Myotonia is a symptom of a small group of neuromuscular disorders. It consists of delayed relaxation of the skeletal muscles after a voluntary contraction or after electrical stimulation, and the muscle shows an abnormal electromyogram. It is the defining symptom of many channelopathies, which are diseases of ion channel transport, among them myotonia congenita, paramyotonia congenita and myotonic dystrophy. Brody disease and several other disorders produce a similar delayed relaxation that is pseudo-myotonia, because the electromyogram is normal. Repeating the contraction often eases the stiffness, a phenomenon called the warm-up reflex, though this does not happen in paramyotonia congenita. People may struggle to release their grip or to rise from a seat and may walk with a stiff, awkward gait. People with myotonic disorders can have life-threatening reactions to certain anaesthetics. This entry is a reference record and not medical advice.
Facts
Classification
ICD-10 ChapterVI: Diseases of the Nervous System 1 Sources
1. National Library of Medicine Clinical Tables: ICD-10-CM codes named Myotonia
National Library of Medicine Clinical TablesICD-10-CM list, code and nameQuote, ICD-10-CM list, code and name
"G71.12", "Myotonia congenita"
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