Intramuscular condition of swallowing-related muscles using shear-wave elastography: A preliminary study in healthy adults.

Background: Assessing the internal condition of swallowing-related muscles and muscle strength and size is important because their deterioration may lead to dysphagia. However, there are few reports on stiffness of swallowing-related muscles measured using shear-wave elastography (SWE) and their qualitative characteristics.

Objectives: We measured stiffness of swallowing-related muscles using SWE to investigate the relationship between muscle stiffness and body composition as well as other relevant variables in healthy adults.

Methods: Thirty healthy adults were included in this cross-sectional study. We evaluated stiffness of the genioglossus muscle (GGM) and geniohyoid muscle (GHM) using SWE. Skeletal muscle mass index, body mass index (BMI), handgrip strength, tongue pressure, and cross-sectional areas of the muscles were measured, and we determined their relationship with muscle stiffness.

Results: For muscle stiffness, the mean value for the middle GGM was 7.08 ± 1.92 kPa, that for the posterior GGM was 9.31 ± 2.68 kPa, and that for the GHM was 8.84 ± 2.15 kPa. In multiple regression analysis, with stiffness of the posterior GGM as the dependent variable, BMI (β = -.473, p = .039) was a significant negative explanatory variable. However, with the GHM stiffness as the dependent variable, BMI (β = .419, p = .033) was a significant positive explanatory variable.

Conclusion: Stiffness of the posterior GGM was positively correlated with BMI and that of the GHM was negatively correlated with BMI. Stiffness, as measured using SWE, has the potential to capture the intramuscular characteristics of swallowing-related muscles, particularly the posterior GGM.