Paramyotonia Congenita

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Paramyotonia Congenita is not the name you expected.

Disorder Subdivisions

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General Discussion

Paramyotonia congenita (PMC) is a rare non-progressive genetic disorder that affects the skeletal muscles. The disorder typically begins in infancy or early childhood. Affected individuals experience spells of muscle stiffness or when the muscles do not relax after contracting (myotonia). Symptoms can be triggered by exposure to the cold or after physical activity. The stiffness most commonly affects the muscles in the neck, face, arms and hands, however it can occur in the lower back and the muscles used for breathing. The stiffness of the muscles can get worse with repeated movements. There are also intermittent periods of a type of muscle weakness in which there is no muscle tone (flaccid paresis). This condition does not necessarily coincide with exposure to cold temperatures or myotonia. There is generally no wasting (atrophy) of muscles; however, there is often increase in bulk (hypertrophy) of muscles with this disorder. There is no cure to PMC; however, with the proper management of diet, lifestyle and medication, patients can lead normal lives. PMC is an autosomal dominant genetic condition caused by a mutation in the muscle sodium channel gene SCN4A.

PMC is classified as a form of periodic paralyses, a group of muscle disorders characterized by irregular episodes of muscle weakness or stiffness.

PMC was first discussed in 1886 by von Eulenburg. It is considered the first recognized temperature-sensitive condition in humans.

Supporting Organizations

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311

Muscular Dystrophy Association

3300 East Sunrise Drive
Tucson, AZ 85718-3208
Tel: (520)529-2000
Fax: (520)529-5300
Tel: (800)572-1717

Periodic Paralysis Association

155 West 68th Street
Apt. 1732
New York, NY 10023
Tel: (407)339-9499
Fax: (407)339-9499

Periodic Paralysis International

2235 B 36th St. SW
Calgary, Alberta, T3E 2Z3
Tel: 4032447213

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report.

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

Last Updated:  6/16/2016
Copyright  2016 National Organization for Rare Disorders, Inc.