Weight Loss From Gastric Bypass Surgery Improves Peripheral Neuropathy

Patients who underwent gastric bypass surgery saw improved nerve fiber density 12 months following surgery.

VANCOUVER, British Columbia — Weight loss associated with bariatric surgery may help improve clinical measures of peripheral nerve function and nerve regeneration in obese patients, data indicate.

The study results were presented at the 2016 annual meeting of the American Academy of Neurology (AAN) in Vancouver.

Prior research has indicated that obese patients are more likely to have subclinical neuropathy. Likewise, lifestyle interventions have been shown to improve distal symmetric polyneuropathy and nerve regeneration.

In order to determine the prevalence of distal symmetric polyneuropathy in these patients and measure the impact of bariatric surgery on peripheral nerve growth and function, A. Gordon Smith, MD, FAAN, of the University of Utah, and colleagues conducted a small study in 11 gastric bypass candidates without clinical evidence of distal symmetric polyneuropathy.

Prior to surgery, participants underwent a neuropathy evaluation, including the Michigan Neuropathy Screening instrument (MNSI), Utah Early Neuropathy Score (UENS), distal leg and thigh skin biopsies to measure intraepidermal nerve fiber density (IENFD), and capsaicin axotomy to measure axonal regenerative capacity. The regeneration assay was repeated beginning 9 months following gastric bypass surgery.

At 12 months following Roux-en-y gastric bypass surgery, a significant improvement in waist circumference was observed (137 +/- 10 to 110 +/-15 cm, P<.000) among participants. Distal leg IENFD improved from 8.0 +/- 4.9 to 9.73 +/- 7.2 fibers/mm (mean improvement 1.73 +/- 5.7 fibers/mm), and 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).

The percentage of baseline thigh IENFD recovered after 1 month of regeneration following capsaicin axotomy was 68% preoperatively and 76% after gastric bypass surgery. Additionally, time to perception of 128 Hz vibratory stimulus at the great toe increased from 11.3 +/- 5.9 to 14.6 +/- 4.1 seconds.

Although not statistically significant for the small sample size, the findings reflect a beneficial effect of bariatric surgery-associated weight loss on peripheral nerve function and regeneration.

Click here for more coverage from the 68th Annual Meeting of the American Academy of Neurology, April 15-21, 2016, in Vancouver, British Columbia, Canada.


Smith AG, Graham T, Volckmann E, et al. Bariatric surgery improves peripheral nerve function and intraepidermal nerve fiber density in obese patients without symptomatic neuropathy. Presented at: The 68th Annual Meeting of the American Academy of Neurology. April 15-21, 2016; Vancouver, British Columbia, Canada. Abstract P1.144.