Bariatric Surgery Improves Peripheral Nerve Function and Intraepidermal Nerve Fiber Density in Obese Patients without Symptomatic Neuropathy (P1.144)

BOBJECTIVE: Determine the prevalence of subclinical distal symmetric polyneuropathy (DSP) in bariatric surgery candidates and assess the impact of surgery on peripheral nerve structure and function. BACKGROUND: Evolving data link obesity to DSP. Prior studies suggest obese patients often have subclinical neuropathy, and that lifestyle interventions enhance nerve regeneration and improve DSP symptoms. We hypothesize Roux-en-y gastric bypass (RYBGP) will reduce ectopic lipid deposition, inflammation and lipid peroxidation resulting in improved nerve function and epidermal regeneration. DESIGN/METHODS: 11 RYGP candidates without clinical evidence of DSP underwent presurgical neuropathy evaluation including the Michigan Neuropathy Screening Instrument (MNSI), Utah Early Neuropathy Score (UENS), distal leg and thigh skin biopsies for intraepidermal nerve fiber density (IENFD) assessment, and a capsaicin axotomy regeneration experiment to measure axonal regenerative capacity. The regeneration assay was repeated beginning 9 months post RYBGP. RESULTS: 12 months after RYGP there was significant improvement in waist circumference (137 +/- 10 to 110 +/-15 cm, p<0.000). Distal leg IENFD improved from 8.0 +/- 4.9 to 9.73 +/- 7.2 fibers/mm (mean improvement 1.73 +/- 5.7 fibers/mm). Knee IENFD increased from 11.9 +/- 3.8 fibers/mm to 13.1 +/- 7.7 fibers/mm.. The percentage of baseline thigh IENFD recovered after one month of post capsaicin axotomy regeneration was 68[percnt] preoperatively and 76[percnt] after RYGP. The time that a 128 hertz vibratory stimulus was perceived at the great toe increased from 11.3 +/- 5.9 to 14.6 +/- 4.1 seconds. Improvements were also observed in the MNSI (4.8 +/- 3.7 to 3.0 +/- 4.0) and UENS (2.83 +/- 3.0 to 1.83 +/- 3.2). These trends were not statistically significant for this small sample. CONCLUSIONS: These findings support the positive impact of weight loss associated with bariatric surgery on clinical measures of peripheral nerve function and epidermal innervation, and suggest an improvement in peripheral nerve regenerative capacity. Disclosure: Dr. Smith has received personal compensation for activities with CSL Behring, Grifols, and Allergan. Dr. Smith has received research support from NIH, the ADA, and Impeto. Dr. Smith has received personal compensation in an editorial capacity for NeuroLear Dr. Graham has nothing to disclose. Dr. Volckmann has nothing to disclose. Dr. Hauer has nothing to disclose. Dr. Aperghis has nothing to disclose. Dr. Solis has nothing to disclose. Dr. Singleton has nothing to disclose.