Anne,

MC is a condition that affects the skeletal muscles. The chloride channels which allow the exchange of chloride and sodium are altered by one or two mutations and this delays relaxation after a muscle is contracted. If you haven't read the MDA Quest article, it has a very good explanation:

Myotonia Congenita - MDA Quest

Although some women only have noticeable symptoms when they are pregnant, most of us begin to experience the stiffness when we are young - some as toddlers, others around puberty.

The muscles affected include arms, legs, hands, feet, abdominals, diaphragm, throat and upper part of esophagus, face, eyelids, ocular (behind the eyes), scalp and tongue. The stiffness disappears as you warm up the muscle, but sets in again after a period of rest, even just minutes of being inactive. Some people have pain and cramping because of damaged muscle cells related to the myotonia, others have no pain and only experience the stiffness.

With the recessive form it seems to be more likely that you can freeze up suddenly which is very dangerous if you trip or are startled. If you fall you can't catch yourself.

MC does not affect smooth muscle as a rule (although some sphincter muscles may morph over time to include some skeletal muscle). So that means your gastrointestinal tract is not affected, and theoretically neither is your heart, although many of us do have palpitations or arrythmias that seem to be correlated with the stiffness.

Hope that helps -

Jan

Type of Myotonia: Thomsen's

Country: USA

Jan
Thank you

Type of Myotonia: Unknown

Country: Australia