[Orbicularis oculi electromyogram in a girl with ocular myasthenia gravis]

A 12-month-old girl with ocular myasthenia gravis was reported. Electromyograms (EMG) of the orbicularis oculi muscle were studied during a period of 16 months. The degree of the waning phenomenon on EMG correlated well with that of her clinical symptoms. The study of post-tetanic exhaustion after repetitive electrical stimulation at 20 Hz for 4 seconds, was the most sensitive technique in the evaluation of the function of neuromuscular junction. EMG showed the waning phenomenon in the initial worsening after a high dose methylprednisolone therapy, and at the symptom-free stage without medication after the steroid therapy. In our patient, orbicularis oculi EMG was useful in the estimation of the severity of ocular myasthenia gravis and the effect of its treatment.