Myotonia congenita

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Superficial anterior muscles

Thomsen's disease; Becker's disease

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:

• Difficulty in swallowing
• Gagging
• Stiff movements that improve when they are repeated
• Shortness of breath or tightening of the chest at the beginning of exercise

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.

The doctor may ask if there is a family history of myotonia congenita.

Tests include:

• Genetic testing
• Muscle biopsy
• Test of the electrical activity in muscles (EMG)

Review Date: 03/21/2010
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Luc Jasmin, MD, PhD, Department of Neurosurgery at Cedars-Sinai Medical Center, Los Angeles, and Department of Anatomy at UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).

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