The disorder is caused by a genetic mutation involving the chloride channel of the muscles. The muscle stiffness, which particularly occurs in the leg muscles, may be enhanced by cold and inactivity, and is often relieved by exercise. Most cases of myotonia congenita do not require treatment. Sometimes, however, symptoms of the disorder may be relieved with quinine, phenytoin and other anticonvulsant drugs. Physical therapy and other rehabilitative measures may be used to help muscle function.
Genetic counseling is available.
While most cases of myotonia congenita are nonprogressive and relatively nonlimiting, other cases may be severe and fatal. A precise diagnosis allows physicians to distinguish mild myotonia congenita from more harmful forms. The goals of these studies are to increase scientific understanding of these disorders and to find ways to prevent, treat, and cure them. This fact sheet is in the public domain. You may copy it.