Title: Mechanisms of Respiratory-Swallow Coordination and the Effects of Skill Training on Swallowing Rehabilitation in Parkinson’s Disease
Description: Respiratory-swallow coordination (RSC) is critical for safe and efficient swallowing. In healthy adults, RSC is most frequently characterized by an exhale-swallow-exhale pattern initiated within the mid-lung volume range with a respiratory pause of approximately one second. This combination in RSC behaviors is thought to be most optimal for swallowing-related bolus clearance and airway protection. Deviations from these RSC behaviors are observed at disproportionately higher rates in people with Parkinson’s disease (PD) when compared to non-dysphagic, healthy adults. However, little is known about which variables influence RSC in PD, if the RSC behaviors that are most optimal for swallowing in healthy adults are also most optimal for swallowing in PD, and if respiratory-swallow training can be used to successfully rehabilitate suboptimal RSC, swallowing safety, and swallowing efficiency in PD. This dissertation document includes a series of four studies that address these important clinical research questions.

Chapter 1 will begin by reviewing the current body of literature as it relates to dysphagia in PD, RSC in healthy adults and PD, respiratory-swallow training as a skill-based treatment for dysphagia rehabilitation, and motor learning considerations for respiratory-swallow skill training in PD. Chapter 2 will be used to examine the relationships among RSC with patient- and swallowing-specific factors in PD. Chapter 2 will also be used to assess the influence of RSC behaviors on measures of swallowing safety (penetration-aspiration) and swallowing efficiency (pharyngeal residue) in PD. Chapter 3 will then evaluate the effects of verbal cueing on RSC in PD as a method of determining if RSC is stimulable for rehabilitative change. Chapter 4 will explore the effects of respiratory-swallow training on swallowing safety and efficiency rehabilitation in a person with mid-stage PD and severe dysphagia within the context of a single-subject experimental design. Chapter 5 will then examine the effects of respiratory-swallow training on dysphagia and RSC rehabilitation within the context of a cohort study.

Chapter 5 will also be used to compare the effects of constant versus variable practice in order to explore how principles of motor learning can be used to enhance respiratory-swallow training outcomes. This document will then conclude by synthesizing the results from Chapters 2-5 and by discussing directions for future research.