Effect of Transcutaneous Auricular Vagus Nerve Stimulation Application on Respiratory Functions in Stroke Patients (TAVNS)

March 31, 2026 updated by: Burcu AKKURT, Fenerbahce University

Effect of TAVNS Application on Respiratory Functions in Stroke Patients

The purpose of this study is to evaluate the effectiveness of Transcutaneous Auricular Vagus Nerve Stimulation (TAVSS) in improving respiratory muscle strength and function in chronic stroke patients. It aims to explore TAVSS as a potential complementary approach in enhancing rehabilitation outcomes for this population.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Detailed Description

Introduction Stroke is one of the leading causes of morbidity and long-term disability worldwide. Respiratory muscle weakness is a common complication in stroke patients, leading to respiratory dysfunction, increased aspiration risk, and higher mortality. Post-stroke, reduced vital capacity, maximum inspiratory and expiratory pressure, and low expiratory reserve volume significantly affect respiratory muscle function.

Objective This study aims to investigate the effects of Transcutaneous Auricular Vagus Nerve Stimulation (TAVSS) on respiratory parameters in chronic stroke patients.

Participants and Methods

The study included 50 chronic stroke patients in their 1st to 3rd year post-stroke, meeting specific motor levels in Brunnstrom Staging.

Participants were randomized equally into experimental (TAVSS + conventional physiotherapy) and control (sham TAVSS + conventional physiotherapy) groups.

Treatment Protocol

Experimental Group: TAVSS and conventional physiotherapy were applied three times per week for a total of 10 sessions. TAVSS was delivered for 20 minutes using a biphasic asymmetric waveform.

Control Group: Sham TAVSS (without current) and conventional physiotherapy were applied with the same frequency and duration.

Both groups received individualized physiotherapy protocols, including strengthening, stretching, balance exercises, electrotherapy, and neurodevelopmental treatment.

Measurements and Evaluation

Chest circumference measurements were taken at the axillary, epigastric, and subcostal regions during deep inspiration and expiration using a tape measure.

Respiratory function parameters (Maximum Inspiratory Pressure, Maximum Expiratory Pressure, Forced Expiratory Volume in 1 Second, Forced Vital Capacity, Forced Expiratory Volume in 1 Second to Forced Vital Capacity Ratio) were measured using the Minispir 2 spirometer before treatment and after the 10th session.

Conclusion and Recommendations The study aims to evaluate the impact of TAVSS on improving respiratory muscle strength and function, presenting an alternative approach in stroke rehabilitation. TAVSS is expected to support respiratory function and positively influence rehabilitation outcomes in stroke patients

Study Type

Interventional

Enrollment (Estimated)

50

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Turkey (Türkiye)
      • Istanbul, Turkey (Türkiye), 34040
        • Recruiting
        • Mediworld Medical Center Physical Therapy and Rehabilitation Department
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Being a chronic stroke patient with an ischemic or hemorrhagic stroke diagnosis made 1-3 years ago
  • Having been diagnosed with stroke for the first time
  • Ability to understand and follow simple verbal instructions
  • Being between the ages of 40 and 80
  • No conditions affecting perioral muscles, such as facial paralysis or swallowing disorders
  • No visual, auditory, or communication problems
  • No cardiopulmonary disorders
  • No additional neurological, cardiovascular, orthopedic, or similar conditions causing balance problems
  • Mini Mental State Examination (MMSE) score ≥24
  • No surgical operations or Botox applications in the last 6 months
  • Scoring 2 or below on the Modified Ashworth Scale

Exclusion Criteria:

