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: Gilles Caty, Li Hu, Valéry Legrain, Léon Plaghki, André Mouraux
• Journal: Pain (Pain) Vol. 154 Issue 11 Pg. 2521-8 (Nov 2013) ISSN: 1872-6623 [Electronic] Netherlands
• PMID: 23891894 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2013 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Topics

• Adolescent
• Adult
• Electroencephalography
• Electrophysiological Processes (physiology)
• Evoked Potentials (physiology)
• Female
• Foot (physiopathology)
• Hand (physiopathology)
• Hot Temperature
• Humans
• Lasers
• Male
• Middle Aged
• Nerve Fibers, Unmyelinated (physiology)
• Neural Pathways (physiopathology)
• Nociceptive Pain (physiopathology)
• Peripheral Nervous System Diseases (physiopathology)
• Psychophysics
• Reaction Time (physiology)
• Reflex Sympathetic Dystrophy (physiopathology)
• Skin Physiological Phenomena
• Young Adult