[Current aspects of the myotonic syndromes]

On the basis of a clinical and physiological definition of the myotonic syndrome, the author define the scope of their research in two directions: a) the true myotonic syndromes, b) the related syndromes. Amongst the former, two entities are studied from the point of view of the recent discoveries in the field : Thomsen's disease, with some new anatomopathological and genetic considerations; Steinert's disease, concerning which there is much more new evidence in regard to clinical findings (ocular, endocrine, digestive, nervous and, in particular, cardiac symptoms) as well as biological and morphological tests. The genetic aspects are of great interest, for they lead to practical applications in genetic counselling (linkage). A brief therapeutic survey follows. Amongst the related syndromes, the best known is Eulenburg's congenital paramyotonia, the main characteristics of which are briefly described.