IVIG Dosing in Autoimmune Encephalitis
The recommended dose of IVIG in autoimmune encephalitis is 2 g/kg divided over 5 days (0.4 g/kg/day for 5 consecutive days), particularly for severe or progressive cases. 1
Severity-Based Treatment Algorithm
Mild to Moderate Autoimmune Encephalitis
- Initial treatment should be methylprednisolone 1-2 mg/kg/day IV without immediate IVIG 1, 2
- IVIG is reserved for cases that fail to improve or progress despite corticosteroids 1
Severe or Progressive Autoimmune Encephalitis
- IVIG 2 g/kg total dose divided over 5 days (0.4 g/kg/day) should be administered concurrently with pulse-dose methylprednisolone (1 g IV daily for 3-5 days) 1
- This combination is specifically indicated when:
Maintenance Therapy Considerations
- For immune-mediated neurological conditions requiring ongoing treatment, maintenance IVIG is typically administered at ≥1 g/kg every 4 weeks 3
- This maintenance dosing applies to patients with persistent or relapsing autoimmune encephalitis who have responded to initial therapy 3
Critical Implementation Details
Timing and Administration
- IVIG should be initiated early in severe cases, not delayed while awaiting antibody confirmation 1
- The 2 g/kg total dose is divided equally: 0.4 g/kg/day for 5 consecutive days 1, 4
- A prospective trial demonstrated significant neurological improvement by day 8 with this dosing regimen 4
Alternative Dosing in Specific Contexts
- Some protocols describe "2 doses at 1 g/kg/dose" for pediatric encephalitis, which equals the same 2 g/kg total 5
- This represents the same cumulative dose administered over fewer days 5
Essential Caveats and Pitfalls
Infectious Exclusion
- Always initiate empiric IV acyclovir until HSV PCR results are negative before or concurrent with IVIG 1, 2
- Rule out bacterial meningitis, metabolic derangements, and CNS malignancy progression 1
Safety Monitoring
- Patients with autonomic dysfunction are at higher risk for aseptic meningitis and severe headaches with IVIG 3
- Monitor for thromboembolic complications, particularly in patients with risk factors 6
- Anaphylactic reactions can occur in IgA-deficient patients with anti-IgA antibodies 7
Escalation Strategy
- If no improvement after IVIG plus pulse corticosteroids, consider plasmapheresis or rituximab in consultation with neurology 1, 2
- Corticosteroid taper should occur over at least 4-6 weeks following acute management 1
Evidence Quality Note
The 2 g/kg over 5 days dosing is consistently recommended across multiple ASCO guidelines from 2018 and 2021 1, with prospective evidence from a 2022 trial demonstrating efficacy and tolerability at 0.4 g/kg/day for 5 days 4. While most evidence comes from immune checkpoint inhibitor-related encephalitis, the dosing principles apply broadly to autoimmune encephalitis of all etiologies 1.