[Relation between electrical and mechanical muscle activity in myotonia]

The relationship between electrical and mechanical muscle activity was investigated in the case of twenty patients with myotonia congenita. Statistically significant correlations were found to exist between the myotonic discharge spasm and the phases of tension and relaxation in the mechanogram. In vitro examination for 9-anthracene carbonic acid of individual muscle fiber bundles and the examination of a patient with recessive generalised myotonia revealed that the incidence of myotonic discharge spasms is accompanied by development of tension in the muscle. These findings lend support to the assumption that in both forms of myotonia it is the electrical activity that induces delay of contraction, and thus accounts for the pathological muscle behavior in myotonia.