Successful dantrolene sodium treatment of a patient with myotonia congenita (Thomsen's disease).

A 3 year, 10 month old male with myotonia congenita (Thomsen's disease) was placed on dantrolene sodium, which successfully abolished the myotonic phenomenon. Dantrolene sodium might therefore be a useful medicine for patients with Thomsen's disease who do not respond to other medicines, such as carbamazepine (CBZ), with a decrease in the myotonic phenomenon.