Myotonia Congenita

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What is myotonia congenita?

Myotonia congenita is an inherited neuromuscular disorder characterized by the inability of muscles to quickly relax after a voluntary contraction.

The condition is present from early childhood, but symptoms can be mild. Most children will be two or three years old when parents first notice their muscle stiffness, particularly in the legs, often provoked by sudden activity after rest.

The disease doesn't cause muscle wasting; in fact, it may cause muscle enlargement and strengthening.

There are two forms of the disorder:

  1. Becker-type (most common form)
  2. Thomsen's disease (rare and milder form)

The disorder is caused by mutations in a gene responsible for shutting off electrical excitation in the muscles.

Most people with myotonia congenita don't require special treatments. Stiff muscles usually resolve with exercise or light movement, especially after resting. When symptoms are more limiting, medications like quinine or anticonvulsant drugs like phenytoin may be beneficial. Physical therapy and other rehabilitative therapies are also used to improve muscle function.

Most individuals with myotonia congenita lead long, healthy lives. Although muscle stiffness may interfere with walking, grasping, chewing, and swallowing, it is usually relieved with exercise.

Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with myotonia congenita?

Consider participating in a clinical trial so clinicians and scientists can learn more about myotonia congenita and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with myotonia congenita at

Where can I find more information about myotonia congenita?

Information may be available from the following organizations and resources:


Muscular Dystrophy Association
Phone: 800-572-1717

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Phone:  301-495-4484 or 877-226-4267

Order publications from the NINDS Catalog
The NINDS Publication Catalog offers printed materials on neurological disorders for patients, health professionals, and the general public. All materials are free of charge, and a downloadable PDF version is also available for most publications.