Diagnosis and Management of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy is an X-linked disorder causing childhood-onset progressive muscular weakness in males. Incidence of the disease is about 20 to 30/100,000 newborn males. Although numerous theories have been advanced as to the cause of the illness, the primary defect has resisted analysis. DIAGNOSIS (Table 1) Symptoms In the typical patient with Duchenne muscular dystrophy, symptoms of weakness are first noted at 3 to 5 years of age by the parents. The symptoms are subtle and consist of motor slowness in comparison with peers, difficulty in climbing, or an inability to run. Although the disease is present from birth, symptoms are uncommonly noticed before age 3 years. Approximately 10% of patients with Duchenne muscular dystrophy, however, will come to the primary physician9s attention because of developmental delay. This may be in the motor sphere, with delayed walking, or of a more global nature. Physical Examination Before 5 years of age, patients with Duchenne muscular dystrophy have findings that are sometimes not quickly recognized, even by those who have seen the disorder previously. Muscles, particularly the triceps and gastrocnemii, may be enlarged to inspection and/or palpation (Fig 1). The texture of the muscles may feel "tougher" than normal. Their generous size seems inconsistent with their lack of strength.