Myasthenia gravis masquerading as amyotrophic lateral sclerosis: a case report

Abstract

Myasthenia gravis is an autoimmune disease that causes weakness in the skeletal muscles. It is considered to be a relatively rare disease. Most commonly the first symptoms are associated with ocular muscle weakness resulting in ptosis and/or diplopia that may be progressive during the periods of muscle exertion and resolve with rest. However, any skeletal muscle group may be affected leading to the variability of clinical symptoms and potential challenges in diagnostics. We present a case report of a 62-year-old male that initially presented with bulbar symptoms and unintentional weight loss, with atypical findings in electromyography study (the absence of decrement amplification in a combination of spontaneous muscular activity) – suggestive for amyotrophic lateral sclerosis (ALS) diagnosis. After a thorough investigation the diagnosis of ALS was not confirmed but myasthenia gravis was highly suspected and anti-MuSK antibodies came positive. The patient was prescribed Pyridostigmine, Prednisolone and underwent plasmapheresis procedure which led to significant relief of the symptoms.