The Good Doctor

Tag: myopathy

  • Duchenne Muscular Dystrophy

    1 in 5,000 males, X-linked recessive hereditary condition (1/3 sporadic, from spontaneous mutation). The diagnosis is usually obvious by the fourth year of life and the patient is severely disabled by 10 years of age.

    • Delayed motor development first noticed from 18 months to 4 years of age
      • 50% not walking before 18 months
      • waddling gait
      • frequent falling
      • trouble with walking or running
      • poor coordination
      • proximal muscle weakness → Gower’s sign
    • 4-6 Years old: some normal muscular development masks the disease process
    • Increasing weakness: waddling gait, increased lumbar lordosis, increasing equinus foot, reduced knee jerk (proximal → distal, i.e. ankle jerk preserved until late)
      • pseudo-hypertrophic calves
      • poor at sports
      • cannot keep up with peers
    • 9-13 Years old: loss of independent mobility
    • Spinal deformity:
      • reduced pulmonary function
      • cardiac failure and arrhythmia
      • mortality 15-25 years
    • non-progressive intellectual impairment (average IQ ~ 85)

    Diagnosis

    • Family History + clinical features
    • serum creatine kinase (CK): 100-200 x normal
    • electromyography: myopathic pattern
    • muscle biopsy:
      • variable fibre diameter, necrosis, regeneration and replacement with flat
        • absence of dystrophin on immune staining
    • molecular testing

    Management

    • Passive physiotherapy
    • Corticosteroids
    • Genetic counselling

    Differential Diagnosis, stratified by anatomical site