Historical collection · First published Nov 20, 2024; added to EM Weekly Oct 27, 2026. This retrospective summary may be superseded by later evidence or guidance.
← All articlesEmbolization of the Middle Meningeal Artery for Chronic Subdural Hematoma
Summary
STEM randomized 310 patients with symptomatic chronic subdural hematoma to adjunctive middle meningeal artery embolization or standard treatment alone after surgical or nonsurgical standard treatment had been selected. In the primary efficacy analysis, the 180-day composite treatment-failure endpoint occurred in 16% with embolization versus 36% with control (OR 0.36, 95% CI 0.20-0.66; P=0.001). Major disabling stroke or death within 30 days occurred in 3% in each group.
Why it matters
Along with EMBOLISE, STEM strengthened the case for MMA embolization as an adjunct in selected symptomatic chronic subdural hematoma patients and helps explain later specialty-guideline adoption. ED clinicians should view this as a consultation and downstream-treatment development rather than a replacement for urgent decompression when clinically indicated.
Study at a glance
- Design
- Randomized trial
- Population
- Adults with symptomatic chronic subdural hematoma for whom surgical or nonsurgical standard treatment had been selected before randomization.
- Sample size
- 310
- Intervention
- Middle meningeal artery embolization as an adjunct to preselected standard surgical or nonsurgical treatment.
- Comparator
- Preselected standard surgical or nonsurgical treatment alone.
- Primary endpoint
- Composite treatment failure within 180 days: recurrent or residual chronic subdural hematoma greater than 10 mm, reoperation or surgical rescue, or major disabling stroke, myocardial infarction, or neurologic death.
Main findings
- The primary efficacy composite occurred in 16% with embolization versus 36% with control (OR 0.36, 95% CI 0.20-0.66; P=0.001).
- Major disabling stroke or death within 30 days occurred in 3% in each group.
- Through 180 days, mortality was 8% with embolization versus 5% with control; neurologic death was 1% versus 2%.
- Of 310 enrolled participants, 189 had surgical and 121 nonsurgical standard treatment selected before randomization.
Limitations
The efficacy endpoint was a composite mixing residual hematoma, reintervention, and major clinical events, and the primary efficacy analysis included fewer patients than the 310 enrolled. Mortality through 180 days was numerically 8% versus 5%, and the trial was funded by Balt USA; other concurrent trials, particularly MAGIC-MT, did not meet their primary efficacy endpoint.
Read the primary source
Full text: Abstract available; full text paywalled.
Original sourcePMID: 39565980
Material reviewed: abstract.
Source retrieved Oct 27, 2026. NEJM publisher metadata verifies publication online on 2024-11-20 even though the print issue was 2025-02-27; PubMed verifies DOI 10.1056/NEJMoa2409845 and PMID 39565980. The publisher abstract and PubMed abstract were reviewed; the full article was not reviewed end-to-end. Later society guidance adopted adjunctive MMA embolization for selected chronic subdural hematoma, but the total randomized evidence remains heterogeneous. No retraction was identified in the targeted cross-check.
Corrections & review history
No corrections recorded. Human review: not yet human-reviewed.