Phantom motor execution may treat phantom limb pain
Re-engagement of central and peripheral circuitry involved in motor execution can reduce phantom limb pain via competitive plasticity and reversal of cortical reorganization, according to a new study.
Between 15 Sept 2014 and 10 April 2015, 14 patients with upper limb amputation and intractable chronic phantom limb pain for which conventional treatments failed were recruited at three clinics in Sweden and one in Slovenia. The patients received 12 sessions of phantom motor execution using machine learning, augmented and virtual reality, and serious gaming.
Assessment tools such as the numeric rating scale, pain rating index, weighted pain distribution scale and a study-specific frequency scale were used to measure changes in intensity, frequency, duration, quality and intrusion of phantom limb pain prior to each session and at follow-up interviews 1, 3 and 6 months after the last session. Changes in medication and prostheses were also monitored.
Patients demonstrated statistically and clinically significant improvements in all metrics of phantom limb pain. From pretreatment to the last treatment session, phantom limb pain decreased by 47 percent (absolute mean change 1.0; p=0.001) for weighted pain distribution, 32 percent (1.6; p=0.007) for the numeric rating scale and 51 percent (9.6; p=0.0001) for the pain rating index.
The numeric rating scale score for intrusion of phantom limb pain in activities of daily living and sleep likewise decreased by 43 percent (absolute mean change 2.4; p=0.004) and 61 percent (2.3; p=0.001), respectively. Two of four patients who were on medication reduced their intake by 81 percent (absolute reduction 1,300 mg, gabapentin) and 33 percent (absolute reduction 75 mg, pregabalin).
Improvements were sustained 6 months after the last treatment.
Motor execution of the phantom limb aided by machine learning, augmented and virtual reality, and gaming is noninvasive, nonpharmacological and engaging with no identified side effects at present; thus, it holds potential value in the treatment of phantom limb pain, according to the investigators.