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AutoimmuneICD-10: G70.0About 14–20 per 100,000 people in the United States

Myasthenia Gravis

Also known as: MG

Myasthenia gravis is a chronic autoimmune neuromuscular disorder in which antibodies block or destroy acetylcholine receptors at the neuromuscular junction, disrupting communication between nerves and muscles. This leads to fluctuating skeletal muscle weakness that worsens with activity and improves with rest. The condition can affect muscles controlling eye movement, facial expression, swallowing, and breathing.

Symptoms

Drooping of one or both eyelids (ptosis)
Double vision (diplopia)
Difficulty speaking (dysarthria)
Difficulty swallowing (dysphagia)
Muscle weakness that worsens with use and improves with rest
Weakness in arms, legs, or neck
Shortness of breath (in severe cases, myasthenic crisis)
Facial muscle weakness affecting expressions

Causes

  • Autoimmune antibodies against acetylcholine receptors (AChR) or muscle-specific kinase (MuSK)
  • Thymus gland abnormalities (thymoma or thymic hyperplasia)
  • Genetic susceptibility factors

Risk Factors

  • Women under 40 and men over 60 (bimodal age distribution)
  • Thymus gland tumors (thymoma)
  • Family history of autoimmune disease
  • Other autoimmune conditions (thyroid disease, rheumatoid arthritis, lupus)

Diagnosis

  • Acetylcholine receptor antibody test (positive in ~85% of generalized MG)
  • Anti-MuSK antibody test if AChR antibodies are negative
  • Edrophonium (Tensilon) test or ice pack test
  • Repetitive nerve stimulation showing decremental response
  • CT or MRI of the chest to evaluate the thymus gland

Treatment

  • Acetylcholinesterase inhibitors (pyridostigmine)
  • Immunosuppressive medications (prednisone, azathioprine, mycophenolate)
  • Thymectomy (surgical removal of the thymus gland)
  • Plasmapheresis or IVIG for acute exacerbations or myasthenic crisis
  • Monoclonal antibodies (eculizumab, efgartigimod) for refractory cases

Prevention

  • No known prevention for myasthenia gravis
  • Avoiding known triggers such as stress, illness, certain medications
  • Regular follow-up with a neurologist to adjust therapy

When to See a Doctor

  • Progressive muscle weakness, especially in the eyes, face, or throat
  • Difficulty breathing or swallowing (emergency — myasthenic crisis)
  • Worsening of symptoms despite current treatment
  • New medication causing muscle weakness (certain antibiotics, beta-blockers)

Frequently Asked Questions

Related Conditions

Multiple Sclerosis

Autoimmune

Lupus

Autoimmune

Peripheral Neuropathy

Neurological

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Medical Disclaimer: This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider.

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