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

NCT ID: NCT06793800

Last Updated: 2025-08-08

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 50 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-08-05
• Study Completion Date: 2027-07-30

Brief Summary

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.

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

Conditions

Hemiplegia; Respiratory Function Loss

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: TREATMENT
• Blinding Strategy: TRIPLE

Study Groups

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).

Group Type: EXPERIMENTAL

Transcutaneous Auricular Vagus Nerve Stimulation

Intervention Type: DEVICE

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.

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).

Group Type: SHAM_COMPARATOR

Transcutaneous Auricular Vagus Nerve Stimulation

Intervention Type: DEVICE

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.

Interventions

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.

Intervention Type: DEVICE

Eligibility Criteria

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

• Minimum Eligible Age: 40 Years
• Maximum Eligible Age: 80 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Fenerbahce University

OTHER

Sponsor Role: lead

Responsible Party

Burcu AKKURT

Assistant Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Burcu AKKURT

Role: STUDY_DIRECTOR

Fenerbahce University

Locations

Mediworld Medical Center Physical Therapy and Rehabilitation Department

Istanbul, , Turkey (Türkiye)

Site Status: RECRUITING

Countries

Turkey (Türkiye)

Central Contacts

Burcu AKKURT, Ph.D.

Role: CONTACT

burcu.akkurt@fbu.edu.tr

+9005536046713

Mustafa AKKURT, Ph.D.

Role: CONTACT

ferit.akkurt@fbu.edu.tr

+9005055762579

Facility Contacts

Okan, MD.

Role: primary

m.okanozturk@gmail.com

+9005548607466

Other Identifiers

80.2024fbu

Identifier Type: -

Identifier Source: org_study_id