VOLITIONAL, BOLUS, AND AGE EFFECTS ON HUMAN SWALLOWING

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This revised competitive renewal seeks to expand work on the biomechanical analysis of the human pharyngeal swallow response to analyze determinants of oropharyngeal dysphagia, and the potential of therapeutic strategies to compensate for observed dysfunction. Work during the first five years of this project has led to the conceptualization of the oropharyngeal swallow as a tightly integrated group of functional elements (closure of the nasopharynx, UES Opening, laryngeal vestibule closure, tongue loading (ramping), tongue pulsion, and pharyngeal clearance), each subject to specific constraints of timing, motion, coordination, and modifiability. An initial aim of the renewal will be to obtain normal values for key observational, timing, mechanical, and coordinative measures of swallowing from appropriate groups of controls (male and female subjects of three age groups: 20-29, 40-49, and equal to or more than 70 yrs). The second aim will focus on determining the minimal set of these swallow measures that discriminates normal from abnormal swallowing function (aspiration, nasopharyngeal regurgitation, residue, or delay). Data from dysphagic populations susceptible to specific dysfunctions will be used to statistically model the set of swallow measures that determine each dysfunction and to develop an "equation of risk" for that dysfunction. The overall hypothesis is that evaluation of this extremely complex mechanical action can be reduced to a relatively small set of measurements that will indicate any significant dysfunction. The third specific aim of the project is to measure the degree of compensation possible for each of the key swallow measures identified for normal subjects, for the relevant dysphagic population, and for individuals identified as having minimal functional reserve for that variable. Means of compensation are drawn from the swallow therapists armamentarium and include use of swallow maneuvers, postural techniques, and increased oral sensory stimulation. Finally, computer-assisted image analysis and 3 dimensional reconstructions will be utilized to model the dynamics of the intrapharyngeal shape. The analysis tool of the 3-dimensional graphics program can quantify instantaneous intrapharyngeal volume, which coupled with pressure data from the pharyngeal outlet, may yield a useful parameter of swallow efficacy.