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

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.

Interventions

• Device Robotics Assisted Education + taVNS
  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.
• Other Robotics Assisted Education + sham
  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.

Primary outcome measures

• Fugl Meyer Upper Extremity Evaluation (FM-UE) [Time frame: Outcome measures will be assessed and recorded at baseline (assessment session) and after intervention (week 5).]

Secondary outcome measures (4)

• Stroke Impact Scale (SIS) [Time frame: Outcome measures will be assessed and recorded at baseline (assessment session) and after intervention (week 5).]
• Maximum Inspiratory Pressure (MIP) [Time frame: Outcome measures will be assessed and recorded at baseline (assessment session) and after intervention (week 5).]
• Maximum Expiratory Pressure (MEP) [Time frame: Outcome measures will be assessed and recorded at baseline (assessment session) and after intervention (week 5).]
• Fatigue Assessment Scale(FAS) [Time frame: Outcome measures will be assessed and recorded at baseline (assessment session) and after intervention (week 5).]

Eligibility criteria

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.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

Turkey (Türkiye) · 1 center

• İstanbul Üniversitesi-Cerrahpaşa Sağlık Bilimleri Fakültesi Büyükçekmece Yerleşkesi — Istanbul

Identifiers

NCT: NCT07259577 · 1439695

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