Itching
Conditions
Brief summary
This project aims to create a reliable, long-lasting itch model by synergistically combining thermal pre-conditioning with the application of histamine or cowhage.
Detailed description
Two areas (4x4 cm, one on each forearm), will be selected. Initially, superficial blood perfusion will be measured in each area, followed by pruritogens application. During the 10 minutes of the application of the pruritogens, itch will be continuously monitored using a VAS scale. After the pruritogens application, assessment of the superficial blood perfusion (SBP), mechanical sensitivity, and thermal sensitivity will be conducted. The session will be identical to the first session, but pre-heat conditioning will be applied prior to pruritogens application.
Interventions
The spicules will be manually inserted. Approximately 30-35 spicules are gently rubbed into a 1 cm diameter skin area on the forearm/face
OTHERHistamine
To deliver histamine, standard allergy skin prick test (SPT) lancets are applied
OTHERHeat
45 °C x 5 min
Sponsors
Aalborg University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
OTHER
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to 60 Years
Healthy volunteers
Yes
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., stroke), or psychiatric diagnoses (e.g., depression, bipolar disorders, acute and chronic psychosis) that may affect the results * Current use of medications that may affect the trial, such as antihistamines, antipsychotics, painkillers, and 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 (forearm/hand). * Consumption of alcohol or painkillers 24 hours before the study days and between these * Acute or chronic pain * Unable to answer the "Transcranial Magnetic Stimulation Adult Safety Screen" (subprojects 2-4) * Contraindications to transcranial magnetic stimulation (TMS) application (history of epilepsy, metal implants in head or jaw, etc.) (subprojects 2-4) * Presence of implanted hearing aids or metal implants on the face, including permanent makeup or tattoos (subprojects 2-4) * Contraindications to capsaicin, including intolerance to chili or burns or wounds at the application sites (subprojects 2, 3, and 4) * Participation in other trials within one week of study entry (four weeks in the case of pharmaceutical trials) * The subject is assessed as unable to engage in the necessary cooperation required by the study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Measuring pain by computerized Visual Analog Scale Scoring | Day 1 | We will ask the subjects to rate the sensation of pain on a 100 |
| Measuring Itch by computerized Visual Analog Scale Scoring | Day 1 | We will ask the subjects to rate the sensation of itch on a 100 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Superficial blood perfusion | Day 1 | Superficial blood perfusion (SBP) is measured by a Speckle contrast imager |
| Alloknesis | Day 1 | Measured using a standardized sensory brush exerting a force of 200 to 400 mN. |
| Mechanically evoked itch (MEI) | Day 1 | MEI is measured by using mildly pruritic, non-painful von Frey nylon filaments of a predetermined intensity (generally 5-30 miliNewton of force). |
| Mechanical Pain Thresholds (MPT) | Day 1 | 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. |
| Mechanical Pain Sensitivity (MPS) | Day 1 | This test is conducted with the same pinprick set used to test the MPT. |
| Cold Detection Thresholds (CDT) | Day 1 | The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
| Warm Detection Thresholds (WDT) | Day 1 | The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
| Cold Pain Thresholds (CPT) | Day 1 | The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
| Heat Pain Thresholds (HPT) | Day 1 | The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
| Pain to Supra-threshold Heat Stimuli (STHS) | Day 1 | The tests of thermal sensation will all be conducted using a PATHWAY ATS (Medoc Ltd, Israel) thermal sensory testing device |
Countries
Denmark
Contacts
CONTACTSilvia Lo Vecchio, PhD
Outcome results
None listed