Swallow Safety and Kinematics in Neurological Impairment: A Comparison of Dysphagia in Parkinson's Disease and Cerebrovascular Accident

Abstract

Dysphagia (swallow impairment) in PWPD is expected to occur at some point during the disease process, with incidence estimated as high as 95%. Dysphagia symptoms in PWPD include deficits in the oral stage (oral residue, tongue pumping), pharyngeal stage (increased residue in the vallecula/pyriform sinuses, increased airway invasion), and/or esophageal stage (decreased upper esophageal sphincter motility). Growing evidence from the literature has indicated swallow kinematics during the pharyngeal stage of swallowing such as laryngeal vestibule closure reaction (how quickly the airway closes) and duration (how long the airway stays closed for) are considered to be major contributors to airway safety (e.g., preventing laryngeal penetration) in this population. The comprehensive body of work presented in this dissertation was designed primarily to increase our knowledge of dysphagia associated with laryngeal dysfunction in people with Parkinson’s disease (PWPD). This work was able to show evidence of dysfunctional airway protection as a ubiquitous trait in PWPD, with high rates of airway invasion and abnormally slow measures of laryngeal kinematics Additionally, these results expand upon the current state of evidence regarding the ability of PWPD to perceive swallow impairment, and how dysphagia may commonly present in PD compared to other causes of dysphagia. The findings in this dissertation provide a framework of future investigation both within this program of research as well as for other clinicians and researchers. Recommendations based on these results include examining other swallow kinematics in the pharyngeal stage of importance, comparing visuoperceptual and pixel-based examinations of swallowing, and targeting laryngeal function as it relates to swallowing in therapeutic interventions. Results regarding bolus characteristics and their effects as a dysphagia management strategy for swallow safety indicate that thicker bolus consistencies reduce airway invasion rates. However, increasing volume mitigates and may even reduce, this improved safety. Recommendations in line with these findings include the effectiveness of thickened liquid use as a strategy for reducing airway invasion in neurogenic etiologies of dysphagia, but utilizing caution when introducing larger volumes of liquid regardless of consistency.