022.9 is the code used in the International Classification of Diseases (ICD-10) for a type of myopathy called Mitochondrial Myopathy. It refers to a group of diseases that affect the mitochondria, which are components of cells that produce energy. Symptoms usually include exercise intolerance, muscle weakness, and muscle pain. Other symptoms may include vomiting, heart problems, and learning delays. Treatment plans vary but may include physical therapy, medications, dietary changes, and supplements.