What is the recommended treatment for an acute myasthenia gravis flare?

Treatment of Myasthenia Gravis Flare

For an acute myasthenia gravis flare (Grade 3-4), immediately hospitalize the patient with ICU-level monitoring, administer IVIG 2 g/kg over 5 days (0.4 g/kg/day × 5 days) or plasmapheresis, continue high-dose corticosteroids (prednisone 1-1.5 mg/kg daily), maintain pyridostigmine, and perform frequent pulmonary function assessments with negative inspiratory force and vital capacity monitoring. 1, 2

Severity Classification and Treatment Algorithm

The Myasthenia Gravis Foundation of America (MGFA) classification system guides treatment decisions based on severity 3:

Grade 3-4 Exacerbations (Severe Flare)

Immediate Actions:

• Admit to ICU for close respiratory monitoring, as these patients are at high risk for respiratory failure 1, 3
• Permanently discontinue any immune checkpoint inhibitors if applicable 3
• Obtain urgent neurology consultation 1

Acute Immunotherapy (choose one):

• IVIG 2 g/kg total dose administered as 0.4 g/kg/day for 5 consecutive days 1, 2, 3
• Plasmapheresis as an alternative to IVIG, with comparable efficacy 1, 3, 4

Both IVIG and plasmapheresis are equally effective for acute exacerbations 3, 4. IVIG may be preferred in pregnant women and has easier administration with fewer complications, though both carry comparable overall risks 3. Sequential therapy (plasmapheresis followed by IVIG) is no more effective than either alone and should be avoided 3.

Concurrent Therapy:

• Continue or initiate high-dose corticosteroids (prednisone 1-1.5 mg/kg orally daily) during IVIG or plasmapheresis 1, 3
• Maintain pyridostigmine unless intubation is required, in which case it may be withheld 3, 5

Critical Monitoring:

• Pulmonary function testing with negative inspiratory force (NIF) and vital capacity (VC) performed frequently, as dysphagia and bulbar weakness are present in more than 50% of cases preceding myasthenic crisis 1, 2, 3
• Daily neurologic assessments to track response 1
• Prepare for intubation if respiratory arrest occurs or patient cannot protect airway 3

Grade 2 Exacerbations (Moderate Flare)

Treatment Approach:

• Optimize pyridostigmine to maximum dose of 120 mg orally four times daily if tolerated 1, 2, 3, 5
• Add or escalate corticosteroids (prednisone 1-1.5 mg/kg orally daily) if pyridostigmine provides insufficient control 1, 3
• Avoid IVIG for Grade 2 symptoms—reserve for Grade 3-4 only 3
• Monitor closely for progression to Grade 3-4, which would require escalation to IVIG or plasmapheresis 1, 3

Critical Medications to Avoid During Flares

Strictly avoid medications that worsen myasthenic symptoms 1, 2, 3:

• β-blockers
• Intravenous magnesium
• Fluoroquinolone antibiotics
• Aminoglycoside antibiotics
• Macrolide antibiotics
• Metoclopramide

These medications interfere with neuromuscular transmission and can precipitate or worsen myasthenic crisis, potentially requiring ICU admission and mechanical ventilation 3.

Important Contraindication

The American Academy of Neurology explicitly recommends against using IVIG for chronic maintenance therapy in myasthenia gravis 1, 3. IVIG is reserved exclusively for acute exacerbations (Grade 3-4) or myasthenic crisis requiring hospitalization 1. Long-term maintenance with IVIG (such as 2 g/kg IV every 3 weeks) is not aligned with current guidelines and should not be used 3.

Post-Crisis Management

Once symptoms are adequately controlled:

• Gradually taper corticosteroids based on symptom improvement 1, 2
• Initiate aggressive physical and occupational therapy as soon as symptoms are controlled, as systematic physical training is safe and improves muscle strength, daily function, and quality of life 3
• Regular neurology follow-up to adjust immunosuppression 1, 3
• Patient education about symptom monitoring, medication timing, and strict avoidance of contraindicated medications 3

Common Pitfalls to Avoid

• Do not use IVIG for mild (Grade 1-2) symptoms—manage with pyridostigmine and corticosteroids only 1, 3
• Do not delay hospitalization for Grade 3-4 symptoms, as respiratory failure can develop rapidly 1, 6
• Do not use sequential IVIG and plasmapheresis—choose one, as combination is no more effective 3
• Do not withhold corticosteroids during acute treatment with IVIG or plasmapheresis—continue them concurrently 1, 3