Influence of command on tongue elevation during swallowing: examination of tongue pressure and ultrasound imaging

Aim and objectives: The purpose of this study was to investigate the difference between swallowing with command and without command. Design: Subjects were eight healthy male young adults with ordinary mastication and/or swallowing functions. Subjects were asked to swallow 3mL of water in the following manner: Trial 1: Swallowing with Command (C) and Trial 2: Swallowing in his usual way (No Command = NC). Tongue pressure distribution was measured and synchronized with midline ultrasound sagittal sections of tongue movement images for further analysis. Results: All subjects exhibited tipper-type swallow in ultrasound images. The second point of peak in tongue pressure corresponded with the point at which the hyoid was in its most elevated position. The duration of palatolingual contact was clearly shorter in the C than in the trial NC (C, 1.26 s; NC, 1.67 s, P < 0.01). The pressure integrals were markedly smaller in the trial C than in the trial NC (P < 0.05). Conclusions: These results indicate that the duration of swallowing is shorter in swallow onset with, than without command. The tongue movement in swallowing with command may be more effective than in swallowing without command.