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Pain Beliefs and Intracortical Excitability During Experimental Pain

2 juli 2026 bijgewerkt door: Guillaume Léonard, Université de Sherbrooke

Influence Of Pain-Related Beliefs On The Modulation Of Intracortical Circuits During Experimental Pain Induced By Topical Capsaicin

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.

Studie Overzicht

Toestand

Nog niet aan het werven

Conditie

Interventie / Behandeling

Gedetailleerde beschrijving

Pain is not only a sensory experience. It is also influenced by psychological, emotional, and contextual factors, including how people interpret pain and the threat they associate with movement. In the presence of pain, individuals often modify the way they move. These adaptations may be protective in the short term, but when maintained over time, they may contribute to persistent movement avoidance and disability.

Within the fear-avoidance framework, kinesiophobia, or fear of movement, is considered an important factor in the relationship between pain, movement, and disability. Individuals with higher kinesiophobia may perceive movement as threatening or potentially harmful. This may influence not only motor behavior, but also the way the nervous system prepares and controls movement. However, the neurophysiological mechanisms linking pain-related beliefs, experimental pain, and motor control remain incompletely understood.

The primary motor cortex is a key brain region involved in voluntary movement. Its excitability can be assessed using transcranial magnetic stimulation, a non-invasive brain stimulation technique. When applied over the primary motor cortex, transcranial magnetic stimulation can evoke motor responses that are recorded from a target muscle using surface electromyography. These responses provide information about corticospinal excitability and about intracortical inhibitory and facilitatory mechanisms.

Previous studies suggest that experimental pain can modify motor cortex excitability, but the direction and magnitude of these changes vary considerably between individuals. Pain-related beliefs, especially kinesiophobia, may partly explain this variability. This study therefore focuses on whether experimental pain changes intracortical excitability in the motor cortex and whether this response differs according to baseline kinesiophobia.

The main objective is to quantify changes in short-interval intracortical inhibition before and during experimental pain induced by topical capsaicin, with particular attention to whether these changes vary according to the participant's baseline level of kinesiophobia. Short-interval intracortical inhibition is used as the primary neurophysiological measure because it reflects inhibitory activity within the motor cortex.

Secondary objectives are to characterize other markers of motor cortex excitability during experimental pain. These include long-interval intracortical inhibition, intracortical facilitation, and corticospinal excitability assessed using input-output recruitment curves. These complementary measures are included to provide a broader characterization of inhibitory, facilitatory, and corticospinal responses to experimental pain.

Healthy adults will complete one experimental session. At the beginning of the session, participants will complete questionnaires assessing pain-related beliefs, including kinesiophobia. Baseline neurophysiological assessments will then be performed using transcranial magnetic stimulation applied over the primary motor cortex, with electromyographic recordings from the first dorsal interosseous muscle of the hand.

After baseline measurements, topical capsaicin cream will be applied to the forearm to induce temporary, moderate experimental pain. Pain intensity will be monitored using a visual analog scale. Once experimental pain is established, the same transcranial magnetic stimulation assessments will be repeated.

Each participant serves as their own control, with neurophysiological measures compared between the baseline condition and the experimental pain condition. The investigators hypothesize that changes in motor cortex excitability during experimental pain will vary between individuals. This variability is expected to be partly related to kinesiophobia, with individuals reporting higher kinesiophobia showing smaller changes in motor cortex excitability during capsaicin-induced pain.

Studietype

Ingrijpend

Inschrijving (Geschat)

30

Fase

  • Niet toepasbaar

Contacten en locaties

In dit gedeelte vindt u de contactgegevens van degenen die het onderzoek uitvoeren en informatie over waar dit onderzoek wordt uitgevoerd.

Studiecontact

Studie Contact Back-up

Studie Locaties

  • Canada
    • Quebec
      • Sherbrooke, Quebec, Canada, J1H 5H3

Deelname Criteria

Onderzoekers zoeken naar mensen die aan een bepaalde beschrijving voldoen, de zogenaamde geschiktheidscriteria. Enkele voorbeelden van deze criteria zijn iemands algemene gezondheidstoestand of eerdere behandelingen.

Geschiktheidscriteria

Leeftijden die in aanmerking komen voor studie

  • Volwassen

Accepteert gezonde vrijwilligers

Ja

Beschrijving

Inclusion Criteria:

  • Aged 18 to 35 years, inclusive
  • Healthy
  • Able to understand the study information and experimental procedures
  • Able to provide informed consent

Exclusion Criteria:

  • 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.

Inability to provide informed consent (e.g., dementia, significant hearing impairment, insufficient language proficiency).

  • Any pain condition within the past 3 months, regardless of origin.
  • Recent musculoskeletal injury or surgery within the past 3 months.
  • Contraindications to transcranial magnetic stimulation (TMS), including a history of epilepsy or the presence of intracranial metallic objects, cochlear implants, or other non-removable metallic implants in or near the head.
  • Use of analgesic or psychotropic medications.
  • Individuals under legal guardianship or curatorship.
  • Pregnant or breastfeeding women.
  • Presence of a cardiac pacemaker or other implanted electronic medical device.
  • Known allergy or previous skin reaction to capsaicin

Studie plan

Dit gedeelte bevat details van het studieplan, inclusief hoe de studie is opgezet en wat de studie meet.

