Regional curare test in evaluation of ocular myasthenia

In 7 of 14 patients with clinically restricted ocular myasthenia gravis, the regional curare test showed latent peripheral involvement. The test consisted of the intravenous administration of 0.2 mg d-tubocurarine into an ischemic arm followed by repetitive supramaximal percutaneous electrical stimulation of the median or ulnar nerves. This produced a decrease in the amplitude of the initial evoked potential and a decrement of greater than 10% in the amplitude of the succeeding three to five potentials at rates of 3, 5, or 15 stimuli/sec. Three patients underwent transcervical thymectomy with subsequent improvement in both electrical and clinical findings. Evaluation of all patients with ocular myasthenia gravis should include regional curare testing of clinically uninvolved peripheral nerves. Thymectomy should be considered for patients with abnormal results.