Impact of Kinesiophobia on Descending Corticospinal and Bulbospinal Projections

Study Overview
=================
Brief Summary
-----------------
Fear of movement (kinesiophobia) is a phenomenon commonly observed in people suffering from chronic pain. The aims of this project are to better understand the neurophysiological basis of this phenomenon, in particular 1) the effect of kinesiophobia (induced by nocebo intervention) on the excitability of corticospinal projections and 2) the association between kinesiophobia and top-down inhibitory mechanisms.

Detailed Description
-----------------
The study will include 44 healthy (pain-free) participants. Corticospinal measurements will be taken before and after the application of capsaicin cream (experimental pain paradigm). The investigators will manipulate kinesiophobia levels (assessed using the Tampa Kinesiophobia Scale) upward by pretending to diagnose a musculoskeletal problem in half of the participants (nocebo ultrasound), and will measure the efficacy of top-down inhibitory mechanisms using a counter-irritation paradigm (thermode and cold pressor test : the subjects will be subjected to 5 thermal stimulations, 7 mechanical stimulations and 1 water bath at 10°C of the hand) and corticospinal parameters using transcranial magnetic stimulation. Together, these results will allow a better understanding of the mechanisms associated with a predictor of pain onset (such as kinesiophobia), by studying its interactions with endogenous pain inhibition systems and the motor system, in order to develop relevant prophylactic treatments.

Official Title
-----------------
Impact of Kinesiophobia on Descending Corticospinal and Bulbospinal Projections During Experimental Pain : A Randomised Controlled Trial

Conditions
-----------------
Kinesiophobia

Intervention / Treatment
-----------------
* Behavioral: Nocebo
* Behavioral: Placebo


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Aged 18 years old or older Healthy Volunteers Capable of understanding instructions Abstain from tobacco and caffeine 2 hours before data collection Abstain from short-acting analgesics 6 hours before data collection Exclusion Criteria: A painful condition or chronic pain Neurological disorders Shoulder pathology Skin diseases Capsaicin allergy Raynaud's syndrome Epilepsy Intracranial metallic foreign bodies, hearing aids and cochlear implants

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Participants will attend two experimental sessions at the Research Center on Aging of the Centre Intégré Universitaire de Santé et de Services Sociaux de l'Estrie, Sherbrooke. During the first one, the efficacy of their excitatory and inhibitory mechanisms will be assessed (thermode and cold water bath) and during the second one, their corticospinal excitability will be assessed by transcranial magnetic stimulation (before and during induced pain + placebo or nocebo echography of shoulder). Subjects will be randomized between 2 arms, nocebo (bad fake result) or placebo echography (good fake result). Participants will be allocated using minimization with 2 factors (age and sex). The two sessions will be separated by at least 48 hours.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: nocebo<br>Ultrasound with fake results of rotator cuff injury. | Behavioral: Nocebo<br>* Nocebo ultrasound with diagnosis of a fake shoulder cuff injury.<br>|
| Active Comparator: placebo<br>Ultrasound with fake results of the healthy rotator cuff. | Behavioral: Placebo<br>* Placebo ultrasound with no diagnosis of injury.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Corticospinal excitability | The corticospinal excitability will be assessed using motor evoked potentials at different intensity of stimulation (from motor threshold to maximal amplitude response). | 1 hour | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| downward inhibition of pain | Inhibitory mechanisms will be assessed by comparing pain levels (measured using a computerized visual analog scale [0 = no pain; 10 = worst pain imaginable]) evoked by a test stimulus before and after a conditioning stimulus. Pain levels evoked by the test stimulus before the conditioning stimulus will be subtracted from pain levels evoked by the test stimulus after the pain stimulus, such that a positive score represents increased pain (hyperalgesia) and a negative score represents decreased pain (hypoalgesia, i.e., inhibitory mechanisms). | 1 hour | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
kinesiophobia, experimental pain, corticospinal excitability, conditioned pain modulation, input output curves