Coexistence Of Myasthenia Gravis And Myotonic Dystrophy In A Thyrotoxicosis Patient

A 28 year old previously healthy female presented with a four month history of difficulty of swallowing and drinking liquids and proximal weakness with fluctuation. At her physical examination, she had bilateral exophtalmus which were compatible with hyperthyroidism. Her facial appearance, distribution of weakness without atrophy and presence of reflex myotonia, quadriparesis, and decreased gag reflex resulted in clinical diagnosis of myasthenia gravis and myotonic dystrophy. Her medical and family history was unrevealing. Her acetylcholine receptor antibody was negative, her laboratory was normal except thyroid hormone tests, but on needle electromyography, myotonic discharges were observed and repetitive nerve stimulation was positive, and she was responsive to anticholinesterase medication. It is well known that myasthenia gravis may be seen with thyrotoxicosis and also overlapped with other autoimmune diseases. The objective of this report is to discuss the unique coexistence of two distinct neuromuscular diseases in the same patient with an overlapped disease.