Tuesday, June 5, 2018

PT Pathologies: Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD)  is a genetic neuromuscular disorder that causes progressive muscle degeneration and weakness.  DMD is caused by lake of dystrophin, a protein that muscles use for movement, strength, and offer protection from injury as muscles contract and relax.  As the disease progresses, fat and connective tissue replace the muscle that is destroyed which leads to lack of muscle contractility.

DMD is an X-linked recessive gene that is carried by the mother and only presents itself in the male offspring.  Diagnosis is usually done between the ages of 2-5 years of age.  First symptoms are walking on the toes, enlargement of the calf muscles, clumsiness, excessive lordosis, difficulty climbing stairs, waddling gait, frequent falls, and sometimes difficulty raising their arms.  DMD primarily  affects the shoulder girdle, pectorals, deltoids, rectus abdominus, gluteals hamstring and calves.  Most children with DMD are using a wheelchair by 7-12 years of age.  Life expectancy is somewhere in the mid twenties, but some research shows that surviving into the early thirties is becoming more common.

There is not much pain associated with DMD, but some people report muscle cramping. Muscular dystrophy does not affect nerves directly so touch and other sensations are normal.  The lack of dystrophin can weaken he myocardium of the heart which is life threatening over time.  Respiratory function can also be weakened by the loss of muscle function making it more difficult for the lungs to move air.  In turn, this can lead to infections due to the inability to cough and shortness of breath.

Physical therapy treatment should include standing a few hours everyday to promote circulation, range of motion exercises to prevent contractures, stretching, water therapy and fun activities such as kickball can be incorporated.  Many types of medical equipment can help with mobility.  Braces support the foot and ankle, AFO can be worn at night to keep the achilles tendon stretched, wheelchairs, mechanical lifts and scooters.

In Summary:

  • DMD is an X-linked recessive trait manifesting in only male offspring while female offspring become carriers
  • Clinical presentation includes waddling gait, proximal muscle weakness, toe walking, pseudohypertrophy of the calf and difficulty walking up stairs.
  • There is usually rapid progression of this disease with the inability to ambulate by 10 to twelve years of age with death occurring as a teenager or in the early 20s

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