Effect of Topical Lidocaine on Warm and Cold Sensation in Healthy Individuals

Study Overview
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Brief Summary
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The purpose of the present study is to systematically test the occurrence of paradoxical and illusory responses to cold and warm stimuli in healthy volunteers with artificial sensory loss.

Detailed Description
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Efficient thermal sensation is important for adequate behavioral response to cold or warm stimuli and early signs of neuropathy can be changes in the thermal sensation. Alterations in thermal perception can results in paradoxical heat sensation (a warm perception when the skin is cooled) or a peculiar/burning sensation when the skin is stiumlated with simultaneous warm and cold (a thermal grill). Clarifying the occurrence of these paradoxical and illusory sensations, may help understanding early signs of peripheral neuropathy as well as thermal sensory perception. The investigators plan to conduct a study on thermal sensory perception using a model of sensory loss in healthy volunteers and systematically test the occurrence of paradoxical heat sensations and responses to the thermal grill.

Official Title
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Effect of Topical Lidocaine on Warm and Cold Sensation in Healthy Individuals - a Randomized Crossover Trial

Conditions
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Neuropathy;Peripheral, Thermal Hypesthesia

Intervention / Treatment
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* Diagnostic Test: Xylocaine spray 100mg/ml
* Diagnostic Test: Ethanol


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy subjects Age between 18 and 40 years Participant is able and willing to give informed consent. Exclusion Criteria: Unable to understand and speak Danish Non-cooperative Chronic pain or acute pain the past week lasting more than 4 hours or pain on the day of investigation Pain medication within the last week Medication within the last week that can affect assessment Psychiatric or neurological disease and diseases that may affect the assessment Sensory disturbances History or symptoms of significant diseases (e.g. psychiatric or neurological disease, diseases that may affect the assessment, sensory disturbances, cancer, diabetes mellitus, liver diseases, kidney diseases, cardiovascular diseases) Pregnancy or lactation Jetlag or sleep deprivation Alcohol or drug abuse Consumption of cannabis the last 4 weeks and consumption of alcohol in the last 48 hours Any abnormality of the skin or of vascular origin at application site History of hypersensitivity to lidocaine, other amide-type anesthetics, or other contents of the lidocaine or vehicle

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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All

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: Diagnostic
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Xylocaine spray 100mg/ml<br>Topical application | Diagnostic Test: Xylocaine spray 100mg/ml<br>* Topical application<br>|
| Placebo Comparator: Ethanol<br>Topical application | Diagnostic Test: Ethanol<br>* Topical application<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Paradoxical heat sensation (PHS) | Number of PHS responders on arm treated with lidocaine 45 minutes after drug application and Number of PHS responders on arm treated with ethanol 45 minutes after drug application | 45 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Thermal Grill (TG) | Number of TG responders on arm treated with lidocaine 75 minutes after drug application and Number of TG responders on arm treated with ethanol 75 minutes after drug application | 75 minutes | 
| Quality of the Thermal Grill (TG) | The participants are asked whether the stimulus is burning, hot, warm, neutral, cold, or freezing cold after the TG-condition (warm and cold), only warm or only cold on arm treated with lidocaine 75 minutes after drug application The participants are asked whether the stimulus is burning, hot, warm, neutral, cold, or freezing cold after the TG-condition (warm and cold) or only warm or only cold on arm treated with ethanol 75 minutes after drug application | 75 minutes | 
| Pain intensity of the Thermal Grill (TG) | The participants are asked to rate the intensity of pain on a visual analog scale (VAS) 0-100 (0 no pain; 100 worst pain imaginable) after the TG-condition (warm and cold), only warm or only cold on arm treated with lidocaine 90 minutes after drug application The participants are asked to rate the intensity of pain on a VAS 0-100 (0 no pain; 100 worst pain imaginable) after the TG-condition (warm and cold), only warm or only cold on arm treated with ethanol 90 minutes after drug application | 90 minutes | 
| Intensity of unpleasantness of the Thermal Grill (TG) | The participants are asked to rate the intensity of unpleasantness on a VAS 0-100 (0 no unpleasantness; 100 worst unpleasantness imaginable) after the TG-condition (warm and cold), only warm or only cold on arm treated with lidocaine 95 minutes after drug application The participants are asked to rate the intensity of unpleasantness on a VAS 0-100 (0 no unpleasantness; 100 worst unpleasantness imaginable) after the TG-condition (warm and cold), only warm or only cold on arm treated with ethanol 95 minutes after drug application | 95 minutes | 
| Intensity of cold of the Thermal Grill (TG) | The participants are asked to rate the intensity of unpleasantness on a VAS 0-100 (0 no cold; 100 extremely cold ) after the TG-condition (warm and cold), only warm or only cold on arm treated with lidocaine 95 minutes after drug application The participants are asked to rate the intensity of unpleasantness on a VAS 0-100 (0 no cold; 100 extremely cold ) after the TG-condition (warm and cold), only warm or only cold on arm treated with ethanol 95 minutes after drug application | 95 minutes | 
| Intensity of warm of the Thermal Grill (TG) | The participants are asked to rate the intensity of unpleasantness on a VAS 0-100 (0 no warm; 100 extremely warm ) after the TG-condition (warm and cold), only warm or only cold on arm treated with lidocaine 95 minutes after drug application The participants are asked to rate the intensity of unpleasantness on a VAS 0-100 (0 no warm; 100 extremely warm ) after the TG-condition (warm and cold), only warm or only cold on arm treated with ethanol 95 minutes after drug application | 95 minutes | 
| Paradoxical heat sensation (PHS) | Number of PHS responders at baseline without any treatment, 30 minutes before drug application | 30 minutes before drug application | 
| Thermal Grill (TG) | Number of TG responders at baseline without any treatment 20 minutes before drug application | 20 minutes before drug application | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Paradoxical Heat Sensations, Thermal Grill Illusion, Lidocaine