A New Curare Test for the Diagnosis of Myasthenia Gravis

A simple, safe, and reliable curare test for the diagnosis of myasthenia gravis, based on the increased sensitivity of persons with myasthenia to tubocurarine, consists of the recording of the grip strength before and after the regional intravenous administration of 0.2 mg of tubocurarine. The only special equipment required is a dynamometer. The injection of 0.2 mg tubocurarine caused a 67.9 ± 7.0% and a 10.0 ± 3.9% decrease of grip strength in patients with generalized myasthenia and normal subjects, respectively. Patients with purely ocular myasthenia gravis behaved as normal subjects. The test gives positive results in cases of myasthenia gravis in which the edrophonium chloride test is negative. Because of its safety and simplicity, the test with tubocurarine is preferable to the conventional curare test.