Transauricular Vagus Nerve Stimulation (taVNS) enhances CPM in healthy subjects: A randomized controlled trial.

BACKGROUND

Evidence suggests that transauricular vagus nerve stimulation (taVNS) modulates the endogenous pain system and may be an alternative treatment for chronic pain conditions.

OBJECTIVE

To investigate the effects of taVNS in pain processing using quantitative sensory testing (QST) as a biomarker for pain sensitivity and modulation.

METHODS

We conducted a randomized double-blinded controlled study with 44 healthy subjects, 22 allocated to taVNS and 22 to sham taVNS. QST metrics (pain-60, temporal summation [TSPS], and conditioned pain modulation [CPM]) were the main outcomes of the study. Self-reported mood and fatigue were secondary outcomes. We performed regression analyses to evaluate the differences between pain-60 scores, TSPS, and CPM before and after intervention comparing taVNS and sham VNS groups. Moreover, Bayesian models were performed as sensitivity analysis.

RESULTS

Our findings showed a statistically significant difference in the CPM score between taVNS and sham taVNS (beta coefficient = 0.80; 95% CI: 0.23-1.37; p = 0.007). The effect size (Cohen's d) of this difference was 0.97, which is considered a large effect size. Bayesian results (non-informative prior) supported the superiority of taVNS showing a strong probability of benefit (99.99%; beta coefficient = 0.80; 95% CrI: 0.25-1.35; BF = 234.29). No differences were found in pain-60 (unadjusted: p = 0.58; adjusted: p = 0.76) or TSPS (unadjusted: p = 0.25; adjusted: p = 0.40). Moreover, the analysis demonstrated a significant correlation between VAS fatigue and mood with CPM improvement in the taVNS group. Also, changes in fatigue significantly mediated taVNS effects.

CONCLUSIONS

This study supports the taVNS positive effects on endogenous pain modulation in health subjects. Future RCTs using VNS in patients with chronic pain are still needed to establish the analgesic effects of taVNS in the clinical setting.

TRIAL REGISTRATION

NCT05801809.

Informations de copyright

Copyright © 2024. Published by Elsevier Inc.

Déclaration de conflit d'intérêts

Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: H.C. and J.S. are directly associated with Neurive Co, a company developing neuromodulation technologies, such as taVNS, to treat common brain diseases. Neurive funds research at the Spaulding Neuromodulation Center. F.F. is a consultant for Neurive.