Non-Motor Symptoms in Myasthenia Gravis Patients: Evaluation of Auditory and Olfactory Functions.

Abstract

Introduction: Myasthenia gravis (MG) is an autoimmune disease characterized by conduction defects at the neuromuscular junction. Recent studies suggest that impairment in acetylcholine neurotransmission occurs not only at the neuromuscular junction but also in the central and peripheral nervous systems. In this context, we aimed to investigate the presence of auditory and olfactory dysfunction, which are non-motor symptoms (NMS), alongside motor symptoms in patients with MG.

Methods: A total of 30 MG patients and 30 healthy controls were enrolled in the study. Demographic characteristics of all participants were recorded. Olfactory functions were assessed using the Connecticut Chemosensory Clinical Research Center (CCCRC) test, while auditory functions were evaluated through pure tone audiometry (PTA) and tympanometric assessment. Additionally, patients were evaluated with MG Foundation of America (MGFA) Clinical Classification, MG-Composite scoring (MGC) and MG-Quality of Life Questionnaire 15-item scale Turkish version (MG-QOL15-T).

Results: No statistically significant difference was found between the MG and control groups for the n-Butanol threshold test score, identification test score, and total test score, which are components of the CCCRC test. There was no significant correlation between the age of disease onset and olfactory scores. A statistically significant moderate negative correlation was found between disease duration and both identification and total olfactory scores (r=-0.447, p=0.013 and r=-0.374, p=0.042, respectively). In the PTA test, the hearing threshold at 2000 Hz frequency in the right ear of patients was higher compared to the control group, and this difference was found to be statistically significant. No association was found between the patients' olfactory and auditory functions with the MG-QOL15- T.

Conclusion: This study suggests partial impairment in olfactory and auditory functions, NMS, in MG patients; however, these findings do not seem to effect the patients' quality of life. It should be considered that MG may be accompanied not only by motor symptoms but also by NMS.