Clinical approach to the diagnosis of autoimmune encephalitis in the pediatric patient

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.

Child Neurology: Creatine Biosynthesis Disorder in an Adolescent With Capgras Syndrome and Reduplicative Paramnesia

This case report and discussion pertain to a 17-year-old female patient with developmental delay and acute onset of psychosis, diagnosed with guanidinoacetate methyltransferase (GAMT) deficiency, a rare creatine biosynthesis disorder. The patient experienced auditory hallucinations, paranoia, and delusional misidentification syndromes (Capgras syndrome and reduplicative paramnesia), following a viral respiratory illness. The neurologic examination was nonfocal but included intermittent negative myoclonus, generalized stiff movements, and a mechanical gait, which initially suggested catatonia or autoimmune encephalitis. MRI of the brain was normal, as was her CSF profile, although EEG revealed diffuse slowing with frequent generalized spike waves. Sequential empiric treatments for catatonia and autoimmune encephalitis provided limited benefit. Subsequent biochemical and genetic testing confirmed GAMT deficiency, supported by a markedly decreased creatine peak on MR spectroscopy of the brain. This case highlights GAMT deficiency as a consideration in young patients with neuropsychiatric symptoms, particularly psychosis with atypical motor findings and a history of developmental delay. The rare presentation of delusional misidentification symptoms expands the spectrum of clinical findings described in patients with GAMT deficiency, a rare disorder reported in at least 130 individuals to date. Treatment with creatine and ornithine supplementation led to marked improvement, returning her incrementally toward baseline functioning. This case broadens the understanding of GAMT deficiency's phenotypic range and underscores the importance of metabolic testing in tandem with or closely following empiric but unsuccessful treatment trials, even when the initial clinical presentation suggests primary psychiatric, autoimmune, or inflammatory etiologies.

Pediatric anti-CaVα2δ autoimmune encephalitis: A case report and literature review

Anti-voltage-gated calcium channel alpha-2/delta subunit (anti-CaVα2δ) encephalitis is a rare autoimmune encephalitis (AE), with only two cases of anti-CaVα2δ AE have been reported in the literatureto date. The clinical characteristics and prognosis of this rare AE need to beexpanded.We present the case of a 9-year-oldgirl, who initially presented with fever and lymphadenitis, which progressed to headaches, drowsiness, frequent seizures, cognitive impairment, memory loss, and involuntary movements. Brain magnetic resonance imaging revealed lesions in the bilateral external capsule. Moreover, anti-CaVα2δ antibodies were detected (1,30) 3 and 5 weeks after symptom onset. Video electroencephalography revealed slow, severely diffuse, background activity with multifocal epileptiform discharges. Although the patient was administered a combined immunotherapy consisting of intravenous immunoglobulin, intravenous methylprednisolone, and rituximab, sheexhibited persistent neurological sequelae at the last follow-up (Modified Rankin Scale score of 4; Pediatric Quality of Life Inventory score of 75). Whileour case shares similar clinical characteristics with previously reported anti-CaVα2δ AE cases, our patientwas unresponsive to immunotherapy and experienced severe neurological sequelae during follow-up. This report broadens the clinical phenotype and prognosis associated with this rare condition, providing further information and clinical insights for the management of future cases.

Towards an optimal diagnostic and prognostic model based on semi-quantitative assessment of 18F-FDG PET in children with autoimmune encephalitis

Purpose

The metabolic pattern in autoimmune encephalitis (AE) has been frequently reported. Through this semi-quantitative analysis, we aim to explore a practical diagnostic model based on positron emission tomography (PET) for timely diagnosis of pediatric AE with high accuracy. Moreover, we aim to identify factors that affect the prognosis of pediatric AE and explore the utility of PET as a prognostic biomarker.

Method

Data were collected from 93 AE patients and 67 non-AE patients (age range: 1-18 years old). Semi-quantitative parameters of 18F-FDG PET imaging were evaluated, including the score of cortical lesion extent and the ratios of lesion-to-basal ganglia and thalamus. The Clinical Assessment Scale in Autoimmune Encephalitis (CASE) was used to rate the disease severity and long-term outcome. Multivariate statistical analysis was used to establish a diagnostic model and analyze predictors.

Results

The diagnostic model includes three PET parameters. The sensitivity, specificity, and accuracy of the model are 91.4%, 85.1%, and 88.8%, respectively. Participants were followed up for a median of 34 months. Logistic regression analysis indicated that male, initial CASE score >4.5,memory dysfunction, and the ratio of the maximum SUV of the lesion to thalamus (SUVRmaxL/T) < 0.577 are independent factors associated with poor prognosis in AE. We established a prognostic model through these predictors.

Conclusion

18F-FDG PET plays a vital role in the diagnosis and prognosis of AE. The PET-based diagnostic model has higher specificity and accuracy than visual analysis. The prognostic model is a useful predictive tool for the long-term prognosis of children with AE.

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.

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.

Differences in innate immune cell populations distinguish autoimmune from herpesvirus-associated encephalitis

BACKGROUND

Autoimmune encephalitis (AIE) is a disabling inflammatory condition of the brain deemed to be due to a dysregulated immune response. Viral infections and malignancies together with certain genetic polymorphisms are thought to contribute to the pathogenesis of AIE, yet the exact mechanisms remain insufficiently understood. Diagnosis of AIE currently relies on clinical consensus criteria. However, diagnostic workup can be challenging in some cases, potentially delaying treatment initiation associated with poor clinical outcomes. This study aims to investigate the systemic and intrathecal immune cell profiles of AIE in comparison to viral meningoencephalitis (VME) as a clinically relevant differential diagnosis and evaluate its diagnostic and therapeutic potential.

METHODS

97 mainly treatment-naïve AIE patients, 47 patients with VME, and 109 somatic symptom disorder (SD) controls were included. Analysis of peripheral blood (PB) and cerebrospinal fluid (CSF) immune cell profiles was performed using multidimensional flow cytometry (mFC) in combination with novel computational approaches.

