[Results of electromyographical and mechanographical investigations in myotonia congenita (author's transl)].

Electrical and mechanical investigations in myotonia were investigated in 20 patients with myotonia congenita. At first the parameters of the myotonic muscle fiber discharges were determined, than the EMG-activity was estimated during slight and maximal force of voluntary muscle contraction and finally the electromyogram and the mechanogram were simultaneously registered after indirect stimulation of the muscle. The results show, that there is a correlation between the myotonic muscle fiber discharges and the EMG- and mechanical findings depending on the frequency of stimulation and the force of contraction. The parameters of muscles did not differ between the patients and the health persons after single stimulation. Repetitive supramaximal stimuli (15 Hz) showed a rapid decline of EMG-amplitude in the patients with myotonia congenita. The fall of amplitude was observed, as soon as myotonia fiber discharges occured. The duration of contraction was longer both in the phase of contraction and in the phase of relaxation. When the frequency of stimulation was increased (30 Hz), the fall of EMG-amplitude was more increased whereas the contraction and relaxation time decreased. The findings are interpreted by means of the author's own experimental results and are discussed in connection with the chloride-hypothesis.