Question: Encounter notes indicate that the provider treated a patient with myotonic atrophica. What is the correct diagnosis code for this condition? Florida Subscriber Answer: You should report G71.11(Myotonic muscular dystrophy) for this patient’s condition. Myotonic atrophica is synonymous with myotonic muscular dystrophy, per ICD-10. There are an inordinate amount of synonyms listed under the codes in the G71.1- set. Here are those codes, along with their synonyms: G71.11 Synonyms G71.12 (Myotonia congenita) Synonyms G71.13 (Myotonic chondrodystrophy) Synonyms G71.14 (Drug induced myotonia) G71.19 (Other specified myotonic disorders) Synonyms