RESULTS

We were able to identify alterations in the adaptive B and T cell-mediated immune response in AIE compared to SD controls which correspond to respective changes in the brain parenchyma. AIE and VME exhibit similar patterns of adaptive B and T cell responses and differ in pattern of innate immunity especially NK cells. MFC together with routine CSF parameters can differentiate AIE from VME and SD controls implying diagnostic potential.

CONCLUSION

AIE is characterized by a B and T cell-mediated systemic and intrathecal immune-cell signature which corresponds to changes reported in the brain parenchyma providing insights into immunopathogenesis. Differences between AIE and VME were most prominent for the innate immune response indicating a potential role of NK cells in the pathogenesis of autoimmunity. Our data provides evidence that mFC could be a novel complementary approach to the diagnosis of AIE with diagnostic, therapeutic, and prognostic implications.

Autoimmune Encephalitis

Autoimmune encephalitides (AE) constitute a broad group of inflammatory brain disorders characterized by prominent neuropsychiatric symptoms, frequently in association with autoantibodies against neural (neuronal or glial) antigens. The most frequent AE are anti-NMDA receptor encephalitis, acute disseminated encephalomyelitis (associated with MOG antibodies in 60% of patients), and limbic encephalitis (with several immunologic subtypes, anti-LGI1 encephalitis being the most frequent). The first 2 predominantly affect children and young adults, whereas limbic encephalitis usually affects patients older than 50 years. Despite the severity of symptoms, prompt diagnosis and treatment lead to substantial recovery in most patients.

Caloric requirement targets for nutritional support in adult autoimmune encephalitis: a retrospective cohort study

BACKGROUND

Autoimmune encephalitis (AE) is a severe neurological disease often accompanied by consciousness disturbances, severe swallowing difficulties, and gastrointestinal dysfunction, increasing the risk of malnutrition. However, the optimal caloric intake target during the acute phase of AE remains unclear.

OBJECTIVE

This study aims to evaluate the impact of caloric intake on short-term clinical outcomes in AE patients, specifically focusing on the improvement in Clinical Assessment Scale for Autoimmune Encephalitis (CASE) scores, to provide recommendations for nutritional support during the acute phase.

METHODS

A retrospective study analyzed clinical data from 128 adult AE patients requiring nutritional support, admitted to West China Hospital, Sichuan University, from January 2020 to January 2024. Patients were categorized into low-calorie intake (below 70% of requirements), standard-calorie intake (70-100% of requirements), and high-calorie intake (above 100% of requirements) groups. Multivariate linear and logistic regression models were used to quantify the associations.

RESULTS

Higher caloric intake was significantly associated with improved CASE scores (β = 8.58, SE = 3.75, 95% CI = 1.14 to 16.03, p = 0.02). Low caloric intake negatively impacted the improvement of CASE scores (p = 0.049), particularly in seizures and speech problems. The low-calorie intake group had significantly longer hospital stays and nutrition therapy durations (45.79 ± 30.98 days, p < 0.01; 40.39 ± 31.92 days, p = 0.02).

CONCLUSIONS

Adequate caloric intake has a significant positive impact on the short-term clinical outcomes of AE patients, suggesting that meeting or exceeding caloric requirements may promote neurological recovery in AE patients. Future prospective studies are needed to validate these findings and further optimize nutritional support strategies.

Clinical features, diagnosis, and treatment of pembrolizumab induced autoimmune encephalitis

Pembrolizumab has shown links to autoimmune encephalitis (AE), yet the exact clinical characteristics remain unclear. This study examines the clinical features of pembrolizumab-induced AE to enhance diagnostic accuracy and therapeutic strategies. Reports on pembrolizumab-induced AE were gathered via a searchable database, culminating on November 30, 2024. The median age at onset among the 34 patients was 68 years (range 47-82), with males constituting 67.6%. The average onset period for AE was 6 months (range 0.3-25) after the initial dose, with an average of 6 cycles (range 1-17). Commonly reported symptoms included confusion (38.2%), fever (35.3%), and decreased consciousness (32.4%). Cerebrospinal fluid analysis revealed elevated protein (55.9%), leukocytosis (70.6%), and normal blood glucose levels (38.2%). Antineuronal antibodies were found to be negative in 41.2% of cases and positive in 35.3%. Magnetic resonance imaging indicated T2/FLAIR hypersignal in 32.4% of cases, while the electroencephalogram revealed slow waves (11.8%) and diffuse slowing (11.8%). Following treatment with steroids, intravenous immunoglobulin, and plasmapheresis, 82.4% of patients experienced symptom improvement or recovery, though 5.9% succumbed to AE. Oncologists must consider the risk of AE when prescribing pembrolizumab. Early diagnosis and intervention for AE are crucial. Further research is needed to define the optimal treatment approach.

Coexistence of Anti-GAD and Anti-GABAAR Antibodies in an Autoimmune Encephalitis Patient: A Case Report

Background

Coexistence of autoimmune encephalitis (AE) with multiple autoantibodies is of particular concern because overlying antibodies may cause variation of clinical manifestations. Coexistence of anti-glutamic acid decarboxylase (GAD) and anti-Gamma-aminobutyric acid-α-receptor (GABAAR) antibodies in AE was rare.

Case Presentation

A 44-year-old female patient presented to our hospital due to cognitive decline for 4 years, seizures, slowed speech and depression for 2 months. Based on her clinical manifestations and laboratory assessment results (positive anti-GAD and anti-GABAAR antibodies), she was diagnosed as AE with coexisting anti-GAD and anti-GABAAR antibodies. After treatment with intravenous methylprednisolone (at dose of 1000mg/d, 500mg/d, 250mg/d, 120mg/d, 80mg/d for 3 days respectively) and intravenous immunoglobulin (400 mg/kg/d for 5 days), her symptoms gradually improved with exception for the slowed speech. Oral prednisone acetate was continued after discharge, her symptoms of slowed speech improved at 6-month follow-up.

