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

Study Overview
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Brief Summary
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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.

Detailed Description
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This study aims: To establish baseline values of DNICs using CPM protocol 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.

Official Title
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Reference Values of Diffuse Noxious Inhibitory Controls (DNIC) Intensity in a Healthy Adult Population and Develop a Clinical Test to Evaluate DNIC

Conditions
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Chronic Pain

Intervention / Treatment
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* Other: Conditioned pain modulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-79 years old Able to provide consent Exclusion Criteria: cardiovascular disease (arrhythmia, cerebrovascular accident, infarction...) Raynaud syndrome severe psychiatric disease (dementia, schizophrenia, psychosis, major depression) injuries or loss sensitivity to their forearms or hands pregnant women or in post-partum period (<1 year)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 79 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy volunteers<br>Conditioned pain modulation (2 stimuli test: heat and pressure points) before and after conditioning stimuli (cold water bath). | Other: Conditioned pain modulation<br>* Conditioned pain modulation (CPM) protocol consist of evaluating pain during two stimuli test (heat and pressure point), before and after one conditioning stimulus (cold water bath); Blood analyses for biochemistry and genes polymorphisms.<br>* Other names: Pressure points;|
| Volunteers with chronic pain<br>Conditioned pain modulation (2 stimuli test: heat and pressure points) before and after conditioning stimuli (cold water bath). | Other: Conditioned pain modulation<br>* Conditioned pain modulation (CPM) protocol consist of evaluating pain during two stimuli test (heat and pressure point), before and after one conditioning stimulus (cold water bath); Blood analyses for biochemistry and genes polymorphisms.<br>* Other names: Pressure points;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Conditioned pain modulation | Alteration (reduction or augmentation) of pain sensitivity after activation of endogenous pain-inhibitory system, measured by computerized visual analog scale (CoVAS) ranging from 0 [no pain] to 100 [most intense pain that could be tolerated] | Once, at baseline, at recruitment (comparison between 1st and 2nd test, after the conditioning stimuli) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| pressure points threshold | On both trapezius muscles | Twice, at baseline, at recruitment (before and after the conditioning stimuli) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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conditioned pain modulation (CPM), Diffuse Noxious Inhibitory Controls (DNIC), pressure pain threshold (PPT), reference values, clinical decision rule