Summary
A look at a new Canadian-led clinical trial showing that EMMA, an additional procedure after surgery for chronic subdural hematoma, dramatically reduces the chance of the brain bleed returning and what it could mean for patients and the health care system.
A brain bleed that comes back after surgery is more common than most people realize and treating it again is costly, risky, and hard on patients. New research led out of Winnipeg may have found a way to largely prevent that from happening in the first place.
The condition in question is called a chronic subdural hematoma: a slow buildup of blood between the brain and its outer covering, most often affecting older adults after a fall or minor head injury. Surgery to drain the blood is standard treatment but the hematoma often returns, sometimes requiring a second operation.
A new Canadian clinical trial, published in JAMA in April 2026, found that adding one additional procedure after surgery dramatically lowers the odds of that happening.
What the Researchers Did
Dr. Jai Shankar, a professor of radiology at the University of Manitoba, led a team that ran a randomized clinical trial across 9 tertiary care centres in Canada, spanning Manitoba, Alberta, Ontario, Quebec, Saskatchewan, Nova Scotia, and British Columbia, between August 2021 and April 2025.
186 patients between the ages of 14 and 88 with a chronic subdural hematoma were split into two groups after undergoing standard surgical drainage. One group received an additional procedure called embolization of the middle meningeal artery, known as EMMA, within 72 hours of surgery. The other group received surgery alone. Both groups were followed for 90 days.
EMMA works by sealing off the blood vessel most responsible for feeding the hematoma, using a liquid embolic agent delivered through a catheter, essentially cutting off the blood supply that allows the hematoma to keep forming or returning.
The Results
The difference between the two groups was stark. Patients who received EMMA in addition to surgery had a recurrence rate of about 4%, compared to 28% in patients who received surgery alone.
The published trial data backs this up precisely: symptomatic recurrence occurred in 4.3% of the EMMA group versus 28% of the control group, a statistically significant difference. When researchers looked at recurrence visible on imaging alone (including cases without symptoms), the gap was still wide: 14% in the EMMA group compared to nearly 50% in the surgery-only group.
Importantly, the rates of serious side effects were similar between both groups, suggesting the added procedure didn’t introduce significant new risk in exchange for its benefit.
Why This Matters Beyond the Numbers
A second surgery isn’t just hard on the patient, but it strains the entire health care system.
As Dr. Shankar put it: “Recurrence is one thing, but more important is that this will reduce the cost that the hospital system will bear for the caring of these patients, and will improve patient care. So overall, it’s good for patients, good for the hospital, good for our health-care system.”
Chronic subdural hematomas disproportionately affect older men, typically between 70 and 80 years old. Men are roughly three times more likely to develop these brain bleeds than women. A treatment that meaningfully reduces the need for repeat brain surgery has real implications for both individual recovery and system-wide capacity.
What Comes Next
This was a large, multi-site, randomized trial, which gives the findings real weight. The next steps will likely involve discussions about whether EMMA should become standard practice alongside surgical drainage for chronic subdural hematoma across Canadian hospitals, and how to scale access to the procedure, which requires specialized interventional radiology expertise not available at every hospital.
For now, the findings represent a significant, made-in-Canada contribution to neurosurgical care, and a rare case where a relatively straightforward addition to an existing procedure produces this large a drop in a serious complication.
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