What is the treatment for myasthenia gravis?

Treatment of Myasthenia Gravis

The treatment of myasthenia gravis should begin with pyridostigmine as first-line therapy, followed by the addition of corticosteroids and steroid-sparing agents for patients with more than mild disease, with consideration for thymectomy in appropriate candidates. 1

Diagnostic Confirmation

Before initiating treatment, confirm diagnosis with:

• Electrodiagnostic studies (repetitive nerve stimulation and single-fiber EMG)
• Antibody testing (AChR, MuSK, LRP4)
• Chest imaging to evaluate for thymoma
• Neurological consultation

Treatment Algorithm

First-Line Treatment

• Pyridostigmine (Acetylcholinesterase Inhibitor)
  • Starting dose: 30 mg orally three times daily 1
  • Gradually increase to maximum of 120 mg four times daily as tolerated 1
  • Maximum daily dose can be up to 600 mg for severe symptoms 1
  • FDA-approved for treatment of myasthenia gravis 2
  • Provides symptomatic relief but only partial benefit in most cases 3

Second-Line Treatment (For More Than Mild Disease)

• Corticosteroids

  • Prednisone 1-1.5 mg/kg PO daily 1
  • Positive response rate: 66-85% 1
  • Initiate when pyridostigmine alone provides inadequate response

• Steroid-Sparing Agents (initiated concurrently with corticosteroids)

  • Methotrexate: 15 mg weekly 1
  • Azathioprine: 2 mg/kg of ideal body weight in divided doses 1
  • Mycophenolate mofetil: 500 mg twice daily increasing to 1000 mg twice daily 1

Crisis Management

• Hospital admission and ICU monitoring
• Treatment options:
  • IVIG: 2 g/kg over 5 days 1
  • Plasmapheresis: for 5 days 1

Surgical Management

• Thymectomy
  • Indicated for all patients with thymoma 1
  • Beneficial in AChR antibody-positive generalized MG up to age 65 1, 4
  • Remission rates of approximately 11.6% after thymectomy 1
  • Minimally invasive approaches including robotic-assisted techniques are available 4

Monitoring and Assessment

• Regular neurological assessments
• Pulmonary function tests:
  • Negative inspiratory force (NIF)
  • Vital capacity (VC)
• NIF interpretation:

  • -60 cm H₂O: Continue routine monitoring

  • -20 to -60 cm H₂O: Close monitoring and potential intervention 1

Special Considerations

Medications to Avoid

• β-blockers
• IV magnesium
• Fluoroquinolones
• Aminoglycosides
• Macrolides 1

Anesthesia Considerations

• Safe anesthetic agents:

  • Propofol, Sevoflurane, isoflurane
  • Fentanyl, remifentanil
  • Lidocaine, bupivacaine
  • Rocuronium (preferred as it can be antagonized with sugammadex) 1

• Avoid:

  • Atracurium
  • Mivacurium
  • Succinylcholine 1

Treatment Based on Disease Subtype

Ocular MG

• Pyridostigmine for symptomatic relief
• Early treatment with corticosteroids when ocular motility is abnormal and fails to respond to symptomatic treatment 4

Generalized MG

• Comprehensive approach as outlined above
• More aggressive immunosuppression may be needed

Emerging Treatments

Recent advances in understanding MG pathophysiology have led to new treatment options targeting:

• B or T cells
• Complement cascade
• Neonatal Fc receptor
• Cytokines 5

Common Pitfalls and Caveats

1. Relying solely on acetylcholinesterase inhibitors - While pyridostigmine is first-line therapy, most patients will eventually require immunosuppressive therapy 3

2. Inadequate monitoring - Regular assessment of respiratory function is essential to prevent crisis

3. Medication interactions - Many medications can exacerbate MG symptoms and should be avoided

4. Delayed immunotherapy - Early initiation of immunosuppressive therapy is important for disease control in moderate to severe cases

5. Overlooking fatigue management - Fatigue is common in MG and should be addressed with physical therapy and psychological support when needed 4