A novel treatment combining surgery with middle meningeal artery (MMA) embolization significantly reduces the recurrence of chronic subdural hematomas. The new technique from the EMBOLISE clinical study, published yesterday in the New England Journal of Medicine, has the potential to significantly change treatment approaches for the condition, which is projected to become the most common cranial neurosurgical disease by 2030.
“This trial provides evidence that adding MMA embolization should be a new standard of care for one of the most common neurosurgical conditions we see,” said co-lead author Jared Knopman, MD, a pioneer of MMA embolization and a neurosurgeon at NewYork-Presbyterian Weill Cornell.
MMA embolization involves inserting a catheter into the middle meningeal artery, delivering a liquid embolic agent to block blood vessels feeding the hematoma. This prevents its recurrence by halting the supply of arterial blood that sustains it.
Subdural hematomas—collections of blood and fluid between the brain and its protective covering—often result from trauma. Chronic cases develop gradually, with symptoms such as weakness, headaches, and dizziness potentially emerging weeks after minor head injuries, especially in older adults. Current treatments primarily involve surgical drainage of the blood, but recurrence rates of up to 20% often require additional procedures.
The EMBOLISE clinical study, led by Knopman and Jason Davies, MD, PhD, associate professor of neurosurgery in the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, enrolled 400 patients with chronic subdural hematomas from 39 medical centers between December 2020 and August 2023. Participants, who had a mean age of 72, were randomized into two cohorts—one group received MMA embolization alongside surgery, while the other received surgery alone. Results showed that recurrence requiring additional surgery occurred in just 4% of the embolization group, compared to 11.3% in the surgery-alone group.
“We are changing subdural hematoma from being a disease that commonly requires multiple surgeries to a disease that can be better treated with a simple, minimally invasive procedure that produces better outcomes.”
Complications from the embolization procedure were rare, with serious adverse events occurring in 2% of patients. The liquid embolic agent used in the trial, Onyx, was supplied by Medtronic, which sponsored the study.
The study also highlighted the challenges faced by older adults with subdural hematomas, particularly those on blood thinners, which increase the risk of bleeding. “A patient with a chronic subdural hematoma who is on a blood thinner presents an even more complicated picture,” said Davies. “If you are on a blood thinner, once you start bleeding, you’re not going to stop.”
In addition to reducing the need for repeat surgeries, MMA embolization may have broader implications for patient care.
“Considering chronic subdural hematomas are more likely to develop in people aged 60 and older, the need for treatment in our aging population is growing,” said Knopman. He also noted the potential of upfront embolization to treat smaller hematomas that do not yet require surgery, possibly preventing the need for invasive procedures altogether.
For both researchers, the findings represent a significant advancement in understanding the condition. “In addition to demonstrating the role that the middle meningeal artery plays in the formation and recurrence of subdural hematomas, we have discovered an entirely new facet about the brain that has gone unknown and untreated for decades,” Knopman concluded.
