Abstract Body: Introduction: Invasive Vagus Nerve Stimulation (VNS) has been shown to improve motor recovery in stroke patients. However, given the inherent risk of surgical procedures, non-invasive Transcutaneous Auricular Vagus Nerve Stimulation (taVNS) may be worth exploring. This prospective cohort study investigates the changes in neural functioning and its link to motor and cognitive improvements after transcutaneous auricular VNS (taVNS) in adults with a first-time cerebrovascular accident (CVA).
Methods: Patients were admitted to an inpatient acute rehabilitation unit and received 45 minutes of taVNS during physical therapy for 5 days a week for 2 weeks (10 sessions). A resting state electroencephalogram (EEG) was recorded just before the first session and just after the last session. To assess motor function, the Fugl-Myer Assessment for Upper Extremity (FMA-U) and the modified Rankin Scale (mRS) were administered pre- and post-taVNS, parallel to EEG. Similarly, to assess cognitive function, the Montreal Cognitive Assessment (MOCA) was administered pre- and post-taVNS.
Results: In this ongoing study, seven patients post-stroke (5 ischemic; 7-19 days post-injury), aged 37-75 (5 males), have been enrolled. Using Wilcoxon signed-rank tests, our preliminary analyses revealed a significant increase in FMA-U Total and FMA-U Subtotal C scores relating to hand/finger movements following taVNS with a mean improvement of 9.1% (p=0.017) and 11.2% (p=0.05), respectively. Using Spearman's rank correlation, EEG analyses revealed that increases in theta/alpha activity in the bilateral parietal region (r = 0.883, p = 0.02), as well as increases in theta activity in the left temporal region (r = 0.883, p = 0.02) are significantly correlated with improvements in Total FMA-U. Additionally, a significant improvement was noted in the Visuospatial/Executive section within the MOCA (p=0.044). However, no significant correlations with EEG were obtained. No significant improvements were noted on the mRS.
Conclusion: These preliminary results suggest that taVNS may be beneficial in improving upper extremity motor recovery and executive functioning. More importantly, our results indicate that motor improvements following taVNS might be related to changes of brain activity in temporo-parietal areas. Changes in alpha waves within parietal regions is particularly interesting since it is usually related to motor activity. However, a bigger sample is needed to confirm these results.