Myotonia
Myotonia refers to slow relaxation of skeletal muscle contraction. This could be congenital and this congenital myotonia is called “Thomsen’s disease” which is an autosomal dominant disorder.
The individual affected will have an associated mental retardation which appears static. Usually, symptoms may manifest in the first decade and affected person may have a normal life expectancy because progression is slow. The muscle atrophy is not as severe as the other dystrophies.
Myotonia dystrophica or also known as “Steinert’s syndrome” has more severe muscle atrophy. The symptoms may begin in the early or late teens but has its full expression in the adult. The disorder is inherited as autosomal dominant and has the following characteristics:
– frontal baldness
– cataracts
– testicular atrophy
– and severe muscle atrophy
– all cardiac and smooth muscles may be affected with electrocardiographic abnormalities and gastrointestinal disturbances
It is also worth to mention that there is a myotonia that is associated with cold temperatures and this is referred to as “Paramyotonia comgenita”. All of these disorders have no known specific treatments. Management is focused on:
– genetic counseling
– patient and family support
– limitation of surgical procedures