Assessment of Nonmotor Symptoms in Myasthenia Gravis: Fatigue and Disease Burden

Abstract

Background:

Patients with myasthenia gravis (MG) experience fatigue throughout their lives, making it essential to distinguish fatigue from muscle weakness. We aimed to provide information about fatigue, its prevalence, its relation to personal and disease-specific factors, and the possible burden of the disease.

Subjects and Methods:

Fifty-three patients with MG who presented to our Neuromuscular Clinic between 2020 and 2022 were enrolled in the study. Patients were in pharmacologic remission or at the minimal manifestation stage according to the Myasthenia Gravis Foundation of America treatment status scale. A definitive diagnosis was based on a positive antibody test, a decrement response in repetitive nerve stimulation tests, and/or increased jitter or block on a single nerve fiber test in electromyography. To confirm a myasthenic exacerbation or crisis, the need for rescue treatment was assessed. Patients were divided into two groups based on whether they received rescue treatment. The Checklist for Individual Strength-Fatigue (CIS) questionnaire, the Quality of Life Questionnaire on Myasthenia Gravis (MG-QoL) assessment of fatigue, and the Quantitative Myasthenia Gravis Score for neurologic examinations were used.

Results:

The average fatigue score was 72, leading to 84% of patients being classified as fatigued, with a cutoff value of 40. The myasthenic crisis group exhibited worse CIS-total, CIS-physical fatigue, and CIS-subjective perception scores, as well as poorer quality of life scores, compared with the other patients. Opinions on the disease burden may vary because all the patients were in remission.

Conclusion:

Patients who experienced more crises throughout the course of the disease were in a more morbidity and had a greater disease burden compared with those who experienced fewer or no crises during remission periods. Fatigue represents a concept distinct from the muscle weakness detected during physical examinations; it significantly impacts patients’ daily lives and serves as a strong indicator of disease burden.