Muscle channelopathies.

Skeletal muscle channelopathies are rare heterogeneous diseases with marked genotypic and phenotypic variability. Despite advances in understanding of the molecular pathology of these disorders, the diverse phenotypic manifestations remain a challenge in diagnosis and therapeutics. These disorders can cause lifetime disability and affect quality of life. There is no treatment of these disorders approved by the US Food and Drug Administration at this time. Recognition and treatment of symptoms might reduce morbidity and improve quality of life. This article summarizes the clinical manifestations, diagnostic studies, pathophysiology, and treatment options in nondystrophic myotonia, congenital myasthenic syndrome, and periodic paralyses.