Management of Myasthenia Crisis

Immediate Crisis Management with IVIG

The American College of Physicians recommends initiating IVIG immediately when patients present with myasthenic crisis defined as respiratory failure requiring mechanical ventilation or impending respiratory failure with severe bulbar dysfunction 1
Start treatment upon ICU admission for Grade 3-4 symptoms: severe generalized weakness limiting self-care activities, respiratory insufficiency, or dysphagia 1
IVIG dosing: 2 g/kg total dose administered as 0.4 g/kg/day for 5 consecutive days 1
Choose IVIG over plasmapheresis in pregnant women, patients with difficult vascular access, or when plasma exchange is contraindicated 1
Avoid sequential therapy (plasmapheresis followed by IVIG) as it provides no additional benefit over either treatment alone 1
Do NOT delay IVIG waiting for diagnostic confirmation in patients with life-threatening respiratory compromise—start treatment immediately while continuing diagnostic workup in parallel 1
Continue pyridostigmine and corticosteroids concurrently during IVIG administration 1
Perform frequent pulmonary function monitoring with negative inspiratory force and vital capacity measurements 1

Consider rituximab for patients with inadequate response to corticosteroids, azathioprine, mycophenolate, or other immunosuppressants after at least 2-4 weeks of treatment 2, 3
Standard dosing: 1000 mg IV repeated on day 15, or 375 mg/m² once weekly for 4 weeks 3
Peak efficacy occurs after several months with onset of effect beginning sooner, making it inappropriate for acute crisis requiring immediate intervention 4
In refractory myositis (similar autoimmune mechanism), rituximab is added only if symptoms worsen or show no improvement after 2 weeks of high-dose corticosteroids and IVIG 2

Check serum IgA levels before first IVIG infusion—IgA deficiency can cause severe anaphylaxis; use IgA-reduced preparations if deficient 3, 5
Never perform plasmapheresis immediately after IVIG—it will remove the immunoglobulin, negating therapeutic benefit 2, 5
Do not use IVIG for chronic maintenance therapy in myasthenia gravis—it is only indicated for acute exacerbations 1
Do not use rituximab as first-line treatment in myasthenic crisis—its delayed onset of action (months) makes it unsuitable for acute management 4
Avoid rituximab in acute crisis when infection risk is elevated, as immunosuppressive effects last 6 months 4
Do not delay IVIG/plasmapheresis while waiting to start rituximab in crisis situations 1

Assess respiratory status: negative inspiratory force, vital capacity, oxygen saturation 1
Grade severity: Grade 3-4 requires immediate ICU admission and IVIG/plasmapheresis 1
Start IVIG 0.4 g/kg/day × 5 days OR plasmapheresis (choose plasmapheresis if faster response needed for severe respiratory compromise) 1
Continue corticosteroids (prednisone 1-1.5 mg/kg/day) 1
Maintain pyridostigmine unless intubated 1
If inadequate response after completing IVIG/plasmapheresis and 2-4 weeks of corticosteroids, consider adding steroid-sparing agents (mycophenolate, azathioprine) 1
Only consider rituximab if patient remains refractory to standard immunosuppression after appropriate trial duration 2
Regular neurology follow-up to adjust immunosuppression and prevent future crises 1