Effects of Food Consistency and Head Posture on Oropharyngeal Swallowing

Objective: This study aimed to describe an electromyographic (EMG) activity pattern of geniglossus (GG) muscle as with the suprahyoid (SHy) muscles during swallowing. Further investigation was to clarify the effects of changes in food consistency and head posture in subjects on the swallowing movement.

Methods: Ten normal adults comprised of eight males and two females served as participants. Test foods prepared were 4-ml of paste made of 0.5% and 1.0% agar, syrup, and liquid. The subject swallowed it in one of the three positions (head neutral position, head flexed position and head rotated position), and EMGs of left GG and SHy muscles were recorded as well as videofluorographic (VF) images. Mean time of onset, peak and offset of EMG burst was measured in each subject. From VF recordings, total swallowing time, oral transit time, pharyngeal transit time, clearance time, fauces transit time, upper esophageal sphincter transit time were measured.

Results: The EMG burst of GG muscle exhibited double peaks, termed as GG1 and GG2 burst, in one swallowing. The offset time and duration of GG1 burst, the peak time and duration of GG2 burst, all the variables of SHy burst significantly increased with the food consistency. On the other hand, there were no significant differences in the bolus transit time among the experimental conditions. The regression analyses showed that there was a significant correlation between peak of GG1 burst and tongue tip touching the palate, between offset of GG1 burst and passage of bolus tail at the fauces, between peak of GG2 burst and passage of bolus tail at the UES, and between offset of SHy burst and passage of bolus tail at the UES.

Conclusion: The results suggest that the GG muscle activity is strongly affected by the food consistency.