The association of myasthenia gravis and immune-mediated myopathies

Abstract

Introduction/Aim: Myasthenia gravis (MG) is a chronic autoimmune disease of the neuromuscular junction, characterized by muscle weakness and fatigability. Idiopathic inflammatory myopathies (IIM) are an immune-mediated group of diseases characterized by progressive painful proximal weakness of the extremities. The coexistence of these two diseases is extremely rare and so far, only about fifty cases have been reported worldwide. The aim of this study was to analyze the frequency of coexistence of IIM and patients with de novo MG. Material and Methods: The study is retrospective in nature and was conducted at the "Neurology Clinic", University Clinical Center of Serbia. It included 97 patients diagnosed with myasthenia gravis between January 1, 2014 and December 31, 2018. Results: The average age of the MG patients was 54.1±18.9 years. At the time of diagnosis, 19 (19.6%) participants had at least one of the anamnestic data observed as potential indicators for the existence of immune-mediated myopathy. Finally, one patient clinically presented with generalized seropositive (anti-AchR positive) myasthenia gravis associated with the diagnosis of antisynthetase syndrome. In addition, the main characteristics of patients with combined occurrence of de novo MG and antisynthetase syndrome are presented. Conclusion: Although the simultaneous occurrence of MG and IIM is a very rare phenomenon, we need to think about the possibility of combined occurrence of these two autoimmune diseases, with the aim of early recognition and adequate treatment, and thus a better prognosis of both diseases.