Repeat IVIG in Myasthenia Gravis
Yes, repeat IVIG is beneficial and recommended for patients with myasthenia gravis who have previously received IVIG treatment, particularly for acute exacerbations, treatment-related fluctuations, and as chronic maintenance therapy in refractory cases. 1, 2, 3
Acute Exacerbations and Repeat Treatment
Repeat IVIG at the standard dose of 2 g/kg divided over 5 days (0.4 g/kg/day) is effective for managing recurrent myasthenic exacerbations. 1, 4 The evidence demonstrates that:
- Clinical improvement typically begins 4.3 ± 1.2 days after starting IVIG, becomes maximal at 8.2 ± 2.0 days, and sustains for an average of 106.6 ± 49.1 days. 2
- In a study of 9 patients receiving repeated courses (ranging from 2 to 5 courses), 20 of 23 courses resulted in satisfactory improvement, with vital capacity increasing from 1845 cc to 2894 cc. 2
- A randomized controlled trial of 51 patients demonstrated significant improvement in the Quantitative MG Score at day 14, with persistent response at day 28, particularly in patients with more severe disease. 4
Chronic Maintenance Therapy
For patients with inadequate response to immunosuppressive treatments or those unable to tolerate standard therapies, regular intermittent IVIG (monthly or bimonthly) significantly reduces exacerbation frequency. 3, 5 Specifically:
- The mean attack frequency decreased from 0.096 attacks/year before regular IVIG to 0.0056 attacks/year after therapy (p = 0.002). 3
- The Mayo Clinic recommends 1-2 g/kg of ideal body weight given over 2 consecutive days (1 g/kg each day) once monthly for 1-6 months for patients with dysphagia, weight loss, or severe weakness. 1
- This approach allows steroid dose reduction by 50% in many patients and complete discontinuation in some cases. 3
Alternative Dosing for Repeat Treatment
An alternative dosing regimen of 1 g/kg on a single day has been shown to be non-inferior to the standard 2 g/kg over 2 days for exacerbations. 6 A trial of 173 patients with myasthenia gravis exacerbations showed no superiority of 2 g/kg over 1 g/kg, suggesting flexibility in dosing for repeat treatments. 6
Preoperative and Perioperative Use
Continue IVIG 2 g/kg divided over 5 days in patients undergoing surgery, such as thymectomy, to maintain medical control of myasthenia gravis. 1, 7 IVIG is preferred over plasma exchange due to easier administration, wider availability, and fewer complications. 7
Critical Safety Considerations
Always check serum IgA levels before administering IVIG to avoid severe anaphylaxis in IgA-deficient patients. 1, 8 If IgA deficiency is detected, use IVIG preparations with reduced IgA levels. 1
Monitoring During Repeat Treatment
- Perform frequent pulmonary function assessments with negative inspiratory force and vital capacity measurements. 1
- Conduct daily neurologic evaluations during acute treatment to monitor disease progression and response. 1
- Monitor for infusion reactions, particularly in IgA-deficient patients. 1
Common Pitfalls to Avoid
Do not administer plasma exchange immediately after IVIG, as it will remove the immunoglobulin and negate the therapeutic effect. 9, 8 If both treatments are needed, proper timing is essential. 9
Be aware that approximately 4 of 9 patients may experience a transient decrease in strength before improvement occurs. 2 This should not be interpreted as treatment failure but rather as part of the expected response pattern. 2
Evidence Quality and Limitations
While multiple studies support repeat IVIG use, the Cochrane review notes that evidence for chronic maintenance therapy comes primarily from case series and smaller trials rather than large randomized controlled trials. 6 However, the consistent benefit demonstrated across multiple studies (including one high-quality placebo-controlled trial for acute exacerbations) 4, combined with the excellent safety profile 5, 4, supports its use in clinical practice for both acute and chronic management. 3, 5