Date of Award

2001

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Communication Sciences and Disorders

First Advisor

Hugh W. Buckingham

Second Advisor

Anne L. Foundas

Abstract

Age-related changes in discrete swallows have been well researched, but few studies have investigated sequential swallowing with little emphasis on age-related changes. It is also unclear whether the cortical representation of swallowing is lateralized to one hemisphere or is bilaterally represented. As such, the aims of this research were to examine deglutitive biomechanics of sequential straw swallowing (Experiment I), and study swallowing lateralization using a dual task paradigm in healthy, young and old adults (Experiment II). Thirty-eight right-handed men (young = 20, old = 18) were studied. Experiment I: Videofluoroscopic swallow samples of two 10-second straw drinking trials were obtained. Hyolaryngeal complex (HLC) movement patterns, leading bolus edge location, airway invasion, number of swallows, and volume per swallow were determined. Experiment II: Subjects were examined at baseline and with interference. Baseline conditions were continuous straw drinking, finger tapping right and left hand, word repetition, and visuospatial processing. Interference tasks, including finger tapping right hand, finger tapping left hand, silent repetition, and silent visuospatial processing were completed with swallowing. Experiment I: Three distinct patterns of HLC movement were identified during sequential straw drinking: (1) an opened laryngeal vestibule between swallows, (2) a closed laryngeal vestibule between swallows, and (3) a mixed movement pattern characterized by interchangeable opened and closed movements. The bolus was frequently in the distal pharynx at swallow onset during consecutive swallowing. This location was strongly associated with a closed laryngeal vestibule. No age-related changes were identified with these patterns. Penetration appeared to be a normal variant in sequential straw swallowing and was associated with a closed laryngeal vestibule and hypopharyngeal bolus location. Penetration was uncommon in the younger adults but occurred more frequently in the older adults. Experiment II: Findings indicated that both the right and left hemispheres contribute to swallowing. Right and left finger tapping, which selectively activates the left and right hemispheres respectively, interfered with swallowing. Silent repetition, which primarily activates the left hemisphere, and visuospatial processing, which primarily activates the right hemisphere, also interfered with swallowing when performed concurrently. Results suggest that bilateral cortical input is critical in the mediation of swallowing.

ISBN

9780493562964

Pages

159

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