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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Paramyotonia congenita

Reviewed August 2015

What is paramyotonia congenita?

Paramyotonia congenita is a disorder that affects muscles used for movement (skeletal muscles). Beginning in infancy or early childhood, people with this condition experience bouts of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally. Myotonia causes muscle stiffness that typically appears after exercise and can be induced by muscle cooling. This stiffness chiefly affects muscles in the face, neck, arms, and hands, although it can also affect muscles used for breathing and muscles in the lower body. Unlike many other forms of myotonia, the muscle stiffness associated with paramyotonia congenita tends to worsen with repeated movements.

Most people—even those without muscle disease—feel that their muscles do not work as well when they are cold. This effect is dramatic in people with paramyotonia congenita. Exposure to cold initially causes muscle stiffness in these individuals, and prolonged cold exposure leads to temporary episodes of mild to severe muscle weakness that may last for several hours at a time. Some older people with paramyotonia congenita develop permanent muscle weakness that can be disabling.

How common is paramyotonia congenita?

Paramyotonia congenita is an uncommon disorder; it is estimated to affect fewer than 1 in 100,000 people.

What genes are related to paramyotonia congenita?

Mutations in the SCN4A gene cause paramyotonia congenita. This gene provides instructions for making a protein that is critical for the normal function of skeletal muscle cells. For the body to move normally, skeletal muscles must tense (contract) and relax in a coordinated way. Muscle contractions are triggered by the flow of positively charged atoms (ions), including sodium, into skeletal muscle cells. The SCN4A protein forms channels that control the flow of sodium ions into these cells.

Mutations in the SCN4A gene alter the usual structure and function of sodium channels. The altered channels cannot effectively regulate the flow of sodium ions into skeletal muscle cells. The resulting increase in ion flow interferes with normal muscle contraction and relaxation, leading to episodes of muscle stiffness and weakness.

Related Gene(s)

Changes in this gene are associated with paramyotonia congenita.

  • SCN4A

How do people inherit paramyotonia congenita?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In many cases, an affected person has one parent with the condition.

Where can I find information about diagnosis or management of paramyotonia congenita?

These resources address the diagnosis or management of paramyotonia congenita and may include treatment providers.

  • Genetic Testing Registry: Paramyotonia congenita of von Eulenburg (
  • Periodic Paralysis International: How is Periodic Paralysis Diagnosed? (

You might also find information on the diagnosis or management of paramyotonia congenita in Educational resources and Patient support.

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook. Read more about genetic testing (, particularly the difference between clinical tests and research tests (

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about paramyotonia congenita?

You may find the following resources about paramyotonia congenita helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for paramyotonia congenita?

  • Eulenburg disease
  • paralysis periodica paramyotonia
  • paramyotonia congenita of von Eulenburg
  • PMC
  • Von Eulenberg's disease

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about paramyotonia congenita?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding paramyotonia congenita?

autosomal ; autosomal dominant ; cell ; contraction ; gene ; inherited ; ions ; muscle cells ; myotonia ; protein ; skeletal muscle ; sodium

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Cavel-Greant D, Lehmann-Horn F, Jurkat-Rott K. The impact of permanent muscle weakness on quality of life in periodic paralysis: a survey of 66 patients. Acta Myol. 2012 Oct;31(2):126-33. (
  • Finsterer J. Primary periodic paralyses. Acta Neurol Scand. 2008 Mar;117(3):145-58. Epub 2007 Nov 20. Review. (
  • Magot A, David A, Sternberg D, Péréon Y. Focal and abnormally persistent paralysis associated with congenital paramyotonia. BMJ Case Rep. 2014 Jun 17;2014. pii: bcr2014204430. doi: 10.1136/bcr-2014-204430. (
  • Miller TM, Dias da Silva MR, Miller HA, Kwiecinski H, Mendell JR, Tawil R, McManis P, Griggs RC, Angelini C, Servidei S, Petajan J, Dalakas MC, Ranum LP, Fu YH, Ptácek LJ. Correlating phenotype and genotype in the periodic paralyses. Neurology. 2004 Nov 9;63(9):1647-55. (
  • Miller TM. Differential diagnosis of myotonic disorders. Muscle Nerve. 2008 Mar;37(3):293-9. Review. (
  • Tamaoka A. Paramyotonia congenita and skeletal sodium channelopathy. Intern Med. 2003 Sep;42(9):769-70. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: August 2015
Published: February 8, 2016