In general, congenital myopathy is expected to worsen or stabilize over time, and is not typically expected to improve. The myopathies that are not congenital, such as infectious, metabolic, or toxic myopathies, may improve once the cause of the myopathy is well controlled.
Getting a good grasp of your specific condition is important to making sure you have the best outcome possible. If you have a type of myopathy that is not expected to improve, you should pay close attention to issues such as atrophy, pressure sores, and making sure that you maintain optimal participation in physical therapy so that you can function at your best.