Not moving a muscle

Abstract This case uses a case to illustrate the common presentations of myotonic dystrophy type 1 and the large variability of phenotypes within a family. It discusses the key differentials to consider when patients present with myotonia, as well as the primary investigations to perform when confirming the diagnosis. It discusses the most important aspects in the multidisciplinary management of the condition, including the key aspects of managing respiratory and cardiac manifestations. It also outlines some of the landmark trials affecting the management of the disease, including the efficacy of mexiletine in treating myotonia and the importance of pacing in this cohort. Thereby it gives an overview of the key aspects of diagnosis and management of myotonic dystrophy for the clinician.