Authors: Ortiz-Catalan M et al., Lancet 2016 Dec 10; 388:2885
A study demonstrates that practicing phantom motor executions based on decoding of intended actions using an augmented-reality computer system can reduce phantom limb pain.
Phantom limb pain is a debilitating condition that occurs in a subset of patients after limb amputation. Growing evidence suggests that such pain may be the result of maladaptive cortical plasticity. Mirror therapy, in which patients observe limb movements of the intact arm using a mirror, can significantly reduce pain. However, mirror therapy is not universally effective and cannot be used in all patients.
In this nonrandomized clinical study, researchers examined the effects of phantom motor execution (PME) using an augmented-reality system in 14 patients with chronic, intractable phantom limb pain; subjects had experienced pain for a mean duration of 10 years before study enrollment. Participants received 12 sessions of PME using an augmented- and virtual-reality setup. More specifically, PME was enabled by decoding the intended movements of the phantom limb using electromyography recordings from nerves in the remaining portion of the amputated limb. The investigators used statistical pattern recognition tools to decode the intended motor action of the phantom limb from the recorded myoelectric activity.
After 12 training sessions, pain was reduced by 47% from pretreatment levels. A significant reduction in pain remained through 6 month follow-up after the end of training. Interference with activities of daily living and with sleep was reduced by about 50%.
This study provides evidence of clinically significant improvements in intractable phantom limb pain after practicing PME using an augmented virtual-reality setup. Although this was a nonrandomized, single-blinded, small study, the results demonstrate that a noninvasive approach may be effective for patients with long-standing intractable pain. These very promising results should lead to larger-scale studies in patients with phantom limb pain.