Clinical, serological, and therapeutic profile of myasthenia gravis in a tertiary center in the Brazilian Amazon: a seven-year retrospective analysis
Abstract
Background: Myasthenia Gravis (MG) is a chronic autoimmune disorder of the neuromuscular junction characterized by fluctuating muscle weakness and fatigability. Although diagnostic and therapeutic advances have improved the prognosis of the disease, epidemiological data from the Northern region of Brazil remain limited, hindering the planning of healthcare strategies tailored to this population. Objective: To describe the clinical, serological, and epidemiological characteristics of patients with MG followed at a specialized outpatient clinic in the Brazilian Amazon. Methods: This was an observational, descriptive, cross-sectional, and retrospective study based on the analysis of secondary data from medical records of patients diagnosed with MG who were followed at the Araújo Lima Outpatient Clinic of the Federal University of Amazonas between January 2017 and December 2023. Demographic, clinical, serological, and therapeutic variables were collected. Data were analyzed using descriptive statistics, adopting a significance level of p < 0.05. Results: A total of 51 patients were included, with a mean age of 38.12 years (±16.83), predominantly female (84.3%). The mean disease duration was 8.18 years (±6.33). Most patients tested positive for anti-acetylcholine receptor (anti-AChR) antibodies (84.31%), while 3.92% were positive for anti-MuSK and 11.76% were classified as seronegative; no cases positive for anti-LRP4 were identified. Thymic alterations included thymic hyperplasia in 13.73% and thymoma in 9.80% of cases, and 13.73% of patients had undergone thymectomy. Clinical evaluation demonstrated a predominance of mild disease forms, with the mode corresponding to grade I of the Myasthenia Gravis Foundation of America (MGFA) classification. Regarding treatment, 84.31% were using non-steroidal immunosuppressants and 50.98% were receiving corticosteroids. Among previously administered therapies, 52.94% had undergone corticosteroid therapy, 35.29% received intravenous immunoglobulin, and 21.57% underwent plasmapheresis. Conclusion: The findings demonstrate a predominance of female patients, a serological profile mainly positive for anti-AChR antibodies, and milder clinical forms among patients followed at a tertiary center in the Amazon region. These data contribute to expanding the understanding of the clinical-epidemiological profile of MG in Northern Brazil and may support the planning of healthcare and research strategies.