Effect of non-invasive transcutaneous auricular vagus nerve stimulation on cerebral motor excitability-Study protocol for a randomized, sham controlled trial

Thorsten Herr; Paula Kleger; Sebastian Strauss; Christoph Szeska; Nura Khalil; Bashar W Badran; Mathias Weymar; Matthias Grothe

doi:10.3389/fneur.2023.1341898

Effect of non-invasive transcutaneous auricular vagus nerve stimulation on cerebral motor excitability-Study protocol for a randomized, sham controlled trial

Front Neurol. 2024 Jan 12:14:1341898. doi: 10.3389/fneur.2023.1341898. eCollection 2023.

Authors

Thorsten Herr^#¹, Paula Kleger^#¹, Sebastian Strauss¹, Christoph Szeska², Nura Khalil¹, Bashar W Badran³, Mathias Weymar^{2

4}, Matthias Grothe¹

Affiliations

¹ Department of Neurology, University Medicine Greifswald, Greifswald, Germany.
² Department of Biological Psychology and Affective Science, Faculty of Human Sciences, University of Potsdam, Potsdam, Germany.
³ Department of Psychiatry and Behavioral Sciences, Neuro-X Lab, Medical University of South Carolina, Charleston, SC, United States.
⁴ Faculty of Health Sciences Brandenburg, University of Potsdam, Potsdam, Germany.

^# Contributed equally.

Abstract

Transcutaneous auricular vagus nerve stimulation (taVNS) is becoming increasingly established in the treatment of various neurological and psychiatric diseases. However, only a few studies have focused on the overall influence of taVNS on cortical excitability in general. The planned study will investigate the effect of taVNS on the excitability of the motor cortex in young healthy subjects. The aim of the study is to gain better understand of the physiological mechanism of taVNS to contribute to new fields of application of taVNS in new areas such as the treatment of stroke or multiple sclerosis. This protocol describes a single-center, prospective, double blind, sham-controlled trial that evaluates the effect of taVNS on motor cortex excitability with a planned sample size of 30 participants. The effect of taVNS is investigated by neuronavigation and electromyography (EMG) coupled transcranial magnetic stimulation (TMS) applied before and after taVNS stimulation. The following parameters are assessed: resting motor threshold (RMT), active motor threshold (AMT), recruitment curve (RC), short intracortical inhibition (SICI), intracortical facilitation (ICF). All parameters will be assessed for taVNS on the basis of perception threshold and tolerance threshold. All investigations performed in the study were reviewed and approved by the local ethics committee of the University Medical Center Greifswald (study reference number: BB048/22).

Clinical trial registration: www.drks.de, number: DRKS00029937.

Keywords: TMS; motor cortex excitability; neurophysiology; taVNS; vagal nerve.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. Open Access funding was made possible and organized by the DEAL project.