What is the treatment for acute exacerbation of myasthenia gravis?

Treatment of Acute Exacerbation of Myasthenia Gravis

For acute exacerbation of myasthenia gravis, the treatment should include immediate hospitalization with potential ICU monitoring, corticosteroids, and either IVIG (2 g/kg over 5 days) or plasmapheresis depending on severity. 1

Initial Assessment and Diagnostic Workup

When a patient presents with an acute exacerbation of myasthenia gravis, a thorough diagnostic workup is essential:

• Acetylcholine receptor (AChR) and antistriated muscle antibodies
• If AChR antibodies are negative, check muscle-specific kinase and lipoprotein-related 4 antibodies
• Pulmonary function assessment with negative inspiratory force and vital capacity
• CPK, aldolase, ESR, and CRP to evaluate for concurrent myositis
• Consider MRI of brain/spine depending on symptoms
• ECG and echocardiogram if respiratory insufficiency or elevated CPK/troponin T present
• Neurology consultation
• Electrodiagnostic studies including neuromuscular junction testing 1

Treatment Algorithm Based on Severity

Grade 2 (Mild to Moderate) Exacerbation

• Hold any immune checkpoint inhibitors if applicable
• Neurology consultation
• Pyridostigmine starting at 30 mg PO TID, gradually increasing to maximum 120 mg QID
• May proceed directly to corticosteroids (prednisone 1-1.5 mg/kg PO daily) 1

Grade 3-4 (Severe) Exacerbation

1. Hospital admission with potential ICU monitoring
2. Neurology consultation
3. Corticosteroids (prednisone 1-1.5 mg/kg PO daily or methylprednisolone IV)
4. IVIG 2 g/kg divided over 5 days OR plasmapheresis for 5 days
5. Frequent pulmonary function assessment
6. Daily neurologic evaluation 1

Medication Considerations

Corticosteroids

• While effective, be aware that some patients may experience initial worsening of symptoms after starting corticosteroids 2
• Risk factors for exacerbation include older age, generalized MG, bulbar symptoms, disease severity, thymoma presence, and recent thymectomy 2
• High-dose IV methylprednisolone (2g every five days) may produce more rapid improvement with less initial worsening compared to daily oral prednisone 3

IVIG

• Equally effective as plasma exchange in treating MG exacerbations 4
• A dose of 1 g/kg may be sufficient rather than the standard 2 g/kg 4
• Most beneficial in patients with moderate to severe disease 4

Important Precautions

• Avoid medications that can worsen myasthenia gravis:

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

• If using anticholinesterase agents (e.g., pyridostigmine), be aware that concomitant use with corticosteroids may produce severe weakness in myasthenia gravis patients 5

  • If possible, anticholinesterase agents should be withdrawn at least 24 hours before initiating corticosteroid therapy
  • If concomitant therapy is necessary, close supervision is required with anticipation of respiratory support needs 5

Long-term Management Following Exacerbation

After stabilization of the acute exacerbation, consider:

• Maintenance immunosuppression with prednisone and azathioprine
• Early "high-dose" immunosuppressive therapy (prednisone ≤1 mg/kg, azathioprine 2-3 mg/kg) has shown significant improvement in outcomes with 50% of patients achieving remission at 2 years 6
• Regular monitoring of pulmonary function
• Gradual tapering of corticosteroids based on clinical response

By following this treatment algorithm, the mortality and morbidity associated with myasthenia gravis exacerbations can be significantly reduced, with improved quality of life for patients.