Clinical and epidemiological aspects of patients with myasthenia gravis in a tertiary center

Background: Myasthenia gravis (MG) is a rare autoimmune disease with variable incidence depending on the geography and over the years. In the literature, there are few studies describing the incidence of MG in centers specializing in neuromuscular diseases and neuromuscular junction disorders, as well as the epidemiological and clinical profile of the population evaluated for this condition. Objective: To describe clinical and epidemiological aspects of patients diagnosed with MG at the neuromuscular diseases in a large tertiary service. Methods: A retrospective analysis was carried out of medical records of patients admitted and diagnosed with MG between the period 2020 and 2024. Data were collected regarding age, sex, ethnicity, onset of symptoms, severity, presence of antibodies, thymectomy, time since thymectomy and response afterwards, number of myasthenic crises, need to use intravenous immunoglobulin and/or plasmapheresis, in addition to associated comorbidities. Results: 217 patients were studied, of whom 152 were females (70%) and 65 were male (30%), with an average age of 51.4 years, ranging from 11 to 90 years. Age of onset of the first symptoms varied from 3 - 69 years (average of 31.7). Generalized myasthenia gravis was the most common clinical presentation, with MGFA IIA, IIIA and IIIB being the most common in the early pre-treatment phase. From those tested for anti-acetylcholine receptor (AChR) and anti-Musk antibodies 88% were AChR positive and almost 6% anti-MuSK. Thymectomy was performed in 107 patients (49%), with an average time to perform thymectomy of 4.3 years and pathology demonstrating thymoma in 16%, with the type B2 being the most common. After thymectomy, 23 patients presented myasthenic crisis requiring immunoglobulin and/or plasmapheresis. Concomitant comorbidities evaluated, most patients had high blood pressure and diabetes. In addition, 4 patients were found with associated rheumatoid arthritis, 1 with multiple sclerosis and 1 with Parkinson’s disease. Conclusion: In this single center study, the data analyzed are similar with other studies in the literature, but with a higher percentage of thymectomized patients. However, comparing to another Brazilian cohort reported, from a different region of the country, the antibodies profile is quite different, and main reflect regional influences (genetic and/or environmental) on immunopathogenesis of MG.