Myasthenia gravis

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Clinical Findings

  • Ocular myasthenia gravis:
    • Main Signs: Fatigability and variability
      • often worsening towards evening
    • Ptosis
      • asymmetrical
      • Cogan lid twitch sign
      • Enhanced contralateral ptosis during elevation of the ipsilateral eyelid
      • Simpson Test
    • Diplopia: Can mimic various forms of ophthalmoplegia
    • Facial muscle weakness
    • Nystagmus: Noted in extreme gaze positions
  • Generalised myasthenia gravis: Additionally presents with chewing weakness, dysphagia, dysarthria, dyspnoea
  • Lee’s 5P:Symptoms not caused by masthenia gravis
    • Pain
    • Proptosis (exception with associated thyroid eye disease)
    • Paraesthesias
    • Perception (visual acuity decrease, visual field defects)
    • Pupil involvement


  • Lab tests: Acetylcholine receptor antibodies, anti-MuSK antibodies, +/- anti-Titin antibodies
  • Rest test/Ice test
  • Tensilon test (Edrophonium)
    • Side effects include sweating, nausea, vomiting, hypersalivation, fever, increased IOP
    • Antidote: Atropin 0.5mg.
  • CT Thorax: To rule out thymoma (70% have thymic hyperplasia, 10% have a thymoma)
  • Consider Single-Fiber EMG: Shows fatigue with repetitive stimulation.
  • Thyroid Function Tests: 5% of patients develop Graves’ disease!

Differential Diagnoses

  • Myotonic dystrophy
  • Chronic Progressive External Ophthalmoplegia (CPEO)
  • Ptosis of other aetiologies
  • Eaton-Lambert Syndrome: Paraneoplastic, associated with small cell lung cancer, impaired pre-synaptic release of ACh, no improvement with Edrophonium


  • in collaboration with neurology
  • Mestinon (Pyridostigmine): An acetylcholinesterase inhibitor
    • Titration scheme: e.g., start with 60mg once daily, increasing the dose every 3 days up to 4x60mg
    • Caution: If gastrointestinal symptoms (diarrhea, cramps) occur, wait or decrease the dose for a few days before increasing again
  • if Mestinon is not sufficient:
    • Steroids: e.g., 10mg Spiricort daily for 3 months, then taper off very slowly (high doses can worsen myasthenic symptoms).
    • If no response, increase Spiricort to max 20mg/day
      • Annual bone density measurement recommended
  • Alternative Treatments: Imurek, Cellcept, Rituximab, IVIG (Privigen infusion), Plasmapheresis, Thymectomy (in case of thymoma, consider in generalised form)

Medications to avoid

  • List , 1
    • not exhaustive, includes medications with the highest evidence of risk
  • Antibiotics
    • Aminoglycosides (e.g., Gentamicin, Neomycin, Tobramycin)
    • Fluoroquinolones (e.g., Ciprofloxacin, Levofloxacin, Moxifloxacin, Ofloxacin)
    • Macrolides (e.g., Erythromycin, Azithromycin, Clarithromycin)
    • Telithromycin
  • Beta-blockers
  • Botulinum toxin
  • Chloroquine and Hydroxychloroquine
  • High-dose corticosteroids
  • D-Penicillamine
  • Desferrioxamine
  • Immune checkpoint inhibitors (e.g., Ipilimumab, Pembrolizumab, Atezolizumab, Nivolumab)
  • Iodine-containing contrast media
  • Intravenous magnesium
  • Procainamide
  • Statins (e.g., Atorvastatin, Pravastatin, Rosuvastatin, Simvastatin)


  • First check approximately 1 week after treatment initiation (to assess medication tolerance)
  • Patient education: In case of systemic manifestations of myasthenia gravis (chewing weakness, dysphagia, dysarthria, dyspnoea), seek immediate medical attention

Video by Dr. Andrew G. Lee


  • EyeWiki Myasthenia Gravis
  • Ocular Myasthenia Gravis by Dr. Andrew G. Lee
  • The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease; Nika Bagheri MD, Brynn Wajda MD, et al; Lippincott Williams&Wilkins; 7th Edition (2016)
  • Kanski’s Clinical Ophthalmology: A Systematic Approach; Jack J. Kanski MD, Brad Bowling MD; Saunders Ltd.; 8th Edition (2015)
  • 1 International Consensus Guidance for Management of Myasthenia Gravis; 2020 Update; Pushpa Narayanaswami, Donald B. Sanders, Gil Wolfe, Michael Benatar, Gabriel Cea, Amelia Evoli, Nils Erik Gilhus, Isabel Illa, Nancy L. Kuntz, Janice Massey, Arthur Melms, Hiroyuki Murai, Michael Nicolle, Jacqueline Palace, David Richman, Jan Verschuuren;