The Effects of Transcutaneous Auricular Vagus Nerve Stimulation and Exercise on Functional Capacity of Chronic Low Back Pain

Background: Mechanical chronic low back pain (CLBP) known as a complex problem with low resolution rate and increased disabilities. Several studies showed vagus nerve stimulation benefit to chronic pain, but no study has evaluated functional outcome of CLBP yet. This study aims to investigate the effects of adding transcutaneous auricular vagus nerve stimulation (tVNS) to exercise therapy on functional capacity (lower extremity strength and functional mobility) of CLBP patients. Methods: A randomized controlled group study was conducted in 22 patients mechanical CLBP aged 16-55. Participants were randomized into an exercise group (control) and an exercise with tVNS group (experimental). Outcome were lower extremity muscle strength measured by Five Times Sit to Sand test (FTSST), and functional mobility using Timed up and Go test (TUG) were evaluated before and after 2 weeks intervention. Results: The mean FTSST of control group pre-test was 12.17± 3.01 and of post-test was 12.12± 4.05 with no significant difference (p=0,945). The mean FTSST of experimental group pre-test was 18.06 ± 9.20 and of post-test was 12.33 ± 2.42, indicating a significant difference (p=0.039), but there was no significant difference on Δ FTSTS between groups (p=0.119). The mean TUG of control group pre-test was 9.23 ± 2.00 and of post-test was 8.71 ± 3.13 indicating no significant difference (p=0.553). The mean TUG of experimental group pre-test was 10.13 ± 2.68 and of post-test was 7.76 ± 1.46 indicating a significant difference (p=0.011), while there was no significant difference on ΔTUG between groups (p=0.117). Conclusion: Our results suggest that tVNS addition to exercise therapy has beneficial effects on lower extremity muscle strength and functional mobility in CLBP patients during relatively short period in two weeks of intervention. Further research is needed to investigate the potential of tVNS therapy in CLBP.