[Myopathia myotonica. A new type of hereditary muscle disease (author's transl)].

A new type of hereditary muscle disease, characterized by weakness and painful spasms during effort, without electrical activity in the shortened muscles, is described. These phenomena are limited principally to the upper limbs. In addition we found electromyographical signs of a generalized myotonic syndrome. The histological and histochemical investigations reveal only minimal non-specific signs of myopathy. The activities of CPK and aldolase in the blood serum are increased at times. A normal elevation of venous lactate was observed during ischemic work. The biochemical studies of muscular tissue exhibit normal activities of the analyzed enzymes, especially as regards phosphorylase. An increased concentration of calcium ions in blood serum may be related to the contraction during strenuous work; it is known that calcium ions are an important factor in the contraction-relaxation cycle of striated muscle. The age of manifestation varied from 4 to 33 years in 4 cases of the relatives observed. The disease shows no signs of aggravation as to the severity and extent of the disorders. The nature of the underlying metabolic defect is still unknown.