What are the indications for Intravenous Immunoglobulin (IVIG) in patients with myasthenia gravis?

Indications for Intravenous Immunoglobulin in Myasthenia Gravis

IVIG is indicated for severe/grade 3-4 myasthenia gravis, myasthenic crisis requiring hospitalization, worsening disease with dysphagia or notable weight loss, and as maintenance therapy when other immunosuppressive treatments have failed. 1, 2

Acute/Severe Disease Indications

Grade 3-4 Myasthenia Gravis (Severe Disease)

• IVIG 2 g/kg divided over 5 days (0.4 g/kg/day) is indicated for grade 3-4 toxicities requiring hospital admission with potential ICU monitoring. 1, 2
• This severity includes patients with respiratory compromise, as progressive myasthenia gravis can lead to respiratory failure requiring mechanical ventilation. 1
• IVIG should be administered concurrently with corticosteroids in this setting. 1

Myasthenic Crisis

• IVIG is recommended during myasthenic crisis, particularly when plasmapheresis is contraindicated or not feasible. 3
• IVIG is safer than plasma exchange in patients with hypotension, autonomic instability, sepsis, elderly patients (>65 years), and children. 3
• Recent evidence shows that patients with myasthenic crisis improve with IVIG, though the benefit over standard care alone remains debated. 4

Rapidly Progressive Weakness

• IVIG has a role as acute treatment in rapidly progressive myasthenia gravis weakness, with rapid onset of effect typically within 12-15 days. 5, 3
• The main advantage is the rapid onset of effect and lack of long-term toxicity. 3

Specific Clinical Scenarios

Patients with Dysphagia, Weight Loss, or Severe Weakness

• IVIG at 1-2 g/kg of ideal body weight, given over 2 consecutive days (1 g/kg each day) once monthly for 1-6 months is indicated. 1, 2
• Check serum IgA levels before administration, as IgA deficiency may lead to severe anaphylaxis. 1, 2
• If IgA deficiency is detected, use IVIG preparations with reduced IgA levels. 1

Preoperative Management (Thymectomy)

• IVIG 2 g/kg divided over 5 days should be continued in patients undergoing surgery. 2
• Medical control of myasthenia gravis must be achieved before any surgical procedure. 2
• IVIG may be preferred over plasma exchange due to easier administration, wider availability, and fewer complications. 2

Maintenance Therapy Indications

Chronic Refractory Disease

• IVIG is indicated as chronic maintenance therapy when other immunosuppressive treatments have failed or cannot be used. 3
• Periodic administration on a bimonthly or monthly basis may stabilize chronic, nonresponding patients. 3
• In maintenance treatment, there is an enduring decline in quantitative myasthenia gravis (QMG) score of approximately 50% with sustained benefit over 6 months. 6, 5
• The delayed beneficial effect results in significant reduction of required doses of additional immunosuppressive agents. 5

Steroid-Sparing Strategy

• IVIG allows reduction of corticosteroid and other immunosuppressive drug doses while maintaining disease control. 5, 4
• Patients treated with IVIG require lower doses of acetylcholine esterase inhibitors at 1 month compared to those without rescue treatment. 4

Important Caveats

Timing Considerations

• The absence of immediate therapeutic effect does not justify IVIG use in acute deterioration requiring immediate intervention. 5
• Most patients show delayed improvement (92%) that becomes effective after 12-15 days, rather than immediate response (37.5%). 5

Dosing Protocols

• Standard acute dosing: 2 g/kg divided over 5 days (0.4 g/kg/day). 1, 2
• Alternative dosing: 1-2 g/kg over 2 consecutive days for maintenance. 1
• For doses >80 g, consider administering over 3-5 days at 0.4 g/kg/day. 1

Monitoring Requirements

• Frequent pulmonary function assessment with negative inspiratory force and vital capacity. 1, 2
• Daily neurologic evaluation during acute treatment. 1
• Monitor for infusion reactions, particularly in IgA-deficient patients. 1, 2