Duchenne muscular dystrophy

• Muscular dystrophy


  A group of inherited conditions that result in progressive muscle weakness and wasting
• Muscular dystrophy


  • The muscles affected are primarily the skeletal (voluntary) muscles
  • There are nine types of muscular dystrophy
  • All include muscle weakness over the lifetime, but it is more severe in some types
  • Most often diagnosed in childhood
  • Affects a variety of muscle groups
• Inheritance pattern


  May be X-linked, autosomal dominant, or recessive
• Genetic mutation


  Results in absence or decrease of a specific muscle protein that prevents normal function of the muscle
• Skeletal muscle fibers are affected, yet there are no structural abnormalities in the spinal cord or the peripheral nerves
• Duchenne muscular dystrophy


  • The most common neuromuscular disorder of childhood
  • Results in a shortened life expectancy
  • Advances in medical care have improved survival into the 30s, 40s, and 50s
  • Incidence is about 1 in 3,600 live male births
• Pathophysiology of Duchenne muscular dystrophy

  1. Gene mutation results in absence of dystrophin, a protein critical for muscle cell maintenance

  2. Gene is X-linked recessive, affecting mainly boys

  3. Absence of dystrophin leads to generalized weakness of voluntary muscles, progressing over time

  4. Hips, thighs, pelvis, and shoulders affected initially, then all voluntary muscles and cardiac/respiratory muscles
• Early signs of Duchenne muscular dystrophy

  • Late in learning to walk
  • Pseudohypertrophy (enlarged appearance) of the calves as toddlers
  • Frequent falling and clumsiness as preschoolers
  • Difficulty climbing stairs and running, cannot get up from the floor
  • Toe or ball of foot walking, waddling gait, balance issues, protuberant belly in school-age children
  • Difficulty raising arms in school-age years
  • Loss of ambulation by ages 7-12
  • Intellectual impairment or learning disabilities common
• Detecting muscular dystrophy: trapezius muscle rises, creating a stepped appearance at the shoulder points; scapulae ride over the lateral thoracic region, giving a wing-like appearance when raising the arms
• Pulmonary function tests evaluate respiratory function