International Consensus Recommendations for the Treatment of Pediatric NMDAR Antibody Encephalitis

Diagnosis and Management of Children With Atypical Neuroinflammation

Pediatric neuroimmune disorders comprise a heterogeneous group of immune-mediated CNS inflammatory conditions. Some, such as multiple sclerosis, are well defined by validated diagnostic criteria. Others, such as anti-NMDA receptor encephalitis, can be diagnosed with detection of specific autoantibodies. This review addresses neuroimmune disorders that neither feature a diagnosis-defining autoantibody nor meet criteria for a distinct clinicopathologic entity. A broad differential in these cases should include CNS infection, noninflammatory genetic disorders, toxic exposures, metabolic disturbances, and primary psychiatric disorders. Neuroimmune considerations addressed in this review include seronegative autoimmune encephalitis, seronegative demyelinating disorders such as neuromyelitis optica spectrum disorder, and genetic disorders of immune dysregulation or secondary neuroinflammation. In such cases, we recommend a broad diagnostic workup to support the presence of neuroinflammation, exclude non-neuroimmune disorders, detect autoantibodies and other biomarkers of known diseases, identify any potential genetic drivers of neuroinflammation, and provide case-specific insights into pathophysiologic mechanisms of inappropriate immune pathway activation or dysregulation. This review includes an extensive list of useful diagnostic tests and potential implications thereof, as well as a proposed algorithm for the diagnosis and management of the pediatric patient with atypical neuroimmune disorders. In general, first-line acute treatment of neuroimmune disorders begins with steroids, along with consideration of plasmapheresis or IV immunoglobulin. Selection of second-line or maintenance therapy is challenging without a definite, specific diagnosis and the associated benefit of established evidence-based treatment options. Immunotherapies may be considered based on the suspected mechanism of neuroinflammation and the likelihood of relapse. For example, rituximab may be considered for possible antibody-mediated or B-cell-mediated inflammation while anti-interleukin (IL)-6 agents, anti-IL-1 agents, or JAK inhibitors may be considered for certain cases of cytokine-mediated inflammation or innate immune system dysregulation. Care should be taken to monitor response and disease activity, revisit the differential diagnosis in the case of unexpected findings or poor treatment response, and weigh the risks of immunotherapy with the benefits of empiric treatment. Over time, further advancements in biomarker identification and omics research may define specific new clinicopathologic diagnoses and thus obviate the need for "n of 1" approaches to what are currently heterogeneous groups of atypical seronegative neuroimmune disorders.

The Clinical Trial Landscape in Autoimmune Encephalitis: Challenges and Opportunities

Autoimmune encephalitis (AE) is an important cause of neurologic morbidity and mortality. Treatment algorithms are primarily based on observational studies, retrospective series, and expert opinion. Despite clinical improvement with empiric therapy, recovery is often incomplete with a substantial burden of residual neurologic deficits and recurring symptoms. There is a pressing need for higher quality evidence-based therapies. However, designing and conducting clinical trials for patients with rare diseases such as AE has specific challenges, including slow recruitment, suboptimal outcome measures, and inclusivity vs exclusivity of the various disease subtypes. The anticipated knowledge gained from AE clinical trials emphasizes the need to overcome these challenges and support the development of the next generation of clinical trials. Yet, given these challenges, alternative approaches may be required. In this article, we review past and present clinical trials in AE with a focus on studies enrolling patients with neural surface antibodies. We discuss the potential challenges and opportunities inherent to clinical trials in rare diseases and provide an outlook for the field.

A boy with autism spectrum disorder with antibodies to the NMDA-type glutamate receptor: nine-year follow-up, changes in cognitive function

Herein, we report a 12-year-old boy with autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) who showed a cognitive decline at age 7 and tested positive for cerebrospinal fluid (CSF) N-methyl-D-aspartate (NMDA)-type glutamate receptor (GluR) antibodies using an enzyme-linked immunosorbent assay (ELISA). His cognitive function developed between ages 3 and 5, reaching a total domain developmental quotient (DQ) of 61 on the revised Kyoto Scale of Psychological Development 2001. Despite multiple treatments, his total domain DQ declined to 21 at 10 years and 3 months of age and further to 16 at 12 years and 0 month. The child regressed in cognitive function, losing previously acquired knowledge and skills, resulting in an unbalanced profile. Previously recorded strengths, weaknesses, and preferences were no longer evident. The anti-NMDA-type GluR antibodies might hinder the regaining of cognitive functions once lost and the reconstruction of developmental characteristics in patients with ASD/ADHD. Patients with ASD and ADHD who test positive for NMDA-type GluR antibodies (ELISA) may not follow a typical clinical course.

A Case Series of Anti-Metabotropic Glutamate Receptor 2 Antibody-Related Diseases with Distinct Neurological Involvement

Background

Anti-metabotropic glutamate receptor 2 (mGluR2)-related diseases are rare autoimmune disorders of the central nervous system that primarily affect the cerebellum and are occasionally associated with malignancies.

Methods

Data, including demographics, symptoms, blood and cerebrospinal fluid (CSF) tests, and brain magnetic resonance imaging (MRI), were retrospectively collected from two patients with informed consent at Xiangya Hospital from February 2024 to October 2024. Autoantibodies associated with autoimmune encephalitis were tested using cell-based assays. The literature describing anti-mGluR2 antibody-related diseases was searched for in PubMed and five cases were reviewed.

Results

Two cases of anti-mGluR2 antibody-related diseases were reported: one with acute cerebellitis and the other with refractory seizures. Brain MRI showed cerebellar involvement in the cerebellitis patient. Anti-mGluR2 antibodies were detected in the serum but not in the CSF of both cases, and both responded well to immunotherapy. A review of five patients (all female, aged 3-78 years) found four with cerebellar ataxia or cerebellitis and one with immune-related epilepsy. Common symptoms included dysarthria, gait instability, and gaze/nystagmus, while seizures were rare. MRI revealed cerebellar involvement in most cases. Anti-mGluR2 antibodies were present in the serum of all patients but only in the CSF of two. Three patients responded well to immunosuppressive treatment, and two had malignancies.

Conclusion

Anti-mGluR2 antibody-related diseases are autoimmune disorders primarily characterized by ataxic manifestations, though seizures may also occur. The effectiveness of immunosuppressive treatment is uncertain and screening for tumors is necessary.

Recurrent anti-NMDA receptor encephalitis in first-trimester pregnancy with initially antibody-negative CSF

Anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis is a paraneoplastic autoimmune encephalomyelitis that predominantly affects females in their reproductive years Dalmau et al., 2007 and Dalmau et al., 2019. It has been infrequently reported during pregnancy Dono et al., 2023 and Joubert et al., 2020. We describe a case of a 25-year-old G4P2 patient at 11 weeks gestation with a history of anti-NMDAR encephalitis who presented with intermittent confusion for two weeks. Initial antibody tests for anti-NMDAR encephalitis in the cerebrospinal fluid (CSF) were negative. Repeat serum labs drawn upon readmission to the emergency department (ED) 3 weeks later were positive, and results were confirmed with repeat CSF testing. Following treatment, the patient returned to baseline and delivered a developmentally healthy, full-term baby. Current gold-standard testing for anti-NMDAR encephalitis is through detection of NMDAR antibodies in the CSF Gresa-Arribas et al., 2014. However, CSF antibody testing early in the disease course may not be as sensitive as traditionally thought, and repeat testing is indicated if high suspicion continues.

Current and emerging therapies for autoimmune encephalitis

INTRODUCTION

Autoimmune encephalitis (AIE) is an inflammatory neurological disorder often associated with autoantibodies targeting neural or glial antigens. Patients with AIE are often treated with immunotherapy, but multiple questions remain about the optimal treatment strategy for common AIE subtypes.

AREAS COVERED

The authors conducted a literature search of PubMed articles and Google Scholar articles using keywords 'autoimmune encephalitis,' 'anti-NMDA receptor encephalitis, 'LG1 encephalitis' from 2005 to 2024. This review briefly outlines the proposed pathophysiology of AIE with autoantibodies toward cell surface vs intracellular antigens. Next, the authors discuss treatments commonly used for AIE, and provide guidance on side effects and monitoring, and the evidence for treatment approaches for anti-NMDAr and LGI1 encephalitis is reviewed. In the final section, an overview of ongoing clinical trials and future therapies for AIE is provided.

EXPERT OPINION

Patients with AIE benefit from treatment with immunotherapy, but the evidence supporting specific treatment strategies is limited to observational studies. Successful clinical trials for AIE will provide new therapy options for patients, and the next generation of therapies may provide more targeted approaches to treating the condition.

