When should patients with myasthenia gravis scheduled for thymectomy receive pre‑operative therapeutic plasma exchange (TPE) or intravenous immunoglobulin (IVIG), such as those with MGFA class III‑IV disease, active bulbar or respiratory weakness, recent exacerbation, or high‑dose corticosteroid therapy?

Pre-operative IVIG or TPE for Myasthenia Gravis Patients Scheduled for Thymectomy

Pre-operative IVIG or TPE is NOT routinely necessary for well-controlled myasthenia gravis patients (MGFA Class I-II with minimal manifestations) scheduled for thymectomy, but should be administered to patients with MGFA Class III-IV disease, active bulbar or respiratory weakness, recent exacerbation, or those requiring high-dose corticosteroids. 1

Patient Stratification for Pre-operative Immunotherapy

Well-Controlled Patients (No Pre-operative Treatment Needed)

Patients who do NOT require pre-operative IVIG or TPE include those with: 1

• MGFA Class I (ocular symptoms only) or Class II (mild generalized weakness) 2, 1
• Minimal manifestations on current therapy 1
• Stable symptoms without recent exacerbation 1
• Forced vital capacity >80% 1
• Quantitative MG score <10 1
• No active bulbar or respiratory symptoms 2, 1

A prospective, randomized, double-blind study (Class I evidence) demonstrated that pre-operative IVIG provided no benefit over placebo in well-controlled MG patients, with only 1 of 47 patients developing myasthenic crisis post-operatively (in the placebo group, managed with non-invasive ventilation without reintubation). 1

High-Risk Patients (Pre-operative Treatment Indicated)

Patients who SHOULD receive pre-operative IVIG or TPE include those with: 2, 3

• MGFA Class III-IV disease (moderate to severe generalized weakness) 2, 3
• Active bulbar symptoms (dysphagia, dysarthria, difficulty managing secretions) 4, 2
• Respiratory muscle weakness with:
  • Vital capacity <20 mL/kg 3
  • Negative inspiratory force <30 cmH₂O 3
  • Maximum expiratory pressure <40 cmH₂O 3
• Recent myasthenic exacerbation (within past 3 months) 2
• High-dose corticosteroid therapy (prednisone >1 mg/kg/day) initiated within past 4 weeks 2
• History of myasthenic crisis with current suboptimal control 3, 1

Choice Between IVIG and TPE

IVIG is Preferred When:

• Easier administration and fewer complications compared to TPE 2
• Pregnancy (TPE requires additional monitoring considerations) 2
• Limited access to apheresis equipment or expertise 2
• Contraindications to TPE exist: renal failure, hypercoagulable states, sepsis, hemodynamic instability 4, 3

IVIG dosing: 2 g/kg total dose over 5 days (0.4 g/kg/day for 5 consecutive days) 2, 3, 5, 6, 7

Comparative studies show IVIG results in shorter intubation periods and surgical duration compared to TPE, with better tolerability profile (fever, shivering, phlebitis vs. cutaneous eruptions and risk of hepatitis C with TPE). 6, 8

TPE is Preferred When:

• Life-threatening symptoms requiring most rapid antibody reduction 4
• Resource-limited settings where cost-effectiveness is prioritized (despite requiring specialized equipment) 2
• Concurrent myocarditis or severe myositis (more aggressive antibody removal needed) 4, 3

TPE regimen: 5 exchanges over 5 days (standard) or 7 exchanges over 14 days for severe cases 3

Critical caveat: Sequential therapy (TPE followed by IVIG) is no more effective than either treatment alone and should be avoided. 2

Timing of Surgery After Immunotherapy

Thymectomy should be performed 9-13 days after starting IVIG (mean 11.2 days) to minimize perioperative complications, as improvement begins 1-9 days after starting treatment and reaches maximum effect in 3-19 days. 7

Essential Pre-operative Assessment

All patients scheduled for thymectomy require: 3, 9

• Pulmonary function testing with NIF and VC measurements 3
• Acetylcholine receptor antibodies and anti-striated muscle antibodies 3, 9
• Cardiac evaluation (ECG, troponin) if respiratory insufficiency or elevated CPK to rule out myocarditis 3
• Medication review to discontinue drugs that worsen MG: β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, macrolides 2, 3, 9

Post-operative Monitoring

All patients require: 3

• Minimum 24 hours ICU/HDU monitoring even after apparent stabilization 3
• Frequent pulmonary function assessment with NIF and VC 2, 3
• Daily neurological evaluation 3
• Pyridostigmine may be discontinued or withheld if intubation required 2

Common Pitfalls to Avoid

• Do not routinely administer IVIG/TPE to all thymectomy patients - this exposes well-controlled patients to unnecessary risks and costs 1
• Do not delay surgery beyond 2 weeks after IVIG - efficacy wanes and perioperative complications increase 7
• Do not use sequential IVIG and TPE - no additional benefit and increased complications 2
• Do not overlook medication review - approximately 30-50% of thymoma patients have MG, and failure to measure anti-AChR antibodies preoperatively can lead to respiratory failure during anesthesia 9