Tongue muscle strength affects posterior pharyngeal wall advancement during swallowing: A cross-sectional study of outpatients with dysphagia.

BACKGROUND: Tongue muscle strength is important for swallowing but decreases with age, in association with reduced skeletal muscle mass. However, the relationships between pharyngeal dynamics and both skeletal muscle mass and tongue muscle strength are unknown. OBJECTIVE: To investigate the effect of reductions in tongue muscle strength on pharyngeal movement during swallowing in patients with dysphagia. METHODS: Subjects were selected from male outpatients ≥65 years old who were examined for the main complaint of dysphagia. Patients with history of neurodegenerative disease affecting tongue movement, cerebrovascular disease or oral cancer were excluded. As a result, 82 men (mean age, 80.6 ± 6.8 years) participated. Skeletal muscle mass index (SMI) as physical parameters and maximum tongue pressure (MTP) as tongue muscles strength were measured. Status and dynamics of the pharyngeal organs, including change in posterior pharyngeal wall advancement (PPWA) when swallowing 3.0 mL of moderately thick liquid, were measured by analysing videofluoroscopic images. Simple bivariate correlation and multiple regression analysis were used to statistically analyse correlations between parameters. RESULTS: MTP showed a significant positive correlation with SMI (r = .43, P < .01). PPWA showed a significant negative correlation with MTP (r = -0.30, P < .01), but no association with SMI. CONCLUSIONS: While tongue muscle strength is affected by skeletal muscle mass, posterior pharyngeal wall advancement is not readily affected by decreases in skeletal muscle mass. Posterior pharyngeal wall advancement may increase to compensate for swallowing function among individuals with reduced tongue muscle strength.