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

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

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.

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.

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