Myotonia is a neuromuscular disorder characterized by the slow relaxation of the muscles after voluntary contraction or electrical stimulation. Generally, repeated effort is needed to relax the muscles, and the condition improves after the muscles have warmed-up. Individuals with the disorder may have trouble releasing their grip on objects or may have difficulty rising from a sitting position and a stiff, awkward gait. The disorder can affect all muscle groups. It may be acquired or inherited, and is caused by an abnormality in the muscle membrane. Myotonia is a symptom commonly seen in patients with myotonic muscular dystrophy and in a group of disorders called channelopathies (hereditary diseases that are caused by mutations in the chloride sodium or potassium channels that affect the muscle membrane). Myotonia also may be triggered by exposure to cold.
National Institute of Arthritis and
Musculoskeletal and Skin Diseases (NIAMS) National Institutes of Health, DHHS 31 Center Dr., Rm. 4C02 MSC 2350 Bethesda, MD 20892-2350 NIAMSinfo@mail.nih.gov http://www.niams.nih.gov Tel: 301-496-8190 877-22-NIAMS (226-4267) |
Muscular Dystrophy Association 3300 East Sunrise Drive Tucson, AZ 85718-3208 mda@mdausa.org http://www.mda.org Tel: 520-529-2000 800-344-4863 Fax: 520-529-5300 |
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Last updated March 12, 2009