Chapter 2: Myasthenia Gravis

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Chapter 2: Myasthenia Gravis
2015-03-10 22:19:41
Myasthenia Gravis
NPTE: Chapter 2
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  1. Definition
    A neuromuscular junction disorder characterized by progressive muscular weakness and fatigability on exertion
  2. Etiology
    Autoimmune anti-body mediated attack on ACh receptors at NM junction
  3. Characteristics
    • Muscle strength worse with continuing contraction, improved with rest
    • Classified into 4 types
    • Course varies = may progress from mild to severe, typically within 18 months
  4. Four Types
    • Ocualar myasthenia (confined to extraocular muscles)
    • Mild generalized myasthenia
    • Severe generalized myasthenia
    • Crisis
  5. Generalized Myasthenia
    Usually involves bulbar (extraocular, facial, and muscle of mastication) and proximal limb-girdle muscles
  6. Myasthenic Crisis
    • Myasthenia gravis with respiratory failure¬†
    • Treat as medical emergency
  7. Examination
    • Cranial nerves
    • Respiratory function
    • Muscle strength
    • Functional mobility skills
  8. Exam: Cranial Nerves
    • Diplopia
    • Ptosis
    • Progressive dysarthria or nasal speech
    • Difficulties chewing and swallowing
    • Difficulties in facial expression (drooping)
  9. Exam: Respiratory Function
    • Breathing difficulties¬†
    • Hoarse voice
  10. Exam: Muscle Strength
    • Prox more involved than distal
    • Fatigability characteristic of this disease
    • Repeated muscle use results in rapid weakness
  11. Exam: Functional Mobility Skills
    • Stair climbing
    • Rising from chair
    • Lifting

    (difficulties similar to myopathies)
  12. EMG and Repetitive Nerve Stimulation Studies
    • Show abnormal responses to repetitive nerve stimulation
    • Failure of transmission
    • Decreased EMG-recorded responses
  13. Medical Intervetntions
    • Acetylchoinesterase inhibitors¬†
    • Corticosteroids
    • Immunosuppressants
    • Alternative treatments = plasmapheresis (removal of blood with filtering and separation of cellular elements from plasma); thymectomy
  14. PT Goals, Outcomes, and Interventions
    • Monitor changes in pt's condition (vital signs, respiration, swallowing
    • Promote independence in FMS and ADLs
    • Teach energy conservation techniques