Effect of Transcutaneous Auricular Vagus Nerve Stimulation 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.

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