Effects of transcutaneous auricular vagus nerve stimulation (TVNS) on heart rate variability (HRV) in chronic low back pain patients

Link of Video Abstract: https://youtu.be/CdSLXupKkQcBackground: Chronic low back pain (LBP) is the second cause of disability. LBP often causes recurrence, which causes disability, affecting productivity and daily activities and affecting quality of life. Transcutaneous auricular vagus nerve stimulation (tVNS) is a technique of electrical stimulation of vagus nerve afferents that is used as a therapy for chronic pain. Methods: This research is an experimental study with a pretest-posttest randomized controlled group study with 22 subjects with chronic mechanical LBP aged 16-55 years who were randomly allocated into an exercise group (control group) and exercise with an additional tVNS group (treatment group). Heart Rate Variability (HRV) parameters assessed were Root Mean Square of Successive Differences Between Normal Heartbeats (RMSSD), Standard Deviation of Normal to Normal R-R intervals (SDNN), Low Frequency/ High Frequency (LF/HF) ratio before and after the intervention. Results: There was a significant improvement in Heart Rate Variability for both groups before and after the intervention, but the treatment group was higher than the control group. Intervention group components RMSSD (p= 0.01), SDNN (p= 0.01), and LF/HF ratio (p= 0.00). In the control group, there were significant differences in RMSSD (p=0.02), SDNN (p=0.06), and LF/HF ratio (p=0.01). Comparison values of Δ RMSSD, Δ SDNN, and Δ LF/HF ratio between groups after 2 weeks of training did not show a significant improvement in RMSSD (p=0.53), SDNN (p=0.87), LF/HF ratio 0.98. The effect size values in the treatment and control groups were small for RMSSD and very small for SDNN and LF/HF ratio. Conclusions: The addition of tVNS to exercise therapy on the HRV parameters of chronic LBP patients for 2 weeks shows better improvements compared to exercise therapy alone. Both tVNS addition to exercise therapy and exercise therapy alone can have a positive effect on improving HRV parameters, although there are no significant differences between the two groups.