SERONEGATIVE MYASTHENIA-GRAVIS ASSOCIATED WITH ATONIC URINARY-BLADDERAND ACCOMMODATIVE INSUFFICIENCY

We report a 20-year-old female with generalized myasthenia gravis (MG) who developed atonic urinary bladder and accommodative insufficiency. Although her sera did not contain antibodies to either nicotinic acet ylcholine receptor (AChR) or voltage-gated calcium channels, a positiv e intravenous edrophonium test and a waning phenomenon on electromyogr aphic studies indicated a diagnosis of seronegative MG. Myasthenic sym ptoms as well as urinary incontinence and impaired near vision disappe ared with slight sequelae after corticosteroid therapy and total remov al of the hyperplastic thymus. These symptoms recurred during a taperi ng course of corticosteroids, and improved again with an increased dos e. Therefore, in this patient, the neuromuscular transmission of musca rinic type of AChR in the smooth muscles was also affected. This patie nt provides insight into the mechanisms by which some smooth muscles a re involved in MG.