Spinal and Supra-Spinal Pain Mechanisms in Patients With Fibromyalgia

Study Overview
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Brief Summary
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Fibromyalgia (FM) patients have increased windup (WU). However, WU of FM patients is only quantitatively but not qualitatively different from healthy controls (HC). Thus WU abnormalities of FM patients could be the result of supra-spinal and not the result of spinal pain mechanisms. The study team will test this hypothesis by sensitizing FM patients with topical capsaicin.

Detailed Description
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The study team hypothesizes that at baseline the slopes of sensitivity adjusted WU of FM patients are not statistically different from HC. However, after capsaicin application, the slopes of sensitivity adjusted WU will be significantly different from baseline and greater than those of HC, suggesting central sensitization. This would imply that FM patients are sensitive to heat pain but not sensitized.

Official Title
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Spinal and Supra-Spinal Pain Mechanisms in Patients With Fibromyalgia

Conditions
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Fibromyalgia, Pain

Intervention / Treatment
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* Drug: Capsaicin Patch 8% or 0.1% Capsaicin Cream
* Other: Vehicle Patch


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: individuals diagnosed with fibromyalgia will have pain of duration > 6 months and meeting the 1990 Research Diagnostic Criteria for FM (ACR). healthy, pain-free age matched controls without chronic pain Exclusion Criteria: Allergy to red chili peppers; Pregnant; Significant hearing loss; Presence of chronic disease (e.g. cancer, cardiovascular disease, liver disease, kidney disease, diabetes, etc.). FM patients must be willing to discontinue or hold their FM related medications for at least 5 half-lives.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Vehicle Patch<br>Control patch will be the same topical solution but will not contain capsaicin. The patch will applied to the hand for 30 - 60 min. Patients will be instructed to not touch or wash their hands during the course of the study to minimize spreading of the patch to other areas of the body. Subsequently, the patch will be immediately removed. | Other: Vehicle Patch<br>* Control patch will be the same topical solution but will not contain capsaicin.<br>|
| Capsaicin Patch 8% or 0.1% Capsaicin Cream<br>8% capsaicin topical patch or 0.1% capsaicin cream. The patch will applied to the hand for 30 - 60 min. The cream will be applied similarly on a 3 cm2 area of the arm. Patients will be instructed to not touch or wash their hands during the course of the study to minimize spreading of the patch to other areas of the body. Subsequently, the patch will be immediately removed. | Drug: Capsaicin Patch 8% or 0.1% Capsaicin Cream<br>* 0.1 ml of 8% capsaicin topical patch or 0.1% capsaicin cream<br>* Other names: Capsaicin No-Fuss;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Progression of Temporal Summation of Second Pain | A Peltier device (Pathway, Medoc) will be used to tap the skin surface with a 3 cm x 3 cm probe. The Peltier device will be used to provide very brief, repetitive, thermal stimuli (for approx. 1s) to the skin using computer controlled temperatures. Heat stimuli at intervals of 2.5 sec produce sensations of increasing pain (temporal summation), depending on the number of stimuli presented. The late sensations of warmth are delayed in onset by approximately 1.5 sec after the probe touches the skin, because the sensation depends upon stimulation of slowly conducting unmyelinated peripheral afferents. | 2 hr |