Conclusion

We report a case of AE co-existing with anti-GAD and anti-GABAAR antibodies, which has different characteristics from previous cases. Coexistence of neural auto-antibodies should be considered when patients suspected with autoimmune encephalitis.

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.

IL-17 in serum and cerebrospinal fluid of pediatric patients with acute neuropsychiatric disorders: Implications for PANDAS and PANS

BACKGROUND

Acute neuropsychiatric disorders are heterogeneous conditions resulting from interaction between genetic and environmental features. Among these, post infectious forms like Pediatric Acute-onset Neuropsychiatric Syndrome (PANS) and Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) are common. Preclinical studies suggest a role of CNS T-helper-17/interleukin-17 (IL-17) inflammatory mediated response in the pathogenesis of these disorders. We analyze serum and cerebral-spinal fluid (CSF)-IL-17 concentrations in a cohort of patients with acute neuropsychiatric disease.

METHODS

We retrospectively included patients <14 years with acute neuropsychiatric symptoms from 2016 to 2020. IL-17 was determined on serum and CSF by means of quantitative sandwich enzyme immunoassay technique, and values were compared to serum and CSF controls. Variables were identified using univariate analysis with Pearson's regression test and X2 test.

RESULTS

58 subjects were included (67.8 % males, average age: 8.5 years). 50.8 % were classified as PANDAS, 11.8 % as PANS. Mean concentrations of serum IL-17 were higher in the study group compared to controls (p < 0.0001). We observe a trend of increasing IL-17 in post-pubertal children both on serum (p = 0.05) and on CSF (p = 0.04). Coupled IL-17 concentration were higher in the CSF than in serum (p = 0.003), with a marked significance in the PANDAS and PANS group (p < 0.001).

CONCLUSION

IL-17 is elevated in children and adolescents with acute neuropsychiatric conditions, both on serum and CSF. IL-17 could be involved in the pathogenesis of acute neuropsychiatric disorders in childhood. Further studies are necessary to validate its potential role as a diagnostic or prognostic biomarker.

Differential diagnosis and comparison of diagnostic algorithms in children and adolescents with autoimmune encephalitis in Spain: a prospective cohort study and retrospective analysis

BACKGROUND

The usefulness of current diagnostic approaches in children with suspected autoimmune encephalitis is unknown. We aimed to assess the diagnosis of autoimmune encephalitis in clinical practice and to compare the performance of two international diagnostic algorithms (one intended for patients of any age [general], the other intended for paediatric patients), with particular emphasis on the evaluation of patients with probable antibody-negative autoimmune encephalitis because this diagnosis suggests that immunotherapy should be continued or escalated but is difficult to establish.

METHODS

We did a prospective cohort study that included all patients (<18 years of age) with suspected autoimmune encephalitis recruited at 40 hospitals in Spain whose physicians provided clinical information every 6 months for 2 years or more. Neural antibody testing to confirm diagnosis of antibody-positive autoimmune encephalitis was done at Institut d'Investigacions Biomèdiques August Pi i Sunyer-Hospital Clínic, Barcelona. Patients were classified according to the most probable diagnosis at last follow-up into four prespecified categories. We used multivariable logistic analysis to assess a potential association between immunotherapy and outcome in individuals with probable antibody-negative autoimmune encephalitis. We also did a retrospective analysis of agreement, assessed with the kappa index, between diagnoses made according to the general and paediatric diagnostic algorithms.

FINDINGS

Between June 1, 2013, and May 31, 2021, 729 children (mean age 7·1 years [SD 4·9]; 383 boys [53%], 346 girls [47%]) with suspected autoimmune encephalitis were recruited. After a median follow-up of 36 months (IQR 26-60), patients were classified according to their most probable diagnosis: definite autoimmune encephalitis or well defined inflammatory or autoimmune disorders (n=230 [32%]); CNS infections (n=112 [15%]); inflammatory CNS disorders of unknown cause (n=81 [11%], including three (4%) with a novel Klüver-Bucy-like syndrome; and non-inflammatory disorders (n=306 [42%]), which were predominantly epileptic or psychiatric disorders (177 [58%] of 306). Neural antibodies were detected in 150 (65%) of 230 patients who had definite autoimmune encephalitis; 127 (85%) of these 150 individuals had antibodies to the NMDA receptor or myelin oligodendrocyte glycoprotein (MOG). Agreement between algorithms was excellent (kappa index 0·99, 95% CI 0·97-1·00) for the diagnosis of children with antibody-positive autoimmune encephalitis, good (0·59, 0·54-0·65) for recommendations of empiric immunotherapy, and poor (0·29, 0·21-0·37) for the diagnosis of probable antibody-negative autoimmune encephalitis. Compared with the general algorithm, the paediatric algorithm included more patients in the probable antibody-negative autoimmune encephalitis category (173 vs 41). These patients included some of those who had a diagnosis of CNS inflammatory disorder of unknown cause at the last follow-up (80 of 81 with the paediatric algorithm vs 31 of 81 with the general algorithm), who might have benefitted from immunotherapy, and some of those diagnosed with a non-inflammatory disorder at the last follow-up (47 of 306 with the paediatric algorithm vs six of 306 with the general algorithm), who did not need immunotherapy.

INTERPRETATION

About a third of children with suspected autoimmune encephalitis eventually had confirmation of this diagnosis, or diagnosis of another well defined inflammatory disorder. Frequent mimics of autoimmune encephalitis were infectious, epileptic, and psychiatric disorders. Both algorithms performed well in the diagnosis of antibody-positive autoimmune encephalitis, but the paediatric algorithm under-recognised definite autoimmune encephalitis that can occur without autoantibodies and might have overdiagnosed patients with probable antibody-negative autoimmune encephalitis. By contrast, the general algorithm might have underdiagnosed patients with probable antibody-negative autoimmune encephalitis. Given that the diagnosis of probable antibody-negative autoimmune encephalitis has treatment implications, inaccuracies on this diagnostic category leads to overuse or underuse of immunotherapy.