Clinical characteristics of children with anti-N-methyl-D-aspartate receptor encephalitis with and without anti-myelin oligodendrocyte glycoprotein antibody

To analyze the clinical characteristics of an overlapping syndrome, MNOS, of anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) coexisting with anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) in children. We included patients with NMDARE at Children's Hospital of Chongqing Medical University between 2018 and 2022 and conducted a comparison between NMDARE with and without MOG-Ab. Among 163 patients with NMDARE, 15 individuals tested positive for MOG-Ab. The median age of MNOS was 11 years (IQR 8-13). Furthermore, 10 out of 15 were female. More than half of MNOS experienced a prior history of encephalitis or demyelinating disorders. Among ten patients with low MOG-Ab titers, two met the diagnostic criteria for MOGAD. All five patients with high MOG-Ab titers satisfied the criteria for MOGAD. A total of seven patients diagnosed with MOGAD presented with acute disseminated encephalomyelitis. The proportion of prodromal symptoms and brain lesions, the neutrophil counts, and the frequency of mycophenolate mofetil administration were significantly higher in MNOS compared to NMDARE patients without MOG-Ab (p < 0.05). The outcomes of MNOS were favorable and comparable to those observed in NMDARE. Nevertheless, MNOS demonstrated a higher tendency to relapse, with rates of 60.0% compared to 3.1% (p < 0.001).

CONCLUSION

Pediatric MNOS exhibited a high prevalence among females, particularly those with a prior history of MOGAD or encephalitis. MNOS had a favorable prognosis but with a high relapse rate. Coexisting MOG-Ab in pediatric MNOS may be pathogenic or a bystander, potentially correlating with antibody titers.

WHAT IS KNOWN

• Pediatric anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) coexisting with anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) generally has a favorable prognosis, albeit with a tendency to relapse. • Pediatric NMDARE coexisting with MOG-Ab may exhibit imaging features indicative of demyelination.

WHAT IS NEW

• Pediatric patients of MOG-Ab coexisting with NMDARE overlapping syndrome (MNOS) were predominantly observed in females, particularly those with a history of MOG-Ab-associated disorder (MOGAD) or encephalitis. • Compared with NMDARE patients, pediatric MNOS patients had higher neutrophil counts and more frequently exhibited abnormal MRI findings in the basal ganglia, insular lobe, temporal lobe, thalamus, and cerebellum.

Case Report: Efficacy of ofatumumab in refractory anti-NMDAR encephalitis: case series and literature review

Anti-NMDAR encephalitis is the most common autoimmune encephalitis. When first-line treatments fail, second-line therapies are employed. However, a standardized approach for second-line treatment has yet to be established. We presented three cases of anti-NMDAR encephalitis with seizures and psychosis as the primary symptom. These patients showed inadequate response to initial treatments, including intravenous immunoglobulin, methylprednisolone, and plasma exchange. However, their symptoms were effectively controlled following subcutaneous administration of ofatumumab. Previous studies have reported that twelve cases of anti-NMDAR encephalitis were effectively treated with ofatumumab. In this study, the modified Rankin scale (mRS) scores at the last follow-up for all fifteen patients (including our three cases) were significantly lower compared to scores at the peak of the disease (p < 0.001). Thirteen patients achieved full recovery. These findings suggest that CD20 monoclonal antibodies, particularly ofatumumab, may offer a promising treatment option for anti-NMDAR encephalitis.

Seizures Associated with Autoimmune Disorders - Current Treatment Approaches

Autoimmune-associated seizures and epilepsy are increasingly recognized in clinical practice and can arise in the setting of acute encephalitis but in some cases may present with chronic focal epilepsy. These conditions are usually resistant to antiseizure therapy but may respond definitively to timely immunotherapy. Early diagnosis and treatment are critical to minimize neural injury and optimize outcomes.Treatment is guided by consensus opinion because definitive trials are currently lacking. The initial management approach usually involves first-line agents such as corticosteroids, intravenous immunoglobulin (IVIg), or plasma exchange, with second-line agents like rituximab or cyclophosphamide. Maintenance therapy is considered to prevent relapses, which occur in up to 35% of patients. Relapse management requires careful differentiation from postencephalitic epilepsy, which in the absence of active inflammation does not respond to immunotherapy.This review discusses treatment strategies for autoimmune-associated seizure disorders, including acute symptomatic seizures and epilepsy. We discuss expected outcomes on the basis of the underlying pathogenesis including cases mediated by autoantibodies targeting specific neuronal surface/synaptic antigens, and intracellular epitopes, and for cases lacking defined biomarkers. Specific approaches are outlined for disorders such as anti-LGI1, anti-NMDAR, anti-GABA-BR, and anti-GAD65 encephalitides, emphasizing tailored immunotherapy based on pathophysiology and clinical context.

Efficacy of dexamethasone combined with intravenous immunoglobulin for the treatment of pediatric autoimmune encephalitis

Introduction

Glucocorticoids and intravenous immunoglobulin (IVIG) have been established as the primary therapeutic agents for treating autoimmune encephalitis (AE). Methylprednisolone is the most frequently utilized glucocorticoid; however, the potential advantages of dexamethasone (DEX) in the management of encephalitis have yet to be fully elucidated. This study aimed to assess the efficacy of DEX in combination with IVIG in the treatment of pediatric AE.

Methods

This retrospective study included 41 pediatric patients who were diagnosed with AE and were categorized into two groups on the basis of their treatment history. Group A (n = 29) comprised children who initially received immunotherapy at other healthcare institutions but were referred to our hospital for DEX+IVIG treatment because of inadequate response to prior therapies. Group B (n = 12) consisted of children who were administered DEX+IVIG treatment early in the acute phase of AE at our hospital. The therapeutic outcomes of DEX+IVIG treatment in children with nonacute AE (Group A) and acute AE (Group B) were evaluated. The modified Rankin scale (mRS) was used to assess the clinical status of all participants.

Results

Ninety percent of the patients were severely ill prior to DEX+IVIG treatment (mRS = 3.8 ± 1.0). Following treatment, the clinical symptoms of children in both the nonacute stage (Group A) and the acute stage (Group B) significantly improved. At the final follow-up, 90.2% of patients (mRS = 0-2) exhibited a favorable prognosis, with a complete response rate (mRS = 0) of 43.9% and a relapse rate of 2.4%. Children who experienced relapse were treated with DEX+IVIG, leading to a positive outcome. No severe adverse events were observed during treatment. The results of this study indicated that DEX+IVIG is an effective treatment for children with acute, nonacute, and relapsing AE.

Discussion

DEX+IVIG was shown to be beneficial at the acute, nonacute, sequelae, and recurrence stages of AE.

Successful Treatment of Anti-N-Methyl-D-Aspartate Receptor Encephalitis With Bilateral Ovarian Teratomas Through Three Surgeries Without Loss of Fertility

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is associated with ovarian teratomas in approximately half of all cases. Surgical removal of these teratomas, combined with immunotherapy, results in rapid improvement in about half of patients. However, the remaining patients exhibit slower improvement and are at risk of severe complications. Additional surgeries may be considered for these patients. Since even microscopic teratomas can contribute to treatment resistance, complete removal of the remaining ovaries is often selected as a surgical approach. However, this approach results in loss of fertility. We report the case of a 28-year-old woman with bilateral ovarian teratomas and a refractory clinical course after initial treatment, including left salpingo-oophorectomy and right cystectomy. She underwent two additional surgeries, one for a residual teratoma and the other for a recurrent teratoma, both involving cystectomies aimed at preserving fertility. She was discharged home a year after admission and gave birth to a baby two years later. Our case is unique in that three surgeries were performed for an anti-NMDA receptor encephalitis patient with teratomas without loss of fertility, and it documents the reproductive outcome of the patient.

Long-Term Clinical and Biological Prognostic Factors of Anti-NMDA Receptor Encephalitis in Children

BACKGROUND AND OBJECTIVES

Anti-NMDAR encephalitis (NMDARE) is a severe neurologic condition, and recently, the NMDAR Encephalitis One-Year Functional Status (NEOS) score has emerged as a 1-year prognostic tool. This study aimed to evaluate NEOS score and biomarker (neurofilament light chains [NfL], total-Tau protein, glial fibrillary acidic protein, and serum cytokines) correlation with modified Rankin Scale (mRS), cognitive impairment, and clinical recovery in pediatric NMDARE over 2 years.

METHODS

In this French multicenter observational study, 104 pediatric patients with NMDARE were followed for a minimum of 2 years. Clinical data and serum/plasma samples were collected. Biomarker levels, measured using electroluminescence mesoscale discovery (MSD) S-PLEX, were compared between patients and controls and assessed for correlations with disease activity, mRS, cognitive/language impairment, and recovery status at 2 years.

