinded-endpoint, adaptive trial

Randomization: 1

Blinding: Blinded endpoint assessment; imaging readers unblinded due to Onyx radiopacity

Enrollment Period: December 2020 – August 2023

Follow-up Duration: 90–180 days

Centers: 39

Countries: United States

Sample Size: 400

Analysis: Intention-to-treat and modified intention-to-treat; multiple imputation; Farrington–Manning test; fixed-sequence testing; SAS v9.4+

Inclusion Criteria

  • Age 18–90 years
  • CT-confirmed subacute or chronic subdural hematoma
  • Indication for surgical evacuation
  • At least one of: neurologic symptoms beyond headache/imbalance/confusion, focal motor deficit, hematoma >15 mm, or midline shift ≥5 mm

Exclusion Criteria

  • Life expectancy <1 year
  • Pre-hematoma modified Rankin scale score 4–5
  • Markwalder Grading Scale ≥3
  • Dangerous vascular anatomy precluding embolization

Arms

FieldMMA Embolization + SurgeryControl
InterventionMiddle meningeal artery embolization using Onyx within 48h of randomization, plus standard surgical evacuation (burr holes or craniotomy)Standard surgical evacuation (burr holes or craniotomy) only
DurationSingle interventionSingle intervention

Outcomes

OutcomeTypeControlInterventionHR / OR / RRP-value
Reoperation for hematoma recurrence or progression within 90 daysPrimary11.3%4.1%7.20%0.008
Functional deterioration at 90 days (mRS ≥3 or worsening)Secondary9.8%11.9%noninferior; not significant
Hospital readmissions within 90 daysSecondary0.3±0.50.3±0.60.60
Serious adverse events at 30 days (embolization-related)Adverse2.0%
Stroke (90 days)Adverse1.5%2.0%0.72
Neurologic death (90 days)Adverse2.0%4.6%0.17
Death from any cause (90 days)Adverse3.0%5.1%0.32
Vision lossAdverse0%0%

Subgroup Analysis

No heterogeneity of treatment effect observed across prespecified subgroups

Criticisms

  • Open-label design with reoperation determined by surgeon may introduce bias
  • Imaging readers could not be blinded due to radiopacity of Onyx
  • 13.2% loss to follow-up may affect robustness
  • Trial not powered to detect differences in stroke or mortality
  • Only Onyx was used—generalizability to other embolic agents is uncertain

Funding

Medtronic

Based on: EMBOLISE (New England Journal of Medicine, 2024)

Authors: J.M. Davies, J. Knopman, M. Mokin, ..., for the EMBOLISE Investigators

Citation: N Engl J Med 2024;391:1890–1900

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