Chronic limb-girdle myasthenia gravis.

The existence of chronic "limb-girdle" form of myasthenia gravis (MG) has been questioned. We report here 12 such patients (10 women and two men) who constituted 3.8% of 314 MG patients in our study. The duration of disease ranged from 4 months to 7 years before the diagnosis. In almost all cases, the initial diagnosis was other than MG. None of the patients had any oculobulbar weakness. Acetylcholine receptor antibody was positive in five cases, although not all in the first assay. Repetitive nerve stimulation test was positive in all cases, although not necessarily the first time. Single-fiber EMG was positive in 11 cases. All patients responded to acetylcholinesterase inhibitors, and two thirds underwent immunotherapy. Diagnosis of limb-girdle MG requires a strong index of suspicion.