Myotonia congenita
Share | - Comprehensive articles covering over 1,700 topics. The articles are organized by the disease, condition overview, symptoms, treatment, and prevention.

Drugs search, click the first letter of a drug name:
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | 1 | 2 | 3 | 4 | 5 | 6 | 8 | 9

Terms search, click the first letter of a term name:
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Online medical services

Medical dictionary is a searchable dictionary of medical terms from medicine and related fields. Search for medical terms with our medical dictionary.

Drugs & Medications Search our drug database for comprehensive prescription and patient information on 24,000 drugs online. - The Internet Drug Index for prescription drugs and medications.

PMS blog Premenstrual syndrome (PMS), PMS headache

Blue waffles disease, blog. Blue waffle infection, blue waffle disease pictures.



Disease Reference

Click on the first letter in the disease name:

| 4 | 5 | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z


Myotonia congenita


Myotonia congenita is an inheritable congenital (present from birth) disorder characterized by slow relaxation of voluntary muscles, such as those in the legs.

Alternative Names

Thomsen's disease


Myotonia congenita can be either an autosomal dominant or autosomal recessive disease. With the autosomal dominant form, a person only needs to inherit the mutation from one parent to be affected. Inheriting the recessive form means a person must inherit the mutation from both parents to be affected. The gene that causes this condition resides on chromosome 7.

The cause of myotonia congenita is believed to be an abnormality in the chloride channels of muscle cells (chloride ions are required for a muscle to relax). The abnormal chloride channels also cause an accumulation of potassium outside the cells and an activation of sodium channels in the muscle cells (sodium ions trigger muscle contraction).

When the cells have more than enough sodium but not enough chloride, abnormal repetitive electrical discharges cause a stiffness called myotonia.


The hallmark of this condition is the myotonia -- the inability of the muscle to quickly relax after voluntary contraction. For example, after a handshake, the affected individual is only very slowly able to open and disengage his hand.

Early symptoms may include gagging and difficulty in swallowing, because oropharyngeal muscles are slow to relax. Initial movements may be stiff but improve with immediate repetition.

Children with myotonia congenita often appear to be muscular and well-developed. There may not be symptoms of myotonia congenita until the child is 2 or 3 years old.

Exams and Tests

  • There is often a family history of myotonia congenita.
  • An EMG demonstrates myotonic potentials.
  • A muscle biopsy may show an absence of type 2B fibers.


Treatment for symptoms of myotonia congenita includes mexiletine, phenytoin, and procainamide.

Outlook (Prognosis)

Affected people do well. 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

  • Frequent choking, gagging, or difficulty swallowing in an infant
  • Aspiration pneumonia, related to swallowing difficulties

When to Contact a Medical Professional

Call your health care provider if symptoms of myotonia congenita develop.


Genetic counseling may be of interest to prospective parents with a family history of myotonia congenita.

Email to a Friend

Your Name:

Friend's Email:

More about Myotonia congenita -
   Myotonia congenita
Amniotic constriction bands
Acidosis - respiratory
Kidney stones
Aphthous ulcer
Agnogenic myeloid metaplasia

Medical dictionary | Natural mosquito repellents | Dust mites pictures | Prescription Drug Information | new 401k rules | Hyperkeratosis pilaris treatment
© Copyright by 2006-2007. All rights reserved