The Effect of Bariatric Surgery on Peripheral Nerve Function and Axonal Regeneration

Study Overview
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Brief Summary
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The goal of this research is understand if obesity is a major factor for neuropathy development in patients with and without Type 2 diabetes. This study will examine the relationship between weight, metabolism, and nerve function and regeneration.

Detailed Description
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Peripheral neuropathy causes progressive injury to the longest nerves of the body, starting in the toes, then progressing slowly up the leg. Neuropathy often causes pain, numbness, and weakness if the feet and can lead to reduced mobility, foot ulcers, and even amputation. The most common cause is diabetes, but work at the University of Utah finds that prediabetes and other consequences of obesity, including abnormal cholesterol levels, may be associated with neuropathy. Research has shown that these risk factors may damage nerves and interfere with the ability of nerves to grow back after an injury. This study aims to characterize peripheral nerve function and cutaneous nerve structure in obese bariatric surgery candidates; evaluate peripheral nerve regeneration capacity (and other nerve function measures) before and after bariatric surgery in obese subjects with no or mild neuropathy; examine the relationship between ectopic lipid accumulation, lipotoxic mediators, neuropathy and regeneration capacity in surgical candidates before and one year after surgery.

Official Title
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The Effect of Bariatric Surgery on Peripheral Nerve Function and Axonal Regeneration

Conditions
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Peripheral Neuropathy, Obesity

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-80 years old Subjects must fulfill criteria for bariatric surgery. Exclusion Criteria: History of foot ulceration or neurogenic arthropathy Family history of non-diabetic neuropathy in a first-degree family member. Presence of any disease known to be associated with peripheral neuropathy including but not limited to vitamin deficiency, toxin exposure, paraproteinemia, heavy alcohol use, hepatitis C, HIV. Coumadin use. Inability to understand or cooperate with the procedures of the trial. Known history of sensitivity to capsaicin products.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 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 |
| --- | --- |
| Group 1<br>All participants will be examined by a neurologist to test sensation, reflexes, and strength and complete a few questionnaires. Tests will be performed to measure nerve function and small punch skin biopsies will be taken to assess nerve fiber density. Blood and urine tests will measure various markers of interest. Participants will be seen before and after their bariatric surgery. | |
| Group 2<br>In addition to the procedures described for Group 1, participants in Group 2 will have the following procedures: During bariatric surgery, a small biopsy from the liver and abdominal fat will be taken to examine how fat is processed within the body. At the first visit, after a skin biopsy is taken, a small capsaicin patch will be placed on the lower thigh. The patch will remain in place for 48 hours and will cause the nerves in the immediate area to pull back from the skin. A biopsy will be taken from the patch area 48 hours, 1 month, and 3 months after the initial biopsy. This procedure will be repeated after surgery. MRIs may be performed before and after bariatic surgery. Participants may be asked to complete additional tests to evaluate nerve function | |
| Group 3<br>Group 3 will comprise of individuals who are not overweight. Participants in this group will undergo a similar evaluation to Group 2. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in reinnervation capacity |  | 4 - 1 months prior to bariatric surgery, compared to 9 - 12 months after surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Utah Early Neuropathy Scale (UENS) |  | Baseline to 12 months after bariatric surgery | 
| Change in Nerve Conduction Study measures | Nerve Conduction Study is a procedure routinely used in the diagnosis of neuropathy. Measures will include Sural sensory and Peroneal motor amplitudes and conduction velocities. | Baseline to 12 months after bariatric surgery | 
| Change in nerve fiber density |  | Baseline to 12 months after bariatric surgery | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Bariatric surgery, Obesity, Neuropathy