RESULTS

At a median follow-up of 39.5 months, 68 percent of patients had unfavorable recovery and 54% had significant cognitive impairment. Both outcomes were strongly associated with younger age at diagnosis (OR 6.10 [1.91-27.3] p < 0.01 and 5.69 [1.46-27.7] p = 0.02, respectively). A higher NEOS score was significantly correlated with increased cognitive impairment (OR 2.53 [1.52-4.21], p < 0.001), higher mRS scores (OR 2.12 [1.34-3.57], p < 0.01), and unfavorable recovery at 2 years (OR 2.00 [1.30-3.06], p = 0.015). Elevated NfL levels were significantly associated with unfavorable recovery (OR 3.62 [1.29-10.9] p = 0.012) and severe cognitive impairment (OR 3.77 [1.38-10.9] p = 0.012) at 2 years. The combined area under the curve (AUC) for NfL and NEOS was significantly higher than the AUCs of NEOS and NfL alone (p = 0.01).

DISCUSSION

The NEOS score strongly predicts long-term outcomes in NMDARE, with its predictive value extending beyond the first-year mR prediction. NfL levels at disease onset seem to improve accuracy in predicting poor outcomes, providing valuable information for treatment decisions and future clinical trials.

Evidence-based diagnostic prediction score for pediatric NMDA receptor encephalitis

OBJECTIVE

Early diagnosis and treatment of anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) are crucial for a favorable prognosis. Detecting the causative autoantibodies can be challenging. Probable diagnostic criteria are useful in adults less so in children. We aimed to develop a novel diagnostic score for pediatric NMDARE using cohort data.

METHODS

We retrospectively analyzed pediatric participants (0-18 years) with suspected autoimmune encephalitis who underwent cerebrospinal fluid analysis for antineuronal antibodies (Abs) between January 2015 and March 2023. Clinical data, including symptoms and laboratory findings, were analyzed. Symptoms were selected through univariate analysis and then analyzed with multivariate logistic regression model. Resulting odds ratios were used to calculate scores. Scoring systems were developed and evaluated with five-fold validation and univariate logistic regression. One scoring system was selected to create a diagnostic prediction score for pediatric NMDARE.

RESULTS

Of the 504 patients, 264 met the inclusion criteria, and 39 tested positive for NMDAR Abs. Comparing clinical symptoms between cohorts and identified 15 variables significantly different (p < 0.05) to create a pediatric NMDARE prediction score. This score showed 82.1 % sensitivity and 82.2 % specificity, with an 8-point cutoff. The area under the curve was 0.888 (95 % confidence interval: 0.838-0.939). A five-fold cross-validation showed a sensitivity of 95.6 %, specificity of 71.4 %, and kappa coefficient of 0.670.

CONCLUSION

We developed a novel evidence-based diagnostic prediction score for pediatric NMDARE that incorporates specific clinical features and laboratory findings. This score may improve diagnostic accuracy and guide early therapy in children with suspected autoimmune encephalitis.

Immunoadsorption is equally effective as plasma exchange in paediatric neuroimmunological disorders - A retrospective multicentre study

BACKGROUND

Therapeutic apheresis (TA) are promising treatment option for neuroimmunological disorders. In paediatrics, the available data is limited, particularly for the use of IA. The aim of this study was to analyse the use of PE and IA in children and adolescents, with emphasis on outcome and neurological course after treatment as well as the safety of the two modalities.

METHODS

Clinical data from paediatric patients with neuroimmunological disorders treated with TA in two German university children's hospitals between 2015 and 2022 were retrospectively analysed.

RESULTS

In total, 39 patients underwent 322 sessions of TA, of which 184 were IA and 138 PE. The most common diagnosis was autoimmune encephalitis in 39 % (n = 15) of the patients. Other indications were central nervous system inflammatory demyelinating disorders in 21 % (n = 8), Guillain-Barré syndrome in 18 % (n = 7), Myelin Oligodendrocyte Glycopeptide-antibody associated syndromes in 8 % (n = 3), Myasthenia gravis in 5 % (n = 2) and other neurological disorders in 10 % (n = 4). Overall, there was an improvement in 76 % of patients (81 % with IA, 70 % with PE; p = 0.41) immediately after treatment and an improvement in 88 % of patients (90 % with IA, 85 % with PE; p = 0.63) one month after treatment. Complications occurred in 13 % of all sessions (13 % with IA and 13 % with PE; p = 1). Most complications were considered as moderate.

CONCLUSION

Both, IA and PE, are effective treatment options in the therapy of neuroimmunological disorders in children and adolescents, with no major differences in terms of efficiency or safety.

Metabolic Characterization of Cerebrospinal Fluid for Patients With Autoimmune Encephalitis: A Preliminary Study

BACKGROUND

Metabolomics offers promise in uncovering potential biomarkers and understanding the pathophysiology of autoimmune encephalitis (AE), which is a cluster of disorders with the host immune system targeting self-antigens expressed in the central nervous system (CNS). In this research, our objective was to explore metabolic characterization in cerebrospinal fluid (CSF) from individuals with AE, aiming to shed light on the pathophysiology of AE.

METHODS

A targeted approach was applied using an ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) system to study CSF metabolites in patients with AE (n = 18), and control subjects without neurological diseases (n = 17).

RESULTS

A total of 21 potential biomarkers were acquired by getting the intersection of the differential metabolites from univariate statistics and multidimensional statistics between the AE (cell-based assay panel, CBA-panel) group and the control group. Specifically, the levels of pyruvic acid and oxoglutaric acid were notably elevated in the AE(CBA-panel) group compared to those in the control group, indicating that the dysregulated TCA cycle may play a pivotal role in the progression of AE(CBA-panel). Interestingly, 27 potential biomarkers were acquired by getting the intersection of the differential metabolites from univariate statistics and multidimensional statistics between the anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) group and the control group, suggesting that the disparities between patients with greater homogeneity and the controls are amplified. In addition, seven differential metabolites were identified by the univariate statistics between the AE (tissue-based assay, TBA) group and the control group, including alpha-linolenic acid and gamma-linolenic acid, suggesting that dysregulated biosynthesis of unsaturated fatty acids and alpha-linolenic acid metabolism might be crucial in the AE(TBA) disease course.

CONCLUSION

Collectively, distinct metabolic profiles were evident in the CSF of the AE group compared to the control group, notably involving metabolites associated with mitochondrial dysfunction, which helped to elucidate the pathophysiology of AE.

Memantine-Assisted Treatment of N-Methyl-D-Aspartate Receptor Antibody Encephalitis: A Mini Review

N-methyl-D-aspartate receptor encephalitis (NMDARE) presents serious neurological manifestations such as reduced consciousness, seizures, and movement disorders, which can escalate to coma or severe autonomic dysfunction. Treatment typically involves immunotherapy and tumor removal to mitigate the autoimmune response. Timely diagnosis and treatment are critical to prevent severe neurological impairment or death. Memantine, an NMDA receptor antagonist, has shown variable effectiveness in treating NMDARE according to several case reports, yet comprehensive analyses remain scarce. This mini review draws on five literature sources and eight case studies from databases including PubMed, Embase, the Cochrane Library, and Web of Science, highlighting both the potential and risks of memantine as an adjunct therapy. We explore how memantine may reduce symptoms by blocking excessive NMDA receptor (NMDAR) antibody binding, while potentially worsening symptoms by reducing extracellular NMDAR availability, thus impairing neuronal communication. This dual effect calls for further investigation into the optimal use and duration of memantine treatment in NMDARE management.

Efficacy and Safety of Rituximab Treatment for Anti-N-Methyl-d-Aspartate Receptor Encephalitis Without Tumor in Children

BACKGROUND

To evaluate the efficacy and safety of rituximab treatment for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis without tumor in children.

METHODS

Eighteen pediatric patients with NMDAR encephalitis treated with rituximab after failure of intravenous immunoglobulin (IVIG) and methylprednisolone treatment were analyzed retrospectively in terms of their medical history, clinical features, laboratory examination results, and treatments. The modified Rankin scale (mRS) score, peripheral blood CD19+ B cells, recurrence, and adverse events were used to evaluate the efficacy and safety of rituximab.

RESULTS

The patients were treated with rituximab 3.2 ± 1.0 days after the end of IVIG and methylprednisolone treatment. After initial rituximab treatment for four weeks, the mRS score and number of CD19+ B cells in all patients were significantly lower than those before treatment (P < 0.05). At the last follow-up (44.1 months, 17.7 S.D.), all patients had recovered well (mRS ≤2), 14 patients (77.8%) recovered completely (mRS = 0), three patients had recurrent seizures, and one patient had mental and language impairment. Two patients had transient mild adverse events during infusion, and none of the other patients experienced severe adverse events during hospitalization or follow-up.

CONCLUSIONS

Rituximab appears safe and may be effective for the treatment of anti-NMDAR encephalitis without tumor in children refractory to first-line agents.

