Predictors of Residue and Airway Invasion in Parkinson's Disease

Abstract

Dysphagia is a highly prevalent disorder in Parkinson's Disease (PD) characterized by changes in swallowing kinematics, residue, and airway invasion. These changes can lead to serious medical morbidities including malnutrition, aspiration pneumonia, and death. However, little is known about the most predictive causes of residue and airway invasion in this patient population. Therefore, the aims of this study were to (1) assess how disease severity affects residue, airway invasion, and swallowing kinematics in PD; and (2) determine which swallowing kinematic variables were most predictive of residue and airway invasion. A secondary analysis of forty videofluoroscopic swallow studies (VFSS) from individuals with early through mid-stage PD was performed. Airway invasion (Penetration-Aspiration Scale 'PAS'), residue (Bolus Clearance Ratio 'BCR'), and ten spatiotemporal swallowing kinematic variables were analyzed. Statistical analyses were used to determine if disease severity predicted residue, depth of airway invasion, and swallowing kinematics, and to examine which swallowing kinematic variables were most predictive of residue and the presence of airway invasion. Results revealed that residue and the presence of airway invasion were significantly predicted by swallowing kinematics. Specifically, airway invasion was primarily influenced by the extent and timing of airway closure, while residue was primarily influenced by pharyngeal constriction. However, disease severity did not significantly predict changes to swallowing kinematics, extent of residue, or depth of airway invasion during VFSS assessment. This study comprehensively examined the pathophysiology underlying dysphagia in people with early to mid-stage PD. The results of the present study indicate that disease severity alone does not predict swallowing changes in PD, and therefore may not be the best factor to identify risk for dysphagia in PD. However, the swallowing kinematics most predictive of residue and the presence of airway invasion were identified. These findings may help to guide the selection of more effective therapy approaches for improving swallowing safety and efficiency in people with early to mid-stage PD.

Keywords: Airway Invasion; Aspiration; Dysphagia; Parkinson’s disease; Predictors; Residue.

Figure 1

Bolus Clearance Ratio (BCR): area outlining bolus immediately prior to PES opening (left) and immediately after PES closing (right).

Figure 2

Laryngeal Constriction Ratio (LCR): area outlining the larynx at rest (left) and at maximal closure during the swallow (right). This is traced by beginning at the junction between the laryngeal surface of the epiglottis and the epiglottic petiole superiorly, tracing anteriorly and inferiorly to the vocal folds (about halfway between the thyroid notch and superior border of the tracheal air column), posteriorly along the vocal folds to the level of the posterior border of the tracheal air column, superiorly to the top of the arytenoids, and back to the epiglottic petiole.

Figure 3

Influence of disease severity (UPDRS’ on depth of airway invasion

Figure 4

Influence of disease severity (using the Unified Parkinson’s Disease Rating Scale/’UPDRS’) on the residue (using the Bolus Clearance Ratio).