We describe our experience with an elderly woman who presented with mastication difficulty and was given a diagnosis of with myasthenia gravis.
The patient was an 80-year-old woman. Her chief complaint was that her jaw felt heavy, making chewing difficult. This symptom did not improve even after her dentures were adjusted at another institute. An investigation was conducted at our institute, with the following results: antiacetylcholine receptor antibodies 47.4 nmol/l, waning （+） electromyography, and a positive tensilon test result.
The patient was given a diagnosis of myasthenia gravis. Oral treatment with mestinon was initiated; however, myasthenia gravis crisis occurred 1 year later, and thymectomy was thus performed.
Subsequently, the mastication difficulty improved.
