Exploring the Neural Correlates of Body Perception Disturbance with a Visual Hand Morph Illusion in Complex Regional Pain Syndrome: An fMRI study

Complex regional pain syndrome (CRPS) is a debilitating chronic pain condition whose causal mechanisms remain poorly understood. Individuals with CRPS often experience distorted perceptions of their affected limb in terms of size and shape, accompanied by feelings of dislike and disownership-- collectively referred to as body perception disturbances (BPD). Evidence that both BPD and pain can rapidly reduce following a visual hand morph illusion suggests modulation of central body representations. To elucidate the neural correlates underlying these rapid perceptual changes, we investigated brain activity during the hand morph illusion using functional magnetic resonance imaging (fMRI). Forty-four participants (22 with upper limb CRPS, 22 pain-free controls) completed the hand morph illusion task during fMRI and provided trial-by-trial ratings of ownership, likeability, and pain of their affected hand. People with CRPS showed greater activation of the left premotor cortex (PMC) during the illusion compared with controls. Functional connectivity between the left PMC and right extrastriate body area (EBA) was also revealed in CRPS during the illusion. No main effects of the illusion, relative to a sham condition, were found on pain intensity, limb ownership, or likeability ratings. These findings provide the first identification of neural correlates of body perception disturbance in CRPS, implicating PMC-EBA networks in altered body representation. Further neuroimaging research is required to define the neural signature underlying this disturbance.