MOVEMENT of a phantom limb using augmented reality and by playing video games is part of a new therapy found to significantly reduce the amount of pain experienced by patients with an upper limb amputation.
A team of researchers designed the new therapy named phantom motor execution to see whether it could relieve the pain felt by patients for whom previous conventional treatment approaches had failed. The therapy involves placing electrodes above the amputated limb to measure myoelectric activity. These signals are then used to create a virtual arm in the location of the missing limb which is then visually fed back to the patient, using augmented reality, on a computer screen.
In the study, researchers recruited 14 patients with upper limb amputation and refractory chronic intractable phantom limb pain. After an initial patient-reported pain evaluation, each patient underwent twelve, 2-hour phantom motor execution sessions twice a week, except one patient who had it daily. Following this, electrodes and a fiducial marker would be attached to the arm to create a virtual representation of the lost arm. Time would then be spent practicing motor execution in augmented reality, playing a racing car game using phantom movements, and matching random target postures of a virtual arm in virtual reality.
The effects of the therapy were measured during the pain evaluation prior to each session and from follow-up interviews at 1, 3, and 6 months after the final session. Overall, the researchers saw a continuous reduction of phantom limb pain, including intensity, quality, and frequency. At the last treatment session, there was roughly a 51% relative mean improvement in the intensity and quality of pain experienced by the patients according to a pain rating index. The intrusion of phantom limb pain in sleep and daily activities was also reduced on average by around 43%. The improvements found in the study were still observed at 6 months.
“The results from our study suggest that it may be useful to ‘exercise’ the phantom limb,” lead author of the study, Prof Max Jair Ortiz Catalan, Chalmers University of Technology, Gothenburg, Sweden, explained. “Our treatment offers an engaging way to do this while also providing a non-invasive and non-pharmacological treatment which was found to reduce chronic pain with no observed side effects. Our findings now need to be confirmed in a large randomised clinical trial.
Jack Redden, Reporter