The Effect of Capsaicin-induced Pain on Homeostatic Plasticity in Healthy Human Participants
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|ClinicalTrials.gov Identifier: NCT04485689|
Recruitment Status : Recruiting
First Posted : July 24, 2020
Last Update Posted : July 24, 2020
|Condition or disease||Intervention/treatment||Phase|
|Healthy||Drug: Capsaicin Topical Drug: Placebo||Not Applicable|
The aim of this study is to investigate the effect of capsaicin-induced pain on homeostatic plasticity.
A within-subject repeated-measures design will be used to evaluate the effect of capsaicin-induced pain on homeostatic plasticity using cathodal transcranial direct current stimulation (tDCS). Each participant will take part in four experimental sessions during which homeostatic plasticity and corticomotor excitability will be induced and measured in the left primary motor cortex. Participants will receive in randomised order capsaicin or placebo patch placed on the dorsal part of the right hand.
Each participant will attend four sessions, being two consecutive sessions separated by two weeks (i.e. wash-out period). During the experiment, participants will be seated comfortably with hands and arms at rest. First, the electromyography electrodes will be placed at the right hand muscle to be used for assessing the corticomotor excitability by recordings of motor evoked potentials by transcranial magnetic stimulation (TMS) on the left primary motor cortex. Then, the cap for tDCS on the left primary motor cortex will be mounted. The optimal scalp position (hot spot) for TMS stimulation will be identified and marked with a pen on the cap for standardisation. A 5 x 7 cm capsaicin/placebo patch will be placed on participants' right hand. After 30 minutes of patch application, baseline measures of pain and motor-evoked potentials will be taken. Then, the homeostatic plasticity induction process will take place followed by motor-evoked potentials recordings every 15 minutes up to 45 minutes post protocol. Finally, ice will be placed over the patch as to reduce pain intensity to zero and homeostatic plasticity will be induced and measured as previously. The patch will be left in place for 24 hours, at which point participants will return to the laboratory and homeostatic plasticity will once again be induced and measured. After a wash-out period of two weeks, participants will go through an identical process but at this time with a different patch.
Homeostatic plasticity will be induced in the left primary motor cortex using tDCS applied for 7 minutes followed by an interval of 3 minutes and another block of 5 minutes of stimulation. A constant current of 2mA will be transmitted through the tDCS system, using two 25 cm2 electrodes placed into holes of a cap over the hot spot and right supraorbital area.
A sample size calculation was conducted using α of 0.05, β of 0.80 and effect size of 0.29 based on motor evoked potential (MEP) analysis of previous studies resulting in a target of 18 participants.
Data distribution will be assessed using the Shapiro-Wilk test. A repeated measures analysis of variance (ANOVA) will be conducted on mean MEPs with factors Intervention (Capsaicin and Placebo), Time (baseline, 0 min, 15 min, min, 30 min, 45 min) and Time with pain (immediate, post pain relief post prolonged pain). A Greenhouse-Geisser correction will be used if Mauchly's test shows that sphericity cannot be assumed. Adjustments will be made for multiple post-hoc comparisons using the Bonferroni correction. Results will be interpreted according to the level of statistical significance p≤0.05 and effect size reported as partial eta squared.
|Study Type :||Interventional (Clinical Trial)|
|Estimated Enrollment :||18 participants|
|Intervention Model:||Crossover Assignment|
|Primary Purpose:||Basic Science|
|Official Title:||The Effect of Capsaicin-induced Pain on Homeostatic Plasticity in Healthy Human Participants|
|Actual Study Start Date :||July 1, 2020|
|Estimated Primary Completion Date :||December 2020|
|Estimated Study Completion Date :||December 2020|
5x7 cm2 capsaicin patch
Drug: Capsaicin Topical
5x7 cm2 capsaicin patch applied on the dorsal area of the hand and left in place for 24 hours
Placebo Comparator: Placebo
5x7 cm2 placebo patch
5x7 cm2 patch applied on the dorsal area of the hand and left in place for 24 hours
- Conspiratorial excitability [ Time Frame: [Time Frame: 0 minutes post homeostatic plasticity induction] ]Corticospinal excitability measured as motor evoked potentials amplitude induced by transcranial magnetic stimulation.
- Conspiratorial excitability [ Time Frame: [Time Frame: 15 minutes post homeostatic plasticity induction] ]Corticospinal excitability measured as motor evoked potentials amplitude induced by transcranial magnetic stimulation.
- Conspiratorial excitability [ Time Frame: [Time Frame: 30 minutes post homeostatic plasticity induction] ]Corticospinal excitability measured as motor evoked potentials amplitude induced by transcranial magnetic stimulation.
- Conspiratorial excitability [ Time Frame: [Time Frame: 45 minutes post homeostatic plasticity induction] ]
- Pain intensity [ Time Frame: Every 10 minutes post capsaicin application ]Pain intensity measured using an 11-point numeric rating scale where 0= no pain and 10 = worst imaginable pain.
To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT04485689
|Contact: Priscilla G Wittkopf, PhDemail@example.com|
|Aalborg, Denmark, 9220|
|Contact: Priscilla G Wittkopf, PhD +4531539979 firstname.lastname@example.org|