Motor correlates of phantom limb pain

Publication date: Available online 25 July 2017
Source:Cortex
Author(s): Sanne Kikkert, Melvin Mezue, David Henderson-Slater, Heidi Johansen-Berg, Irene Tracey, Tamar R. Makin
Following amputation, individuals ubiquitously report lingering sensations of their missing limb. While phantom sensations can be innocuous, they are often manifested as painful. Phantom limb pain (PLP) is notorious for being difficult to monitor and treat. A major challenge in PLP management is the difficulty in assessing PLP symptoms, given the physical absence of the affected body part. Here, we offer a means of quantifying chronic PLP by harnessing the known ability of amputees to voluntarily move their phantom limbs. Upper-limb amputees suffering from chronic PLP performed a simple finger-tapping task with their phantom hand. We confirm that amputees suffering from worse chronic PLP had worse motor control over their phantom hand. We further demonstrate that task performance was consistent over weeks and did not relate to transient PLP or non-painful phantom sensations. Finally, we explore the neural basis of these behavioural correlates of PLP. Using neuroimaging, we reveal that slower phantom hand movements were coupled with stronger activity in the cortical sensorimotor phantom hand territory, previously shown to associate with chronic PLP. By demonstrating a specific link between motor control and PLP, our findings open up new avenues for PLP management and improvement of existing PLP treatments.



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