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

Abstract

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.

Keywords: dysphasia; pharyngeal motion; posterior pharyngeal wall; skeletal muscles mass index; tongue pressure.

FIGURE 1

Lateral view from a videofluoroscopic swallowing study with marked points and lines for laryngeal position at rest. The straight line joining the anteroinferior corner of the second cervical vertebra (C2) and the anteroinferior corner of the fourth cervical vertebrae (C4) is taken as the y‐axis. The line perpendicular to the y‐axis passing through C2 is set as the x‐axis. Laryngeal position at rest (LPR) is measured by drawing a line perpendicular to the y‐axis from the anterosuperior margin of the thyroid cartilage, and measuring the distance from the point of intersection to the anteroinferior corner of C2

FIGURE 2

Lateral view from a videofluoroscopic swallowing study with marked points and lines for laryngeal anterior displacement (LAD) and laryngeal superior displacement (LSD). The straight line joining the anteroinferior corner of the second cervical vertebra (C2) and the anteroinferior corner of the fourth cervical vertebrae (C4) is taken as the y‐axis. The line perpendicular to the y‐axis passing through C2 is set as the x‐axis. LAD and LSD were determined by subtracting (a) the initial position of the thyroid cartilage from (b) peak position reached in the X direction and Y direction, respectively, during swallowing

FIGURE 3

Lateral view from a videofluoroscopic swallowing study with marked points and lines for posterior pharyngeal wall advancement (PPWA). The straight line joining the anteroinferior corner of the second cervical vertebra (C2) and the anteroinferior corner of the fourth cervical vertebrae (C4) is taken as the y‐axis. The line perpendicular to the y‐axis passing through C2 is set as the x‐axis. The distance from an intersection point (PPW) of the posterior pharyngeal wall and the x‐axis to the origin was measured from images (a) at rest and (b) at maximum constriction