The authors present a case of Thomsen's myotonia, in a man 21 years old, the fifth of eight brothers, born in Brazil, of Italian ascendency, without any other personal or familial antecendent. The disease was stationary and manifest since the early years. There were no myotonic signs in the ocular or cardiac muscles, and no other neuropsychiatric or neurovegetative manifestations. Quinine sulphate, in the dose of 1 gram per os, was always effective, disappearing the myotonia 15 to 45 minutes after the ingestion of the agent, and returning after 10 to 12 hours. The tolerance to quinine was complete during ten days of successive administration. The myotonia and the antimyotonic action of quinine were tested by means of myograms, ergograms, electromyograms and moving pictures. After making general considerations about pathogenesis and the-the treatment of myotonia consists in the finding of the minimal efrapeutics of myotonia, the authors conclude that the only difficulty in fective and well tolerated dose of quinine salt. The authors suggest the treatment with serum of patients with myasthenia gravis, and finally refer are using quinine salts in the treatment of sportmen's cramps.
