An alternative to traditional mirror therapy: illusory touch can reduce phantom pain when illusory movement does not.

OBJECTIVES There is evidence that amputation leads to cortical reorganization, and it has been suggested that phantom pain might be related to a consequently emerging incongruence of motor intention, somatosensation and visual feedback. One therapeutic approach that has the potential to temporarily resolve this visuo-proprioceptive dissociation is mirror therapy, during which amputees typically move their intact limb while observing its reflection in a mirror, which in turn evokes the illusory perception of movement of their phantom limb. However, while the action of moving the phantom relieves pain for some patients, it can actually increase cramping sensations in others. In the current study we therefore implemented an alternative version of the mirror therapy involving a visuotactile illusion, to explore whether it might be effective with amputees for whom the action of moving the phantom increases phantom pain. METHODS We recruited six upper limb amputees who had been previously exposed to the classical mirror therapy with no or limited success, and exposed them to two differential experimental conditions involving visualization paired with either illusory movement or illusory touch of the phantom hand. RESULTS While none of the participants benefitted from the movement condition, five participants showed a significant pain reduction during the stroking condition. DISCUSSION Albeit preliminary, our results represent an encouraging finding of possible future clinical relevance, and indicate that the type of multisensory stimulation that most efficiently reduces phantom pain can vary in different sub-populations of amputees.