Study on the Relationship between Swallowing-Related Muscle Activity and Respiratory Muscle Function in Stroke Patients with Dysphagia

<bold>Objective</bold> To study the effect of respiratory muscle weakness on the activity of swallowing-related muscle groups during swallowing in stroke patients with dysphagia by surface electromyography (sEMG), and to investigate the correlation between activity of swallowing-related muscle groups and respiratory muscle function. <bold>Methods</bold> A total of forty patients with dysphagia after stroke who met the inclusion criteria from December 2022 to October 2023 at Jiangsu Shengze Hospital of Nanjing Medical University were selected as the research group,and another 15 healthy individuals with matched data were selected as the control group. Maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) of all subjects were assessed using a pulmonary function tester. The 40 stroke patients were divided into non-respiratory muscle weakness group (MIP≥70% and/or MEP≥70% of predicted values) of 15 patients and respiratory muscle weakness group (MIP&lt;70% and MEP&lt;70% of predicted values) of 25 patients based on the results of MEP and MIP tests. sEMG was used to collect the signals from the submental muscles and infrahyoid muscles on both the healthy and affected sides of all subjects while swallowing 5 mL of water. The root mean square values and peak amplitudes were compared among the three groups and between the healthy and affected sides, and a correlation analysis was performed between the sEMG signals and respiratory muscle function in the study group. <bold>Results</bold> MIP and MEP of the respiratory muscle weakness group were significantly lower than those of the non-respiratory muscle weakness group and the control group (<italic>P</italic>&lt;0.05). The root mean square and peak amplitude of sEMG signals from submental muscles of the affected side in the respiratory muscle weakness group were significantly lower than those in the non-respiratory muscle weakness group and the control group (<italic>P</italic>&lt;0.05), and the peak amplitude of sEMG signals from submental muscles of the healthy side in the respiratory muscle weakness group was significantly lower than that of the control group (<italic>P</italic>&lt;0.05). The root mean square and peak amplitude of the sEMG signals from the submental muscles on the affected side in the respiratory muscle weakness group were significantly lower than those on the healthy side (<italic>P</italic>&lt;0.05). The root mean square and peak amplitude of the submental muscles on the affected side, and the peak amplitude of the submental muscles on the healthy side were significant and positively correlated with MIP (<italic>r</italic>=0.366, <italic>r</italic>=0.415, <italic>r</italic>=0.317, <italic>P</italic>&lt;0.05). The root mean square and peak amplitude of the affected submental muscles, the healthy submental muscles and the affected infrahyoid muscles were positively correlated with MEP (<italic>r</italic>=0.534, <italic>r</italic>=0.595, <italic>r</italic>=0.332, <italic>r</italic>=0.455, <italic>r</italic>=0.323, <italic>r</italic>=0.375, <italic>P</italic>&lt;0.05). <bold>Conclusion</bold> Patients with post-stroke dysphagia who have respiratory muscle weakness exhibit a significant decrease in the strength of the submental muscle group, and there is a correlation between swallowing-related muscle group activity and respiratory muscle function in stroke patients with dysphagia.