Hoe is de studie opgezet?

Ontwerpdetails

  • Primair doel: Fundamentele wetenschap
  • Toewijzing: NVT
  • Interventioneel model: Opdracht voor een enkele groep
  • Masker: Geen (open label)

Wapens en interventies

Deelnemersgroep / Arm
Interventie / Behandeling
Experimenteel: Experimental pain
Participants complete one experimental session. Motor cortex excitability is first assessed at baseline using transcranial magnetic stimulation with electromyographic recordings from the first dorsal interosseous muscle. Topical capsaicin cream is then applied to the forearm to induce temporary, moderate experimental pain. Once pain is established, the same neurophysiological assessments are repeated during the pain condition.
Geneesmiddel: Topical Capsaicin Cream (1%)
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.

Wat meet het onderzoek?

Primaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Change in Short-Interval Intracortical Inhibition
Tijdsspanne: At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
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.
At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)

Secundaire uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Change in Short-Interval Intracortical Facilitation
Tijdsspanne: At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
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.
At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
Change in Pain Intensity
Tijdsspanne: From baseline through completion of the experimental session, an average of 2 hours
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.
From baseline through completion of the experimental session, an average of 2 hours
Change in Intracortical Facilitation
Tijdsspanne: At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
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.
At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
Change in Long-Interval Intracortical Inhibition
Tijdsspanne: At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
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.
At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
Change from baseline in corticospinal excitability
Tijdsspanne: At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)
Corticospinal excitability will be assessed using single-pulse transcranial magnetic stimulation applied over the primary motor cortex, with electromyographic recordings from the first dorsal interosseous muscle. Single magnetic pulses of increasing intensity will be delivered to construct input-output recruitment curves for each participant. Stimulation intensity will be increased in 5% steps, and 10 stimuli will be delivered at each intensity level. Motor evoked potentials will be recorded using surface electromyography. Input-output curves will be modeled using a Boltzmann sigmoidal function, and the slope, plateau, and S50 parameters will be extracted. The outcome will be expressed as the change in these input-output curve parameters from pre- to post-application of topical capsaicin cream.
At baseline (before capsaicin cream application); at pain stabilization (after capsaicin cream application)

Andere uitkomstmaten

Uitkomstmaat
Maatregel Beschrijving
Tijdsspanne
Pijncatastroferen gerelateerd aan pijn
Tijdsspanne: Baseline
Pijncatastroferen wordt beoordeeld met de Frans-Canadese versie van de Pain Catastrophizing Scale (PCS-CF), een zelfrapportagevragenlijst die is ontworpen om catastrofale gedachten met betrekking tot pijn te meten. De PCS-CF bevat 13 items die worden beoordeeld op een Likertschaal van 0 ("helemaal niet") tot 4 ("de hele tijd"), met drie dimensies: ruminatie, vergroting en hulpeloosheid. Itemscores worden opgeteld om een totaalscore tussen 0 en 52 te verkrijgen, waarbij hogere scores wijzen op meer pijncatastroferen. Een totaalscore ≥30 is voorgesteld om klinisch relevante niveaus van pijncatastroferen te identificeren.
Baseline
Kinesiophobia
Tijdsspanne: Baseline
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.
Baseline

Medewerkers en onderzoekers

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Sponsor

Université de Sherbrooke

Onderzoekers

  • Hoofdonderzoeker: Guillaume Léonard, Ph.D., Université de Sherbrooke

Studie record data

Deze datums volgen de voortgang van het onderzoeksdossier en de samenvatting van de ingediende resultaten bij ClinicalTrials.gov. Studieverslagen en gerapporteerde resultaten worden beoordeeld door de National Library of Medicine (NLM) om er zeker van te zijn dat ze voldoen aan specifieke kwaliteitscontrolenormen voordat ze op de openbare website worden geplaatst.

Bestudeer belangrijke data

Studie start (Geschat)

1 augustus 2026

Primaire voltooiing (Geschat)

30 november 2026

Studie voltooiing (Geschat)

31 december 2026

Studieregistratiedata

Eerst ingediend

25 juni 2026

Eerst ingediend dat voldeed aan de QC-criteria

2 juli 2026

Eerst geplaatst (Werkelijk)

7 juli 2026

Updates van studierecords

Laatste update geplaatst (Werkelijk)

7 juli 2026

Laatste update ingediend die voldeed aan QC-criteria

2 juli 2026

Laatst geverifieerd

1 juli 2026

Meer informatie

Termen gerelateerd aan deze studie

Trefwoorden

Aanvullende relevante MeSH-voorwaarden

Andere studie-ID-nummers

  • 2027-6267

Plan Individuele Deelnemersgegevens (IPD)

Bent u van plan om gegevens van individuele deelnemers (IPD) te delen?

NEE

Informatie over medicijnen en apparaten, studiedocumenten

Bestudeert een door de Amerikaanse FDA gereguleerd geneesmiddel

Nee

Bestudeert een door de Amerikaanse FDA gereguleerd apparaatproduct

Nee

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