Common Thoracic Problem

Myasthenia Gravis

Myasthenia Gravis (重肌無力症) - Generalised muscle fatigue symptom


  1. Self Auto-immune over activity against own body components
  2. Antibodies against Acetycholine muscle end plate receptors, blocking normal neuromuscular transmission.
  3. Usually become symptomatic from young adulthood (triggering factor unknown)

Related body changes and diseases

  1. Thymic disease

    Thymic carcinoma
    Thymic tumour (benign)
    Thymic hyperplasia, enlarged thymus

  2. Thyotoxicosis thyroid disorder

    Autoimmune thyroid diesase, may affect eyes

  3. Thyroid disorder

    Thyoiditis or low thyroid hormone

  4. Non thymic carcinoma

    Carcinoma of lung (Eaton Lambert syndrome)

Treatment of Myasthenia Gravis

  1. Chronic disease

    - Medications
    - Imnunosuppresant: Steroid & Non-sternoid
    - Operation: Total thymectomy

  2. Acute disease or excerbation

    - Medication
    - Respiratory support- ventilation, oxygen
    - Plasmapharesis
    - Intravenous immunoglobulin

  3. Prognosis (outlook)

    - Over 70% show response to surgery after 6 month
    - Final outcome depend on stage, extent of involement (Osler staging)
    - Surgical outcome related to timing of surgery after symptom onset, completeness of surgery, ocular Myasthenia traditionally not good response but up to challange nowadays

  4. Surgical advance in Myasthenia Gravis thymectomy

    - Single port endoscopic total thymectomy
    - Subpxiphoid endoscopic thymectomy
    - Robotic assisted thoracopic thymectomy