Myotonia is a neuromuscular disorder. It causes slow relaxation of the muscles after voluntary contraction or electrical stimulation. It can affect all muscle groups. Myotonia is a symptom often seen in patients with myotonic muscular dystrophy. It is also seen in a group of disorders called channelopathies. These are hereditary diseases. They are caused by mutations in the chloride sodium or potassium channels. These channels affect the muscle membrane. It also may be triggered by exposure to cold.


It may be acquired or inherited. It is caused by an abnormality in the muscle membrane.


  • Individuals may have trouble releasing their grip on objects.

  • They may have difficulty rising from a sitting position.

  • They may have a stiff, awkward gait.


Often, repeated effort is needed to relax the muscles. The condition improves after the muscles have warmed-up. Treatment may include anticonvulsant drugs. Physical therapy and other rehabilitative measures may help muscle function.

This can be a static or a progressive disorder. Symptoms may improve later in life.