Reliability of ultrasound real-time tissue elastography in evaluating swallowing-related muscle elasticity and effects of swallowing exercises

IntroductionEvaluating swallowing function, essential for eating, is necessary to detect functional decline, enabling the provision of effective interventions. There is a growing demand for a simple method for evaluating swallowing dynamics. Conventional methods of evaluating swallowing function, such as the fibreoptic endoscopic evaluation of swallowing or videofluoroscopic swallowing study, are highly invasive and require specific equipment only available at certain hospitals, making it difficult for older adults to receive convenient evaluations. Therefore, we used ultrasound real-time tissue elastography (RTE), a low-invasive method, to evaluate tissue elasticity as the strain ratio (SR). This study primarily aimed to verify whether RTE can evaluate the elasticity of swallowing-related muscles (SRMs) and determine intra- and inter-rater reliabilities. The secondary aim was to investigate the effect of swallowing exercises, such as head-lifting exercises, on SRM elasticity.MethodsIntraclass correlation coefficients for SR were calculated using ultrasound B-mode images to determine the reliability of SRM elasticity. SRs before and after the Shaker swallowing exercise were compared using the Wilcoxon signed-rank test.ResultsHigh ICCs for intra- and inter-rater reliabilities were obtained for all targeted SRMs. SR after the Shaker exercise indicated a significant decrease in the geniohyoid muscle and both sides of the digastric muscles, whereas both sides of the masseter exhibited no changes.ConclusionRTE can be used as a novel simple and non-invasive method for assessing and capturing differences in SRs of SRMs after light exercise. Further research may develop a relationship with swallowing function in patients with dysphagia or older individuals.