Transcutaneous auricular vagus nerve stimulation on upper limb motor function with stroke: a functional near-infrared spectroscopy pilot study

Likai Wang; Fei Gao; Yongli Dai; Zhan Wang; Feng Liang; Jingyi Wu; Mengchun Wang; Litong Wang

doi:10.3389/fnins.2023.1297887

Transcutaneous auricular vagus nerve stimulation on upper limb motor function with stroke: a functional near-infrared spectroscopy pilot study

Front Neurosci. 2023 Nov 21:17:1297887. doi: 10.3389/fnins.2023.1297887. eCollection 2023.

Authors

Likai Wang^#¹, Fei Gao^#¹, Yongli Dai¹, Zhan Wang¹, Feng Liang², Jingyi Wu¹, Mengchun Wang¹, Litong Wang¹

Affiliations

¹ Department of Rehabilitation Medicine, The Second Hospital of Dalian Medical University, Dalian, China.
² First Clinical Medical College, Shanxi Medical University, Taiyuan, China.

^# Contributed equally.

Abstract

Background: Transcutaneous auricular vagus nerve stimulation (taVNS) emerges as a promising neuromodulatory technique. However, taVNS uses left ear stimulation in stroke survivors with either left or right hemiparesis. Understanding its influence on the cortical responses is pivotal for optimizing post-stroke rehabilitation protocols.

Objective: The primary objective of this study was to elucidate the influence of taVNS on cortical responses in stroke patients presenting with either left or right hemiparesis and to discern its potential ramifications for upper limb rehabilitative processes.

Methods: We employed functional near-infrared spectroscopy (fNIRS) to ascertain patterns of cerebral activation in stroke patients as they engaged in a "block transfer" task. Additionally, the Lateralization Index (LI) was utilized to quantify the lateralization dynamics of cerebral functions.

Results: In patients exhibiting left-side hemiplegia, there was a notable increase in activation within the pre-motor and supplementary motor cortex (PMC-SMC) of the unaffected hemisphere as well as in the left Broca area. Conversely, those with right-side hemiplegia displayed heightened activation in the affected primary somatosensory cortex (PSC) region following treatment.Significantly, taVNS markedly amplified cerebral activation, with a pronounced impact on the left motor cortical network across both cohorts. Intriguingly, the LI showcased consistency, suggesting a harmonized enhancement across both compromised and uncompromised cerebral regions.

Conclusion: TaVNS can significantly bolster the activation within compromised cerebral territories, particularly within the left motor cortical domain, without destabilizing cerebral lateralization. TaVNS could play a pivotal role in enhancing upper limb functional restoration post-stroke through precise neuromodulatory and neuroplastic interventions.

Keywords: functional near-infrared spectroscopy; pre-motor and supplementary motor cortex; primary motor cortex; primary somatosensory cortex; stroke; transcutaneous auricular vagal nerve stimulation; upper limb motor function.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This project was partly supported by the Basic scientific research project of Liaoning Provincial Department of Education (LJKMZ20221292) and the Dalian Chinese Medicine Scientific Research Project (22Z12018).