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Alternative Names Return to topThomsen's disease; Becker's disease
Definition Return to top
Myotonia congenita is an inherited condition that affects muscle relaxation. It is congenital, meaning that it is present from birth.
Causes Return to top
Myotonia congenita is caused by a change (mutation) to a gene. It is passed down from either one or both parents to the children (inherited).
Myotonia congenita is believed to be caused by a problem in the part of the muscle cells that are needed for muscles to relax. Abnormal repeated electrical discharges occur in the muscles, causing a stiffness called myotonia.
Symptoms Return to top
The hallmark of this condition is the myotonia -- the inability of the muscle to quickly relax after contracting. For example, after a handshake, the person is only very slowly able to open and pull away his hand.
Early symptoms may include:
Children with myotonia congenita often appear to be muscular and well-developed. The child may not have symptoms of myotonia congenita until age 2 or 3.
Exams and Tests Return to top
The doctor may ask if there is a family history of myotonia congenita.
Treatment Return to top
Treatment for symptoms includes:
Outlook (Prognosis) Return to top
People can do well with this condition. Symptoms only occur when a movement is first started. After a few repetitions, the muscle relaxes and the movement becomes normal. Symptoms may improve later in life.
Possible Complications Return to top
When to Contact a Medical Professional Return to top
Call your health care provider if your child has symptoms of myotonia congenita.
Prevention Return to top
Genetic counseling may be of interest to couples who want to have children and have a family history of myotonia congenita.
References Return to top
Barohn RJ. Muscle diseases. Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 447.
Bernard G, Shevell MI. Channelopathies: a review. Pediatr Neurol. 2008 Feb;38(2):73-85.Update Date: 4/22/2009 Updated by: A.D.A.M. Editorial Team: David Zieve, MD, MHA, Greg Juhn, MTPW, David R. Eltz. Previously reviewed by Luc Jasmin, MD, PhD, Departments of Anatomy & Neurological Surgery, University of California, San Francisco, CA. Review provided by VeriMed Healthcare Network (4/28/2009).