IVIG Dosing for Myasthenia Gravis Crisis
For myasthenia gravis crisis (Grade 3-4 severity with respiratory compromise), administer IVIG at a total dose of 2 g/kg divided over 5 consecutive days (0.4 g/kg/day × 5 days). 1, 2
Standard Dosing Protocol
- The established dose is 2 g/kg total body weight, administered as 0.4 g/kg/day for 5 consecutive days 1, 2
- This dosing regimen has been validated in multiple controlled trials and represents the consensus recommendation across major neurology guidelines 3
- The total dose calculation is based on actual body weight (e.g., for a 70 kg patient: 140 grams total = 28 grams daily for 5 days) 2
Clinical Context for IVIG Use in Crisis
IVIG is specifically indicated when patients present with:
- Grade 3-4 myasthenic crisis with severe generalized weakness requiring hospitalization 1, 2
- Respiratory compromise necessitating ICU-level monitoring 1, 2
- Acute deterioration unresponsive to conventional therapy (pyridostigmine and corticosteroids) 4
- Situations where plasmapheresis is contraindicated or not feasible 2, 5
Expected Clinical Response
- Improvement typically begins within 3-6 days of initiating IVIG 4, 6
- Peak therapeutic effect is reached within 7-14 days 4, 6
- The greatest improvement occurs in patients with more severe disease (QMG Score >10.5) 3
- All patients requiring mechanical ventilation in one series were successfully weaned within 6-11 days after starting IVIG 6
Concurrent Management During Crisis
While administering IVIG, you must:
- Continue corticosteroids concurrently (methylprednisolone 2-4 mg/kg/day or prednisone 1-1.5 mg/kg/day) 1, 2
- Maintain pyridostigmine unless intubation is required 2
- Perform frequent pulmonary function assessments (negative inspiratory force and vital capacity monitoring) 1, 2
- Conduct daily neurologic evaluations 1, 2
- Admit to ICU with capability for mechanical ventilation 1, 2
Critical Medication Avoidance
Strictly avoid medications that worsen myasthenic symptoms: β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolides 1, 2
IVIG vs. Plasmapheresis Decision-Making
IVIG is preferred over plasmapheresis in specific clinical scenarios:
- Pregnant women 2
- Patients with hypotension or autonomic instability 5
- Elderly patients (>65 years) 5
- Patients with sepsis 5
- Children 5
- Settings where specialized equipment for plasmapheresis is unavailable 5
Both therapies have comparable efficacy, but sequential therapy (plasmapheresis followed by IVIG) is no more effective than either alone and should be avoided 2
Important Caveats
- IVIG should NOT be used for chronic maintenance therapy in myasthenia gravis 2
- The exception is refractory patients who have failed or cannot tolerate immunosuppressive therapy, where periodic administration every 4-6 weeks may be considered 5, 4
- For Grade 2 (moderate) symptoms, manage with pyridostigmine and corticosteroids—IVIG is not indicated 2
- IVIG is safe with minimal serious side effects, making it advantageous for rapid intervention 5, 3