Investigation of Corticospinal Excitability Aspects of Itch and Pain
NCT Number: NCT06470737
Status: NOT_YET_RECRUITING
Study Type: INTERVENTIONAL
Phases: NA
Conditions: Itch|Pain
Interventions: OTHER: Hypertonic Saline|OTHER: Histamine|OTHER: Cowhage|DEVICE: Transcranial magnetic stimulation (TMS)
Sponsor: Aalborg University
Sex: ALL
Age: ADULT
Enrollment: 30
Study Design: Allocation: NA|Intervention Model: SINGLE_GROUP|Masking: NONE|Primary Purpose: BASIC_SCIENCE
Start Date: 2024-07-01
Completion Date: 2026-12-31

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.

Primary Outcome Measures: Numeric rating scales (NRS), 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., 1 minute after every itch/pain induction|Measuring corticospinal excitability, 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., Baseline|Measuring corticospinal excitability, 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., 1 minute after every itch/pain induction for 10 minutes|Measuring corticospinal excitability, 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., post induction (1 minute)|Measuring corticospinal excitability, 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., post induction (30 minutes)|electromyography (EMG) recordings, For electromyography (EMG) recordings, two electrodes (Disposable Electrode Pack - AMBU Neuroline 720) will be placed on the muscle belly of the FDI muscle. The reference electrode will be placed on the ulnar styloid process of the left arm., 1 minute after every itch/pain induction
Secondary Outcome Measures: Pain Catastrophizing Scale (PCS)., The PCS assesses negative and exaggerated coping concerning anticipated or experienced painful stimuli. Thirteen items have to be answered on a 5-point Likert-type scale., Baseline|Itch Catastrophizing Scale (ICS)., he ICS assesses negative and exaggerated coping concerning anticipated or experienced itchy stimuli. Thirteen items have to be answered on a 5-point Likert-type scale., Baseline|Reinforcement Sensitivity Theory - Personality Questionnaire (RST-PQ)., The RST-PQ contains the following subscales: the Fight-Flight-Freeze System (FFFS, 10 items), which represents a defensive factor related to active avoidance of adverse stimuli; the Behavioral Inhibition System (BIS, 23 items), which represents a defensive factor related to anxiety and passive avoidance of adverse stimuli; and the Behavioral Approach System (BAS, 32 items), which reflects reward interest, goal-drive persistence, reward reactivity, and impulsivity. In total, 65 items have to be answered on a 4-point Likert-type scale, Baseline|The Pittsburg Sleep Quality Index (PSQI), The PSQI consists of 19 items generating seven component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The seven component scores can be summarized in a global score ranging from zero to 21 with higher scores reflecting a worse overall quality of sleep, Baseline|Depression, Anxiety, Stress Scale (DASS-21), he questionnaire measures the magnitude of depression, anxiety, and stress. Each of these three subscales consists of 7 questions answered using a 0-3 Likert scale, with 0 meaning "it did not apply to me", and 3 meaning "it applied to me very much"., Baseline|Learned Helplessness Scale (LHS), The questionnaire consists of 20 items, and the participant's response to each item is rated on a 4-point Likert scale ranging from strongly agree (1) to strongly disagree (4)., Baseline|Positive And Negative Affect Schedule (PANAS), PANAS measures positive and negative affect dimensions. Twenty words are associated with the subject's current feelings and have to be rated on a 5-points Likert-type scale., Baseline