Pain Beliefs and Intracortical Excitability During Experimental Pain

ConditionsKinesiophobia (Fear of Movement)Experimental Pain

Trial statusNot yet recruiting

Trial phaseNot applicable

Trial typeInterventional

Biological sexAll

Age18-35

SponsorUniversité de Sherbrooke

About this trial

Pain can influence the way the motor system functions. However, responses to pain vary widely between individuals, and this variability may be partly related to pain-related beliefs such as kinesiophobia.

This study examines whether temporary experimental pain changes intracortical excitability in the motor cortex, and whether this response differs according to baseline kinesiophobia. Healthy adults will complete one experimental session. Motor cortex excitability will first be assessed at baseline using transcranial magnetic stimulation, a non-invasive brain stimulation technique. A topical capsaicin cream will then be applied to the forearm to induce temporary, moderate experimental pain. Once pain is established, the same neurophysiological assessments will be repeated.

The main objective is to measure changes in short-interval intracortical inhibition before and during capsaicin-induced pain, with particular attention to whether these changes are associated with baseline kinesiophobia.

Secondary objectives are to characterize other markers of motor cortex excitability, including long-interval intracortical inhibition, short-interval intracortical facilitation, intracortical facilitation, and corticospinal excitability assessed using input-output recruitment curves. Pain intensity will be monitored using a visual analog scale to characterize the experimental pain response. Baseline kinesiophobia will be assessed using the Tampa Scale of Kinesiophobia and examined as a factor associated with interindividual variability in neurophysiological responses to experimental pain.

The researchers expect that changes in motor cortex excitability during experimental pain will vary between individuals, and that individuals with higher kinesiophobia may show smaller changes in motor cortex excitability during capsaicin-induced pain.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

Aged 18 to 35 years, inclusive

Healthy

Able to understand the study information and experimental procedures

Able to provide informed consent

Disqualifiers

History of psychiatric disorders (including intellectual disability or severe cognitive, behavioral, or affective impairment) that could interfere with understanding the study or providing informed consent.

History of neurological disorders, including epilepsy, stroke, brain or spinal cord surgery, or any neurological disease affecting motor or sensory function.

Any pain condition within the past 3 months, regardless of origin.

Recent musculoskeletal injury or surgery within the past 3 months.

Trial design

Design model

Single group

Treatments tested in this trial

Topical Capsaicin Cream (1%)
Drug
Topical capsaicin cream (1%) is applied to the forearm to induce temporary, moderate experimental pain. Motor cortex excitability is assessed before and during capsaicin-induced pain using transcranial magnetic stimulation.

Treatment groups

30 Participants

are divided into 1 treatment group

Group A: Experimental painExperimental treatment 1 intervention

Trial outcomes

Primary outcomes

Change in Short-Interval Intracortical Inhibition

Short-interval intracortical inhibition will be assessed using paired-pulse transcranial magnetic stimulation over the primary motor cortex, with electromyographic recordings from the first dorsal interosseous muscle. A subthreshold conditioning stimulus set at 80% of resting motor threshold will be followed by a suprathreshold test stimulus set at 120% of resting motor threshold, with an interstimulus interval of 3 ms. Fifteen conditioned trials will be recorded for this measure. The outcome will be expressed as the change in conditioned motor evoked potential amplitude relative to the unconditioned test response from pre- to post-application of topical capsaicin cream.

Time frame

At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)

Secondary outcomes

Change in Short-Interval Intracortical Facilitation

Short-interval intracortical facilitation will be assessed using paired-pulse transcranial magnetic stimulation over the primary motor cortex, with electromyographic recordings from the first dorsal interosseous muscle. A suprathreshold conditioning stimulus set at 120% of resting motor threshold will be followed by a subthreshold test stimulus set at 80% of resting motor threshold, with an interstimulus interval of 2 ms. Fifteen conditioned trials will be recorded for this measure. The outcome will be expressed as the change in conditioned motor evoked potential amplitude relative to the unconditioned test response from pre- to post-application of topical capsaicin cream.

Time frame

At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)

Change in Pain Intensity

Pain intensity will be assessed using a visual analog scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. The outcome will be expressed as the change in pain intensity from pre- to post-application of topical capsaicin cream.

Time frame

From baseline through completion of the experimental session, an average of 2 hours

Change in Intracortical Facilitation

Intracortical facilitation will be assessed using paired-pulse transcranial magnetic stimulation over the primary motor cortex, with electromyographic recordings from the first dorsal interosseous muscle. A subthreshold conditioning stimulus set at 80% of resting motor threshold will be followed by a suprathreshold test stimulus set at 120% of resting motor threshold, with an interstimulus interval of 15 ms. Fifteen conditioned trials will be recorded for this measure. The outcome will be expressed as the change in conditioned motor evoked potential amplitude relative to the unconditioned test response from pre- to post-application of topical capsaicin cream.

Time frame

At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)

Change in Long-Interval Intracortical Inhibition

Long-interval intracortical inhibition will be assessed using paired-pulse transcranial magnetic stimulation over the primary motor cortex, with electromyographic recordings from the first dorsal interosseous muscle. A suprathreshold conditioning stimulus set at 120% of resting motor threshold will be followed by a suprathreshold test stimulus set at 120% of resting motor threshold, with an interstimulus interval of 100 ms. Fifteen conditioned trials will be recorded for this measure. The outcome will be expressed as the change in conditioned motor evoked potential amplitude relative to the unconditioned test response from pre- to post-application of topical capsaicin cream.

Time frame

At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)

Other outcomes

Kinesiophobia

Kinesiophobia will be assessed using the French-Canadian version of the Tampa Kinesiophobia Questionnaire (EKT-CF). It takes the form of a self-reported questionnaire of 17 items using a Likert scale ranging from 1 (strongly disagree) to 4 (strongly agree), with an acceptable degree of internal consistency (Cronbach's alpha = 0.71), satisfactory construct validity, and high sensitivity to change (intra-class correlation coefficient \> 0.7). The total score is obtained by adding the value of the responses and is between 17 and 68. The value of 37/68 is considered as the threshold value at which kinesiophobia becomes significant.

Time frame

Baseline

Pain catastrophizing related to pain

Pain catastrophizing will be assessed using the French-Canadian version of the Pain Catastrophizing Scale (PCS-CF), a self-report questionnaire designed to measure catastrophic thoughts related to pain. The PCS-CF includes 13 items rated on a Likert scale from 0 ("not at all") to 4 ("all the time"), covering three dimensions: rumination, magnification, and helplessness. Item scores are summed to yield a total score ranging from 0 to 52, with higher scores indicating greater pain catastrophizing. A total score ≥30 has been proposed to identify clinically relevant levels of pain catastrophizing.

Time frame

Baseline

Sponsors and contacts

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Université de Sherbrooke

Lead sponsor

Source ClinicalTrials.gov

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