Efficacy of methylprednisolone administration in a case of continuous abnormal muscle activity syndrome.

We report a 20-year-old woman with continuous abnormal muscle activity syndrome in which pharmacological blockade of different sites of the motor unit demonstrates a peripheral nerve origin for the abnormal muscle activity. The case showed no markers of autoimmune disease. A rapid recovery after high dose i.v. methylprednisolone was observed supporting the hypothesis of an autoimmune pathogenesis.