Adjunctive middle meningeal artery embolization reduces treatment failure for chronic subdural hematoma

New research by Society of Neurolnterventional Surgery (SNIS) members found that adjunctive middle meningeal artery embolization (MMAE) for the treatment of chronic subdural hematoma (CSDH) resulted in a lower risk of treatment failure than standard treatment alone, without resulting in an increased incidence of disabling stroke or death in the short term. 

Following preliminary findings presented at the International Stroke Conference, the final results of the Squid Trial for the Embolization of the Middle Meningeal Artery for the Treatment of Chronic Subdural Hematoma (STEM) published in the New England Journal of Medicine (NEJM) demonstrate MMAE to be a beneficial adjunctive treatment for CSDH, cutting the overall rate of failure from 36% to 16%. 

In light of these findings, SNIS is urging the field to consider MMAE as they plan treatment protocols, ensuring eligible CSDH patients have access to this safe and effective treatment. 

CSDH is associated with significant morbidity and mortality, resulting in a tremendous health care resource burden in the U.S. This disorder refers to the gradual accumulation of blood over the surface of the brain, primarily affecting elderly patients. As the U.S. population continues to age, studies show that CSDH may be the most prevalent neurosurgical diagnosis that requires treatment within the next decade. 

The existing standard of care for treating CSDH has a high rate of surgical failure. It involves either drilling holes into the skull to drain the blood (i.e., surgical management) or watchful waiting with various medical interventions (i.e., non-surgical management) for patients who do not require early surgical intervention and/or are poor surgical candidates. However, an average of 10% to 30% of patients experience recurrence of CSDH after surgery, often necessitating reoperation. Studies like STEM show these surgical failure rates are higher among elderly patients, and failure rates among patients initially managed non-surgically are reported to be even higher. 

The technically straightforward and minimally invasive MMAE procedure is performed using small catheters inserted through a blood vessel in the arm or leg. These small catheters are then navigated into the middle meningeal artery and liquid agents are injected into these blood vessels, solidifying within them (like a glue), blocking them off and stopping the chronic bleeding into the subdural space. 

Adjunctive MMAE with liquid agents started in 2018 with two members of SNIS who went on to lead the pivotal STEM trial (sponsored by BALT USA) -; former SNIS President Adam Arthur, MD, MPH and David Fiorella, MD, PhD. 

The final results of STEM demonstrate the positive impact that adjunctive MMAE can have in the lives of CSDH patients, giving them the best possible odds of a successful treatment. This is a significant achievement for the field of neurointerventional surgery." 

Dr. David Fiorella, MD, PhD, professor of neurosurgery, Stony Brook University

It is important to acknowledge that STEM was performed under investigational device exemptions within the context of an FDA-regulated prospective clinical trial. No liquid embolic agent currently has FDA clearance for MMAE and regulatory review is pending. 

"This treatment represents a major shift in the management of this disease," said Dr. Arthur, chair of neurosurgery at the University of Tennessee Health Sciences Center and Semmes-Murphey Clinic. "As neurointerventionalists and neurosurgeons, we strive to provide the best for our patients through evidence-based, effective and minimally invasive strategies. My SNIS colleagues are continually working together to challenge the status quo and advance the field. There are other important studies of this treatment underway and we hope to do a combined analysis in the near future. I look forward to what's to come."