• Subdural
• Embolic
• Liquid Embolic Material

In the recent editorial on middle meningeal artery embolization for chronic subdural hematoma,1 Levitt et al assert that the three recently published randomized trials of middle meningeal artery embolization (MMAE) indicate that the treatment is effective and should be considered routinely in the course of clinical care, particularly as an adjunct to surgical treatment. I have great admiration for the trialists and the hard work and expertise that completing these trials required. We must not allow our enthusiasm for this procedure to blind us to the actual results of this high quality research.

First, MAGIC-MT (Managing non-acute subdural hematoma using liquid materials: a Chinese randomized trial of middle meningeal artery treatment) is a negative trial.2 There was no statistically significant difference in the primary endpoint of symptomatic recurrence or progression of the subdural hematoma. The numerical difference in favor of the treatment group was a mere 2.2%, and only 0.5% in the group that had surgical drainage. Second, there was no difference in neurological outcomes, as measured by the modified Rankin Scale score or health related quality of life scores, and no difference in hospital length of stay or readmission rate. Third, there was absolutely no difference in subdural hematoma thickness, volume, or midline shift at 90 days. If MMAE does not reduce the size of the subdural hematoma, how is it proposed to work? Exactly what benefit was achieved by the addition of MMAE to the treatment group?

The EMBOLISE (Embolization of the Middle Meningeal Artery With ONYX Liquid Embolic System for Subacute and Chronic Subdural Hematoma) trial demonstrated that the addition of MMAE to surgical drainage in the treatment group resulted in 7.2% absolute reduction in the need for a second surgery.3 The number needed to treat was 14. As in Magic-MT, the addition of …