Dear Pain Matters blog readers,
‘Augmented reality’ not only forms the basis for Pokémon Go for entertainment, but it may also offer novel treatment for some patients with phantom limb pain.
Phantom limb pain is very common in amputees affecting up to 70% of all people who have lost a limb.
A successful case study involving augmented reality:
A 72-year old man suffered moderate to unbearable phantom limb pain since the loss of his arm below his elbow joint in 1965 caused by traumatic injury. Since the amputation, this patient lived with constant burning pain that changed hourly, ranging from ‘3’ (on a scale from 0 – 10) to ‘excruciating pain levels’. He also awoke nightly as a result of intense episodes of pain.
Conventional pain treatment failed him, and for almost half a century, he was never completely free of pain.
After 48 long years of severe phantom limb pain, and following experimental treatment involving augmented reality and gaming, this man finally found significant pain relief. Using the myoelectric signals (‘myoelectric pattern recognition’) at the arm stump, it was now possible to volitionally and directly control the ‘virtual arm’ (through the prediction of motion intent). This in turn resulted in reduced phantom limb pain (Ortiz-Catalán et al, 2014).
Specifically, augmented reality pain treatment involved:
- ‘Projection of a virtual reality arm’ from the patient’s painful limb stump –
- This virtual arm was superimposed onto the patients’ painful limb stump (to resemble a real arm) on the computer screen;
- Real-time recording of muscle signals from the painful arm stump –
- This recording of residual electrical signals in the muscles via electromyography (EMG) is done via electrodes on the skin of the arm stump; and
- Conversion (via software using complex algorithms) of the electrical signals from muscles in the arm stump –
- The converted data was used to control specific movements of a virtual arm in augmented reality.
- Specifically, the patient was able to imagine driving a car by ‘moving’ his virtual arm (that represented his missing arm) on the computer screen. This enabled him to control his superimposed virtual arm in real-time during a computer car racing game.
A YouTube video and 2 photos are provided below for further details:
Please note: Audio is not available for this YouTube.
Above, photo #1:
The patient can see his virtual arm that is now superimposed onto his missing arm on the computer screen. The patient can control his virtual arm via converted residual muscle signals arising from his arm stump.
Above, photo #2:
(A) Surface electrodes on the arm stump
(B) See first photo (above)
(C) Patient playing a computer car racing game by imagining ‘moving his missing arm’ to drive a car. Specifically, the patient imagines specific and/or random arm movements, as requested by the computer during the car racing game.
(D) Patient using the ‘Target Achievement Control’ test for rehabilitation.
Credit (YouTube video and photos): Ortiz-Catalán et al, Frontiers in Neuroscience
The patient stated that his pain was drastically reduced, albeit slowly, over 18 weeks. He even enjoyed nil pain during some of his augmented reality treatments, and he no longer wakes up at night due to intense pain.
Quoting the patient:
“These pain-free periods are something almost new to me and it is an extremely pleasant sensation.”
Quoting the patient’s wife:
“My husband can live 10 years more than I expected, as pain now plays a less important role in his life and those close to him can see it.”
(Ortiz-Catalán et al, 2014)
The patient also said that his phantom (missing) hand, that was painfully clenched in a permanent posture for 48 long years, was now ‘open and relaxed’ following augmented reality treatment.
Given that the electrical signals are obtained from the arm stump, this may indicate that the arm stump itself is driving the chronic and severe phantom limb pain suffered by the patient for 48 years. Hence, in this particular patient, the phantom limb pain appears to be peripherally-induced (not centrally-induced).
Quoting Max Ortiz Catalán:
“…the control signals are retrieved from the arm stump, and thus the affected arm is in charge…The promotion of motor execution and the vivid sensation of completion provided by augmented reality may be the reason for the patient improvement…”
(Chalmers University of Technology, 2014)
Max Ortiz Catalán, Assistant Professor
Chalmers University of Technology, Gothenburg, Sweden.
Ortiz Catalán and his team are optimistic that pain therapy involving augmented reality and gaming may offer hope for some phantom limb pain patients including bilateral amputees with phantom limb pain. This new augmented reality/gaming treatment may also be a lot more fun and engaging than conventional pain treatments, hence encouraging increased patient compliance.
A follow-up multi-center clinical trial, led by Chalmers University of Technology, and performed at 4 hospitals, being:
- Sahlgrenska University Hospital, Gothenburg, Sweden;
- Örebro University, Örebro, Sweden;
- BräckeDiakoni Rehabcenter Sfären, Stockholm, Sweden; and
- University Rehabilitation Institute, Ljubljana, Slovenia,
was recently completed to assess the potential efficacy of augmented reality pain therapy for patients with chronic, intractable phantom limb pain.
We can expect some exciting results! (Watch for an upcoming paper by Ortiz Catalán et al.)
Ortiz Catalán and his colleagues also helped implement augmented reality pain treatment in clinics in Belgium, the Netherlands, Slovenia and Japan (with Austria and Latvia to follow) for selected phantom limb pain patients who are refractive to other pain treatments.
Lower limb amputees with phantom limb pain are now included in the clinical trials.
(Source: Email dated 3 August 2016 from Assistant Professor Max Ortiz Catalán.)
This is great news for all phantom limb pain sufferers!
PS Quoting from Assistant Professor Max Ortiz Catalán’s email dated 3 August 2016:
“You are welcome to encourage patients and clinicians to contact me if they would like to try this technology. It’s non-invasive and safe so it poses little to no risks. They can contact me at this e-mail:
Thank you again for your interest in our work.”
(1A) Lewis, Tanya; Staff Writer, Live Science
Virtual Reality Treatment Relieves Amputee’s Phantom Pain
25 February 2014
(1B) Chalmers University of Technology
Phantom Limb Pain Relieved When Amputated Arm Is Put Back To Work
25 February 2014
(2) Ortiz-Catalán M, Sander N, Kristoffersen MB, Håkansson B and Brånemark R (25 February, 2014)
Treatment of phantom limb pain (PLP) based on augmented reality and gaming controlled by myoelectric pattern recognition: a case study of a chronic PLP patient.
Front. Neurosci. 8:24.
Includes Supplementary Material – Video (audio unavailable)