Effect of Transcutaneous Auricular Vagus Nerve Stimulation in Chronic Low Back Pain: A Pilot Study

Abstract

Background/Objectives: Chronic low back pain (CLBP) is a common condition with limited long-term treatment options. Vagus nerve stimulation (VNS) has shown potential for pain improvement, but its use in CLBP remains underexplored. Our aim was to evaluate the efficacy, feasibility and tolerability of transcutaneous auricular vagus nerve stimulation (taVNS) in reducing pain and improving functional outcomes in CLBP patients. Methods: Thirty adults with CLBP (VAS ≥ 40/100) participated in this open-label pilot study (NCT05639270). Patients were treated with a taVNS device on the left ear for 30 min daily over a period of 3 months. The primary outcome was a reduction in pain intensity (VAS) at 1 month. Secondary outcomes included pain intensity at 3 months, disability (Oswestry Disability Index, ODI), quality of life (EQ-5D-5L), catastrophizing and psychological distress. In addition, compliance and adverse events were monitored. Results: After 1 month, 27 patients were evaluated. VAS scores decreased significantly by 16.1 (SD = 17.9) mm (p < 0.001) and by 22.5 (25) mm (p < 0.001) after 3 months (24 patients were analyzed). Functional disability improved with an average reduction in ODI of 11.9 (11.1) points (p < 0.001) after 3 months. Other patient-reported outcomes also improved significantly over the 3-month period. Overall, 51.9% of the patients achieved clinically meaningful pain reduction (≥20 mm), and no serious adverse events were reported. Treatment adherence was good, with half of the patients achieving 80% adherence. Conclusions: This pilot study suggests that taVNS is a feasible, safe and potentially effective treatment for CLBP that warrants further investigation in a randomized controlled trial compared to sham stimulation.

Keywords: chronic low back pain; disability; non-pharmacological therapy; pain; vagus nerve stimulation.

Figure 1

TaVNS device kit. Left to right: Description of the cymba concha, electrode positioning on the cymba concha, a TENSeco2 device (VAGUSTIM) and the conductive gel (copyright Schwa-Medico, adapted from Courties et al. (2022) [16]).

Figure 2

A box-and-whisker plot illustrating the evolution of low back pain VAS at any time point, including the weekly phone calls during the first month. The plot shows the median (bold line within the box), the interquartile range (box edges), the minimum and maximum values within 1.5 times the interquartile range (whiskers) and outliers (individual data points outside this range).