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The treatment of a subdural hematoma received a major boost with three new randomized controlled trials all showing large and significant benefits of a new embolization process done as an endovascular procedure, reducing the need for surgery.

Compared with medical therapy alone, the embolization process was shown to reduce the rate of hematoma progression or recurrence and/or the need for surgery in patients with smaller subdural hematomas and to reduce the need for repeat surgery in those with larger hematomas who had undergone initial surgical treatment.

The EMBOLISE and MAGIC-MT trials, which used the Onyz embolization product manufactured by Medtronic, and the STEM trial, which used the Squid embolization product manufactured by Balt, were reported at last week's International Stroke Conference (ISC) 2024 held in Phoenix, Arizona.

'A Landmark Moment'

Chair of the ISC 2024 meeting, Tudor Jovin, MD, chief of neurology at Cooper Medical School of Rowan University, Camden, New Jersey, described the three trials reporting at the same time as "a landmark moment in the treatment of subdural hematoma."

Jovin, who was not involved in the research, compared the situation to the time several years ago when the first positive endovascular trials of thrombectomy in large vessel occlusion stroke were reported.

"This is for subdural hematoma the 2015 thrombectomy moment," he told theheart.org | Medscape Cardiology.

"All these three trials are positive. They are essentially showing the same thing and provide strong class 1 level evidence that endovascular treatment for subdural hematoma is strongly beneficial," Jovin commented. "I'm delighted to see these results. They will change practice, I'm 100% convinced of that."

A Common Condition

A subdural hematoma occurs when a blood vessel in the space between the covering of the brain, the dura, and the brain itself, known as the subdural space, is damaged, often after a knock to the head. Blood leaks into the subdural space exerting pressure on the brain. Symptoms can include headache, cognitive impairment, dysarthria or dysphasia, ataxia or unsteadiness, paresis, sensory loss, and seizures.

Subdural hematoma is a common condition, with an incidence in the general population estimated at 1-21 per 100,000 individuals per year. Older people have high risk, with an estimated incidence of 7-74 per 100,000 individuals in those aged over 65. The condition is increasing as the population ages and is predicted to be the most common cranial neurosurgical condition among adults by 2030.

Co-lead investigator of the EMBOLISE study, Jason Davies, MD, a neurosurgeon from the State University of New York, Buffalo, New York, explained to theheart.org | Medscape Cardiology that as people age, the brain shrinks, causing the blood vessels connecting the brain and the dura to become stretched and more vulnerable to leaking.

Traditional treatment of a subdural hematoma involves surgery to remove the fluid and breakdown products from the dural space, but this is an invasive procedure and can have many complications, especially in the elderly, and there are still rates of recurrence requiring treatment of around 12%-20%.

The new embolization products consist of an organic solvent containing particles that form a solution that solidifies when mixed with blood. This is delivered via a transcatheter procedure to the middle meningeal artery (MMA) that supplies the leaking vessels in the subdural space. The embolization product then solidifies and blocks the arteries supplying blood to the dura.

"Essentially, we are gluing shut the artery that feeds the dura," Davies said.

EMBOLISE Trial

Davies presented preliminary results from the EMBOLISE study, along with fellow co-lead investigator Jared Knopman, MD, associate professor of neurological surgery at Weill Cornell Medical College, New York City.

The EMBOLISE study included patients with both surgical and nonsurgical subdural hematoma, but the current presentation focused only on the surgical cohort, as the nonsurgical part of the trial is still underway.

"In the EMBOLISE trial, MMA embolization with the Onyx product led to an almost threefold reduction in need for repeat surgical drainage of the subdural hematoma," Knopman reported.

The surgical arm of the study included 400 patients from across the United States with a subdural hematoma who met criteria for surgical evacuation and were randomized to receive surgery alone (control group) vs surgery with adjunctive MMA embolization using the Onyx device.

The primary endpoint was the rate of hematoma recurrence/progression requiring repeat surgical drainage within 90 days.

This occurred in 4.1% of the embolization group vs 11.3% of the control group (relative risk, 0.36; P = .0081).

The secondary clinical endpoint of deterioration in neurologic function (as measured on the modified Rankin scale [mRS]) at 90 days was noninferior in the Onyx group (11.9%) vs 9.8% in the control (P for noninferiority = .0022).

