Abstract TP353: Alterations in Resting-state Cortical Electroencephalogram Rhythms and Network Measures Following Short-Term Transcutaneous Vagus Nerve Stimulation and Transcutaneous Spinal Cord Stimulation in People with Chronic Stroke

Introduction: Transcutaneous vagus nerve stimulation (tVNS) and transcutaneous spinal cord stimulation (tSCS) have shown beneficial effects on cognitive and upper limb motor function in people with stroke, potentially by promoting neuroplasticity and facilitating functional reorganization after stroke. However, their underlying neural mechanisms are not fully understood, as there are only a few neurophysiological and neuroimaging studies in this population. Objective: This pilot study aimed to investigate the effects of short-term tVNS and tSCS on resting-state electroencephalogram (EEG) power and network measures in people with chronic stroke. Methods: Twenty individuals with chronic stroke were recruited and randomly allocated to receive either tVNS (n=10) or tSCS (n=10) for 30 minutes. Resting-state whole brain EEG was recorded from 64 scalp channels before and after the 30-minute stimulation. EEG rhythmic powers and hemispheric asymmetry were analyzed. In addition, based on the graph theory, clustering coefficient and global efficiency were calculated to assess functional segregation and integration, respectively. Results: The results revealed that both tVNS and tSCS reduced hemispheric asymmetry ( t = 3.46 and 2.30; p = 0.007 and 0.047, respectively). Significant increases in the normalized power at the theta frequency band in the frontal ( t = -2.67; p = 0.026) and central regions ( t = -3.98; p = 0.003) were observed after tVNS, while decreases in the normalized power at the delta frequency band in the central ( t = 3.71; p = 0.005) and posterior regions ( t = 3.69; p = 0.005) were found after tSCS. Additionally, tVNS significantly increased the clustering coefficient at the theta and alpha frequency bands, while tSCS reduced global efficiency at the delta frequency band in people with stroke. Conclusions: The preliminary results showed that both tVNS and tSCS altered EEG power rhythmic and functional network measures in people with stroke, suggesting potential neural mechanisms of tVNS and tSCS on cortical reorganization after stroke. Both tVNS and tSCS can be potential neuromodulation techniques to facilitate neuroplasticity and recovery in people after stroke. Further studies with a larger sample size with the inclusion of sham-stimulation are needed to provide a more comprehensive evaluation of the effects of tVNS and tSCS.