In Children, N-Methyl-D-Aspartate Receptor Antibody Encephalitis Incidence Exceeds That of Japanese Encephalitis in Vietnam

Background

The recognition of autoimmune causes of encephalitis has led to epidemiological shifts in the worldwide characteristics of encephalitis. N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis leads to well-established complex neuropsychiatric manifestations. In low- and middle-income countries, including Vietnam, its relative incidence, especially in children, is unknown and most neurologists currently consider infectious encephalitis prior to autoimmune etiologies.

Methods

The study was prospectively conducted at Children's Hospital 1 in Ho Chi Minh City between March 2020 and December 2022. Any child admitted to the Department of Infectious Diseases and Neurology fulfilling the case definition of encephalitis was eligible to participate. Cerebrospinal fluid samples were collected alongside meta-clinical data for analysis.

Results

We recruited 164 children with a clinical diagnosis of encephalitis. Etiologies were determined as NMDAR antibody encephalitis in 23 of 164 cases (14.0%), Japanese encephalitis virus in 14 of 164 (8.5%), and herpes simplex virus in 4 of 164 (2.4%). Clinical categorizations suggested idiopathic viral encephalitis in another 71 (43.3%), and autoimmune encephalitis of unknown origin in the remaining 52. Factors including demographics, specific clinical features, cerebrospinal fluid and electroencephalogram findings, and length of hospital stay were significantly different between NMDAR antibody encephalitis and Japanese encephalitis.

Conclusions

At a tertiary children's hospital in Vietnam, the prevalence of NMDAR antibody encephalitis exceeds that of Japanese encephalitis, the most common infectious encephalitis cause in Southeast Asia. NMDAR antibody encephalitis is associated with long hospital stay and poor outcomes. These findings should change pediatric diagnostics, to earlier consider autoimmune treatments in this clinical setting.

Recent advances in autoimmune encephalitis

Since the description of autoimmune encephalitis (AE) associated with N-methyl-D-aspartate receptor antibodies (anti-NMDARE) in 2007, more than 12 other clinical syndromes and antibodies have been reported. In this article, we review recent advances in pathophysiology, genetics, diagnosis pitfalls, and clinical phenotypes of AE associated with cell surface antibodies and anti-GAD associated neurological syndromes. Genetic studies reported human leukocyte antigen (HLA) associations for anti-LGI1, anti-Caspr2, anti-IgLON5, and anti-GAD. Follow-up studies characterized cognitive dysfunction, psychiatric symptoms, sleep disorders, and adaptative behavior dysfunction, mainly for anti-NMDARE. Late-onset anti-NMDARE and anti- GABA-B receptor (GABA-BR) encephalitis patients were described to have worse prognoses and different tumor associations. Additionally, the clinical spectrum of anti-LGI1, anti-AMPAR, anti-CASPR2, and anti-IgLON5 was expanded, comprising new differential diagnoses. The diagnostic criteria for AE were adapted to the pediatric population, and a diagnostic algorithm was proposed, considering potential mimics and misdiagnosis. We also review the limitations of commercial assays for AE and treatment recommendations, as well as clinical scales for short and long-term assessment of AE patients, along with cognitive evaluation.

Targeted Treatments for Myasthenia Gravis in Children and Adolescents

Myasthenia gravis (MG) is an antibody-mediated disorder of the neuromuscular junction affecting children and adults. MG is a treatable condition with most patients requiring immunosuppression for disease control and/or remission. Juvenile myasthenia gravis (JMG) is rare in comparison with adult-onset MG but given the same underlying pathophysiology, treatment strategies are similar to those in adults. Until recently, there were only a few randomised controlled trials (RCTs) for MG treatments in adults and none in children, and management strategies were primarily based on expert consensus. In addition, treatment options for refractory MG cases have been severely limited, resulting in poor long-term quality of life in such patients due to the significant disease burden. Recently, there have been several RCTs focussing on novel therapeutic strategies with potentially promising outcomes, suggesting a change in MG management over the coming years and access to more effective and faster-acting drugs for MG patients. This paper will review current and new MG treatments including efgartigimod, eculizumab, rozanolixizumab, ravulizumab, and zilucoplan, with a focus on juvenile myasthenia gravis.

A Prospective Single-Arm Cohort Study of Immune-mediated Seizures/Epilepsy Without Encephalopathy (ISEWE) in Children from a Tertiary Care Hospital in South India

Acute-onset seizures in children pose a diagnostic and therapeutic dilemma. Some epilepsy cases presenting with seizures but without encephalopathy, though treatable with immunotherapy, are often missed due to lack of suspicion of immune mechanism in the context of absent encephalitis. A prospective study was conducted on premorbidly normal children with new-onset seizures occurring in clusters, with normal neuroimaging. Investigations included electroencephalogram (EEG), cerebrospinal fluid examination, and testing for autoantibodies. All cases received methylprednisolone pulse therapy along with antiseizure medications (ASMs), followed by monthly dexamethasone oral pulse therapy. Fifteen cases were enrolled (11 males, four females). Mean age at seizure onset was 4.6 years. Focal seizures were present in 13/15 (86.7%) cases. Magnetic resonance imaging of the brain was normal in all. EEG showed interictal epileptiform discharges in 12 cases (focal in nine) and ictal record in two cases. On monthly oral steroids, number of ASMs could be reduced. Eight cases never had a relapse, while seven did have it. Relapses were more common if more than three ASMs were tried and less if steroids were started within 30 days. Immune-mediated seizures/epilepsy without encephalopathy is a new, important, and treatable entity. Early diagnosis and institution of immunotherapy results in significant improvement in seizure control and also reduces the need for long-term polytherapy. Awareness of this entity is crucial, especially when premorbidly normal children present with new-onset clusters of refractory seizures.

Predicting the future of autoimmune encephalitides

The concept that many neurologic and psychiatric disorders of unknown cause are immune-mediated has evolved fast during the past 20 years. The main contribution to the expansion of this field has been the discovery of antibodies that attack neuronal or glial cell-surface proteins or receptors, directly modifying their structure and function. These antibodies facilitate the diagnosis and prompt treatment of patients who often improve with immunotherapy. The identification of this group of diseases, collectively named "autoimmune encephalitides", was preceded by many years of investigations on other autoimmune CNS disorders in which the antibodies are against intracellular proteins, occur more frequently with cancer, and associate with cytotoxic T-cell responses that are less responsive to immunotherapy. Here, we first trace the recent history of the autoimmune encephalitides and address how to assess the clinical value and implement in our practice the rapid pace of autoantibody discovery. In addition, we review recent developments in the post-acute stage of the two main autoimmune encephalitides (NMDAR and LGI1) focusing on symptoms that are frequently overlooked or missed, and therefore undertreated. Because a better understanding of the pathophysiology of these diseases relies on animal models, we examine currently available studies, recognizing the existing needs for better and all-inclusive neuro-immunobiological models. Finally, we assess the status of biomarkers of disease outcome, clinical scales, current treatment strategies, and emerging therapies including CAR T-cell technology. Altogether, this overview is intended to identify gaps of knowledge and provide suggestions for improvement and insights for future research.

Isolated Psychiatric Symptoms in Children With Anti-N-Methyl-d Aspartate Receptor Encephalitis

BACKGROUND

Isolated psychiatric symptoms can be the initial symptom of pediatric anti-N-methyl-d-aspartate (NMDA) receptor autoimmune encephalitis (pNMDARE). Here we report on the prevalence of isolated psychiatric symptoms in pNMDARE. We also assess whether initial neurodiagnostic tests (brain magnetic resonance imaging [MRI], electroencephalography [EEG], and/or cerebrospinal fluid [CSF] white blood cell count) are abnormal in children with isolated psychiatric symptoms and pNMDARE.

METHODS

This multicenter retrospective cohort study from CONNECT (Conquering Neuroinflammation and Epilepsies Consortium) from 14 institutions included children under age 18 years who were diagnosed with pNMDARE. Descriptive statistics using means, medians, and comparisons for continuous versus discrete data was performed.

RESULTS

Of 249 children included, 12 (5%) had only psychiatric symptoms without other typical clinical features of autoimmune encephalitis at presentation. All but one (11 of 12 = 92%) had at least one abnormal finding on initial ancillary testing: eight of 12 (67%) had an abnormal EEG, six of 12 (50%) had an abnormal MRI, and five of 12 (42%) demonstrated CSF pleocytosis. The single patient with a normal MRI, EEG, and CSF profile had low positive CSF NMDA antibody (titer of 1:1), and symptoms improved without immunotherapy.