In terms of safety, serious adverse events related to the embolization procedure occurred in 2% of patients, but there were no serious adverse events related to Onyx device.

Neurologic death occurred in 4.6% of the embolization group and 2.0% of the control group, a nonsignificant difference (P = .17). There was also no difference in rates of stroke (2.0% in the embolization group vs 1.5% in the control group, P = .72).

"Adjunctive MMA embolization with Onyx was associated with significantly reduced rates of reoperation without compromising neurologic function or safety," Knopman concluded. "MMA should be considered for patients presenting with symptomatic subacute/chronic subdural hematoma requiring surgery."

The other two studies presented — MAGIC-MT and STEM — reported on both the surgical and nonsurgical cohorts of patients with subdural hematoma.

MAGIC-MT

The MAGIC-MT trial, which also use the Onyx embolization product, was presented by Ying Mao, MD, Huashan Hospital, Fudan University, Shanghai, China.

The trial enrolled 722 patients with a subdural hematoma across 31 centers in China. They were randomized to the current standard of care — surgery or medical management alone (control group) or MMA embolization.

The primary outcome was symptomatic subdural hematoma recurrence (defined as a hematoma exceeding 10 mm or re-operation in patients who received surgery) or progression (a hematoma increasing over 3 mm compared to the baseline or surgical rescue in the medical management group) within 90 days.

This occurred in 7.2% of the embolization group vs 12.2% of the control group (P = .02).

Subgroup analysis suggested that the benefit of the embolization procedure appeared greater in the nonsurgical patients.

Among these medically managed patients, symptomatic subdural hematoma progression occurred in 1.9% of the embolization group vs 4.7% of controls.

In the surgical group, a symptomatic subdural hematoma recurred in 4.7% of the embolization group vs 5.2% of controls.

In terms of secondary endpoints, functional outcomes as measured by the mRS were similar in embolization and control patients, with both groups showing a median mRS score of 0 at 90 days, indicating that most patients recovered well, Mao reported.

Serious adverse events occurred in fewer patients receiving embolization (6.6%) than in controls (11.6%).

"Among patients with symptomatic nonacute subdural hematoma, addition of middle meningeal artery embolization is superior to usual care alone, producing less hematoma recurrence or progression, or death within 90 days," Mao concluded.

STEM Trial

Finally, the STEM trial was presented by Adam Arthur, MD, chair of neurosurgery at the University of Tennessee Health Science Center, Memphis, Tennessee.

The trial enrolled 310 patients (mainly from the United States) with symptomatic chronic subdural hematomas who were designated as appropriate for either medical management or surgical drainage. They were then randomized to either standard therapy (medical management or surgery, which was the control group) or standard therapy plus embolization with the Squid device.

The primary endpoint was failure of treatment defined as residual or re-accumulation of the subdural hematoma (> 10 mm), re-operation (in the surgical group) or surgical rescue (in the nonsurgical group), or major disabling stroke, myocardial infarction, or death from any cause within 6 months of randomization.

This primary endpoint occurred in 39.2% of the standard management groups vs 15.2% of the group who received standard management pus embolization therapy, giving an odds ratio for treatment failure of 3.60 (P = .0001).

Safety outcomes at 30 days of all-cause death or major disabling stroke were similar in the two groups.

Benefit of the embolization procedure was seen in both the surgical and nonsurgical patient populations.

In the surgical group, the primary endpoint occurred in 25.4% of control patients vs 12.3% in those that received embolization (odds ratio, 2.4; P = .058).

In the nonsurgical arm, the primary endpoint occurred in 59.2% of control patients vs 19.1% in those receiving embolization (odds ratio, 6.1; P = .0001).

"These data show that this embolization procedure should enable many patients with subdural hematoma to avoid having surgery altogether. And in the patients with larger hematomas who have to have surgery, use of these embolization products will lower the risk of repeat surgery being needed," Arthur told theheart.org | Medscape Cardiology.

"These preliminary data are exciting and likely offer a large step forward in the treatment of a very common disease that is becoming even more frequent as the population ages," he added.

The EMBOLISE trial was sponsored by Medtronic. The MAGIC-MT trial was funded by Huashan Hospital, affiliated to Fudan University, and Shanghai Changhai Hospital. The STEM trial was sponsored by Balt.