Effects of Vagus Nerve Stimulation on Motor Function, Respiratory Muscle Strength, and Quality of Life in Stroke Patients

Istanbul University - Cerrahpasa30 enrolled

Overview

Stroke is one of the leading causes of death and permanent disability worldwide. Loss of upper extremity (UE) function after stroke significantly reduces independence and quality of life. Moreover, weakness in the respiratory muscles negatively affects trunk control and respiratory function, limiting overall functional recovery. In recent years, robot-assisted training (RAT) and non-invasive neuromodulation techniques-particularly transcutaneous auricular vagus nerve stimulation (taVNS)-have emerged as promising approaches to enhance neuroplasticity in stroke rehabilitation. This study aims to investigate the effects of taVNS combined with robot-assisted training on upper extremity motor function, respiratory muscle strength, and quality of life in individuals with stroke. This randomized controlled trial will be conducted in collaboration between Istanbul University-Cerrahpaşa and Istanbul Medeniyet University. Thirty individuals aged 18-70 years, with moderate-to-severe upper extremity weakness and a history of stroke of at least six months, will be included. Participants will be randomly assigned to two groups: RAT + taVNS (n=15), RAT + sham taVNS (n=15). Both groups will receive conventional rehabilitation for 45 minutes, three times per week for five weeks. Additionally, each group will undergo 45-minute sessions of RAT twice per week for five weeks, with either active or sham taVNS applied concurrently. The primary outcome measure will be the Fugl-Meyer Upper Extremity Motor Assessment (FM-UE). Secondary outcomes will include the Stroke Impact Scale (SIS), Maximum Inspiratory Pressure (MIP), Maximum Expiratory Pressure (MEP), and Fatigue Assessment Scale (FAS). Assessments will be conducted at baseline and at the end of the fifth week. Combining taVNS with robot-assisted upper extremity rehabilitation is expected to result in greater improvements in motor function, respiratory muscle strength, and quality of life compared to robot-assisted rehabilitation alone. This study will provide valuable insights into the synergistic effects of neuromodulation and robotic therapy in stroke rehabilitation and contribute to the growing body of evidence supporting non-invasive, technology-assisted treatment approaches.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Interventions

Robotics Assisted Education + taVNSDEVICE

Conventional rehabilitation will be administered 3 days a week, 45 minutes per day, for 5 weeks. The combination of Upper Extremity Robotic-Assisted Training and Transcutaneous Auricular Vagus Nerve Stimulation will be administered 2 days a week, 45 minutes per day, for 5 weeks.

Robotics Assisted Education + shamOTHER

Conventional rehabilitation will be administered 3 days a week, 45 minutes per day, for 5 weeks. The combination of Upper Extremity Robotic-Assisted Training and Sham Transcutaneous Auricular Vagus Nerve Stimulation will be administered 2 days a week, 45 minutes per day, for 5 weeks.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 70 Years

Medical Language ↔ Plain English

Inclusion Criteria: * 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), * 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.

Outcomes

Primary Outcomes

Fugl Meyer Upper Extremity Evaluation (FM-UE)

We will use the Fugl-Meyer Upper Motor Assessment score, which is the most sensitive for treatment outcomes in stroke patients presenting with unilateral paresis in the post-stroke period. It measures upper extremity use and impairment, measuring shoulder, elbow, forearm, wrist, finger, and reflex movements from proximal to distal, synergistic to extrinsic. The score ranges from 0 to 66 and consists of 33 items. 0-28 indicates severe motor impairment; 29-42 indicates moderate motor impairment; and 43-66 indicates mild motor impairment. Higher scores indicate better performance. The FM-UE consists of one component, each rated on a 3-point ordinal scale (0=not achieved, 1=partially contributed, 2=completely contributed). The minimum clinically meaningful change on the FM-UE for chronic stroke has been determined to be 4.25 to 7.25. Consistent with the literature, we define an improvement of at least 6 points or more as significant.