Maria Grazia D’Angelo, Sandra Gandossini
Duchenne muscular dystrophy (DMD) affects 1:3500 live male births; it is caused by mutations in the dystrophin gene on the X chromosome at Xp21. Males are affected and females are carriers of the gene mutation. Boys with DMD present in early childhood with abnormal gait, calf hypertrophy, and difficulty in rising from the floor and in climbing stairs, delayed walking, increased falls and decreased motor activity.
Glucocorticoids are the only medication currently available that slows the decline in muscle strength and function in DMD, which in turn reduces the risk of scoliosis and stabilises pulmonary function; nevertheless, this treatment has several side effects, two of which relate to child height and weight growth. Short stature is a common feature in DMD: the patients lose height during the first years of life, following which they grow within a lower growth channel. Almost 50% of dystrophic children are obese by the age of 13 and around the same percentage are underfed by the age of 18.
Progression of muscle weakness and leg contractures leads to loss of walking and complete wheelchair dependence at a mean age of 10–12 years, and the ensuing early teenage years are marked by the development of progressive scoliosis. Respiratory, orthopaedic, and cardiac complications emerge, and without intervention, the mean age at death is around 19 years. The leading cause of death is respiratory insufficiency, although a minority die because of cardiac complications such as dilated cardiomyopathy. Non-progressive cognitive dysfunction (comprehensive developmental delay and speech and language disorders) and difficulties in social functioning (autism spectrum disorders, emotional adjustment, and coping) might also be present. The multisystem complications of DMD necessitate a multidisciplinary team approach for optimal surveillance and management.
NeuroMuscular Unit, Department of NeuroRehabilitation, IRCCS E. Medea, Italy