Tongue pressure modulation during swallowing: Water versus nectar-thick liquids

Purpose: Evidence of tongue-palate pressure modulation during swallowing between thin and nectar-thick liquids stimuli has been equivocal. This mirrors a lack of clear evidence in the literature of tongue and hyoid movement modulation between nectar-thick and thin liquid swallows. In the current investigation, the authors sought to confirm whether tongue-palate pressures are modulated between discrete swallows of water and nectar-thick juice. Method: Tongue-palate pressures were measured at 3 sites (anterior, medial, and posterior palate) using an adhered 3-bulb pressure strip in 20 healthy, young adults during discrete swallows of water and nectar-thick apple juice. Results: Pressure modulation was not noted with respect to pressure amplitudes (in mm Hg), but was identified both in the pressure patterns observed (the sites and number of bulbs activated) and temporal aspects of pressure duration. Conclusion: Tongue-palate pressure amplitude modulation does not occur for nectar-thick swallows compared to thin liquid swallows. Modulation does, however, occur with respect to the tongue-palate contact surface area and pressure durations. The authors introduce the concept of pressure slope as a meaningful way to examine tongue-palate pressure application in swallowing.