CONCLUSIONS

Isolated first-episode psychiatric symptoms in pNMDARE are uncommon, and the majority of children will exhibit additional neurodiagnostic abnormalities. Delaying immunotherapy in a child with isolated psychiatric symptoms and normal neurodiagnostic testing may be warranted while awaiting confirmatory antibody testing.

Pediatric Autoimmune Encephalitis: A Nationwide Study in Latvia

BACKGROUND

Autoimmune encephalitis (AE) is the third most common encephalitis in children. Diagnosis can be challenging due to overlapping and diverse clinical presentations as well as various investigation results. This study aims to characterize the clinical, diagnostic features, as well as treatment and outcomes of AE in children and determine the incidence of pediatric AE in Latvia.

METHODS

The study was conducted at the Children's Clinical University Hospital in Riga. The study participants were patients under the age of 18 years diagnosed with AE from 2014 to 2022. Data regarding clinical characteristics, investigation findings, treatment strategy, and outcomes were retrospectively collected from the medical history data system.

RESULTS

We included 18 pediatric patients diagnosed with AE. The mean incidence of pediatric AE in Latvia was 0.56 per 100,000 children. Most patients (66.6%) had seronegative AE. In the seropositive group, the most common was anti-methyl-D-aspartate receptor AE, with two patients having other antibodies. The most prevalent clinical features were personality change, cognitive impairment, autonomic dysfunction, and movement disorders. The majority of patients (58.8%) received first-line treatment only. More than half (55.6%) of our AE patient group had long-term sequelae.

CONCLUSIONS

Our study shows that the pediatric AE incidence in Latvia is similar to what has been previously reported in other studies. A relatively high proportion of seronegative AE was present in our cohort, indicating that awareness of possible misdiagnosis should be raised. Further research is needed to better understand the underlying mechanisms, characterize clinical features, and determine the treatment of choice in different situations to improve long-term outcomes.

Injectable body temperature responsive hydrogel for encephalitis treatment via sustained release of nano-anti-inflammatory agents

Skull defects are common in the clinical practice of neurosurgery, and they are easily complicated by encephalitis, which seriously threatens the life and health safety of patients. The treatment of encephalitis is not only to save the patient but also to benefit the society. Based on the advantages of injectable hydrogels such as minimally invasive surgery, self-adaptation to irregularly shaped defects, and easy loading and delivery of nanomedicines, an injectable hydrogel that can be crosslinked in situ at the ambient temperature of the brain for the treatment of encephalitis caused by cranial defects is developed. The hydrogel is uniformly loaded with nanodrugs formed by cationic liposomes and small molecule drugs dexmedetomidine hydrochloride (DEX-HCl), which can directly act on the meninges to achieve sustained release delivery of anti-inflammatory nanodrug preparations and achieve the goal of long-term anti-inflammation at cranial defects. This is the first time that DEX-HCl has been applied within this therapeutic system, which is innovative. Furthermore, this study is expected to alleviate the long-term suffering of patients, improve the clinical medication strategies for anti-inflammatory treatment, promote the development of new materials for cranial defect repair, and expedite the translation of research outcomes into clinical practice.

An exploration of blood-based biomarkers of negative symptoms of psychosis in men

Negative symptoms in the context of psychosis are still poorly understood and diagnosed, which impairs the treatment efficacy of current therapies and patient's integration in society. In this study, we aimed to test hypothesis-based and exploratory associations of negative symptom domains, as defined by the Brief Negative Symptom Scale (BNSS), with hormonal and hematological variables, and, complementarily, with standard psychological/cognitive and psychopathological measures. Fifty-one male patients diagnosed with a psychotic disorder underwent a structured interview and blood collection. Standard Spearmen bivariate correlations were used for data analysis. We obtained evidence of hypothesis-based associations between specific negative symptoms and oxytocin, thyroid stimulating hormone levels and neutrophil-to-lymphocyte ratio; as well as novel and hypothesis-free associations with erythrocyte and lymphocyte count, mean corpuscular volume and red cell distribution width. Complementarily, we also obtained some validation of previous associations of negative symptoms with illness resolution, cognitive symptom severity and social performance, and a novel association with anger contagion. We hope our results can generate new hypotheses in psychosis research. Our work suggests further avenues in research on erythrocytic, inflammatory, thyroid and oxytocin-related markers and abnormalities in psychosis, especially in regards to specific negative symptoms, towards more precise and comprehensive etiological, diagnostic and therapeutic models.

Innovation and optimization in autoimmune encephalitis trials: the design and rationale for the Phase 3, randomized study of satralizumab in patients with NMDAR-IgG-antibody-positive or LGI1-IgG-antibody-positive autoimmune encephalitis (CIELO)

Background

Autoimmune encephalitis (AIE) encompasses a spectrum of rare autoimmune-mediated neurological disorders, which are characterized by brain inflammation and dysfunction. Autoantibodies targeting the N-methyl-d-aspartic acid receptor (NMDAR) and leucine-rich glioma-inactivated 1 (LGI1) are the most common subtypes of antibody-positive AIE. Currently, there are no approved therapies for AIE. Interleukin-6 (IL-6) signaling plays a role in the pathophysiology of AIE. Satralizumab, a humanized, monoclonal recycling antibody that specifically targets the IL-6 receptor and inhibits IL-6 signaling, has demonstrated efficacy and safety in another autoantibody-mediated neuroinflammatory disease, aquaporin-4 immunoglobulin G antibody-positive neuromyelitis optica spectrum disorder, and has the potential to be an evidence-based disease modifying treatment in AIE.

Objectives

CIELO will evaluate the efficacy, safety, pharmacodynamics, and pharmacokinetics of satralizumab compared with placebo in patients with NMDAR-immunoglobulin G antibody-positive (IgG+) or LGI1-IgG+ AIE.

Study design

CIELO (NCT05503264) is a prospective, Phase 3, randomized, double-blind, multicenter, basket study that will enroll approximately 152 participants with NMDAR-IgG+ or LGI1-IgG+ AIE. Prior to enrollment, participants will have received acute first-line therapy. Part 1 of the study will consist of a 52-week primary treatment period, where participants will receive subcutaneous placebo or satralizumab at Weeks 0, 2, 4, and every 4 weeks thereafter. Participants may continue to receive background immunosuppressive therapy, symptomatic treatment, and rescue therapy throughout the study. Following Part 1, participants can enter an optional extension period (Part 2) to continue the randomized, double-blind study drug, start open-label satralizumab, or stop study treatment and continue with follow-up assessments.

Endpoints

The primary efficacy endpoint is the proportion of participants with a ≥1-point improvement in the modified Rankin Scale (mRS) score from study baseline and no use of rescue therapy at Week 24. Secondary efficacy assessments include mRS, Clinical Assessment Scale of Autoimmune Encephalitis (CASE), time to rescue therapy, sustained seizure cessation and no rescue therapy, Montreal Cognitive Assessment, and Rey Auditory Verbal Learning Test (RAVLT) measures. Safety, pharmacokinetics, pharmacodynamics, exploratory efficacy, and biomarker endpoints will be captured.

Conclusion

The innovative basket study design of CIELO offers the opportunity to yield prospective, robust evidence, which may contribute to the development of evidence-based treatment recommendations for satralizumab in AIE.

Pediatric Autoimmune Neurologic Disorders

OBJECTIVE

This article discusses common principles in diagnosing and managing autoimmune neurologic conditions in children.

LATEST DEVELOPMENTS

The key to improving outcomes in all patients with autoimmune neurologic diseases is making an early diagnosis, promptly initiating treatment, and identifying patients who will benefit from long-term maintenance treatment. Some neuroinflammatory syndromes can be diagnosed with an antibody biomarker (eg, aquaporin-4 antibodies, N-methyl-d-aspartate [NMDA] receptor antibodies), whereas others require clinical diagnostic criteria (eg, multiple sclerosis, opsoclonus-myoclonus syndrome). A proportion of children will be labeled as seronegative, and further investigations for other inflammatory or monogenetic etiologies need to be carried out in parallel with treating the central nervous system inflammation. Time to treatment and treatment escalation were shown to correlate with outcomes in many patients with these disorders. The choice and duration of treatment should be evaluated considering side effects and risks in the short and long terms. The presence of a highly inflammatory disease process in children supports the use of highly effective disease-modifying therapies in pediatrics.

ESSENTIAL POINTS

The phenotypes of pediatric autoimmune neurologic conditions may change across different age groups, as the brain is still actively developing. In general, the presentation in children is more inflammatory, but overall disability is lower, likely because of better neuroplasticity and repair. Convincing evidence has increasingly emerged to support the biological rationale that effective immunosuppressive therapies used in adult neuroimmunology are equally effective in children.

