Speech characteristics in individuals with myasthenia gravis: a case control study.

Introduction: Myasthenia Gravis (MG) is an autoimmune disease. The characteristic symptoms of the disease are muscle weakness and fatigue. These symptoms affect de oral muscles causing dysarthria, affecting about 60% of patients with disease progression.

Purpose: Describe the speech pattern of patients with MG and comparing with healthy controls (HC).

Material and methods: Case-control study. Participants were divided in MG group (MGG) with 38 patients MG diagnosed and HC with 18 individuals matched for age and sex. MGG was evaluated with clinical and motor scales and answered self-perceived questionnaires. Speech assessment of both groups included: recording of speech tasks, acoustic and auditory-perceptual analysis.

Results: In the MGG, 68.24% of the patients were female, with average age of 50.21 years old (±16.47), 14.18 years (±9.52) of disease duration and a motor scale of 11.19 points (±8.79). The auditory-perceptual analysis verified that 47.36% (n = 18) participants in MGG presented mild dysarthria, 10.52% (n = 4) moderate dysarthria, with a high percentage of alterations in phonation (95.2%) and breathing (52.63%). The acoustic analysis verified a change in phonation, with significantly higher shimmer values in the MGG compared to the HC and articulation with a significant difference between the groups for the first formant of the /iu/ (p = <.001). No correlation was found between the diagnosis of speech disorder and the dysarthria self-perception questionnaire.

Conclusion: We found dysarthria mild in MG patients with changes in the motor bases phonation and breathing, with no correlation with severity and disease duration.