The tongue enacts complex mechanical events during swallowing, the most important of which is the propulsion of a bolus from the oral cavity to the pharynx. Successful bolus transport requires the tongue to interact with other oral structures, especially the hard palate, to generate sufficient impulsive force or pressure gradients that drive the bolus toward the oropharynx. Our knowledge of deglutitive lingual pressure dynamics is at best incomplete. The available data on oral tongue pressure phenomena are based exclusively on commanded single swallows. Oral pressure changes during other important everyday eating activities (e.g., cup drinking) have not been studied to date. Past investigations revealed that rapid sequential swallowing during continuous drinking, in contrast to commanded discrete swallows, had unique tongue-palate contact patterns, surface electromyographic response characteristics, and hyoid displacement profiles. Given the different biomechanical properties and motor strategies, we hypothesize that oral lingual pressure profiles for sequential swallowing are also different, that sequential swallows require less impulsive force, and that selected dysphagic patients, especially those whose swallowing deficits are associated with impaired tongue strength, will perform sequential swallows more efficiently than they do discrete swallows. This protocol, therefore, proposes to test these hypotheses in healthy adults (21-95 in age), and in patients with reduced tongue strength and oral/oropharyngeal dysphagia associated with neurologic disorders, musculoskeletal diseases, or head and neck cancer. Our goals are to: (a) acquire a better and more complete understanding of normal tongue pressure phenomena in response to swallowing task demands; (b) determine the association between task-specific lingual pressure distribution and palatal shape/curvature; (c) characterize the interrelationship between task-induced lingual pressure differences and clinical diagnostic findings of swallowing function in patient populations; and (d) identify predictors for dysphagic patients who can and those who cannot benefit from sequential swallowing as a compensatory strategy for swallowing rehabilitation.? ? Having completed the collection of normative data in 2005, our focus in early 2006 was on the analysis of the collected oral pressure and surface EMG data. Results showed significant main effects of age, pressure locus, and swallowing task. In addition, striking differences were observed in overall oral pressure profile for the 5-second strength test between our healthy young and healthy senior subjects. Our evidence further suggests the co-existence of patterned/stereotypic responses and task-induced changed in both deglutitive lingual motor system and submental muscle complex. The task of rapid sequential swallowing, in particular, is typically completed by reducing the linguopalate surface contact area, suggesting modification of the motor control strategy for task accommodation. Manuscripts are being prepared to disseminate our findings.? ? In addition to completing the above analysis, considerable time has been spent in 2006 in the digitization, extraction, and reduction of palatal shape data from the dental casts of over 90 subjects as well as correlational analysis to determine the association between palatal curvature and deglutitive oral pressure distribution. We expect this analysis to be completed in two months.