FUNDING

Instituto de Salud Carlos III, Fundació Clínic per la Recerca Biomèdica, The Edmond J Safra Foundation, and la Caixa Foundation.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Pediatric Neuroimaging of Multiple Sclerosis and Neuroinflammatory Diseases

Using a pediatric-focused lens, this review article briefly summarizes the presentation of several demyelinating and neuroinflammatory diseases using conventional magnetic resonance imaging (MRI) sequences, such as T1-weighted with and without an exogenous gadolinium-based contrast agent, T2-weighted, and fluid-attenuated inversion recovery (FLAIR). These conventional sequences exploit the intrinsic properties of tissue to provide a distinct signal contrast that is useful for evaluating disease features and monitoring treatment responses in patients by characterizing lesion involvement in the central nervous system and tracking temporal features with blood-brain barrier disruption. Illustrative examples are presented for pediatric-onset multiple sclerosis and neuroinflammatory diseases. This work also highlights findings from advanced MRI techniques, often infrequently employed due to the challenges involved in acquisition, post-processing, and interpretation, and identifies the need for future studies to extract the unique information, such as alterations in neurochemistry, disruptions of structural organization, or atypical functional connectivity, that may be relevant for the diagnosis and management of disease.

D-Serine May Ameliorate Hippocampal Synaptic Plasticity Impairment Induced by Patients' Anti-N-methyl-D-aspartate Receptor Antibodies in Mice

Objective: To establish a mouse model of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis and assess the potential therapeutic benefits of D-serine supplementation in mitigating synaptic plasticity impairments induced by anti-NMDAR antibodies. Methods: Anti-NMDAR antibodies were purified from cerebrospinal fluid (CSF) samples of patients diagnosed with anti-NMDAR encephalitis and verified using a cell-based assay. CSF from patients with non-inflammatory neurological diseases served as the control. These antibodies were then injected intraventricularly into C57BL/6 mice. Forty-eight hours following the injection, mice were administered either D-serine (500 mg/kg) or sterile saline intraperitoneally for three consecutive days. Subsequent analyses included Western blotting, immunofluorescence, electrophysiological studies, and a series of behavioral tests to assess pathological changes caused by anti-NMDAR antibodies. Results: Mice injected with anti-NMDAR antibodies exhibited a significant reduction in hippocampal long-term potentiation compared to controls, which was notably ameliorated by D-serine treatment. Additionally, these mice displayed decreased levels of hippocampal membrane NMDAR1 protein and postsynaptic NMDAR1 density. However, D-serine administration did not significantly alter these conditions. Notably, no significant behavioral differences were observed between mice injected with anti-NMDAR antibodies and controls in open fields, elevated plus maze, novel object recognition, or Morris water maze tests. Conclusions: Our findings indicate that exogenous D-serine can improve hippocampal plasticity impairments caused by anti-NMDAR antibodies but does not reverse the decreased expression of NMDAR. Furthermore, a single intraventricular injection of patients' antibodies was insufficient to induce anti-NMDAR encephalitis-related behaviors in mice.

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.

Rate of Autoimmune Encephalitis in Children With First-Episode Psychosis

BACKGROUND

Autoimmune encephalitis (AE) can present as first-episode psychosis (FEP) in children. An FEP diagnostic algorithm has been proposed, but how this algorithm applies to children is unknown. We assess the FEP diagnostic algorithm in children with FEP.

METHODS

The FEP algorithm was applied to a retrospective cohort of children with FEP without other neurological symptoms.

RESULTS

Twenty-four patients were included, with five AE (anti-N-methyl-d-aspartate receptor encephalitis) and 19 non-AE patients (12 primary psychiatric, two headaches, mycoplasma-related encephalitis, post-coronavirus disease 2019 encephalitis, drug reaction with eosinophilia and systemic symptoms [DRESS] syndrome, cobalamin C deficiency, and two unknown). Some non-AE patients (five of 19 = 26%) received immunotherapies, with symptom resolution in one of five (20%) with immunotherapy and in four of 14 (29%) without immunotherapy. The FEP algorithm recommended cerebrospinal fluid (CSF) testing in all (five of five = 100%) patients with AE and in six of 19 (32%) non-AE patients, resulting in 100% sensitivity (95% confidence interval [CI]: 100% to 100%) and 45.5% specificity (95% CI: 16% to 75%), with a negative predictive value of 100% (95% CI: 100% to 100%).

CONCLUSIONS

FEP can occur in children from different causes, including AE and metabolic conditions. Evaluation of FEP should be broad, especially without CSF evidence of inflammation. The FEP algorithm is useful to assess patients who would benefit from CSF testing and should be assessed in larger cohorts.

Frequency of anti-MOG antibodies in serum and CSF of patients with possible autoimmune encephalitis: Results from a Brazilian multicentric study

INTRODUCTION

MOGAD encephalitis and ADEM share several clinical features with autoimmune encephalitis (AE) associated with antineuronal antibodies (ANeA); nonetheless, treatment and prognosis differ. Anti-MOG antibodies (abs) are not routinely tested in possible AE, and epidemiological studies on MOGAD encephalitis are scarce.

OBJECTIVES

To determine the frequency of anti-MOG abs in the serum and CSF in a cohort of possible AE and to compare the clinical characteristics of MOGAD patients and those with seropositive AE.

METHODS

481 patients with possible AE from the Brazilian Autoimmune Encephalitis Network underwent tissue-based assay and cell-based assay (CBA) for ANeA. Anti-MOG abs were assessed in serum and CSF with in-house CBA. Clinical and laboratory characteristics of MOGAD and seropositive AE patients were compared.

RESULTS

Of the 481 patients, 87 (18 %) had ANeA, and 17 (3.5 %) had anti-MOG abs. Three AE patients with anti-MOG abs and ANeA were excluded from further analysis. Anti-MOG abs were detected in 4 (1.2 %) of the 328 adults and 10 (6.5 %) of the 153 children. Of the 14 patients with MOGAD, nine had ADEM (mostly children), and five had encephalitis (including three adults). Only one patient with ADEM had anti-MOG abs exclusively in CSF. All patients with MOGAD encephalitis were seropositive for anti-MOG abs, and three had normal brain MRI. Patients with MOGAD had fewer behavioral changes (MOGAD 21 % x AE 96 %, p ≤ 0.0001) and movement disorders (MOGAD 42 % x AE 81 %, p = 0.0017) and more demyelinating symptoms, such as myelitis and optic neuritis (MOGAD 14 % x AE 0 %, p = 0.013).

