What is the progression of Duchenne muscular dystrophy (DMD) following loss of ambulation?

Updated: Aug 17, 2020
  • Author: Twee T Do, MD; Chief Editor: Jeffrey D Thomson, MD  more...
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Answer

The second important phase in Duchenne MD is the loss of ambulation. This usually occurs between the ages of 7 and 13 years, with some patients becoming wheelchair-bound by age 6 years. With early initiation of steroid treatment, prolongation of ambulation potential has been well documented. However, If children with MD are still ambulating well after the age of 13 years, the diagnosis of Duchenne MD should be questioned, because these patients may have Becker MD, the milder form of MD.

In Emery's work, [14] the 50th percentile for loss of ambulation in patients with Duchenne MD was age 8.5 years, with the 95th percentile at 11.9 years and the 99th percentile at 13.2 years. With the child's loss of ambulation, there is usually a rapidly progressive course of muscle or tendon contractures and scoliosis.

Most authors have recommended posterior spinal fusion at 20° when the vital capacity is at its best. [22, 13, 16, 23, 24] However, some reports showed that respiratory function after spinal fusion did not significantly differ. [25, 26, 27, 28, 29] The investigators concluded that respiratory failure resulted from muscle weakness and not the mechanical bellows of the chest cage, as was previously assumed.

Duchenne MD is a terminal disease in which death usually occurs by the third decade of life (mostly from cardiopulmonary compromise), despite steroid treatment. [13] The most common inciting event is a respiratory infection that progresses extremely rapidly despite its initial benign course. The resultant respiratory failure can easily occur from the underlying progressive nocturnal hypoventilation and hypoxia or from an acute cardiac insufficiency.


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