There is not much information on the juvenile form of CMD. There is a really good 30 minutes video about the Childhood forms (Red link at end of column). There is also a drug under development by Ionic Pharmaceuticals in Carlsbad, CA.
BREAKING NEWS ON TREATMENTS: A recent study (Dec 2015) by Japanese and Polish researchers have found that Erythromycin an FDA approved drug might help with the treatment of Myotonic Dystrophy. This drug helped with the treatment of gastric symptoms in patients with myotonic dystrophy in a separate study in 2002. As the Juvenila and Childhood forms will be there for years your doctor may want to consider this treatment. Read more about this potential treatment here.