Effect of Transcutaneous Auricular Vagus Nerve Stimulation Combined With Upper Extremity Robot-Assisted Training on Upper Extremity Motor Functions in Stroke Patients

Effect of Transcutaneous Auricular Vagus Nerve Stimulation Combined With Upper Extremity Robot-Assisted Training on Upper Extremity Motor Functions in Stroke Patients

The effects of stroke on the upper extremity are a common and significant cause of long-term disability, with 65% of patients reporting an inability to participate in daily activities with the affected upper extremity after 6 months. Robotic-assisted training (RAT) has been widely used in recent years to improve upper extremity function. RAT positively impacts upper extremity function and activities of daily living by inducing motor learning from intense, highly repetitive, and task-focused movements of the upper extremity. However, current, limited clinical solutions, including minimally invasive transcutaneous auricular vagus nerve stimulation (taVNS), have not yielded promising results. Therefore, the aim of this study was to investigate the effects of the combination of taVNS and RTA on motor impairment, upper extremity motor function, grip strength, daily living characteristics, and quality of life in individuals with stroke. Stroke medications were randomly assigned to RDE+taVNS (n=15) and RDE+sham taVNS (n=15). All participants will receive conventional treatment for 45 minutes per day, 3 days per week, for 5 weeks. One group will also receive RDE+taVNS treatment for 45 minutes per day, 2 days per week, for 5 weeks, while the other group will receive RDE+sha taVNS. Participants will be assessed using the Fugl-Meyer Upper Extremity Assessment, ARAT (Action Research Arm Test), and Box and Block Test as primary outcomes at baseline and after 5 weeks.

This project will contribute to the literature by demonstrating the effectiveness of taVNS, one of the most promising methods available. Furthermore, the results will prompt discussion on the applicability of the method not only to stroke patients but also to other disease groups. The unique value of this project is that it is the first study to investigate product improvements in taVNS systems.

Inclusion Criteria:

• 1) Individuals aged 18-70 years diagnosed with ischemic or hemorrhagic stroke lasting longer than 6 months,
• Moderate to severe upper extremity weakness (20-50 out of 66 on the Fugl-Meyer Upper Extremity Motor Assessment Scale),
• Ability to communicate and understand (Mini Mental State Examination (MMSE) score ≥ 23), and 4) Upper extremity spasticity of 2 or less on the Modified Ashworth Scale.

Exclusion Criteria:

• Use of any stimulation device, such as a pacemaker or other neurostimulator,
• Presence of a medical or cognitive condition (personality disorder, anxiety, depression, etc.) that would prevent participants from participating in the study,
• Receiving a Botox injection into the affected upper extremity at least 4 weeks prior,
• Severe spasticity in the upper extremity (Modified Ashworth Scale ≥3),
• Presence of dysphagia or aphasia,
• Presence of cardiac problems such as atrial fibrillation, atrial flutter, sick sinus syndrome, or atrioventricular block.