Recent advances in neuromuscular diseases have also widened the diagnostic spectrum of
myotonic disorders. Treatment, prognosis, and genetic aspects are different in the various
syndromes and mandate a correct diagnosis. The combination of neurologic examination,
standard EMG, exercise test, cold exposure, potassium loading, eye examination, and
pedigree analysis allows correct classification of nearly all patients with myotonic disorders.
In this review emphasis is placed on clinical features and electrophysiologic evaluation.