pediatrics
Myotonia Congenita
Symptoms and Signs of Myotonia Congenita
In children with myotonia congenita, there is delayed relaxation after muscle contraction, which can cause muscle stiffness. Parents describe weakness or clumsiness in their children, as well as stiffness. Myotonic symptoms lessen with age but do not disappear, and they are most noticeable after a period of rest. Patients typically have hypertrophy of the skeletal muscles due to the sustained muscle activity and the increased muscle bulk gives them an "athletic" appearance. In Thomsen disease, onset is in infancy or early childhood and begins in the upper limbs and face, whereas in Becker disease it begins later in childhood in the lower limbs and has more pronounced muscle hypertrophy. There is no weakness in Thomsen disease, but Becker disease is associated with transient weakness after prolonged rest and sometimes with progressive weakness. 