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Myasthenia gravis

Background knowledge 🧠


Myasthenia Gravis is an autoimmune disorder characterized by weakness and fatigue of the skeletal muscles due to the destruction or inactivation of postsynaptic acetylcholine receptors at the neuromuscular junction.


The exact cause of Myasthenia Gravis is unknown. However, it is associated with thymic abnormalities such as thymoma or thymic hyperplasia. It is also linked with other autoimmune diseases like rheumatoid arthritis and systemic lupus erythematosus.


  • The immune system produces antibodies that target and destroy acetylcholine receptors at the neuromuscular junction.
  • This leads to a reduction in the number of available receptors for acetylcholine, impairing muscle contraction.
  • Over time, this results in muscle weakness and fatigue.

Clinical Features

Clinical Features

  • Fluctuating muscle weakness that worsens with activity and improves with rest.
  • Commonly affected muscles include those controlling eye and eyelid movement, facial expression, chewing, swallowing, and speaking.
  • Symptoms may include ptosis (drooping eyelids), diplopia (double vision), dysphagia (difficulty swallowing), and dysarthria (difficulty speaking).
  • Severe cases can lead to myasthenic crisis, a life-threatening condition where respiratory muscles become too weak to function.

Investigations 🧪


  • Serum antibodies: Detection of acetylcholine receptor antibodies or anti-MuSK antibodies.
  • Electromyography (EMG): Demonstrates a characteristic decremental response to repetitive nerve stimulation.
  • Edrophonium test: Temporary improvement in muscle strength following administration of edrophonium chloride.
  • Imaging: Chest CT or MRI to check for thymoma.

Management 🥼


  • Acetylcholinesterase inhibitors: Pyridostigmine is commonly used to improve neuromuscular transmission.
  • Immunosuppressants: Corticosteroids, azathioprine, and mycophenolate mofetil to reduce the immune response.
  • Thymectomy: Surgical removal of the thymus gland, which can lead to remission or improvement in symptoms.
  • Plasmapheresis and intravenous immunoglobulin (IVIG): Used for rapid improvement in severe cases or myasthenic crisis.


  • Myasthenic crisis: Severe respiratory muscle weakness requiring mechanical ventilation.
  • Adverse effects of long-term immunosuppressant therapy: Increased risk of infections, osteoporosis, and other side effects.
  • Thymectomy complications: Risks associated with surgical procedures.

Key Points

  • Myasthenia Gravis is a chronic autoimmune disorder affecting the neuromuscular junction.
  • Characterized by fluctuating muscle weakness and fatigue.
  • Diagnosis involves antibody testing, EMG, and imaging.
  • Management includes acetylcholinesterase inhibitors, immunosuppressants, thymectomy, and plasmapheresis or IVIG.
  • Complications can be severe and require prompt treatment.

One Comment

  1. Hannah Marshall says:

    hia – this page is glitched and is about migraines not MG

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