INFORMATION ON THOMSEN’S MYOTONIA

Thomsen’s Myotonia is an inheritable congenital (present from birth) disorder characterized by slow relaxation of voluntary muscles, which are same those in the legs.

CAUSES OF THOMSEN’S MYOTONIA

Myotonia congenita may be either an autosomal dominant or autosomal recessive disease. With the autosomal dominant form, a person only needs to be left 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 which is responsible for 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 is also the reason for 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 sufficient sodium but not enough chloride, abnormal repetitive electrical discharges cause a stiffness called myotonia.

SYMPTOMS OF THOMSEN’S MYOTONIA

The hallmark of this condition is the myotonia -- the muscle are unable to relax quickly after voluntary contraction. For example, after a handshake, the affected person is only very slowly able to open and disengage his hand.
Early symptoms may include gagging and difficulty in digesting, because oropharyngeal muscles are slow to relax. starting movements may be firm but improve with immediate repetition.
Children with myotonia congenita often appear to be muscular and well-enlarged. There may not be symptoms of myotonia congenita until the child is 2 or 3 years

TREATMENT OF THOMSEN’S MYOTONIA

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