UT Dallas researchers use virtual reality to help amputees with phantom limb pain

UT Dallas researchers use virtual reality to help amputees with phantom limb pain

Every morning and every evening for a month, Dean Peterson put on virtual reality glasses to help him fall asleep. Once a heavy sleeper, he hadn’t slept well since having his left leg amputated in 2005.

The carpenter and former Navy combat medic tossed and turned in his bed, kept awake by pain where his leg was supposed to be. The sensation, known as phantom limb pain, was manageable with the distractions of the day, but the silence of the night made it hard to ignore.

Sometimes the brain sends signals to a missing limb, causing feelings like itching or cramping, but there is no way for the amputee to relieve this feeling. Researchers at the University of Texas at Dallas designed the software to help people who have lost a limb trick their brains into thinking the missing limb is still there and can be moved without discomfort.

When he looked at the VR screen, Peterson saw himself with the two legs he used to play games like popping virtual bubbles with his feet or tapping colorful, moving circles.

After a few weeks of using the technology, called the Mixed Reality System for Phantom Pain Management, or Mr. MAPP, Peterson found he was falling asleep faster. It worked so well that he didn’t want to return the technology at the end of the study.

“I fall asleep easier than before,” Peterson said. “I have already let them know that when they are ready for the next phase of testing, to sign me up.”

Mr MAPP is a modern approach to mirror therapy, a tool that has been used for decades to help amputees visualize their missing limb and minimize the pain that occurs when the brain tries to send nerve signals to part of the body that is no longer there. An estimated 80% of them experience some form of phantom limb pain, according to the Cleveland Clinic.

Balakrishnan Prabhakaran and his team at UT Dallas are still tinkering with the device, but the computer science professor said MAPP has the potential to give amputees an even more realistic treatment option that could reduce the need medical painkillers.

Prabhakaran partnered with the North Texas Veterans Health Care System to produce the therapy and conduct a pilot trial with 12 Dallas VA Medical Center patients. For four weeks, patients used a laptop, camera and VR headset to generate a 3D model of their missing limb.

Retired Navy veteran Frederick Dean Peterson (left), with the help of UTD Ph.D. candidate...
Retired Navy veteran Frederick Dean Peterson (left), with the help of UTD Ph.D. candidate Yo-Yen Chung, demonstrated a new therapy, called Mr.MAPP (system of mixed reality for phantom pain management) at the University of Texas at Dallas in Richardson on Monday, November 28, 2022. Peterson participated in the clinical trial of the therapy which helps users by creating a virtual image of their missing limbs. (Shafkat Anowar / Personal Photographer)

The software includes three exercises that require the leg to make different movements. These exercises come in the form of games, and the software keeps track of the number of tasks completed successfully, such as popping bubbles or pressing pedals.

One of the games plays a sound each time the patient hits a virtual colored circle on the floor.

“That’s part of the motivation with this one. You hit a button on the floor and it makes a little tone, and that actually makes it pretty fun,” Peterson said.

Peterson and the other study participants provided detailed feedback to the UT Dallas team on what worked and what didn’t. He found playing the game in shorts and without shoes was more effective because he saw “flesh and blood”, which made the games feel more real.

Mr. MAPP is easy to use, Peterson said, even though he had never tried a virtual reality system before. The biggest challenge was keeping her pup away from the device when doing her exercises.

The researchers are still working on some bugs in the software and trying to make it as appealing as possible. Yu Yen Chung, who holds a doctorate in computer science. candidate working on the project, redesigned the camera setup so patients could see themselves in first person, rather than having to look at themselves as they would in a mirror.

Being able to look down and see both legs can help the body communicate better with the brain, Chung said. The first-person perspective has yet to be rolled out to patients, although the team intends to start testing it soon.

Despite the excitement surrounding the technology’s success, Peterson said he was hesitant to tell other amputees in the tight-knit community about the loss of a limb from participating in the trial for fear of raising their hopes. .

UTD Assistant Professor Dr. Balakrishnan Prabhakaran talks about a new therapy, called...
UTD Assistant Professor Dr. Balakrishnan Prabhakaran talks about a new therapy, called M.MAPP (Mixed Reality System for Phantom Pain Management) at the University of Texas at Dallas in Richardson on Monday, November 28 2022. Therapy that helps the user by creating a virtual image of a missing limb. (Shafkat Anowar / Personal Photographer)

Although there are other treatments for phantom limb pain, ranging from mirror therapy to prescription painkillers to spinal surgery, the results are mixed and can even be dangerous. Peterson has tried mirror box therapy before but found no relief.

For some people, the pain can be debilitating.

“It’s something very real, just like, say, you hit your finger with a hammer and feel that kind of pain. Phantom limb pain can be just as real as any of those pain sensations. for specific individuals with no mechanism or ability to fix it,” said Jared Howell, director of the Center for Prosthetic and Orthotic Care at Baylor College of Medicine.

The highly addictive opioid medications sometimes prescribed for phantom pain relief can come at a high cost. A February study of more than 2,000 lower limb amputees found nearly 55% were using opioids at the time of their surgery and nearly 45% had prolonged opioid use.

“The opioid crisis is really a threat,” Prabhakaran said. “The problem with the way the drug works is that it rewires your brain. And, in this case, we’re not rewiring our brain. We’re tricking the brain, but we’re not rewiring it in a harmful way. .

One patient in the trial reported that after using Mr MAPP, he stopped taking pain medication. Whenever he felt the urge to take the drug, he would play the game, Prabhakaran said.

“It really made us feel really good because in the opioid crisis so many people are getting addicted,” Prabhakaran said. “If we can make a difference to this crisis, then we should.”

UT Dallas and Veterans Affairs have secured a provisional patent for Mr. MAPP with hopes of finalizing the full patent trial in late winter or early spring 2023. The team is already working to find a partner for license the technology and bring it to market as early as next year.

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