What is myotonia?
Myotonia is the phenomena of impaired relaxation of muscle after forceful voluntary contraction and most commonly involves the hands and eyelids.
Myotonia is due to repetitive depolarization of the muscle membrane.
Patients may complain of muscle stiffness or tightness resulting in difficulty releasing their handgrip after a handshake, unscrewing a bottle top, or opening their eyelids if they shut their eyes forcefully.
Myotonia classically improves with repeated exercise, while in contrast, paramyotonia is typically worsened by exercise.
Exposure to cold makes both myotonia and paramyotonia worse.