CONCLUSION

Approximately 3.5 % of patients with possible AE harbor anti-MOG abs, and 0.9 % of the adults had MOGAD encephalitis. Anti-MOG abs were more frequent than other ANeAs regularly tested in AE. We provide evidence that MOGAD is a differential diagnosis in possible AE, even in adult patients with normal brain MRI, and that serum anti-MOG should be considered as an add-on diagnostic tool in AE among adults and pediatric patients.

Pediatric MOG-Ab-Associated Encephalitis: Supporting Early Recognition and Treatment

BACKGROUND AND OBJECTIVES

Antibodies to myelin oligodendrocyte glycoprotein (MOG-Ab) have recently been reported in patients with encephalitis who do not fulfill criteria for acute disseminated encephalomyelitis (ADEM). We evaluated a cohort of these children and compared them with children with ADEM.

METHODS

This retrospective, multicenter cohort study comprised consecutive patients <18 years of age with MOG-Ab who fulfilled criteria for autoimmune encephalitis. These patients were stratified into (1) children not fulfilling criteria for ADEM (encephalitis phenotype) and (2) children with ADEM. Clinical/paraclinical data were extracted from the electronic records. Comparisons were made using the Mann-Whitney U test and χ2 Fisher exact test for statistical analysis.

RESULTS

From 235 patients with positive MOG-Ab, we identified 33 (14%) with encephalitis and 74 (31%) with ADEM. The most common presenting symptoms in children with encephalitis were headache (88%), seizures (73%), and fever (67%). Infective meningoencephalitis was the initial diagnosis in 67%. CSF pleocytosis was seen in 79%. Initial MRI brain was normal in 8/33 (24%) patients. When abnormal, multifocal cortical changes were seen in 66% and unilateral cortical changes in 18%. Restricted diffusion was demonstrated in 43%. Intra-attack new lesions were seen in 7/13 (54%). When comparing with children with ADEM, children with encephalitis were older (median 8.9 vs 5.7 years, p = 0.005), were more likely to be admitted to intensive care (14/34 vs 4/74, p < 0.0001), were given steroid later (median 16.6 vs 9.6 days, p = 0.04), and were more likely to be diagnosed with epilepsy at last follow-up (6/33 vs 1/74, p = 0.003).

DISCUSSION

MOG-Ab should be tested in all patients with suspected encephalitis even in the context of initially normal brain MRI. Although exclusion of infections should be part of the diagnostic process of any child with encephalitis, in immunocompetent children, when herpes simplex virus CSF PCR and gram stains are negative, these features do not preclude the diagnosis of immune mediated disease and should not delay initiation of first-line immunosuppression (steroids, IVIG, plasma exchange), even while awaiting the antibody results.

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.

Social network characteristics and their relationships with physical activity in children with multiple sclerosis

BACKGROUND

Physical activity has been found to associate with improved health outcomes in children with multiple sclerosis (MS). Social networks may facilitate physical activity in children with MS.

OBJECTIVES

To estimate associations between social network characteristics and physical activity in children with MS compared to children with monophasic acquired demyelinating syndrome (mono-ADS).

METHODS

Children with MS and mono-ADS recruited from the Hospital for Sick Children completed questionnaires on social network and physical activity. Descriptive and inferential analyses estimated differences between cohorts and correlations.

RESULTS

Children with MS (n = 16) and mono-ADS (n = 22) did not differ in outcomes. Higher physical activity associated with larger social networks (rs= 0.681, p < 0.01), more Emotional Support (rs= 0.604, p < 0.05), Camaraderie (rs= 0.585, p < 0.05), more social network members with post-secondary education (rs= 0.680, p < 0.05), and members who exercise 3 to 4 times a week (rs= 0.744, p < 0.01). These associations were not found in children with mono-ADS.

CONCLUSION

Larger social network size, more emotional support and camaraderie, and more individuals with post-secondary education and who regularly exercise in the social network associated with higher physical activity in children with MS. Social network characteristics may help understand health behaviors in children with MS.

Decompressive craniectomy in the acute fulminant cerebral edema

Acute fulminant cerebral edema is a type of rapidly progressive encephalitis that occurs in children and is associated with significant morbidity and mortality. We present a clinical case with seizures, rapid neurological deterioration and the early appearance of cerebral herniation signs. Although the radiological tests were initially normal and there are no established parameters that predict the evolution of encephalitis to a rapidly progressive subtype, the clinical evolution forced to consider the decompressive craniectomy due to the lack of response to the medical management of the cerebral edema. It may be necessary take a brain biopsy to confirm the etiology of the encephalitis origin of acute fulminant cerebral edema. The objective of surgery should be not only to increase survival, but also to reduce subsequent neurological sequelae.

Paediatric antibody prevalence in seizure score to predict autoimmune aetiology in seizure disorders

AIM

To modify the antibody prevalence in epilepsy (APE) score of children with suspected autoimmune central nervous system disease with seizures.

METHODS

We retrospectively analysed the cerebrospinal fluid of 157 children (aged 0-18 years) with suspected autoimmune central nervous system disease for antineuronal antibodies in our laboratory from 2016 to 2023. Participants were randomly divided into the development cohort (n = 79, 35 females; median 7 years, SD 4 years 7 months, range 4-11 years) and validation cohort (n = 78, 28 females; median 7 years, SD 4 years 5 months, range 4-12 years). A paediatric antibody prevalence in seizure (PAPS) score was created for one cohort and evaluated in the other. Seven variables were selected through univariate and multivariate analysis to create a PAPS score.

