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Neuro Update

Penn State Health Neurosurgery participates in groundbreaking SQUID trial for treatment of chronic subdural hematomas

Chronic subdural hematomas (cSDH) are most prevalent in elderly patients, with a peak onset age of 80.1 This presents challenges for neurosurgeons, as older patients have higher rates of morbidity, and those with cSDH often have poor long-term outcomes.2

Traditional treatment pros and cons

Although burr hole drainage is often a successful method of treatment, it comes with significant drawbacks.

“The traditional treatment of burr hole drainage is highly effective, but it is plagued by a high recurrence rate,” said Dr. Ephraim W. Church, assistant professor of neurosurgery, neurology and radiology in the Department of Neurosurgery at Penn State College of Medicine and director of the Cerebral Revascularization Program at Penn State Health Milton S. Hershey Medical Center. “Recurrence can be as high as 20% to 30%. Often these patients are elderly, and repeated brain surgeries take their toll.”

Additionally, burr hole or craniotomy may not be an option for certain patients, including those on blood thinners, patients who have thrombocytopenia and those who are critically ill.

A new alternative

As part of a pivotal international randomized and controlled clinical trial, Penn State Health is performing a new leading-edge treatment for cSDH called middle meningeal artery (MMA) embolization. Church and his team were the first to perform the procedure using SQUID technology in the state of Pennsylvania.

The goal of the SQUID Trial for the Embolization of the Middle Meningeal Artery for Treatment of Chronic Subdural Hematomas (STEM) is to evaluate the safety and efficacy of SQUID, a nonadhesive liquid embolic device. Made from ethylene vinyl alcohol copolymer dissolved in dimethylsulfoxide, it is designed for the embolization of lesions in the peripheral and neurovasculature.

“MMA embolization is a highly promising treatment that could potentially revolutionize our ability to care for patients with cSDH safely and effectively,” Church said. “We viewed our involvement in the trial as absolutely essential to help move our field forward and improve patient care.”

Patients in the trial receive monitored anesthesia care or general anesthesia, and then surgeons guide a .017-inch embolization catheter through the femoral or radial artery and into the MMA.

“We believe that neovascularization of tiny branches from this vessel supply membranes within the cSDH and contribute to growth and recurrence,” Church said. “By injecting a tiny amount of SQUID surgical glue in the vessel, we can shut down supply to the blood collection.”

Unlike those who undergo traditional burr hole drainage, patients who received this treatment had significantly less chance of cSDH recurrence.

“The way I describe this to patients is we are turning off the faucet that supplies the cSDH collection. The traditional treatment, burr hole drainage, removes the collection but doesn’t turn off the faucet,” Church said. “While MMA embolization doesn’t make the collection go away immediately, over the coming weeks and months, the patient’s body is able to remove the collection and heal.”

Clear advantages

Early results from the procedure show promising potential for this procedure to become a new standard of care for patients with cSDH.

“The preliminary data indicate that catheterizing and embolizing the MMA through the femoral or radial artery effectively and safely treats cSDH with a very low recurrence rate,” Church said. “At Penn State Health, we have seen excellent outcomes without significant complications.”

Other studies have revealed similarly positive results.2

“These studies have shown that MMA embolization may cut recurrence and failure rates by 75%, and complication rates are 50% less than traditional burr hole drainage,” Church said. “Potentially, this treatment could completely change the way cSDH is managed.”

MMA embolization is a minimally invasive procedure without the risks of burr hole drainage, making it a viable option to a much wider range of patients. It also offers immediate benefits, including a procedural timeframe of less than an hour from start to finish and faster recovery. Most patients spend one night in the hospital, and some go home the same day. Burr hole drainage requires several days in the hospital with a higher risk of complications.

“Whether this treatment will represent an improvement over traditional treatments remains to be proven in the randomized trial, but initial results are promising,” Church said. “We could potentially offer a more effective and safer operation for patients with this condition.”

Sponsored by Balt USA, the trial began in November 2020 and is currently underway at 27 facilities across the United States, France, Germany and Spain.

Church and his team at Penn State Health are continuing to recruit for participants in the study.

A head-and-shoulders photo of Ephraim W. Church, MD, FAANS

Ephraim W. Church, MD, FAANS

Assistant Professor of Neurosurgery, Neurology and Radiology
Director, Cerebral Revascularization Program
Phone: 717-531-0895
Fellowship: Cerebrovascular Neurosurgery, Stanford University Medical Center, Stanford, Calif. Endovascular Neurosurgery, Penn State Health, Hershey, Pa.
Residency: Neurosurgery, Penn State Health, Hershey, Pa.
Medical School: University of Pennsylvania School of Medicine, Philadelphia
Connect with Ephraim W. Church, MD, FAANS, on Doximity


  1. Uno M, Toi H and Hirai S. Chronic subdural hematoma in elderly patients: Is this disease benign? Neurologia medico-chirurgica. 2017 Aug; 57(8): 402–409. doi: 10.2176/nmc.ra.2016-0337
  2. Cristofori AD, Remida P, Patassini M, et al. Middle meningeal artery embolization for chronic subdural hematomas: A systematic review of the literature focused on indications, technical aspects, and future possible perspectives. Surgical Neurology International. 2022; 13: 94. doi: 10.25259/SNI_911_2021
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