Clinical implications of a very late presentation in myasthenia gravis: real world experience in a tertiary center.

Background: Myasthenia gravis (MG) is an immune-mediated disease with a bimodal incidence: early-onset (< 50 years, predominantly female) and late-onset (> 50 years, predominantly male). Recently, a subgroup with very late-onset (≥ 65 years) has been described; however, its clinical relevance concerning disease course and prognosis remains uncertain. Objective: To evaluate the potential clinical implications of very late presentations of MG. Methods: The present is a retrospective cohort study comprising all patients diagnosed with MG currently followed up in the Neuromuscular Disorders Unit of a tertiary center. Clinical and paraclinical parameters including number of hospitalization and current regime were evaluated. Results: A total of 92 patients were included, 51 (55.4%) of whom were female. Concerning the age of onset, 23 (25.6%) patients were classified as very late-onset. In order to better understand the clinical implications of a later onset, we compare the very late-onset subgroup to the late-onset subgroup. Gender distribution and number of patients with minimal manifestation status or better did not statistically differ between these subgroups. Myasthenic crisis and refractoriness were more frequent in the late-onset subgroup compared with very late-onset, but no statistical difference was found ( Conclusion: Our study suggests that the recently established subgroup of very late-onset may not be clinically distinct from late-onset MG, as these patients seem to exhibit a similar clinical trajectory.