Patterns of Neuropsychiatric Manifestations of Ovarian Teratomas: A Systematic Review of Case Reports

Ovarian teratomas are germ cell tumors composed of multiple cell types. Ovarian teratomas may express antigens found in the nervous system or neuroendocrine proteins. These neural antigens and neuroendocrine proteins may lead to an autoimmune response with associated encephalitis. There are a growing number of case reports of autoimmune encephalitis in patients with ovarian teratomas. However, the patterns of neuropsychiatric manifestations of ovarian teratomas associated with encephalitis have not been established. The aim of this article is to conduct a systematic review to determine the patterns of neuropsychiatric manifestations of ovarian teratoma-associated encephalitis, focusing on their frequency and clinical course. Thirty-three case reports were collected and analyzed for a systematic review. The studies were full-text, peer-reviewed journal publications from April 2014 to April 2024. Fifty-eight patients were included in our study. The age group of 22-35 years old was the most reported, with 25 (43.1%) patients. The most commonly reported symptoms were memory impairment in 29 (50%) patients, hallucinations in 25 (43.1%) patients, and aggressive behavior in 23 (39.7%) patients. Neuropsychiatric symptoms had a prodromal phase of flu-like symptoms in 31 (53.4%) patients. The neuropsychiatric symptoms preceded the diagnosis of ovarian teratoma in 57 (98.3%) patients. In 53 (91.4%) patients, patients did not respond to psychiatric medications. Autoimmune antibodies to neural antigens were found in 45 (77.6%) patients, with 25 (43.1%) patients having neural tissue present in the teratoma. Treatment of the underlying teratoma and encephalitis led to full recovery in 37 (63.8%) patients. However, long-term outcomes such as relapse and mortality were discussed in only 11 (19.0%) patients. Findings suggest that neuropsychiatric symptoms correlate with teratoma-associated encephalitis and often precede tumor detection. The treatment of the teratoma led to full recovery of the neuropsychiatric manifestations; however, the long-term outcomes of the patients need to be further studied. Future research is needed on the prognosis of patients with neuropsychiatric manifestations of ovarian teratoma.

Higher incidence of acute symptomatic seizures in probable antibody-negative pediatric autoimmune encephalitis than in major antibody-positive autoimmune encephalitis

Purpose

To delineate the characteristics of probable antibody-negative pediatric autoimmune encephalitis (probable Ab-negative AE), we compared the clinical features of probable Ab-negative AE to those of major antibody-positive AE.

Methods

We retrospectively reviewed the clinical features of 18 patients with probable Ab-negative AE, 13 with anti-N-methyl-D-aspartate receptor encephalitis (NMDARE), and 13 with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Clinical characteristics, neuroimaging findings, treatments, and outcomes were analyzed.

Results

The age of onset and length of hospital stay were significantly higher in the NMDARE group than in the other groups (p = 0.02 and p < 0.01). Regarding initial neurological symptoms, acute symptomatic seizures in the probable Ab-negative AE group (67%) were significantly more frequent than in the NMDARE (15%) and MOGAD (23%) groups (p < 0.01). Paraclinical evidence of neuroinflammation within 1 month of disease onset revealed that single-photon emission computed tomography (SPECT) detected abnormal alterations in 14/14 (100%), cerebrospinal fluid (CSF) analysis in 15/18 (83%), and magnetic resonance imaging (MRI) in 11/18 (61%) in patients with probable Ab-negative AE. In the probable Ab-negative AE group, seven patients (39%) developed autoimmune-associated epilepsy, whereas one patient (8%) had both NMDARE and MOGAD (not statistically significant, p = 0.07).

Conclusion

Patients with probable Ab-negative AE exhibited acute symptomatic seizures as initial neurological symptoms significantly more frequently. They developed autoimmune-associated epilepsy more frequently than those with NMDARE and MOGAD, which was not statistically significant. SPECT within 1 month of disease onset might be a valuable surrogate marker of ongoing neuroinflammation and neuronal dysfunction, even in patients with negative MRI findings.

Management of Autoimmune Encephalitis in a 7-Year-Old Child With CTLA-4 Haploinsufficiency and AMPA Receptor Antibodies: A Case Report

OBJECTIVES

We report on the therapeutic management of early-onset severe neurologic symptoms in cytotoxic T lymphocyte antigen-4 haploinsufficiency (CTLA-4h) and the presence of antibodies to the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) as an important finding.

METHODS

This is a case report from a Dutch academic hospital. Repeated clinical examinations, repeated brain MRI and extended diagnostics on serum and CSF were performed. We used the CARE checklist.

RESULTS

A 7-year-old boy was diagnosed with CTLA-4h based on family screening. On diagnosis, he had mild chronic diarrhea and autism spectrum disorder, but no abnormalities in extensive laboratory screening. Six months later, he presented with sudden-onset autoimmune encephalitis. Repeated brain MRI revealed no abnormalities, but immunohistochemistry analysis on serum and CSF showed the presence of AMPAR antibodies. Treatment was initially focused on immunomodulation and targeted CTLA-4 replacement therapy. Because of the persistent fluctuating cerebellar and neuropsychiatric symptoms and the potential clinical significance of the AMPAR antibodies, treatment was intensified with repetition of first-line immunomodulation and rituximab. This combined therapy resulted in sustained clinical improvement and served as a bridge to curative hematopoietic stem cell transplantation.

DISCUSSION

This case illustrates the rare early onset of autoimmune encephalitis and presence of AMPAR antibodies in CTLA-4h. Targeted CTLA-4 replacement therapy resulted in a partial response. However, awaiting its optimal therapeutic effect, refractory CNS symptoms required intensification of immunomodulation. The identification of AMPAR antibodies guided our treatment decisions.

CLASSIFICATION OF EVIDENCE

This provides Class IV evidence. It is a single observational study without controls.

Brazilian consensus recommendations on the diagnosis and treatment of autoimmune encephalitis in the adult and pediatric populations

BACKGROUND

 Autoimmune encephalitis (AIE) is a group of inflammatory diseases characterized by the presence of antibodies against neuronal and glial antigens, leading to subacute psychiatric symptoms, memory complaints, and movement disorders. The patients are predominantly young, and delays in treatment are associated with worse prognosis.

OBJECTIVE

 With the support of the Brazilian Academy of Neurology (Academia Brasileira de Neurologia, ABN) and the Brazilian Society of Child Neurology (Sociedade Brasileira de Neurologia Infantil, SBNI), a consensus on the diagnosis and treatment of AIE in Brazil was developed using the Delphi method.

METHODS

 A total of 25 panelists, including adult and child neurologists, participated in the study.

RESULTS

 The panelists agreed that patients fulfilling criteria for possible AIE should be screened for antineuronal antibodies in the serum and cerebrospinal fluid (CSF) using the tissue-based assay (TBA) and cell-based assay (CBA) techniques. Children should also be screened for anti-myelin oligodendrocyte glucoprotein antibodies (anti-MOG). Treatment should be started within the first 4 weeks of symptoms. The first-line option is methylprednisolone plus intravenous immunoglobulin (IVIG) or plasmapheresis, the second-line includes rituximab and/or cyclophosphamide, while third-line treatment options are bortezomib and tocilizumab. Most seizures in AIE are symptomatic, and antiseizure medications may be weaned after the acute stage. In anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, the panelists have agreed that oral immunosuppressant agents should not be used. Patients should be evaluated at the acute and postacute stages using functional and cognitive scales, such as the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Modified Rankin Scale (mRS), and the Clinical Assessment Scale in Autoimmune Encephalitis (CASE).

CONCLUSION

 The present study provides tangible evidence for the effective management of AIE patients within the Brazilian healthcare system.

Unusual imaging findings associated with abdominal pediatric germ cell tumors

Germ cell tumors of childhood are tumors arising from germline cells in gonadal or extragonadal locations. Extragonadal germ cell tumors are characteristically located in the midline, arising intracranially or in the mediastinum, retroperitoneum, or pelvis. These tumors are generally easily diagnosed due to typical sites of origin, characteristic imaging findings, and laboratory markers. However, germ cell tumors can be associated with unusual clinical syndromes or imaging features that can perplex the radiologist. This review will illustrate atypical imaging/clinical manifestations and complications of abdominal germ cell tumors in childhood. These features include unusual primary tumors such as multifocal primaries; local complications such as ovarian torsion or ruptured dermoid; atypical presentations of metastatic disease associated with burned-out primary tumor, growing teratoma syndrome, and gliomatosis peritonei; endocrine manifestations such as precocious puberty and hyperthyroidism; and antibody mediated paraneoplastic syndrome such as anti-N-methyl-D-aspartate-receptor antibody-mediated encephalitis. This review aims to illustrate unusual imaging features associated with the primary tumor, metastatic disease, or distant complications of abdominal germ cell tumors of childhood.

