Myotonia congenita is an inherited disorder that affects skeletal muscles. Beginning in childhood, people with this condition experience bouts of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally. Although myotonia can affect any skeletal muscles, including muscles of the face and tongue, it occurs most often in the legs. Below you may find medications used to treat or help with Myotonia Congenita. More about Myotonia Congenita