RESULTS

One hundred and fifty-seven children who fulfilled the inclusion criteria were enrolled; 49 tested positive for antineuronal antibodies. The sensitivity and specificity of an APE score of 4 and greater were 92% and 22.2% respectively; the sensitivity and specificity of a PAPS score of 2.5 and greater were 83.3% and 77.8% respectively. The area under the curve was 0.832 (95% confidence interval = 0.743-0.921), which was significantly better than that for the APE score (p < 0.001).

INTERPRETATION

The APE score had high sensitivity but low specificity in children. The PAPS score may be useful for determining the need for antineuronal antibody testing.

WHAT THIS PAPER ADDS

The antibody prevalence in epilepsy (APE) score had high sensitivity but low specificity in children. The sensitivity and specificity of the paediatric antibody prevalence in seizure (PAPS) score were 83.3% and 77.8% respectively. There were significant differences in the area under the curve for the APE and PAPS scores.

Seronegative autoimmune encephalitis in children: What's in a name?

This commentary is on the original article by Madani et al. on pages 1310–1318 of this issue.

Clinical features and outcomes in children with seronegative autoimmune encephalitis

AIM

To characterize the presenting features and outcomes in children with seronegative autoimmune encephalitis, and to evaluate whether scores at nadir for the Modified Rankin Scale (mRS) and Clinical Assessment Scale for Autoimmune Encephalitis (CASE) or its paediatric-specific modification (ped-CASE) are predictive of outcomes.

METHOD

This observational study included children younger than 18 years of age with seronegative autoimmune encephalitis. Demographics and clinical data were collected. The mRS and CASE/ped-CASE scores were used to evaluate disease severity. Descriptive statistics and logistic regression were used for data analysis and to evaluate associations between scale scores and outcomes.

RESULTS

Sixty-three children were included (39 [62%] females, median age 7 years, interquartile range [IQR] 4 years 1 months-11 years 6 months), with follow-up available for 56 out of 63 patients (median follow-up 12.2 months, IQR 13.4-17.8). The most frequent presenting neurological manifestation was encephalopathy (81%). Median CASE/ped-CASE and mRS scores at nadir were 12.0 (IQR 7.0-17.0) and 1.0 (IQR 0-2.0) respectively. Thirty-three patients (59%) had persistent neurological deficits at follow-up. Both scoring systems suggested good functional recovery (mRS score ≤2, 95%; CASE/ped-CASE score <5, 91%). CASE/ped-CASE score was more likely than mRS to distinguish children with worse outcomes.

INTERPRETATION

Children with seronegative autoimmune encephalitis are likely to have neurological deficits at follow-up. CASE/ped-CASE is more likely to distinguish children with worse outcomes than MRS.

WHAT THIS PAPER ADDS

Encephalopathy was the most common reason for presentation in children with seronegative autoimmune encephalitis. Children with seronegative autoimmune encephalitis are likely to have neurological deficits at follow-up. The Clinical Assessment Scale for Autoimmune Encephalitis or its paeditric version at nadir was better at distinguishing children with poor outcomes than the Modified Rankin Scale.

B-cell Depletion Therapy in Pediatric Neuroinflammatory Disease

PURPOSE OF REVIEW

B-cell depletion therapy, including anti-CD20 and anti-CD19 therapies, is increasingly used for a variety of autoimmune and conditions, including those affecting the central nervous system. However, B-cell depletion therapy use can be complicated by adverse effects associated with administration and immunosuppression. This review aims to summarize the application of anti-CD20 and anti-CD19 therapies for the pediatric neurologist and neuroimmunologist.

RECENT FINDINGS

Most existing literature come from clinical trials with adult patients, although more recent studies are now capturing the effects of these therapies in children. The most common side effects include infusion related reactions and increased infection risk from immunosuppression. Several strategies can mitigate infusion related reactions. Increased infections due to persistent hypogammaglobulinemia can benefit from replacement immunoglobulin. B-cell depletion therapies can be safe and effective in pediatric patients. Anticipation and mitigation of common adverse effects through primary prevention strategies, close monitoring, and appropriate symptomatic management can improve safety and tolerability.

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.

Cognitive impairments in autoimmune encephalitis: the role of autoimmune antibodies and oligoclonal bands

Introduction

The presence of oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) is a pivotal diagnostic marker for multiple sclerosis (MS). These bands play a crucial role in the diagnosis and understanding of a wide array of immune diseases. In this study, we explore the relationship between the cognitive profile of autoimmune encephalitis (AIE) and the presence of OCBs in CSF, with a particular emphasis on NMDA receptor antibodies.

Methods

We studied a cohort of 21 patients across five tertiary centers, segregated into two distinct categories. One group comprised individuals who tested positive only for autoimmune encephalitis antibodies indicative of encephalitis, while the other group included patients whose CSF was positive for both autoimmune encephalitis antibodies and OCBs. Our investigation focused primarily on cognitive functions and behavioral alterations, supplemented by auxiliary diagnostic assessments such as CSF cell count, magnetic resonance imaging (MRI), and electroencephalogram (EEG) results, evaluated for the two patient groups. To validate our findings, we employed statistical analyses such as Fisher's exact test with Benjamini-Hochberg correction.

Results

Our study included 21 patients, comprising 14 who were presented with only autoimmune encephalitis antibodies, and 7 who were dual-positive. Among these patients, we focused on those with NMDA receptor antibodies. Of these, five were dual positive, and nine were positive only for NMDA receptor antibodies. The dual-positive NMDA group, with an average age of 27 ± 16.47 years, exhibited significantly higher CSF cell counts (p=0.0487) and more pronounced language and attention deficits (p= 0.0264). MRI and EEG results did not differ significantly between the groups.

Conclusions

Our results point to OCBs as an additional marker of disease severity in AIE, especially in NMDA receptor-antibody positive patients, possibly indicating a broader inflammatory process, as reflected in elevated CSF lymphocytes. Regular testing for OCBs in cases of suspected AIE may aid in disease prognosis and identification of patients more prone to language and attention disorders, improving diagnosis and targeting treatment for these cognitive aspects.

