Objective: The aim of this study was to confirm whether transcranial direct current stimulation over the vagus nerve can improve swallowing function in patients with poststroke dysphagia. Design: This is a parallel-group, randomized, double-blind, sham-controlled clinical trial. Methods: Sixty-four patients with poststroke dysphagia were randomly allocated to receive real or sham transcranial direct current stimulation over the vagus nerve combined with routine swallowing rehabilitation therapy. Swallowing function was assessed by Fiberoptic Endoscopic Dysphagia Severity Scale, Modified Mann Assessment of Swallowing Ability Scale, Functional Communication Measure, and Rosenbek Penetration-Aspiration Scale before and after treatment. Results: After 4 weeks of treatment, swallowing function improved in both the transcranial direct current stimulation over the vagus nerve group and control group. Intragroup changes in the Fiberoptic Endoscopic Dysphagia Severity Scale, Modified Mann Assessment of Swallowing Ability Scale, Functional Communication Measure, and Rosenbek Penetration-Aspiration Scale scores were more significant in the transcranial direct current stimulation over the vagus nerve group than in the control group. Conclusions: This preliminary study suggested that the performance of transcranial direct current stimulation over the vagus nerve improved the swallowing function in patients with poststroke dysphagia and extended the clinical application of transcranial direct current stimulation in poststroke dysphagia.

Dysphagia affects a significant proportion of stroke survivors and leads to malnutrition and aspiration pneumonia. Conventional therapies often lack direct resistance targeting pharyngeal constrictor muscles. We aimed to evaluate the efficacy of Pharyngeal Balloon Muscle Resistance Treatment (PBMRT) on swallowing function in post-stroke patients. This randomized controlled trial included 60 patients with post-stroke dysphagia. Patients were randomized into a Control Group (CG, n=30) receiving standard rehabilitation and an Intervention Group receiving standard rehabilitation plus Pharyngeal Balloon Muscle Resistance Treatment (PBMRTG, n=30). The PBMRT involved swallowing against a water-filled balloon to generate resistance. The primary outcome was the Fiberoptic Endoscopic Dysphagia Severity Scale (FEDSS). Secondary outcomes included the Mann Assessment of Swallowing Ability (MASA), Functional Oral Intake Scale (FOIS), Functional Communication Measure (FCM), Penetration-Aspiration Scale (PAS), and surface Electromyography (sEMG) of submental muscles. Statistical analyses used Welch's two-sample t-test for continuous variables, Pearson's chi-squared test for categorical variables, and Wilcoxon rank-sum tests for ordinal outcomes. Subgroup analyses were performed using ANCOVA models adjusting for baseline values to assess interaction effects. Sixty patients were enrolled and fifty-nine completed the study. At baseline, there were no significant differences in demographic characteristics or swallowing function scores between the two groups (p>0.05). Following the intervention, the PBMRTG demonstrated significantly lower FEDSS scores (W=305.50, p=0.029) and PAS scores (W=271.50, p=0.011) than the CG. Conversely, the intervention group achieved significantly higher MASA scores (t=2.23, p=0.030) and FOIS levels (W=603.50, p=0.008). Notably, the improvement in FCM scores (ΔFCM) was significantly greater in the intervention group (W=674.00, p<0.001). Furthermore, sEMG analysis revealed significantly higher mean amplitudes (t=2.13, p=0.038) and peak amplitudes (t=2.49, p=0.016) during swallowing tasks in the PBMRTG. In this single-center exploratory randomized trial, PBMRT added to conventional rehabilitation was associated with greater short-term improvements in swallowing safety, functional oral intake, and submental muscle activation compared to conventional rehabilitation alone. Given the modest sample size, short intervention duration, and absence of long-term follow-up, these findings should be considered preliminary and warrant confirmation in larger multicenter trials.