The overall purpose of this protocol is to characterize normal and abnormal deglutitive tongue pressure as a function of swallowing task. The goals are to: (1) Quantify the normal modulation of propulsive lingual pressure during discrete versus rapid sequential swallows, (2) contrast how task-induced pressure dynamics changes with aging in healthy adults and with reduced tongue strength in neuromuscular/musculoskeletal disorders, (3) determine the relationship between task-induced oral tongue pressure profiles of patients with their diagnostic MBS finding and clinical oral motor signs, and (4) characterize the clinical profiles of patients who can and those who cannot benefit from sequential swallowing as a compensatory strategy. To date we have studied 14 healthy volunteers and 4 patients with neurologic impairments. Our measurements included total duration (TD) of pressure bulb activation, peak pressure distribution ratios [(time to peak mmHg)/TD and (peak-to-end time)/TD], peak mmHg, start-to-peak and peak-to-end slopes, and area under curve. Significant main effects of Task (p<.0124) and Bulb (p<.0001) were found with no significant interaction. Further task comparisons for each bulb with Tukey adjustments of p attributed most of the significant contrasts to the posterior bulb. The most salient findings were: for RSeq swallows, peak pressure was reached proportionally 1.5-fold farther into the swallow than for discrete tasks, and the rate of pressure change from peak to baseline was twice as rapid. RSeq swallows also differed in bulb activation pattern. For example, two subjects showed an """"""""on and partial off"""""""" pattern for anterior and mid bulbs; in four other subjects, these bulbs (or the anterior alone) were not activated for selected RSeq swallows. In addition, we found: (1) considerable intra- and inter-subject variability across all tasks, but relatively more so for discrete than for RSeq swallows; (2) no striking task-based difference in peak pressure; and (3) a trend for RSeq swallows to be shorter in TD (thus smaller in area under curve). Our preliminary findings suggest task-induced differences in pressure distribution strategy and a more efficient way of swallowing for RSeq by delaying the peak, thus devoting a greater portion of the swallow to bolus propulsion. This supports our thesis of the potential clinical application of rapid sequential swallowing in selected patient populations.