Update in Pediatric Neurocritical Care: What a Neurologist Caring for Critically Ill Children Needs to Know

Currently nearly one-quarter of admissions to pediatric intensive care units (PICUs) worldwide are for neurocritical care diagnoses that are associated with significant morbidity and mortality. Pediatric neurocritical care is a rapidly evolving field with unique challenges due to not only age-related responses to primary neurologic insults and their treatments but also the rarity of pediatric neurocritical care conditions at any given institution. The structure of pediatric neurocritical care services therefore is most commonly a collaborative model where critical care medicine physicians coordinate care and are supported by a multidisciplinary team of pediatric subspecialists, including neurologists. While pediatric neurocritical care lies at the intersection between critical care and the neurosciences, this narrative review focuses on the most common clinical scenarios encountered by pediatric neurologists as consultants in the PICU and synthesizes the recent evidence, best practices, and ongoing research in these cases. We provide an in-depth review of (1) the evaluation and management of abnormal movements (seizures/status epilepticus and status dystonicus); (2) acute weakness and paralysis (focusing on pediatric stroke and select pediatric neuroimmune conditions); (3) neuromonitoring modalities using a pathophysiology-driven approach; (4) neuroprotective strategies for which there is evidence (e.g., pediatric severe traumatic brain injury, post-cardiac arrest care, and ischemic stroke and hemorrhagic stroke); and (5) best practices for neuroprognostication in pediatric traumatic brain injury, cardiac arrest, and disorders of consciousness, with highlights of the 2023 updates on Brain Death/Death by Neurological Criteria. Our review of the current state of pediatric neurocritical care from the viewpoint of what a pediatric neurologist in the PICU needs to know is intended to improve knowledge for providers at the bedside with the goal of better patient care and outcomes.

Suspected autoimmune encephalitis: A retrospective study of patients referred for therapeutic plasma exchange

INTRODUCTION

Autoimmune encephalitis (AE) comprises a heterogeneous group of autoantibody-mediated disorders targeting the brain parenchyma. Therapeutic plasma exchange (TPE), one of several first-line therapies for AE, is often initiated when AE is suspected, albeit prior to an established diagnosis. We sought to characterize the role of TPE in the treatment of suspected AE.

METHODS

A single-center, retrospective analysis was performed of adults (≥18 years) who underwent at least one TPE procedure for "suspected AE." The following parameters were extracted and evaluated descriptively: clinicopathologic characteristics, treatment course, TPE-related adverse events, outcomes (e.g., modified Rankin scale [mRS]), and diagnosis once investigation was complete.

RESULTS

A total of 37 patients (median age 56 years, range 28-77 years, 62.2% male) were evaluated. Autoimmune antibody testing was positive in serum for 43.2% (n = 16) and cerebrospinal fluid for 29.7% (n = 11). Patients underwent a median of five TPE procedures (range 3-16), with 97.3% (n = 36) via a central line and 21.6% (n = 8) requiring at least one unit of plasma as replacement fluid. Fifteen patients (40.5%) experienced at least one TPE-related adverse event. Compared with mRS at admission, the mRS at discharge was improved in 21.6% (n = 8), unchanged in 59.5% (n = 22), or worse in 18.9% (n = 7). Final diagnosis of AE was determined to be definite in 48.6% (n = 18), probable in 8.1% (n = 3) and possible in 27.0% (n = 10). Six (16.2%) patients were ultimately determined to have an alternate etiology.

CONCLUSION

Empiric TPE for suspected AE is generally well-tolerated. However, its efficacy remains uncertain in the absence of controlled trials, particularly in the setting of seronegative disease.

Anti-NMDAR encephalitis in a child with long impaired consciousness and persistent antibodies: a case report and mini review

We described a challenging case of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis in a young girl. Despite enduring months of reduced consciousness with ongoing antibody presence, she ultimately exhibited remarkable improvement within a 5-year follow-up period. Additionally, we conducted a concise review of relevant literature on anti-NMDAR encephalitis, with a specific focus on anti-NMDAR antibodies. Our findings enhance the clinical comprehension of anti-NMDAR encephalitis and offer valuable insights to clinicians for its management.

Treatment Approaches in Pediatric Relapsing Autoimmune Encephalitis

Purpose of review

Autoimmune encephalitis (AE) is increasingly recognized as a treatable cause of encephalitis in children. While prior observational studies demonstrate improved motor outcomes with early immunotherapy, less is known about long-term management and treatment for relapsing disease. In this review, we present current treatment approaches to pediatric AE, in particular relapse risk and treatment for relapsing AE in children.

Recent findings

A recent meta-analysis of anti-NMDAR encephalitis demonstrated that disease onset in adolescence was associated with an increased odds of relapse whereas treatment with rituximab and IVIG for 6 months or longer were associated with a non-relapsing course. However, no specific pediatric sub-analyses were reported. A single-center study on adult and pediatric AE showed that rituximab use was associated with a reduction in time to relapse and recurring relapses although the data for the pediatric cohort did not achieve statistical significance.

Summary

The use of second-line immunotherapy during the initial attack may reduce the risk for relapsing disease in pediatric AE. Larger studies are needed to investigate relapse risk and treatment in both anti-NMDAR and non-NMDAR encephalitis in children.

Autoimmune encephalitis in Israeli children - A retrospective nationwide study

Immune-mediated or autoimmune encephalitis (AE) is a relatively new, rare and elusive form of encephalitis in children. We retrospectively collected seropositive children (0-18 years old) with well characterized antibodies through 3 reference laboratories in Israel. Clinical symptoms, MRI and EEG findings and treatment courses were described. A total of 16 patients were included in the study, with 10 females. Anti NMDA encephalitis was most common followed by anti HU and anti mGLuR1. Psychiatric symptoms, abnormal movements, seizures and behavioral changes were the most common presentation. Pathological MRI and EEG findings were described in 37% and 56% of children, respectively. Treatment with corticosteroids, Intravenous immunoglobulins (IVIG) was first line in most children. Following inadequate response children were treated with plasmapheresis and/or rituximab. Two patients relapsed following both first and second line protocols. In terms of long term prognosis, 9 children (56%) had one or more residual behavioral, psychiatric or neurologic findings. Three children required hospitalization for rehabilitation. AE remains a rare diagnosis with variable presenting symptoms, requiring a high index of suspicion. Consensus recommended treatment is generally effective in the pediatric population. Female gender was associated with a higher chance of severe disease. Larger cohorts would be needed to identify prognostic factors in the pediatric population.

Second-line immunotherapy in new onset refractory status epilepticus

Several pieces of evidence suggest immune dysregulation could trigger the onset and modulate sequelae of new onset refractory status epilepticus (NORSE), including its subtype with prior fever known as febrile infection-related epilepsy syndrome (FIRES). Consensus-driven recommendations have been established to guide the initiation of first- and second-line immunotherapies in these patients. Here, we review the literature to date on second-line immunotherapy for NORSE/FIRES, presenting results from 28 case reports and series describing the use of anakinra, tocilizumab, or intrathecal dexamethasone in 75 patients with NORSE. Among them, 52 patients were managed with anakinra, 21 with tocilizumab, and eight with intrathecal dexamethasone. Most had elevated serum or cerebrospinal fluid cytokine levels at treatment initiation. Treatments were predominantly initiated during the acute phase of the disease (92%) and resulted, within the first 2 weeks, in seizure control for up to 73% of patients with anakinra, 70% with tocilizumab, and 50% with intrathecal dexamethasone. Cytokine levels decreased after treatment for most patients. Anakinra and intrathecal dexamethasone were mainly initiated in children with FIRES, whereas tocilizumab was more frequently prescribed for adults, with or without a prior febrile infection. There was no clear correlation between the response to treatment and the time to initiate the treatment. Most patients experienced long-term disability and drug-resistant post-NORSE epilepsy. Initiation of second-line immunotherapies during status epilepticus (SE) had no clear effect on the emergence of post-NORSE epilepsy or long-term functional outcomes. In a small number of cases, the initiation of anakinra or tocilizumab several years after SE onset resulted in a reduction of seizure frequency for 67% of patients. These data highlight the potential utility of anakinra, tocilizumab, and intrathecal dexamethasone in patients with NORSE. There continues to be interest in the utilization of early cytokine measurements to guide treatment selection and response. Prospective studies are necessary to understand the role of early immunomodulation and its associations with epilepsy and functional outcomes.

Pediatric neuroinflammatory diseases in the intensive care unit

Inflammatory disorders of the central nervous system (CNS) include a wide spectrum of autoimmune, autoinflammatory, and paraneoplastic diseases. While many affected patients require acute hospital admission, a subset may present with severe neurological symptoms requiring intensive care unit (ICU) escalation due to disordered consciousness, respiratory failure, status epilepticus, intracranial hypertension, and/or severe autonomic dysregulation.

