Reference Values and Clinical Screening Test of Diffuse Noxious Inhibitory Controls (DNIC)

Chronic Pain

conditioned pain modulation (CPM), Diffuse Noxious Inhibitory Controls (DNIC), pressure pain threshold (PPT), reference values, clinical decision rule

Chronic pain (CP) is disabling for people triggering important costs for society. A deficit of diffuse noxious inhibitory controls (DNIC) is one of the CP mechanisms. DNICs are evaluated in research setting using a CPM protocol (conditioned pain modulation). There is a lack of reference values on the effectiveness of DNICs. Wider research on DNIC will help to understand CP and to develop a clinical screening test evaluating DNICs.

This study aims: 1. To establish baseline values of DNICs using CPM protocol 2. To identify the variables that will be integrated in the algorithm of the clinical screening test (clinical decision rule). First the target population will be healthy volunteers, male and female, stratified by age. The reference values will be established via a non-parametric method for a standard CPM protocol in which two different pain stimuli are applied. Two stimuli tests of the same intensity and nature (heat) will be applied before and after the application of another conditioning stimulus (cold water bath). The perceived pain difference between the 1st and 2nd stimuli tests will reflect the intensity of the DNICs. Secondly, these results will be compared to those from volunteers suffering of chronic pain. The clinical decision rule will result from clinical and paraclinical elements correlating with the amplitude of the efficacy of CPM (serum noradrenaline, intensity of pain, heart rate and blood pressure measurements, psychometric questionnaires assessing anxiety, depressive feelings and pain catastrophizing). Logistic regression analysis will determine the best predictors of a CPM deficit.

Canada