Swallowing dysfunction in myasthenia gravis patients examined with high-resolution manometry

Objective: To prospectively compare oropharyngeal swallowing dysfunction in myasthenia gravis (MG) patients presenting with difficulty in swallowing between the neutral and chin-down positions, based on the results of high-resolution manometry (HRM) examination. Methods: We prospectively compared the HRM results of swallowing studies of seven MG patients showing difficulty in swallowing (neutral and chin-down positions) at the Department of Neurology of our institution during the period February-December 2018. The HRM assessment parameters were as follows: maximum swallowing pressure (SP) at the soft palate, meso-hypopharynx, and upper esophageal sphincter (UES), and the duration of relaxation pressure at the UES. These parameters were compared between the two positions and their correlations with the results of neurological evaluations, such as the Quantitative Myasthenia Gravis (QMG) score (total and neck muscles alone), and grip strength, were also analyzed. Results: In comparison with the neutral position, in the chin-down position the maximum SP at the meso-hypopharynx was significantly increased (p < 0.05), the maximum SP at the UES was significantly decreased (p < 0.05), and the duration of relaxing SP at the UES was significantly increased (p < 0.05). Interestingly, there were no correlations between the SP at any location and the results of the neurological evaluations. Conclusions: The chin-down position appears useful for improving pharyngeal clearance in MG patients, by promoting increased SP at the meso-hypopharynx, relaxing SP at the UES, and increasing the duration of relaxation pressure at the UES. (C) 2021 Oto-Rhino-Laryngological Society of Japan Inc. Published by Elsevier B.V. All rights reserved.