Augmented reality may help reduce phantom limb pain in amputees who fail to benefit from other treatments, a new study has found. Phantom limb pain occurs when amputees experience painful sensations which seem to come from their missing limb.
Most amputees experience some pain after losing a limb, but for a third of cases it becomes very severe leading to poor quality of life, worse disability, poorer mental health and greater difficulty in prosthesis use than for amputees without phantom limb pain. "Phantom limb pain is a difficult condition to treat that can seriously hinder patients' quality of life," said Max Ortiz Catalan from Chalmers University of Technology in Sweden.
The study involved 14 patients who began experiencing phantom limb pain soon after they had their arm amputated between two and 36 years ago and had not benefitted from other treatments. Researchers placed sensors on the patients' stumps to detect muscular activity for the missing arm. The signals were then fed into a computer that decoded and used them to create an active virtual arm on a computer screen, representing the missing limb.
There were three parts to the therapy, which involved patients training the virtual limb, driving a virtual race car around a track using their phantom movements and copying the movements of an on-screen limb with their phantom movements in 12 two-hour treatment sessions. Patients rated the intensity, quality, and frequency of pain before each treatment session, as well as the intrusion of pain in sleep and activities of daily living.
Once they completed all 12 sessions they had follow-up interviews one, three and six months after their treatment. The study is the first to follow-up patients with phantom limb pain as long as six months after their treatment. The study found that on average the intensity, quality and frequency of phantom limb pain halved following treatment - with a 32 per cent reduction in the intensity of the pain, a 51 per cent reduction in pain quality and intensity and a 47 per cent reduction in its duration, frequency and intensity.
When looking at how this affected patients' day-to-day lives, the researchers found that there was a 43 per cent reduction in the amount that pain interrupted patients' daily activities and a 61 per cent reduction in how often pain interrupted their sleep. The number of patients feeling constant pain reduced from 12 to six patients at six month follow-up and 'stabbing' and 'tiring/exhausting' pains in the phantom limb were less common after the treatment. The study was published in The Lancet journal.
