Myasthenia Gravis with Idiopathic Inflammatory Myopathy and Sjögren Syndrome, A Triad of Immune-Mediated Diseases

This report illustrates a 73-year-old woman with Sjögren's syndrome and idiopathic inflammatory myopathy with elevated creatine kinase that subsequently deteriorated with an increased dose of steroids, resulting in a myasthenic crisis requiring hospitalization in the intensive care unit; the patient responded successfully to treatment with intravenous immunoglobulin. The patient showed moderate elevation of creatine kinase at the initial diagnosis, with positive anti-Ro/SSA antibodies. Schirmer’s test, anti-Ro52 and anti-Ku antibodies, electromyography, and muscle biopsy were performed to confirm inflammatory myopathy. During the observation in the intensive care unit, creatine kinase increased to 1520 U/L, and a repetitive stimulation test and total anti-acetylcholine receptor antibodies supported the diagnosis of myasthenia gravis. The patient received intravenous immunoglobulin, evolving with clinical improvement. This case is being reported to illustrate the chronic clinical course of a patient with inflammatory myopathy who deteriorated following steroid adjustment, ultimately presenting with myasthenic crisis.