Pharyngeal Structure and Dysphagia in Patients with Parkinson's Disease and Related Disorders

Pharyngeal muscle changes occur in patients with Parkinson's disease and related disorders (PRD); however, the association between the structural alterations in the pharynx and the symptoms of dysphagia remains unclear. We assessed structural changes and contractile forces by measuring pharyngeal wall thickness and width. We aimed to define the pharyngeal measurements and determine their value as diagnostic tools for dysphagia. The pharyngeal wall thickness (PWT), pharyngeal width at rest (PWR), and shortest pharyngeal width at swallowing (PWS) were measured using lateral neck roentgenograms and videofluoroscopic swallowing study. We compared the PWR and PWT between the PRD and control groups using an independent t-test. The Kendall correlation test was performed on the radiological data of the pharynx (PWT, PWR and PWS), dysphagia scales (Penetration-Aspiration scale [PAS] and Dysphagia Outcome and Severity Scale [DOSS]), and Hoehn and Yahr scale (HY scale). The PWT was smaller and the PWR greater in the PRD than in the control group (p < 0.05). The dysphagia scales (PAS and DOSS) were correlated with the radiological data (PWT and PWS) and the HY scale (p < 0.05). The HY scale score also correlated with the PWT (p < 0.05). The optimal cutoff points of the PWT and PWR for predicting aspiration were 4.05 and 16.05 mm in the PRD group, respectively. Using the PWT, PWR and PWS, muscle atrophy and contractile strength of the pharynx can be estimated. The combination of the PWT and PWR can be a simple indicator for predicting swallowing disorders at the bedside.