title: Psychophysical and electrophysiological evidence for nociceptive dysfunction in complex regional pain syndrome.
abstract: The aim of this study was to assess the function of the thermo-nociceptive system in 25 patients with long-lasting, medium-to-severe refractory complex regional pain syndrome (CRPS)-1 using behavioral (detection rates and reaction times) and electrophysiological (event-related brain potentials) responses to brief (50 milliseconds) and intense (suprathreshold for Aδ-nociceptors) carbon dioxide laser stimuli delivered to the affected and contralateral limbs, and by comparing these responses to the responses obtained in the left and right limbs of age- and sex-matched healthy controls. Compared with healthy controls and compared with the contralateral limb, the detection rate of pricking pain related to the activation of Aδ-fibers was markedly reduced at the affected limb. Furthermore, reaction times were substantially prolonged (>100 milliseconds in 84% of patients and >300milliseconds in 50% of patients). Finally, the N2 and P2 waves of laser-evoked brain potentials were significantly reduced in amplitude, and their latencies were significantly increased. Taken together, our results show that in the majority of patients with chronic CRPS-1, thermo-nociceptive pathways are dysfunctional. A number of pathological mechanisms involving the peripheral nervous system and/or the central nervous system could explain our results. However, the primary or secondary nature of these observed changes remains an open question.
authors.affiliation: Institute of Neuroscience (IoNS), Université Catholique de Louvain, Avenue Mounier 53, Bte B1.53.04, B-1200 Brussels, Belgium Key Laboratory of Cognition and Personality (Ministry of Education) and School of Psychology, Southwest University, Chongqing 400715, PR China Institute of Neuroscience, Faculty of Medicine, Université catholique de Louvain, B-1200 Brussels, Belgium Department of Experimental and Clinical Health Psychology, Ghent University, B-9000 Genth, Belgium.
authors.forename: Gilles
authors.initials: G
authors.lastname: Caty
authors.forename: Li
authors.initials: L
authors.lastname: Hu
authors.forename: Valéry
authors.initials: V
authors.lastname: Legrain
authors.forename: Léon
authors.initials: L
authors.lastname: Plaghki
authors.forename: André
authors.initials: A
authors.lastname: Mouraux
mesh_terms: D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D055724:Electrophysiological Phenomena / Q000502:physiology; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D005528:Foot / Q000503:physiopathology; D006225:Hand / Q000503:physiopathology; D006358:Hot Temperature; D006801:Humans; D007834:Lasers; D008297:Male; D008875:Middle Aged; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009434:Neural Pathways / Q000503:physiopathology; D059226:Nociceptive Pain / Q000503:physiopathology*; D010523:Peripheral Nervous System Diseases / Q000503:physiopathology; D011601:Psychophysics; D011930:Reaction Time / Q000502:physiology; D012019:Reflex Sympathetic Dystrophy / Q000503:physiopathology*; D012879:Skin Physiological Phenomena; D055815:Young Adult
keywords: Aδ fibers; CRPS; Laser-evoked potentials; Neuropathic pain; Psychophysics
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