Genotype-driven therapeutics in DEE and metabolic epilepsy: navigating treatment efficacy and drug resistance

Neonatal intensive care unit (NICU), particularly in treating developmental and epileptic encephalopathy (DEE) and metabolic epilepsy (ME), requires a deep understanding of their complex etiologies and treatment responses. After excluding treatable cases such as infectious or autoimmune encephalitis, our focus shifted to a more challenging subgroup of 59 patients for in-depth genetic analysis using exome sequencing (ES). The ES analysis identified 40 genetic abnormalities, significantly including de novo variants. Notably, we found structural variation as duplications in regions 2q24.3, including SCN1A and SCN2A were observed in 7 cases. These genetic variants, impacting ion channels, glucose transport, transcription regulation, and kinases, play a crucial role in determining medication efficacy. More than one-third (34.2%) of patients with DEE had an unfavorable response to anti-seizure medications (ASMs) in the chronic phase. However, since the ketogenic supplementary diet showed a positive effect, more than three-quarters (80%) of these drug-resistant patients improved during a 3-month follow-up. In contrast, the ME had a lower adverse reaction rate of 9.1% (2/22) to specialized medications, yet there were 5 fatalities and 10 cases with unidentified genetic etiologies. This study suggests the potential of categorizing drug-resistant variants and that a ketogenic diet could be beneficial in managing DEE and ME. It also opens new perspectives on the mechanisms of the ketogenic diet on the discovered genetic variants.

Prognostic factors and treatment outcomes in pediatric autoimmune encephalitis: a multicenter study

Introduction

The last few decades have increased our understanding of autoimmune encephalitis (AE). In both the pediatric and adult populations, it proves to be a disease of dramatic acute onset of heterogeneous clinical manifestations, notably encephalopathy with neuropsychiatric symptoms, seizures, and extrapyramidal symptoms. More often, it is triggered by a viral infection in the pediatric age groups, as suggested by the preceding febrile symptoms in over half of cases, and more ostensibly, NMDAR encephalitis post herpes encephalitis. An underlying neoplasm may be present in certain types (i.e., NMDAR encephalitis). The rising rate of antibody detection and subsequent confirmation has been boosted by improved live cellular assay detection methods. The corresponding clinical phenotypes, common underlying malignancies, and histopathological findings have helped improve our management regarding intervention and choice of immunotherapy. New assessment tools such as the Clinical Assessment Scale in Autoimmune Encephalitis (CASE score) have helped improve the objective assessment of impact on cognitive functions (1). Early intervention with immunotherapy (and tumor removal in proven underlying neoplasms) has improved overall outcomes in most presenting patients. But nearly 40% of cases fail to respond to the first tier of treatment (2). The complex interplay between pathogenic autoantibodies, T-cells, B-cells, and cytokines has led to the emergence of additional immunotherapy agents (i.e., tocilizumab and bortezomib).

Methods

In this retrospective observational study of pediatric AE conducted at two tertiary care centers, we observed the clinical characteristics, autoantibody yield, treatment modalities used, and disability scores during presentation and follow-up. Our secondary aim was to delineate prognostic factors for poor outcomes.

Results

Neuropsychiatric symptoms, encephalopathy, and seizures were the predominant manifestations in most of our patients. Younger age groups, refractory seizures, profound encephalopathy, and refractory disease harbored higher disability scores. The group that received combined immunotherapy has shown mitigation of disability score from severe to mild during long-term follow-up, signifying the role of multifaceted immunotherapy in pediatric refractory AE.

Conclusion

Early implementation of combined immunotherapy in refractory cases significantly improved longterm disability scores, in spite of lingering residual effects on neurologic functions, notably cognition, behavior, and speech.

Uncommon Pediatric Immune-Mediated Epilepsy: Disease Course, Diagnosis, and Outcome - A Series of Three Cases

Immune-mediated epilepsy (IME) constitutes a substantial proportion of drug-refractory epilepsies. Rapid diagnosis and prompt immunosuppression are required along with antiseizure medications (ASMs). Here we report three unrelated children who presented with fever, encephalopathy, and refractory epilepsy and subsequently tested positive for rare intraneuronal and surface receptor antibodies, namely, contactin-associated protein like 2 (CASPR2), glutamic acid decarboxylase (GAD65), and paraneoplastic antigen Ma2 (PNMA2). In all of them, brain magnetic resonance imaging (MRI) was noncontributory. Electroencephalography showed nonspecific interictal epileptic discharges. F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) brain scan revealed abnormality in metabolic pattern with hypermetabolism in basal ganglia, thalami, frontotemporal cortices, and cerebellar hemispheres, consistent with autoimmune encephalitis. Immunosuppression was initiated along with ASMs. Complete seizure freedom was achieved in GAD65 antibody IME and >50% seizure reduction in CASPR2 and PNMA2 antibody IME. A variable degree of behavioral problems persisted in all. Early immunosuppression is warranted in IME, but does not universally guarantee a complete response.

Clinical characteristics and long-term outcome of CASPR2 antibody-associated autoimmune encephalitis in children

BACKGROUND

Contactin-associated protein-2(CASPR2) antibody-associated autoimmune encephalitis(AE) is rare in children. This study aimed to report the clinical characteristics and long-term outcome of CASPR2 autoimmunity in children to expand the disease spectrum.

METHODS

Children who were hospitalized in our hospital with clinically suspected AE from May 2015 to April 2022 and underwent neuronal surface antibodies detections were retrospectively analyzed. Clinical data of patients with CASPR2 autoimmunity were collected.

RESULTS

Patients who were positive for NMDAR-IgG, CASPR2-IgG, LGI1-IgG and IgLON5-IgG occupied 95.2%(119/125),3.2%(4/125),0.8%(1/125) and 0.8%(1/125), respectively.The median onset age of the 4 patients with CASPR2-IgG was 5.6 years. The most common symptoms were psychiatric symptoms/abnormal behavior(3/4) and sleep dysfunction(3/4). One patient developed a phenotype of Rasmussen encephalitis(RE). Tumor was absent in our patients. Two patients showed abnormal findings on initial brain magnetic resonance imaging(MRI) scans. All the patients showed favorable response to immunotherapy except the patient with RE experienced recurrent symptoms who finally achieved remission after surgery. All the patients had a favorable long-term outcome at the last follow-up(33-58months).

