Novel Combination of Surgery and Embolization for Subdural Hematoma Reduces Risk of Recurrence

By 2030, chronic subdural hematomas are expected to become the most prevalent cranial neurosurgical condition globally. Symptoms of a subdural hematoma, such as weakness, numbness, headaches, nausea, confusion, or dizziness, may develop slowly over days or weeks, often following a fall or other head injury. For over a century, doctors have treated symptomatic subdural hematomas through surgery, typically by creating a small hole in the skull or removing a portion of the skull to drain the blood. However, even after the blood is drained, the hematoma can recur about 15% of the time, requiring another surgery and extended hospitalization. This recurrence happens because the hematoma recruits arterial blood vessels that supply it, meaning the condition can return even after surgical drainage. This poses a particular challenge for older patients, who are the primary group affected by chronic subdural hematomas.

Now, researchers at Weill Cornell Medicine (New York, NY, USA) and the University at Buffalo (Getzville, NY, USA) have discovered that a novel combination of surgery and embolization can reduce the risk of recurrence and the need for follow-up surgeries. Embolization is a minimally invasive technique that involves blocking specific blood vessels to halt abnormal bleeding. This discovery comes from the EMBOLISE trial, a multi-center, randomized clinical study that compared the recurrence rates of chronic subdural hematomas in patients treated with surgery and middle meningeal artery (MMA) embolization versus the standard treatment of surgery alone. The study was sponsored by Medtronic (Dublin, Ireland), the company that produces Onyx, the embolic agent used in the treatment group. The MMA embolization procedure involves inserting a small catheter into the middle meningeal artery, which runs through the membranes covering the brain. This catheter delivers an embolic agent that blocks the blood vessels feeding the hematoma. The researchers had previously developed the MMA embolization procedure and published successful preliminary results in 2019.

In their latest research, published in the New England Journal of Medicine, the researchers showed that the combination of MMA embolization and surgery significantly reduced the recurrence of hematomas and the need for additional surgeries. Only about 4% of patients who underwent MMA embolization and surgery experienced recurrence or progression leading to another surgery, compared to more than 11% of patients who had surgery alone. Between December 2020 and August 2023, the study involved 400 adults with chronic subdural hematomas from 39 medical centers. The average age of the patients was 72, and they were randomly assigned to receive either MMA embolization plus surgery (197 in the treatment group) or surgery alone (203 in the control group). Within 90 days of the initial surgery, 4% of the treatment group experienced recurrence or progression requiring another surgery, compared to 11.3% in the control group. Serious adverse events related to MMA embolization occurred in 2% of the patients who underwent the procedure. Researchers are now exploring the potential role of upfront MMA embolization in treating smaller chronic subdural hematomas that may not require surgery. As this may become one of the most common procedures performed by neurosurgeons in the next decade, it holds the potential to lower healthcare costs and improve outcomes for the aging population.

“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 and pioneer of MMA embolization, Dr. Jared Knopman, director of Cerebrovascular Surgery and Interventional Neuroradiology, an associate professor of neurological surgery at Weill Cornell Medicine. “If we embolize these patients early, we may decrease the number who need to be taken to surgery later. 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.”