Investigation of Corticospinal Excitability Aspects of Itch and Pain

NCT ID: NCT06470737

Last Updated: 2024-11-22

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 30 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-07-01
• Study Completion Date: 2024-10-31

Brief Summary

The experiment consists of three experimental sessions conducted over a period of two weeks. In the first experimental session, we apply in your hand: either an injection of salt water (7% NaCl) or we apply small needles from the plant mucuna pruriens or histamine (1%). For 10 minutes after this, you are to assess the itch and pain you perceive. We will also apply non-invasive magnetic stimulations to your brain. During the experiment, you should fill in questionnaires. The second and third experimental sessions are conducted in the same way as the first session.

The purpose of this experiment is to investigate the changes appearing in the brain during artificially applied itch and pain corticomotor adaptations.

Detailed Description

The experiment consists of three experimental sessions conducted over a period of two weeks. The duration of each session is approx. two hours. In the first experimental session, we apply one of three experimental methods in your hand: either an injection of salt water (7% NaCl) or we apply small needles from the plant mucuna pruriens or histamine (1%) Histamine is an itch-provoking substance formed in the human body. For 10 minutes after this, you are to assess the itch and pain you perceive on a scale from 0 to 10, in which 0 is no itch/pain and 10 is worst itch/pain imaginable. We will also apply non-invasive magnetic stimulations to your brain. This is done using a magnetic coil which is held over your head. During the experiment, you should fill in questionnaires about how you experience itch/pain and about your personality. The second and third experimental sessions are conducted in the same way as the first session. However, we will apply one of the other two experimental methods than the one used in the first session (i.e., first session: histamine, second session: plant needles, third session: injection with salt water). The experimental methods will be applied in random order.

Conditions

Itch; Pain

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Healthy volunteers

Group Type: EXPERIMENTAL

Hypertonic Saline

Intervention Type: OTHER

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 0.2 mL

Histamine

Intervention Type: OTHER

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

Intervention Type: OTHER

This insertion is conducted by forceps using a stereo-microscope, and 30-35 spicules are gently rubbed into a 1 cm diameter skin area.

Transcranial magnetic stimulation (TMS)

Intervention Type: DEVICE

Transcranial magnetic stimulation (TMS) will be used to evoke motor-evoked potentials (MEPs) in the muscle of interest and cortical responses (TMS-evoked potentials - TEPs) in the motor cortex with a figure-eight-shaped cone coil.

Interventions

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 0.2 mL

Intervention Type: OTHER

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

Intervention Type: OTHER

Cowhage

This insertion is conducted by forceps using a stereo-microscope, and 30-35 spicules are gently rubbed into a 1 cm diameter skin area.

Intervention Type: OTHER

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 (TMS-evoked potentials - TEPs) in the motor cortex with a figure-eight-shaped cone coil.

Intervention Type: DEVICE

Eligibility Criteria

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.) (subproject 1 and 2)
• Presence of implanted hearing aids or metal implants on the face, including permanent makeup or tattoos (subproject 1 and 2)
• Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials)
• Lack of ability to cooperate

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

Aalborg University

OTHER

Sponsor Role: lead

Responsible Party

Silvia Lo Vecchio

Associate Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Aalborg University

Gistrup, , Denmark

Countries

Denmark

Other Identifiers

N-20240004 1st subproject

Identifier Type: -

Identifier Source: org_study_id