A Survey on Pediatric Anti-N-Methyl-D-Aspartate-Receptor Encephalitis Treatment Strategies in China
Pediatric anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe autoimmune disorder characterized by neuropsychiatric symptoms, seizures, and movement abnormalities. Despite its increasing recognition, standardized treatment protocols remain elusive. This article synthesizes findings from a comprehensive survey conducted in China to evaluate current therapeutic approaches, comparing them with prior international studies to identify consensus areas and unresolved challenges.
Background and Motivation
The absence of standardized treatment guidelines for pediatric anti-NMDAR encephalitis has led to significant variability in clinical practice. Previous international surveys, such as those by Kahn et al. (2017) and Bartolini et al. (2017), highlighted differences in immunotherapy initiation, agent selection, and treatment duration across specialties and regions. However, these studies lacked emphasis on critical aspects like the utility of the modified Rankin Scale (mRS), corticosteroid tapering strategies, CD19+ B cell monitoring for rituximab dosing, and long-term immunosuppressive therapy for relapse prevention. To address these gaps and advance toward protocol standardization, a nationwide survey was conducted among Chinese pediatric neurologists, capturing data from 200 senior clinicians across 125 hospitals.
Methodology and Respondent Profile
The survey comprised 30 questions exploring multiple dimensions of treatment strategies, including:
- First-line immunotherapy selection, dosages, and duration
- Use of mRS scores in clinical decision-making
- Transition timing to second-line therapies
- Rituximab administration practices
- Long-term immunosuppression for relapse prevention
- Indications for discontinuing immunotherapy
Most respondents were chief pediatric neurologists managing 1–9 cases annually. This expertise ensured high-quality insights into real-world practices.
First-Line Immunotherapy Practices
Agent Selection and Duration
Combination therapy with methylprednisolone pulse therapy and intravenous immunoglobulin (IVIG) dominated first-line treatment, preferred by 75% of respondents. Plasma exchange was less frequently utilized (15%), contrasting with Bartolini et al.’s findings where adult neurologists favored this approach. The reluctance in pediatric settings likely stems from its invasiveness and technical challenges in younger patients.
- Methylprednisolone Pulse Therapy: Administered for >3 to ≤5 days in most cases. Post-pulse therapy, one-third of clinicians prescribed high-dose oral prednisone, though tapering schedules varied widely.
- IVIG: Typically delivered at 2 g/kg over 2–5 days, aligning with international practices.
Role of mRS Scores
Only 20% of clinicians used mRS scores to initiate methylprednisolone pulse therapy, prioritizing clinical severity instead. This contrasts with Kahn et al.’s observation that immunotherapy initiation relied on symptoms rather than serological markers.
Total First-Line Treatment Duration
Oral prednisone tapering extended the total first-line duration to >3 to ≤6 months for 60% of respondents. Kahn et al. reported a 6-month median duration, suggesting broad consensus on prolonged regimens despite limited evidence linking duration to outcomes.
Second-Line Immunotherapy Strategies
Indications and Timing
Second-line agents were initiated after first-line failure (80% of cases), with rituximab as the primary choice (78%). Cyclophosphamide was secondary (18%), while combinations (e.g., rituximab + cyclophosphamide) were rare (4%).
- Transition Timing: 50% of clinicians waited >14 to ≤28 days before escalating therapy, diverging from Bartolini et al.’s global cohort, where 65% initiated second-line agents within ≤2 weeks.
- mRS Thresholds: An mRS score ≥3 triggered second-line therapy for 70% of respondents, emphasizing functional impairment as a key criterion.
Rituximab Administration
Rituximab was prescribed at 375 mg/m² weekly for 4 weeks (85% of cases). Notably, <10% adjusted doses based on CD19+ B cell counts, despite evidence linking B cell depletion to reduced relapse risk. Bartolini et al. found similar underutilization of CD19+ monitoring globally, highlighting a critical gap in personalized dosing.
Long-Term Immunosuppressive Therapy
Only 40% of clinicians endorsed long-term immunosuppression for relapse prevention, primarily prescribing mycophenolate mofetil (55%) or azathioprine (30%) for >6 to ≤12 months. This contrasts with adult neurologists in Bartolini et al.’s survey, who more frequently used long-term agents. Retrospective studies, however, suggest prolonged therapy improves recovery and reduces relapses, underscoring a need for evidence-based guidelines.
Treatment Discontinuation Criteria
Decisions to stop immunotherapy relied on:
- Clinical improvement (65%)
- Normalization of CSF/serum anti-NMDAR antibodies (20%)
- Brain MRI/EEG normalization (10%)
- mRS score ≤2 (5%)
The reliance on clinical judgment over biomarkers reflects limited access to antibody testing in some regions and underscores the need for standardized biomarkers of remission.
Regional and Global Comparisons
Plasma Exchange Utilization
Chinese pediatric neurologists used plasma exchange less frequently (15%) than adult neurologists globally (35% in Bartolini et al.), likely due to procedural risks in children.
First-Line Rechallenge
In cases of first-line failure, 45% of Chinese clinicians repeated methylprednisolone/IVIG before escalating, mirroring Kahn et al.’s U.S.-centric findings. Bartolini et al., however, noted global variability, with European clinicians favoring earlier escalation.
Second-Line Agent Preferences
Rituximab’s dominance in China (78%) aligns with its global ascendancy over cyclophosphamide, driven by superior safety and retrospective efficacy data. However, Bartolini et al. reported higher combination therapy use (e.g., rituximab + cyclophosphamide) outside China, suggesting regional preference differences.
Unresolved Challenges and Future Directions
- Optimal First-Line Duration: Prolonged regimens (3–6 months) lack robust evidence, necessitating trials correlating duration with relapse rates.
- CD19+ B Cell Monitoring: Underutilization persists despite its potential to optimize rituximab dosing and reduce adverse effects.
- Long-Term Immunosuppression: Clarifying its role requires prospective studies evaluating mycophenolate/azathioprine efficacy.
- Biomarker-Driven Discontinuation: Standardized antibody testing and MRI/EEG criteria are needed to reduce subjective decision-making.
Study Limitations
The survey’s exclusive focus on China limits generalizability, and respondent bias may skew results toward tertiary-center practices. Ambiguities in survey questions (e.g., “clinical improvement”) and exclusion of alternative second-line agents (e.g., tacrolimus) further constrain data interpretation.
Conclusion
This survey illuminates China’s therapeutic landscape for pediatric anti-NMDAR encephalitis, revealing consensus areas with global practices (e.g., methylprednisolone/IVIG first-line, rituximab second-line) and unresolved issues (e.g., CD19+ monitoring, long-term immunosuppression). Multinational collaborations and randomized trials are imperative to transform these insights into standardized, evidence-based protocols.
doi.org/10.1097/CM9.0000000000001308
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