II. Epidemiology

  1. Exclusively affects males

III. Pathophysiology

  1. X-linked recessive inheritance

IV. Symptoms

  1. Difficulty performing Exercises
    1. Climbing
    2. Running
    3. Jumping
    4. Hopping

V. Signs

  1. Symmetric, progressive proximal Muscle Weakness
    1. Affects hip and Shoulder girdle
  2. Palpable Muscle enlargement
    1. Initial Muscle hypertrophy
    2. Later fat and connective tissue replace Muscle

VI. Associated Conditions

  1. Tendon and Muscle contractures
  2. Kyphoscoliosis (progressive)
  3. Impaired pulmonary function
  4. Cardiomyopathy
  5. Intellectual Impairment

VII. Course

  1. Age 5 years: Onset of symptoms and signs
  2. Age 8-10 years: Leg braces necessary for ambulation
  3. Age 12 years: Nonambulatory
  4. Age 25 years: Survival rare beyond this point

VIII. Labs

  1. Muscle Enzymes elevated
    1. Creatine Phosphokinase (CPK) increased
    2. Aldolase increased
  2. Electromyogram (EMG)
    1. Myopathy
  3. Muscle Biopsy
    1. Necrotic Muscle fibers with regeneration
    2. Fatty replacement of Muscle
  4. Electrocardiogram (EKG)
    1. Cardiomyopathy
    2. Deep Q Waves across precordium

IX. Complications

X. Management

  1. Passive muscle Stretching
  2. Tenotomy
  3. Bracing
  4. Physiotherapy
  5. Mechanical Assistive Devices
  6. Avoid prolonged immobility

XI. Reference

  1. Mendell in Wilson (1991) Harrison's IM, p. 2112

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