Skip to Main Content

Key Features

  • Occurs both as dominantly and recessively inherited forms

  • In the dominant form, generalized myotonia without weakness is usually present from birth, but symptoms may not appear until early childhood

  • The recessive form has later onset

Clinical Findings

  • The dominant form is characterized by muscle stiffness that is enhanced by cold and inactivity and relieved by exercise, as well as muscle hypertrophy, at times pronounced

  • The recessive form is associated with slight weakness and atrophy of distal muscles

Diagnosis

  • In the dominant form, the responsible gene on chromosome 7 encodes a voltage-gated chloride channel

Treatment

  • Procainamide, tocainide, mexiletine, or phenytoin may help the myotonia, as in myotonic dystrophy

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.