Anti-NMDA Receptor Encephalitis Related to Renal Cell Carcinoma: A Case Report

Anti-NMDA receptor (NMDAR) encephalitis is characterized by a well-defined neuropsychiatric syndrome and CSF antibodies against the GluN1 subunit of the NMDAR. 40% of cases are related to underlying tumors, the vast majority ovarian teratomas (94%). We report a case of anti-NMDAR encephalitis associated with renal cell carcinoma (RCC). A 20-year-old female presented to the ED with behavioral changes, involuntary movements, tachycardia, and alternating obtundation with agitation which progressed over 3 weeks. Involuntary movements were severe, requiring intubation and sedation for control, and were accompanied by rhabdomyolysis. Brain MRI showed bilateral mesiotemporal T2/FLAIR hyperintensities. Anti-NMDAR antibodies were present in the serum (1:640) and CSF (1:320). Malignancy screening revealed a renal mass concerning for RCC, which was confirmed upon resection. She was started on high dose IV methylprednisolone and plasmapheresis, followed by rituximab. Lack of response led to escalating immunotherapy with cyclophosphamide. Clinical course was complicated by prolonged ICU admission, prolonged sedation, severe dysautonomia and bacteremia. Improvement began 2 months after immunotherapy, and she was discharged to rehabilitation 100 days after admission with mild neuropsychiatric symptoms. Repeat malignancy screenings, including whole-body imaging and transvaginal ultrasound were consistently negative. Herein, we describe a case of definite anti-NMDAR encephalitis in the setting of newly diagnosed RCC. This case illustrates how tumors other than ovarian teratomas may act as immunological triggers, as well as the complex and prolonged symptomatic and immunosuppressive therapies required in severe presentations of anti-NMDAR encephalitis.

Immune-mediated encephalitis

A neurological deterioration in a child presents a significant worry to the family and often a diagnostic challenge to the clinician. A dysregulated immune response is implicated in a wide and growing spectrum of neurological conditions. In this review we consider the current paradigms in which immune-mediated encephalopathies are considered; the development of paediatric specific diagnostic criteria that facilitate early consideration and treatment of immune-mediated conditions and the limitations and potential developments in diagnostic testing. We consider the expanding phenotype of myelin oligodendrocyte glycoprotein antibody, the spectrum of virus-associated encephalopathy syndromes, and the strategies that have been employed to build an evidence base for the management of these rare conditions. Looking forward we explore the potential for advanced molecular investigations to improve our understanding of immune-mediated encephalitides and guide future treatment strategies. Recently characterized immune-mediated central nervous system disorders include new antibodies causing previously recognized phenotypes. Aggregation of conditions with similar clinical triggers, and characterization of unique imaging features in virus-associated encephalopathy syndromes. Immune treatment iscurrently guided by meta-analysis of individualized patient data and/or multi-national consensus.

Encephalitis is an Important Phenotype of Myelin Oligodendrocyte Glycoprotein Antibody-Associated Diseases: A Single-Center Cohort Study

BACKGROUND

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is considered a demyelinating disease of the central nervous system, but an increasing number of encephalitis cases associated with MOG antibodies have been reported recently.

METHODS

This was a single-center, retrospective study. All data for pediatric patients with MOGAD diagnosed at Beijing Children's Hospital from January 2017 to January 2022 were collected. Clinical characteristics and outcomes were analyzed, and treatment responses were compared between the rituximab (RTX) and mycophenolate mofetil (MMF) groups.

RESULTS

A total of 190 patients (age range: 5 months to 16 years; median age: 7.2 years; females: 97) were included in this study. The phenotypes of the first attack included acquired demyelinating syndromes (105 [55%]), encephalitis other than acute disseminated encephalomyelitis (82 [43%]), and isolated meningitis (3 [2%]). After a median follow-up of 30.4 months (interquartile range: 14.8-43.7), 64 (34%) patients had relapses. Fifty-one of the 64 (80%) patients who had relapse received maintenance therapy, including MMF (41), RTX (11), maintenance intravenous immunoglobulin (two), and tocilizumab (two). The annualized relapse rates decreased significantly after treatment in both the RTX and MMF cohorts (P < 0.05); however, there were no significant differences between the two groups (P = 0.56). A total of 178 (94%) patients had complete (175 patients) or almost complete (three patients) recovery (modified Rankin scale [mRS] < 2), and 12 had moderate to severe deficits (mRS ≥ 2).

CONCLUSIONS

The spectrum of pediatric MOGAD is broader than previously reported and includes demyelinating syndromes and encephalitis. Encephalitis is an important initial phenotype observed in pediatric patients with MOGAD.

Mapping the global research landscape and trends of autoimmune encephalitis: A bibliometric analysis

Background

Autoimmune encephalitis (AE) is a neuroautoimmune disease featured by the presence of antibodies targeting neuronal surface, synaptic, or intracellular antigens. An increasing number of articles on its clinical manifestations, treatments, and prognosis have appeared in recent years. The objectives of this study were to summarize this growing body of literature and provide an overview of hotspots and trends in AE research using bibliometric analysis.

Methods

We retrieved AE-related articles published between 1999 and 2022 from the Web of Science Core Collection. Using bibliometric websites and software, we analyzed the data of AE research, including details about countries, institutions, authors, references, journals, and keywords.

Results

We analyzed 3348 articles, with an average of 32.83 citations per article and an H-index of 141. The USA (1091, 32.587%), China (531, 15.860%), Germany (447, 13.351%), England (266, 7.945%), and Japan (213, 6.362%) had the greatest numbers of publications. The top five institutions by numbers of publications were Oxford (143, 4.271%), the Udice French Research Universities (135, 4.032%), the University of Pennsylvania (135, 4.032%), l'Institut National de la Sante de la Recherche Medicale Inserm (113, 3.375%), and the University of Barcelona (110, 3.286%). The most productive authors were J. Dalmau (98, 2.927%), A. Vincent (65, 2.479%), H. Pruess (64, 1.912%), C. G. Bien (43, 1.284%), and F. Graus (43, 1.284%). "autoimmune encephalitis" was the most frequently used keyword (430), followed by "antibodies" (420), "NMDA receptor encephalitis" (383), and "limbic encephalitis" (368). In recent years, research hotspots have focused on the diagnosis and immunotherapy of NMDAR encephalitis and on limbic encephalitis.

Conclusion

Developed Western countries have made significant contributions to this field. China has shown a steady increase in the number of publications in recent years, but the quality and influence of these articles warrant efforts at improvement. Future directions in AE research lie in two key areas: (i) the clinical manifestations, prevalence, and prognosis of AE (enabled by advances in diagnosis); and (ii) the efficacy and safety of targeted, individualized immunotherapy.

Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults

Autoimmune encephalitis is increasingly recognized as a neurologic cause of acute mental status changes with similar prevalence to infectious encephalitis. Despite rising awareness, approaches to diagnosis remain inconsistent and evidence for optimal treatment is limited. The following Canadian guidelines represent a consensus and evidence (where available) based approach to both the diagnosis and treatment of adult patients with autoimmune encephalitis. The guidelines were developed using a modified RAND process and included input from specialists in autoimmune neurology, neuropsychiatry and infectious diseases. These guidelines are targeted at front line clinicians and were created to provide a pragmatic and practical approach to managing such patients in the acute setting.

Anti-N-methyl-D-aspartate receptor-associated encephalitis: A review of clinicopathologic hallmarks and multimodal imaging manifestations

Anti-N-methyl-D-aspartate receptor-associated encephalitis (NMDARE) is a rare immune-mediated neuroinflammatory condition characterized by the rapid onset of neuropsychiatric symptoms and autonomic dysfunction. The mechanism of pathogenesis remains incompletely understood, but is thought to be related to antibodies targeting the GluN1 subunit of the NMDA receptor with resultant downstream dysregulation of dopaminergic pathways. Young adults are most frequently affected; the median age at diagnosis is 21 years. There is a strong female predilection with a female sex predominance of 4:1. NMDARE often develops as a paraneoplastic process and is most commonly associated with ovarian teratoma. However, NMDARE has also been described in patients with small cell lung cancer, clear cell renal carcinoma, and other benign and malignant neoplasms. Diagnosis is based on correlation of the clinical presentation, electroencephalography, laboratory studies, and imaging. Computed tomography, positron emission tomography, and magnetic resonance imaging are essential to identify an underlying tumor, exclude clinicopathologic mimics, and predict the likelihood of long-term functional impairment. Nuclear imaging may be of value for prognostication and to assess the response to therapy. Treatment may involve high-dose corticosteroids, intravenous immunoglobulin, and plasma exchange. Herein, we review the hallmark clinicopathologic features and imaging findings of this rare but potentially devastating condition and summarize diagnostic criteria, treatment regimens, and proposed pathogenetic mechanisms.