In the treatment of a myasthenia crisis, do you prefer Intravenous Immunoglobulin (IVIG) or plasmapheresis?

Treatment of Myasthenic Crisis: Plasmapheresis vs IVIG

For life-threatening myasthenic crisis with respiratory and bulbar involvement, plasmapheresis is the preferred treatment option, as it provides faster clinical response and shorter ICU stays compared to IVIG. 1, 2

Primary Recommendation

Plasmapheresis should be your first-line choice in true myasthenic crisis because:

• The European Society for Medical Oncology guidelines specifically identify plasma exchange as the favorable option for life-threatening symptoms with respiratory and bulbar involvement 1
• Real-world prospective data demonstrates plasmapheresis significantly reduces ICU stay length (p = 0.018) and produces earlier clinical response at one-week off-ventilation compared to IVIG 2
• Plasmapheresis shows superior early improvement in quantitative myasthenia gravis scores (p = 0.003), manual muscle testing (p = 0.020), and activities of daily living (p = 0.011) at one week 2

When IVIG is Appropriate

IVIG serves as the primary alternative when plasmapheresis is contraindicated or unavailable 1. Use IVIG instead of plasmapheresis if the patient has:

• Renal failure 1
• Hypercoagulable states 1
• Hemodynamic instability 1
• Poor vascular access making plasmapheresis technically difficult 3

Treatment Protocols

Plasmapheresis Protocol

• Administer 4-5 sessions over 5 days (one calculated plasma volume per session, typically 200-250 mL/kg) 1, 4
• Combine with methylprednisolone 1-2 mg/kg daily 1
• Combine with pyridostigmine 30-600 mg daily orally 1
• Monitor for hypocalcemia from citrate anticoagulation 1

IVIG Protocol

• Administer 0.4 g/kg/day for 5 consecutive days (total dose 2 g/kg) 4, 3
• Combine with standard immunosuppression 3

Critical Timing Consideration

Never administer plasmapheresis immediately after IVIG - this will remove the immunoglobulin just administered, making the sequence completely counterproductive 1, 5. If switching therapies, allow adequate time between treatments.

Evidence Reconciliation

While one 2015 randomized controlled trial showed no statistical difference between IVIG and plasmapheresis at 14 days (both groups improved by 4.0 points on Quantitative Myasthenia Gravis Score) 3, and a 2025 study suggested both rescue treatments and no rescue treatment had similar outcomes at 1 month 6, these findings must be interpreted carefully:

• The 2015 study included both crisis and exacerbations, diluting the crisis-specific effect 3
• The 2025 study's finding that no rescue treatment worked equally well is likely explained by the fact that 93% of all patients improved regardless of treatment, suggesting many cases were less severe 6
• The most recent prospective cohort (2022) specifically in AChR-positive myasthenic crisis demonstrates clear superiority of plasmapheresis for rapid response 2

Prognostic Factors

Better response to plasmapheresis correlates with:

• Higher baseline myasthenia gravis severity scores 1
• Higher immunoglobulin G removal rates 1

Common Pitfalls to Avoid

• Do not delay treatment while debating which therapy to use - both are effective, but plasmapheresis acts faster in true crisis 2
• Do not use plasmapheresis in patients with contraindications listed above 1
• Historical case reports showing plasmapheresis rescue after IVIG failure 7 support plasmapheresis as the more robust option when rapid response is critical
• IVIG may be preferred in less severe exacerbations due to ease of administration and cost 3, but this is not the scenario in true myasthenic crisis