  • Presence of infection, ulcer, or scar on the auricle
  • Metallic implants in the skull, hypersensitivity, injury, or inflammation inside the ear
  • Chronic pulmonary and/or cardiac diseases
  • Resting heart rate below 60 beats per minute
  • Devices such as pacemakers or cochlear implants
  • Uncontrolled hypertension
  • Chronic obstructive pulmonary disease (COPD) or asthma unrelated to stroke
  • History of surgical operation or Botox application within the last 6 months
  • Presence of aphasia, apraxia, or neglect syndrome
  • History of 2 or more strokes (SVO)
  • Comorbid conditions affecting respiratory functions (e.g., Multiple Sclerosis, Parkinson's, spinal cord injury, contractures, deformities after fractures, active upper or lower respiratory infections, etc.)
  • Lack of cooperation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Triple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: experimental (TAVSS + conventional physiotherapy)
TAVSS and conventional physiotherapy will be applied for a total of 10 sessions, three times a week. TAVSS application electrodes will be placed on the tragus and the inner and posterior surfaces of the concha in both the right and left outer ear. The stimulation will be delivered continuously for 20 minutes with a biphasic asymmetric waveform, a pulse duration of 300 microseconds, and a frequency of 25 hertz. Electrical stimulation will be increased in 0.1 mA increments until the perception threshold is reached. Individualized conventional physiotherapy protocols tailored to the specific needs of the patients in the experimental group will be administered by a physiotherapist for a total of 10 sessions, three times a week. The conventional physiotherapy interventions will generally include strengthening exercises, stretching exercises, proprioceptive neuromuscular facilitation, electrotherapy, balance exercises, fine motor exercises, active range of motion exercises (45 minutes).
Device: Transcutaneous Auricular Vagus Nerve Stimulation
TAVSS is an application system that uses an electrical transcutaneous stimulation device placed on the concha or tragus of the ear. Functional Magnetic Resonance Imaging studies have shown that stimulation of these areas activates the ipsilateral nucleus tractus solitarius (NTS) via vagal projections to the brainstem and forebrain. Unlike cervical vagus nerve stimulation, TAVSS utilizes a physiological pathway to activate the NTS and the dorsal motor nucleus, which subsequently sends impulses bilaterally to the heart surface via efferent cervical vagus nerves. Therefore, this technique eliminates the possibility of directly and asymmetrically stimulating cardiac motor efferent fibers, which could lead to adverse cardiac events. TAVSS combines advantageous qualities such as being non-invasive, cost-effective, convenient, and efficient.
Sham Comparator: control (sham TAVSS + conventional physiotherapy)
shamTAVSS and conventional physiotherapy will be applied for a total of 10 sessions, three times a week. TAVSS application electrodes will be placed on the tragus and the inner and posterior surfaces of the concha in both the right and left outer ear without any current. Individualized conventional physiotherapy protocols tailored to the specific needs of the patients in this group will be administered by a physiotherapist for a total of 10 sessions, three times a week. The conventional physiotherapy interventions will generally include strengthening exercises, stretching exercises, proprioceptive neuromuscular facilitation, electrotherapy, balance exercises, fine motor exercises, active range of motion exercises (45 minutes).
Device: Transcutaneous Auricular Vagus Nerve Stimulation
TAVSS is an application system that uses an electrical transcutaneous stimulation device placed on the concha or tragus of the ear. Functional Magnetic Resonance Imaging studies have shown that stimulation of these areas activates the ipsilateral nucleus tractus solitarius (NTS) via vagal projections to the brainstem and forebrain. Unlike cervical vagus nerve stimulation, TAVSS utilizes a physiological pathway to activate the NTS and the dorsal motor nucleus, which subsequently sends impulses bilaterally to the heart surface via efferent cervical vagus nerves. Therefore, this technique eliminates the possibility of directly and asymmetrically stimulating cardiac motor efferent fibers, which could lead to adverse cardiac events. TAVSS combines advantageous qualities such as being non-invasive, cost-effective, convenient, and efficient.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Inspiratory muscle strength
Time Frame: From enrollment to the end of treatment at 4 weeks
Inspiratory muscle strength will be measured using the Minispir 2 spirometer by Medical International Research. This spirometer, classified as a Class II medical device (medium risk) by Health Canada, is a non-invasive tool for assessing respiratory function. It evaluates lung ventilation by measuring the air volume during inspiration and expiration. The device records inspiratory effort and lung capacity, helping determine respiratory muscle performance.
From enrollment to the end of treatment at 4 weeks
Expiratory muscle strength
Time Frame: From enrollment to the end of treatment at 4 weeks
Expiratory muscle strength will be measured using the Minispir 2 spirometer by Medical International Research. This spirometer, classified as a Class II medical device (medium risk) by Health Canada, is a non-invasive tool for assessing respiratory function. It evaluates lung ventilation by measuring air volume during expiration, helping assess expiratory muscle performance and overall pulmonary function.
From enrollment to the end of treatment at 4 weeks
Forced Expiratory Volume in 1 Second (FEV₁)
Time Frame: From enrollment to the end of treatment at 4 weeks
Forced Expiratory Volume in 1 Second (FEV₁) will be measured using the Minispir 2 spirometer by Medical International Research. This spirometer, classified as a Class II medical device (medium risk) by Health Canada, is a non-invasive tool for assessing respiratory function. It evaluates lung ventilation by measuring the air volume exhaled in the first second of a forced expiration, providing critical data on airway obstruction and pulmonary function.
From enrollment to the end of treatment at 4 weeks
Forced Vital Capacity (FVC)
Time Frame: From enrollment to the end of treatment at 4 weeks
Forced Vital Capacity (FVC) will be measured using the Minispir 2 spirometer by Medical International Research. This spirometer, classified as a Class II medical device (medium risk) by Health Canada, is a non-invasive tool for assessing respiratory function. It evaluates lung ventilation by measuring the maximum air volume forcefully exhaled after a deep inhalation, providing essential data on pulmonary function and lung capacity.
From enrollment to the end of treatment at 4 weeks
Forced Expiratory Volume in 1 Second (FEV₁) to Forced Vital Capacity (FVC)
Time Frame: From enrollment to the end of treatment at 4 weeks
Forced Expiratory Volume in 1 Second (FEV₁) to Forced Vital Capacity (FVC) ratio will be measured using the Minispir 2 spirometer by Medical International Research. This spirometer, classified as a Class II medical device (medium risk) by Health Canada, is a non-invasive tool for assessing respiratory function. It evaluates lung ventilation by determining the proportion of air exhaled in the first second relative to total forced vital capacity, providing key insights into airway obstruction and pulmonary function.
From enrollment to the end of treatment at 4 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Chest Circumference Measurement
Time Frame: From enrollment to the end of treatment at 4 weeks
The chest circumference of patients in the Experimental and Control groups will be measured during deep inspiration and expiration using a measuring tape. Measurements will be taken at the axillary, epigastric, and subcostal regions as both baseline (initial) and post-treatment (final) assessments.
From enrollment to the end of treatment at 4 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Fenerbahce University

Investigators

  • Study Director: Burcu AKKURT, Fenerbahçe University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 5, 2025

Primary Completion (Actual)

August 26, 2025

Study Completion (Estimated)

July 30, 2027

Study Registration Dates

First Submitted

January 21, 2025

First Submitted That Met QC Criteria

January 21, 2025

First Posted (Actual)

January 27, 2025

Study Record Updates

Last Update Posted (Actual)

April 1, 2026

Last Update Submitted That Met QC Criteria

March 31, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 80.2024fbu

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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