The experiment consists of three experimental sessions conducted on three consecutive days. In all experimental sessions, the participant will fill in a series of questionnaires about how you perceive itch and pain, and about some traits of your personality, such as depression, anxiety and stress. In the first session, we will mark six test areas in your face (three on each side on jaw, cheek, and temple, respectively). Thent a series of measure-ments in each test area will be conducted:measurement of the blood flow in the skin and sensitivity tests to pressure, pinprick and stroke with a brush. In the second session, histamine will be applied in one side of the face. On the other side, cowhage spicules will be applied. After 10 minutes, all the tests will be conducted again. The third session will be identical to the second. However, instead of histamine and spicules, patches containing capsaicin will be applied. In the other side, we will apply patches with placebo (i.e., a non-active patch). After 20 minutes all the tests will be conducted again.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
30
To deliver histamine, standard allergy skin prick test (SPT) lancets are applied
The spicules will be manually inserted. Approximately 30-35 spicules are gently rubbed into a 1 cm diameter skin area on the forearm/face
Capsaicin patches (dosage form: transdermal patch 8% Qutenza, Astellas) will be applied on 3 squared areas in the face.
Placebo patch (demo patch, containing the same formulation as the active treatment with the exception of capsaicin) will be applied on 3 squared areas in the face.
Aalborg University
Gistrup, Aalborg, Denmark
RECRUITINGMeasuring pain by computerized Visual Analog Scale Scoring
We will ask the subjects to rate the sensation of pain on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no pain" and 100 indicates "worst pain imaginable".
Time frame: Baseline
Measuring itch by computerized Visual Analog Scale Scoring
We will ask the subjects to rate the sensation of itch on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no itch" and 100 indicates "worst itch imaginable".
Time frame: Baseline
Measuring pain by computerized Visual Analog Scale Scoring
We will ask the subjects to rate the sensation of pain on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no pain" and 100 indicates "worst pain imaginable".
Time frame: Immediately after the intervention
Measuring itch by computerized Visual Analog Scale Scoring
We will ask the subjects to rate the sensation of itch on a 100 mm VAS scale ranging from 0 to 100 where 0 indicates "no itch" and 100 indicates "worst itch imaginable".
Time frame: Immediately after the intervention
Superficial blood perfusion
Superficial blood perfusion (SBP) is measured by a Speckle contrast imager
Time frame: Baseline
Superficial blood perfusion
Superficial blood perfusion (SBP) is measured by a Speckle contrast imager
Time frame: Immediately after the intervention
Alloknesis
Measured using a standardized sensory brush exerting a force of 200 to 400 mN.
Time frame: Baseline
Alloknesis
Measured using a standardized sensory brush exerting a force of 200 to 400 mN.
Time frame: Immediately after the intervention
Mechanically evoked itch (MEI)
MEI is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).
Time frame: Baseline
Mechanically evoked itch (MEI)
MEI is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force).
Time frame: Immediately after the intervention
Mechanical Pain Thresholds (MPT)
This test is conducted using a pinprick set. The set consists of 7 needles each with a diameter of 0.6 mm and different force applications: 8, 16, 32, 64, 128, 256, and 512 mN.
Time frame: Baseline
Mechanical Pain Thresholds (MPT)
This test is conducted using a pinprick set. The set consists of 7 needles each with a diameter of 0.6 mm and different force applications: 8, 16, 32, 64, 128, 256, and 512 mN.
Time frame: Immediately after the intervention
Mechanical Pain Sensitivity (MPS)
This test is conducted with the same pinprick set used to test the MPT.
Time frame: Baseline
Mechanical Pain Sensitivity (MPS)
This test is conducted with the same pinprick set used to test the MPT.
Time frame: Immediately after the intervention
Cold Detection Thresholds (CDT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Baseline
Cold Detection Thresholds (CDT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Warm Detection Thresholds (WDT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Baseline
Warm Detection Thresholds (WDT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Cold Pain Thresholds (CPT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Baseline
Cold Pain Thresholds (CPT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Heat Pain Thresholds (HPT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Baseline
Heat Pain Thresholds (HPT)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
Pain to Supra-threshold Heat Stimuli (STHS)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Baseline
Pain to Supra-threshold Heat Stimuli (STHS)
The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device
Time frame: Immediately after the intervention
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 ranging from 0 (Not at all) to 4 (all the time).
Time frame: Baseline
Itch Catastrophizing Scale (ICS).
The 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 ranging from 0 (Not at all) to 4 (all the time).
Time frame: 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).
Time frame: 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).
Time frame: 10 minutes after every induction
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 ranging from 0 (Not at all) to 4 (all the time).
Time frame: 10 minutes after induction
Itch Catastrophizing Scale (ICS).
The 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 ranging from 0 (Not at all) to 4 (all the time).
Time frame: 10 minutes after induction
Depression, Anxiety, Stress Scale (DASS-21)
The 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"
Time frame: Baseline
Reinforcement Sensitivity Theory - Personality Questionnaire (RST-PQ).
The RST-PQ contains in total, 65 items must be answered on a 4-point Likert-type scale
Time frame: Baseline
Difficulties in Emotion Regulation Scale Short Form (DERS-SF)
The questionnaire is an 18-item measure used to identify emotional regulation issues in adults. Participants rate each item on a 5-point Likert scale (from 1 to 5).
Time frame: Baseline
Emotion Regulation Questionnaire (ERQ
This questionnaire is designed to assess individual differences in the habitual use of two emotion regulation strategies: cognitive reappraisal and expressive suppression. Respondents answer each item on a 7-point Likert-type scale ranging from 1 (strongly disagree) to 7 (strongly agree), where 4 means (neutral).
Time frame: Baseline
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