BUFFALO, N.Y. -- A dramatic, threefold reduction in repeat operations in patients surgically treated for chronic subdural hematoma was achieved when the artery supplying the brain covering was blocked, according to results of a national clinical trial led by neurosurgeons at the University at Buffalo and Weill Cornell Medicine that was published Nov. 21 in the New England Journal of Medicine.

"We are changing the way that we are treating this very common disease," says Jason M. Davies, MD, PhD, corresponding author and associate professor of neurosurgery in the Jacobs School of Medicine and Biomedical Sciences at UB. "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."

Led by Davies and Jared Knopman, MD, associate professor of neurological surgery at Weill Cornell Medicine, the EMBOLISE trial followed 400 participants at 39 community and academic hospitals with chronic/subacute subdural hematoma, 197 of which were randomized to the treatment group and 203 to the control group. Their average age was 72. Of the 400 patients, 40 were enrolled through UBMD Neurosurgery and treated through the Gates Vascular Institute.

"The problem we wanted to address was whether or not we could change the way we treat this disease that's very common in the elderly," says Davies. "Our study found a threefold reduction in the rates of recurrence. So, for every hundred patients who undergo treatment for this disease, we've reduced the number of recurrences from about 11 to about four."

Common in older adults

Subdural hematomas are collections of blood and fluid that accumulate between the surface of the brain and the protective covering around it, called the dura. They typically result from head injuries, and there are two types: acute and chronic. Acute subdural hematomas result from traumatic injuries, such as car accidents, and are the most serious type.

The study dealt only with chronic subdural hematomas, which can result either from a head injury or because of normal aging. As we age, the brain atrophies so that veins that connect the surface of the brain to the dura may become stretched and leaky, leading to a subdural hematoma. And even if someone experiences a mild fall from which they immediately recover, that fall can jar the brain and cause a hematoma to form.

Complications from blood thinners

Already quite common in older adults, Davies notes that by 2030, chronic subdural hematomas are expected to be the most common cranial neurosurgical disease in the world. What complicates the picture for older patients is that they often have other medical problems, some of which require them to be on blood thinners.

"A patient with a chronic subdural hematoma who is on a blood thinner presents an even more complicated picture," says Davies. "If you are on a blood thinner, once you start bleeding, you're not going to stop."

Symptoms of a chronic subdural hematoma can come on slowly over days or weeks, sometimes after a fall that at first didn't seem serious. Symptoms include weakness, numbness, headaches, nausea, confusion or dizziness.

"These hematomas often get bigger over time and can be very irritating to the brain, exerting more pressure and preventing the brain from functioning properly," says Davies.

Although some chronic subdural hematomas may heal on their own, many older adults with chronic subdural hematomas will require surgical drainage of the blood and fluid through craniotomy, which involves drilling a small hole into the skull.

"Right now, the problem is that in up to 20% of these patients who require surgery, the hematoma will come back, so they have to undergo another craniotomy," says Davies. "Every time they go back to the OR, it's going to cause that patient more pain and suffering. It's no fun to have to get a hole in the head. It increases the risk of infection and contributes to an increase in morbidity and mortality, in addition to higher health care costs. So we really want to reduce the number of times they go back to the OR."

In the study, the 197 patients who received the intervention underwent a nonsurgical procedure called middle meningeal artery embolization, aimed at reducing the blood supply to inflamed vascular membranes in the dura. Blocking or essentially gluing shut the artery in the brain that is bleeding resulted in a far lower rate of hematoma recurrence.

To do it, the investigators used Onyx, made by Medtronic, a liquid embolic agent that is used to occlude blood vessels. The liquid is administered non-surgically through the endovascular system via catheterization in the patient's wrist or groin, another important advantage.

Davies says the next phase in the trial involves patients who do not require surgery initially, assessing whether embolization of the middle meningeal artery can avoid the need for surgery in the first place.

"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 added.

"The publication of the EMBOLISE trial results in the New England Journal of Medicine is a testament to the dedication and expertise of the neurosurgeons at the Jacobs School," says Allison Brashear, MD, vice president for health sciences at UB and dean of the Jacobs School. "This significant advancement in treating chronic subdural hematoma, particularly for our elderly population, underscores our commitment to improving patient outcomes through innovative research and clinical excellence."

The paper lists more than 40 co-authors from the participating centers, including Adnan Siddiqui, MD, PhD, vice chair and professor of neurosurgery in the Jacobs School. Both Davies and Adnan Siddiqui are with UBMD Neurosurgery.