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Enhanced pain and autonomic responses to ambiguous visual stimuli in chronic C omplex R egional P ain S yndrome ( CRPS ) type I
Author(s) -
Cohen H.E.,
Hall J.,
Harris N.,
McCabe C.S.,
Blake D.R.,
Jänig W.
Publication year - 2012
Publication title -
european journal of pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.305
H-Index - 109
eISSN - 1532-2149
pISSN - 1090-3801
DOI - 10.1016/j.ejpain.2011.06.016
Subject(s) - complex regional pain syndrome , vasomotor , medicine , sensory system , autonomic nervous system , psychology , chronic pain , autonomic function , physical medicine and rehabilitation , anesthesia , neuroscience , heart rate , heart rate variability , blood pressure
Abstract Cortical reorganisation of sensory, motor and autonomic systems can lead to dysfunctional central integrative control. This may contribute to signs and symptoms of C omplex R egional P ain S yndrome ( CRPS ), including pain. It has been hypothesised that central neuroplastic changes may cause afferent sensory feedback conflicts and produce pain. We investigated autonomic responses produced by ambiguous visual stimuli ( AVS ) in CRPS , and their relationship to pain. Thirty CRPS patients with upper limb involvement and 30 age and sex matched healthy controls had sympathetic autonomic function assessed using laser Doppler flowmetry of the finger pulp at baseline and while viewing a control figure or AVS . Compared to controls, there were diminished vasoconstrictor responses and a significant difference in the ratio of response between affected and unaffected limbs (symmetry ratio) to a deep breath and viewing AVS . While viewing visual stimuli, 33.5% of patients had asymmetric vasomotor responses and all healthy controls had a homologous symmetric pattern of response. Nineteen (61%) CRPS patients had enhanced pain within seconds of viewing the AVS . All the asymmetric vasomotor responses were in this group, and were not predictable from baseline autonomic function. Ten patients had accompanying dystonic reactions in their affected limb: 50% were in the asymmetric sub‐group. In conclusion, there is a group of CRPS patients that demonstrate abnormal pain networks interacting with central somatomotor and autonomic integrational pathways.