Question: Encounter notes indicate that the provider performed a level-three evaluation and management (E/M) service for an established patient with Steinert disease. What is the correct ICD-10 code for this condition? Kansas Subscriber Answer: You’ll report 99213 (Office or other outpatient visit for the evaluation and management of an established patient, which requires a medically appropriate history and/or examination and low level of medical decision making. When using time for code selection, 20-29 minutes of total time is spent on the date of the encounter.) for the E/M with G71.11 (Myotonic muscular dystrophy) appended to represent Steinert disease. Myotonic disorders primer: G71.11 is the first code in the G71.1- (Myotonic disorders) code set. These codes represent several disorders, and they also contain a multitude of synonyms for each ICD-10 descriptor. Check out this list of myotonic disorders you’ll find in G71.11, along with the terms ICD-10 considers synonymous with each descriptor: 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