Characterization of Secondary Hyperalgesia in Healthy Volunteers

Study Overview
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Brief Summary
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In this prospective trial we aim to investigate the intra-individual and inter-individual variance in secondary hyperalgesia following pain elicited by the experimental pain model: Brief Thermal Sensitization. Furthermore we wish to investigate how precise the psychological tests, Pain Catastrophizing Scale and Hospital Anxiety and Depression Scale predict the size of the area of secondary hyperalgesia.

Official Title
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Characterization of Secondary Hyperalgesia in Healthy Volunteers

Conditions
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Experimental Pain in Healthy Males

Intervention / Treatment
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* Other: Brief thermal sensitization
* Other: Long thermal stimulation
* Other: Heat-pain-detection threshold


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age >18 years and <35 years Speak and understand Danish Male gender Test subjects who have understood and signed the informed consent No prescription medicine during the last 30 days Exclusion Criteria: Test subjects that cannot cooperate to the test Test subjects with an alcohol and/or substance abuse, assessed by the investigator Test subjects, who have consumed one or several types of analgesics 2 <days before the study Test subjects, who have consumed antidepressant medication during the last 30 days before the study Test subjects with chronic pain Test subjects with psychiatric diagnoses Test subjects with tattoos on the extremities Body Mass Index of >30 or <18

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experiemental pain models<br>all study participants will be tested with the same experimental pain models: Brief thermal sensitization, Long thermal stimulation, and Heat-pain-detection threshold. | Other: Brief thermal sensitization<br>* A small area of the skin of the study participants are heated to 45 degree celsius for 3 minutes, followed by evaluation of secondary hyperalgesia.<br>* Other names: Experimental thermal pain model;Other: Long thermal stimulation<br>* A small area of the skin of the study participants are heated to 45 degrees celsius for 1 minute. During the 1 minute period, the study participant will continually report pain on an electronic visual analog scale.<br>* Other names: Experimental pain model;Other: Heat-pain-detection threshold<br>* The threshold for heat pain are evaluated by heating a small area of the study participants skin. When the study participant feels pain, the temperature (degrees celsius) is registered. 4 threshold measurements per session. Heat pain threshold is defined as the average temperature of the 4 measurements.<br>* Other names: Experimental pain model;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in area of secondary hyperalgesia following brief thermal sensitization | To determine the intra- and inter-individual variance, and the inter- and intra-observer variance of the secondary hyperalgesia areas following brief thermal sensitization on 4 separate experimental days with two different observers. | Study day 1, 2, 3, and 4. A minimum of 4 weeks. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Score of Pain Catastrophizing Scale | How precise does the score of the Pain Catastrophizing Scale predict the size of the area of secondary hyperalgesia? | 7 days | 
| Score of Hospital Anxiety and Depression Scale | How precise does the score of the Hospital Anxiety and Depression Scale predict the size of the area of secondary hyperalgesia? | 7 days | 
| Score of Subscales of Pain Catastrophizing Scale and Hospital Anxiety and Depression Scale | How precise do the subscales in the two psychological tests (PCS-rumination, PCS-magnification, PCS-helplessness, and HADS-Anxiety, HADS-Depression) predict the size of the area of secondary hyperalgesia? | 7 days | 
| Heat-pain-detection threshold registered by degrees celsius | How precise do the Heat-pain-detection threshold evaluated on the 4 experimental days predict the size of the area of secondary hyperalgesia on the respective 4 experimental days? 4 sessions of Heat-pain-detection threshold on 4 separate experimental days with 1 session per experimental day. | 1 minute per session | 
| Pain following Long Thermal Stimulation, evaluated by maximum on the visual analog scale | How precise does the Max. VAS-score following Long Thermal Stimulation evaluated on the 4 experimental days predict the size of the area of secondary hyperalgesia on the respective 4 experimental days? 4 sessions of Long Thermal Stimulation on 4 separate experimental days with 1 session per experimental day. | 1 minute per session | 
| Pain following Long Thermal Stimulation, evaluated by Area under the curve of the visual analog scale. | How precise does the VAS-Area Under the Curve following Long Thermal Stimulation evaluated on the 4 experimental days predict the size of the area of secondary hyperalgesia on the respective 4 experimental days? 4 sessions of Long Thermal Stimulation on 4 separate experimental days with 1 session per study day. | 1 minute per session | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Anxiety, Pain, Secondary hyperalgesia, thermal sensitization, Catastrophization