Reliability of the conditioned pain modulation paradigm assessed with the nociceptive withdrawal reflex

J.A. BIURRUN MANRESA; P.H. VUILLEUMIER; R. FRITSCHE; C. OEHLER; L. ARENDT-NIELSEN; O.K. ANDERSEN; M. CURATOLO

San Diego

Encuentro; Neuroscience 2013; 2013

BackgroundThe vast majority of conditioned pain modulation (CPM) measures in healthy subjects and pain patients have been performed using psychophysical measures, showing a great variability in the assessment methods. Electrophysiological measures, such as the nociceptive withdrawal reflex (NWR), are an objective and viable alternative for the assessment of CPM. However, test-retest reliability of CPM assessed with the NWR has not been reported to date. Establishing such reliability is important in regard to future experimental studies or clinical applications.AimTo investigate the test-retest reliability of CPM assessed using NWR thresholds, electrical pain detection thresholds and pain intensity ratings after suprathreshold electrical stimulation.MethodsThirty nine pain-free subjects participated in two experimental sessions, separated at least by one week. Repeated assessments of CPM using the NWR threshold, pain detection threshold after single electrical stimulation and pain intensity ratings after suprathreshold electrical stimulation of the skin were performed, with the cold pressor test (i.e. submerging a hand in ice saturated water) as conditioning stimuli. The size of the CPM effect (ΔCPM) was defined as the difference between thresholds during cold pressor test and the thresholds before the test. Thresholds were compared using repeated measures analysis of variance (RM ANOVA), where session (first or second), and time (before or during CPM) were regarded as factors. Reliability was assessed using the coefficient of variation (CV), and the intraclass correlation coefficient (ICC).ResultsCPM was successfully induced by the cold pressor test in both sessions (RM ANOVA, p