Hypertonic SalineHistamineCowhageTranscranial magnetic stimulation (TMS)
Hypertonic Saline: A bolus injection of hypertonic saline (7% NaCl) will be administered to the FDI muscle using a 1 mL syringe with a disposable needle (27G), and the volume of the bolus will be 0.1 mL
Histamine: A small drop of histamine dihydrochloride will be applied to a previously determined area on the volar forearm, followed by a prick through the drop
Cowhage: This insertion is conducted by forceps using a stereomicroscope, and 30-35 spicules are gently rubbed into a 1 cm diameter skin area.
Transcranial magnetic stimulation (TMS): Transcranial magnetic stimulation (TMS) will be used to evoke motor-evoked potentials (MEPs) in the muscle of interest and cortical responses (TMSevoked potentials - TEPs) in the motor cortex with a figure-eight-shaped cone coil.
Study summary
The aim of this project is to determine the effects of performing a motor imagery task on cortical excitability during acute experimental muscle pain (induced by hypertonic saline), acute histaminergic itch (induced by histamine), and non-histaminergic itch stimulation (triggered by Cowhage). We hypothesize that motor imagery will counteract the alterations in cortical excitability observed during experimental muscle pain and both itch models.
Eligibility
Sex
ALL
Min age
18 Years
Max age
60 Years
Healthy volunteers
Accepted
Inclusion Criteria:
* Healthy men and women
* 18-60 years
* Speak and understand English
Exclusion Criteria:
* Pregnancy or lactation
* Drug addiction defined as any use of cannabis, opioids, or other addictive drugs
* Previous or current history of neurological (e.g. neuropathy), immunological (e.g. asthma, immune deficiencies, arthritis), musculoskeletal (e.g. muscular pain in the upper extremities,), cardiac disorder (e.g., heart stroke), or psychiatric diagnoses (e.g. depression) that may affect the results
* Current use of medications that may affect the trial, such as antihistamines, antipsychotics, and painkillers, as well as systemic or topical steroids
* Skin diseases (e.g., atopic dermatitis, pruritus nodularis, eczema, psoriasis)
* Moles, scars, or tattoos in the area to be treated or tested.
* Consumption of alcohol or painkillers 24 hours before the study days and between these
* Acute or chronic pain
* Unable to pass the "Transcranial Magnetic Stimulation Adult Safety Screen" (subproject 1 and 2)
* Contraindications to transcranial magnetic stimulation (TMS) application (history of epilepsy, metal implants in head or jaw, etc.)
* Presence of implanted hearing aids or metal implants on the face, including permanent makeup or tattoos
* Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials)
* Lack of ability to cooperate
Primary outcome measure(s)
Numeric rating scales (NRS) — 1 minute after every itch/pain induction NRS are essentially VAS but have tick marks spaced every centimeter so as to create 11-point scale (from 0 to 10).
Subject can use these tick marks as a guide when they mark their severity on the scale.
Measuring cortical excitability (TEPs) — Baseline Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). This assessment will last for 7 minutes before inducing itch or pain.
Measuring cortical excitability (TEPs) — During Itch/pain stimulation for 10 minutes Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). This assessment will last for 7 minutes during itch or pain. The pain or itch sensation will last 10 minutes.
Measuring cortical excitability (TEPs) — During motor imagery task for 7 minutes Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). This assessment will last for 7 minutes during motor imagery task.
Measuring cortical excitability (TEPs) — Post induction of itch or pain Transcranial magnetic stimulation (TMS) with a figure-eight-shaped cone coil will be used to evoke cortical responses in the motor cortex. The resulting TMS-evoked potentials (TEPs) will be collected using an electroencephalogram (EEG). Similar to the baseline, this assessment will last for 7 minutes after itch or pain.
This page summarises publicly available registry data for informational purposes — not medical advice. Eligibility is determined by each study team; patients should discuss participation with their clinician.
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