Illusory touch temporarily improves sensation in areas of chronic numbness: A brief communication

Abstract

Background: Creating the visual illusion of touch can improve tactile perception in healthy subjects. Objective: We were interested in seeing if creating the illusion of touch in an insensate area could improve sensation in that area. Methods: Fourteen people with chronic numbness participated in a randomised cross-over experiment. The four conditions were: 1. Stimulation over the un-affected limb with mirror visual feedback (experimental condition). 2. Stimulation over the affected limb with mirror visual feedback 3. Stimulation over the un-affected limb without mirror visual feedback. 4. Stimulation over the affected limb without mirror visual feedback. Participants were assessed pre and post each condition using the Ten-Test and mechanical detection thresholds. Data were analysed using linear mixed models. Result: Only the experimental condition produced a change in the Ten-Test (mean difference -1.1 95% CI: -1.8 to -0.4; p=0.003), corresponding to a 24% improvement in sensation. No differences were observed for any condition in mechanical detection thresholds. Conclusion: Creating the illusion of touch may improve sensory function in areas of chronic numbness. This preliminary finding adds to the growing body of evidence supporting the use of techniques which directly target cortical function in people with peripheral nerve injury.