VR Technology Helps Retrain the Brain After Limb Loss
A virtual reality system developed in collaboration with researchers at the University of Georgia is being used to help amputees retrain their brains and reduce phantom limb pain.
The technology was used during the recovery of Lulu Gribbin, a 15-year-old girl from Alabama who lost her left arm and right leg in a shark attack off the Gulf Coast of Florida. Doctors at OrthoCarolina’s Reconstructive Centre for Lost Limbs in Charlotte, North Carolina, used the system during her 77-day stay, as she underwent extensive surgeries to prepare for prosthetics.
The virtual reality technology was developed largely by University of Georgia College of Engineering professor Kyle Johnsen and Ethan Bowmar, who earned his master’s degree in electrical and computer engineering at UGA. They worked with doctors and residents at Axolo Health in North Carolina to develop the technology.
The system was intended to reduce phantom limb pain while helping to prepare the brain for prosthetic use. Gribbin’s experience attracted national attention in 2024 and led to the creation of a foundation in her name to raise money for the technology developed with help from UGA researchers.
Phantom limb pain is the sensation of pain in an arm or leg that has been lost through amputation. After acute or chronic trauma results in limb loss, the brain can continue to expect feedback from the missing limb. When that feedback is no longer available, other parts of the brain begin to fill the gap. The resulting pain can be experienced as burning, cramping, or a sensation of the missing limb being locked in a clenched position.
The technology developed by Axolo Health uses virtual and augmented reality to address that problem by retraining the brain after amputation. Company members worked with Johnsen and Bowmar to create VR and XR software and a headset that enables patients to see and manipulate a representation of their missing limb. The artificial presence is designed to help re-establish neural pathways and reduce phantom pain.
Axolo Health was founded by Ryan Serbin, an orthopaedic resident physician and researcher, alongside attending physicians Dr Glenn Gaston and Dr Bryan Loeffler and fellow orthopaedic resident Ty Frix. Gaston is a UGA graduate. Frix earned his undergraduate engineering degree at UGA, a master’s degree from the Terry College of Business, and his Doctor of Medicine from the Augusta University/UGA Medical Partnership.
Frix also played as a long snapper for UGA’s football team from 2009 to 2013 and served as a link between the university and the company through UGA’s innovation ecosystem.
Before the current work began, Frix had worked with Johnsen on a start-up that used Fitbits to track people in healthcare facilities. He later taught an elective engineering entrepreneurship class at UGA. After completing his master’s degree, he entered medical school and later undertook his residency under Gaston and Loeffler at OrthoCarolina.
The idea for the VR treatment developed after a long-term amputee patient described using a family member’s virtual reality headset. The patient had been able to see a virtual hand and experienced relief from phantom pain. Gaston and Loeffler began considering how the technology could be developed into a treatment, and Frix connected them with Johnsen, who ran UGA’s virtual reality laboratory.
Johnsen travelled to Charlotte and worked on an early version of the system designed for a single patient. After receiving positive feedback, the group began developing a broader VR application. The team then applied for a presidential seed grant and received additional funding from UGA to develop a more clinical version of the technology.
Serbin also took a year away from his residency to focus on orthopaedic research and emerging technologies. During that time, he reviewed hundreds of research papers on established approaches to phantom limb pain, including mirror therapy and Australian work on Graded Motor Imagery.
The work with Johnsen and Bowmar led to a four-phase VR therapy known as Targeted Brain Rehabilitation, or TBR. The system is hands-free and controlled through the user’s gaze. It uses guided exercises intended to retrain the brain through techniques supported by clinical trials to reduce discomfort and restore a sense of control.
Axolo licenses the current TBR software from UGA through Innovation Gateway, the university’s technology transfer hub.
The first phase teaches users to identify whether a displayed hand is right or left. The second phase is meditative and requires the patient to imagine an amputated hand moving again. The third phase uses mirror therapy, with movement of the intact limb reflected so that the patient perceives it as the missing limb. The fourth phase focuses on moving the amputated limb itself, making virtual reality a central part of the treatment.
Doctors and residents at the North Carolina clinic worked closely with Johnsen and Bowmar as each phase was developed. The collaboration brought together researchers, physicians and former university colleagues, while Bowmar later became Axolo’s first employee.
Results from the collaboration have been reported as promising. In single-session VR use, relief from phantom limb pain has lasted about six to eight hours, described as essentially the same duration as relief from an opioid or anti-inflammatory pain medication.
Trials involving between 60 and 70 upper-extremity amputees have also shown reductions in reported pain. Acute patients, defined in the source as people who have recently undergone amputation, had average pre-treatment pain scores of 9 and reached scores of about 2 after treatment. Chronic patients reported reductions of more than 50 per cent.
The technology has been registered with the US Food and Drug Administration as a Class II Software as a Medical Device. The team is also working on a study that would allow amputees to take VR headsets home and follow a six-week treatment protocol.
The approach is based on the idea that repeated use could train the brain over a longer period. The researchers are also studying whether early intervention could limit the cortical remodelling associated with persistent phantom limb pain and prevent maladaptive changes that contribute to long-term symptoms.
Further work is needed for applications involving lower-extremity amputees. The source notes that these cases are more difficult to transfer into virtual reality because fixed-camera algorithms can track hands but not feet. The proprietary work being developed for this area is still too new for UGA and Axolo Health to discuss in detail.
The treatment has also been tested with patients who have lived with phantom limb pain for many years. At the amputee clinic, which receives patients from across the region, the researchers began testing the completed four-phase system.
One patient had experienced a phantom hand that had remained fixed in the same position for 15 years following a shark attack. After undergoing the treatment, the patient showed an emotional response when the headset was removed.
The result came after months of development and testing by the researchers and clinicians involved in the project. Their work continues to examine how virtual reality can be used to retrain the brain after amputation and address phantom limb pain.
