n.
Disorder causing difficulty relaxing contracted voluntary muscle s.
All or only a few may be affected. Myotonia seems to originate in the muscles (myopathy) rather than the nervous system . Certain toxin s can cause it. A hereditary form, myotonia congenita (Thomsen disease), can affect eyelid and eye motion, swallowing, or talking. Quick movements cause muscle stiffening. There is also a myotonic form of muscular dystrophy . Analgesic s, anesthetic s, and anticonvulsant drugs can alleviate the symptoms.