Does transcutaneous Vagus Nerve Stimulation (tVNS) reduce pain intensity in chronic low back pain patients? A randomized controlled pilot study

Background: Low back pain, if poorly treated, is responsible for a decline in patients' quality of life. In addition to medication and exercise therapy, transcutaneous vagus nerve stimulation (tVNS) emerges as one of the modalities for chronic pain. Currently, studies on the effect of tVNS on pain intensity, particularly in chronic low back pain cases, are still scarce. This study aims to examine the effect of tVNS in addition to exercise treatment on patients with chronic low back pain. Methods: Twenty-two patients were randomly assigned to one of two groups: the control group, which included eleven patients who received only exercise therapy, and the intervention group, which included eleven patients who received exercise therapy with tVNS as an additional therapy. The demographic data of the participants and the results of the Numerical Pain Rating Scale (NPRS) were used as outcome measures. Data were collected before and after the two-week treatment period. Safety and adverse events were monitored throughout the study. Results: The mean NPRS decreased in both groups, with the intervention group decreasing from 5.45 to 1.73 (p < 0.001) and the control group decreasing from 5.82 to 3.27 (p < 0.001). Although the intervention group's average NPRS score decreased more than the control groups, no significant difference was found (p=1.04). Following Cohen's D, the effect size of the intervention group was more significant (2.22) than that of the control group (1.62). Conclusion: These findings imply that tVNS should be considered an additional therapy for chronic low back pain patients. During the study, no side effects were discovered.