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Condition/Disorder Synonyms

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  • Childhood pseudohypertrophic muscular dystrophy

  • Adult pseudohypertrophic muscular dystrophy

  • Duchenne muscular dystrophy

  • Becker's muscular dystrophy

  • Benign X-linked recessive muscular dystrophy

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ICD-9-CM Codes

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  • 359.0 Congenital hereditary muscular dystrophy

  • 359.1 Hereditary progressive muscular dystrophy

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ICD-10-CM Codes

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  • G71.0 Muscular dystrophy

  • G71.2 Congenital myopathies

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Preferred Practice Pattern1

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Key Features

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Description

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  • Group of genetic disorders that result in progressive muscle weakness due to loss of myofibrils

  • Causes defects in muscle proteins: weakens the musculoskeletal system

  • Muscle cell and tissue death

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Essentials of Diagnosis

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  • Nine major types of muscular dystrophy

  • Diagnosed through molecular characteristics

  • Diagnosis is dependent on

    • Age of patient at onset of symptoms

    • Areas of body involved

    • Rate of progression of symptoms

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General Considerations

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  • Duchenne MD (type I)

    • Symptoms begin around 3 to 5 years of age

    • Characterized by pseudohypertrophy of calves

    • Progresses quickly

  • Becker's MD (type II)

    • Symptoms begin around 11 years of age

    • Characterized by muscle weakness of shoulder girdle, trunk, and extremities

    • Progresses slowly

  • Congenital muscular dystrophies

    • Congenital MD with central nervous system disease (Fukuyama syndrome, Walker-Warburg syndrome, muscle-eye-brain-disease)

    • Integrin-deficient congenital MD

    • Merosin-deficient congenital MD

    • Congenital MD with normal merosin

      • Symptoms begin at birth

      • Characterized by hypotonia and contractures at birth

      • Progresses slowly but varies

  • Congenital myotonic MD

    • Symptoms begin at birth

    • Characterized by severe hypotonia and muscle weakness at birth

    • Progresses slowly

    • Cognitive impairment present

  • Childhood-onset facioscapulohumeral MD

    • Symptoms begin by 2 to 10 years of age

    • Characterized by muscle weakness of face and shoulder girdle

    • Progresses slowly

    • Eventually becomes non-ambulatory

  • Emery-Dreifuss (humeroperoneal) MD

    • Symptoms begin prior to teenage years

    • Characterized by contractures of posterior cervical muscles, biceps, and plantar flexors

    • Progresses slowly, but often cardiac involvement

  • Limb-girdle MD

    • Symptoms begin during teen years to adulthood

    • Characterized by muscle weakness of the shoulder and pelvic girdles

    • Progresses slowly

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Demographics

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  • Duchenne MD: 1:3500 males

  • Becker's MD: 1:20,000 births

  • Congenital myotonic MD: 1:8000 births

  • Childhood-onset facioscapulohumeral MD: 3 to 10 per 1,000,000 births

  • Emery-Dreifuss MD: rare

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Clinical Findings

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Signs and Symptoms

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  • Fatigue

  • Complaint of muscle cramps (Becker's)

  • Progressive weakness and atrophy of involved muscles

  • Fasciculations (of tongue)

  • Dysphagia

  • Dysarthria

  • Contractures at birth (congenital and congenital myotonic forms of MD)

  • Scoliosis

  • Cognitive impairment

  • Learning disabilities (Duchenne and Becker's)

  • Waddling gait

  • Inability to run

  • Inability to jump

  • Gower's sign

  • Difficulty stair climbing

  • Toe walking

  • Falls

  • Decreased maximal vital capacity

  • Scapular winging

  • Clubfoot (talipes equinovarus)

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Functional Implications

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  • Progressive dependence for assistance with activities of daily living

  • Easily fatigued

  • Loss of mobility

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Possible Contributing Causes2,...

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