[Myasthenia gravis is improved temporarily at postburn period]

A 62-year-old woman with a 25-year history of myasthenia gravis (MG) was admitted to our hospital due to burn injury over 20-25% of the total body surface area. Five months before admission, the serum concentration of acetylcholine receptor (AchR) antibodies was 80.9 nmol.l-1 (normal range < 0.3 nmol.l-1). Anticholinesterase agents had been administered for MG, but were discontinued six days after admission due to muscarinic side effects, but no symptoms of MG appeared. Thirteen days after admission, the AchR antibody titer was 21.2 nmol.l-1. Free skin grafting was performed under general anesthesia without any event. About 80 days after admission, weakness of extraocular muscles appeared. Positive tensilon test and the characteristic electromyographic findings revealed deterioration of MG, and anticholinesterase agents were resumed. Ten months after admission, the AchR antibody titer was 50.4 nmol.l-1. The mechanism of the temporary improvement of MG symptoms does not appear to be explained by the diffuse immunosuppression after burn. At a postburn period, nicotinic AchRs at the neuromuscular junction are known to be temporarily induced. This up-regulation may have caused the temporary improvement in this patient.