Objectives. This study sought to explore and characterize referred sensations (RS) in patients with complex regional pain syndrome (CRPS) type 1 and test the hypothesis that pain in CRPS is associated with central sensory changes. Methods. Subjects underwent standardized neurological examination involving light touch, pinprick and vibration sense with eyes closed and then with eyes open. The subjects described the location and sensation emanating from the stimulated site and whether they experienced any sensations (similar or different) elsewhere. Results. Five of 16 subjects recruited demonstrated RS. These were experienced in real time, were modality specific (touch and pinprick) and were located on the body part immediately adjacent, on Penfield's cortical homunculus, to the stimulated site. The RS were diminished or absent when the subject visualized the stimulated area. They disappeared when stimulation ceased and on clinical improvement. Conclusions. This is the first report of RS in CRPS and provides further evidence of central reorganization in what was previously thought to be a peripheral disorder.
McCabe, C. S., Haigh, R. C., Halligan, P. W., & Blake, D. R. (2003). Referred sensations in patients with complex regional pain syndrome type 1. Rheumatology, 42(9), 1067-1073. https://doi.org/10.1093/rheumatology/keg298