Quantitative Assessment of Dysphagia in Myasthenia Gravis.

Objective Dysphagia is a common and disabling symptom in patients with myasthenia gravis (MG). Moreover, it is caused by muscle weakness or fatigability in the pharynx, swallowing, and respiration discoordination. The current study aimed to establish a novel method for evaluating swallowing difficulty in patients with MG. Methods The ventilation patterns and submental surface electromyography (sEMG) activity of the swallowing reflex were simultaneously recorded for 10 min during the continuous infusion of distilled water (150 mL/h) into the pharynx in 10 patients with MG and 22 healthy controls. Moreover, we assessed excessive expiratory flows, clusters of excessive expiratory flows, high-inspiratory flows, and prolonged EMG patterns. Results Patients with MG who presented with dysphagia had abnormal excessive expiratory flows, clusters of excessive expiratory flows, high inspiratory flows, and prolonged EMG patterns compared to healthy controls (all p<0.05). Among these parameters, the incidence of an excessive expiratory flow, cluster of excessive expiratory flows, and prolonged EMG pattern significantly improved after treatment (p<0.05). Conclusion Based on this study, the respiratory patterns and submental sEMG are likely to reflect the severity of pharyngeal muscle weakness/fatigability and thus can be used as a quantitative parameter for dysphagia in patients with MG.