CONCLUSIONS

CASPR2 autoimmunity may be the second most common anti-neuronal surface antibodies associated neurological disease in children. Psychiatric symptoms/abnormal behavior and sleep disorder were common in children with CASPR2-associated AE. Tumor was rare in those patients. Most pediatric patients had a favorable long-term outcome.

Cerebrospinal fluid characteristics of patients presenting for evaluation of pediatric acute-neuropsychiatric syndrome

Objectives

This study characterizes cerebral spinal fluid (CSF) indices including total protein, the albumin quotient, IgG index and oligoclonal bands in patients followed at a single center for pediatric acute-neuropsychiatric syndrome (PANS) and other psychiatric/behavioral deteriorations.

Methods

In a retrospective chart review of 471 consecutive subjects evaluated for PANS at a single center, navigational keyword search of the electronic medical record was used to identify patients who underwent lumbar puncture (LP) as part of the evaluation of a severe or atypical psychiatric deterioration. Psychiatric symptom data was ascertained from parent questionnaires and clinical psychiatric evaluations. Inclusion criteria required that subjects presented with psychiatric deterioration at the time of first clinical visit and had a lumbar puncture completed as part of their evaluation. Subjects were categorized into three subgroups based on diagnosis: PANS (acute-onset of severe obsessive compulsive disorder (OCD) and/or eating restriction plus two other neuropsychiatric symptoms), autoimmune encephalitis (AE), and "other neuropsychiatric deterioration" (subacute onset of severe OCD, eating restriction, behavioral regression, psychosis, etc; not meeting criteria for PANS or AE).

Results

71/471 (15.0 %) of patients underwent LP. At least one CSF abnormality was seen in 29% of patients with PANS, 45% of patients with "other neuropsychiatric deterioration", and 40% of patients who met criteria for autoimmune encephalitis. The most common findings included elevated CSF protein and/or albumin quotient. Elevated IgG index and IgG oligoclonal bands were rare in all three groups.

Conclusion

Elevation of CSF protein and albumin quotient were found in pediatric patients undergoing LP for evaluation of severe psychiatric deteriorations (PANS, AE, and other neuropsychiatric deteriorations). Further studies are warranted to investigate blood brain barrier integrity at the onset of the neuropsychiatric deterioration and explore inflammatory mechanisms.

Examining cognition and brain networks using magnetoencephalography in paediatric autoimmune encephalitis and acute disseminated encephalomyelitis: a preliminary study

Paediatric autoimmune encephalitis, including acute disseminated encephalomyelitis, are inflammatory brain diseases presenting with cognitive deficits, psychiatric symptoms, seizures, MRI and EEG abnormalities. Despite improvements in disease recognition and early immunotherapy, long-term outcomes in paediatric autoimmune encephalitis remain poor. Our aim was to understand functional connectivity changes that could be associated with negative developmental outcomes across different types of paediatric autoimmune encephalitis using magnetoencephalography. Participants were children diagnosed with paediatric autoimmune encephalitis at least 18 months before testing and typically developing children. All completed magnetoencephalography recording at rest, T1 MRI scans and neuropsychology testing. Brain connectivity (specifically in delta and theta) was estimated with amplitude envelope correlation, and network efficiency was measured using graph measures (global efficiency, local efficiency and modularity). Twelve children with paediatric autoimmune encephalitis (11.2 ± 3.5 years, interquartile range 9 years; 5M:7F) and 12 typically developing controls (10.6 ± 3.2 years, interquartile range 7 years; 8M:4F) participated. Children with paediatric autoimmune encephalitis did not differ from controls in working memory (t(21) = 1.449; P = 0.162; d = 0.605) but had significantly lower processing speed (t(21) = 2.463; P = 0.023; Cohen's d = 1.028). Groups did not differ in theta network topology measures. The paediatric autoimmune encephalitis group had a significantly lower delta local efficiency across all thresholds tested (d = -1.60 at network threshold 14%). Theta modularity was associated with lower working memory (β = -0.781; t(8) = -2.588, P = 0.032); this effect did not survive correction for multiple comparisons (P(corr) = 0.224). Magnetoencephalography was able to capture specific network alterations in paediatric autoimmune encephalitis patients. This preliminary study demonstrates that magnetoencephalography is an appropriate tool for assessing children with paediatric autoimmune encephalitis and could be associated with cognitive outcomes.

Review of the Longitudinal Management of Autoimmune Encephalitis, Potential Biomarkers, and Novel Therapeutics

Purpose of Review

Increasing awareness and earlier diagnosis of autoimmune encephalitis (AE) have led to a greater number of patients being cared for longitudinally by neurologists. Although many neurologists are now familiar with the general approach to diagnosis and acute immunosuppression, this review aims to provide neurologists with guidance related to management beyond the acute phase of disease, including long-term immunosuppression, monitoring, potential biomarkers of disease activity, outcome measures, and symptom management.

Recent Findings

Observational studies in AE have demonstrated that early diagnosis and treatment is associated with improved neurologic outcomes, particularly in AE with antibodies targeting neuronal cell surface/synaptic proteins. The literature regarding long-term management is evolving. In addition to traditional immunosuppressive approaches, there is emerging use of novel immunosuppressive therapies (ISTs) in case series, and several randomized controlled trials are planned. Novel biomarkers of disease activity and methods to measure outcomes and response to treatment are being explored. Furthermore, it is increasingly recognized that many individuals have chronic symptoms affecting quality of life including seizures, cognitive impairment, fatigue, sleep disorders, and mood disorders, and there are emerging data supporting the use of patient centered outcome measures and multidisciplinary symptom-based care.

Summary

This review aims to summarize recent literature and offer a practical approach to long-term management of adult patients with AE through a multidisciplinary approach. We summarize current knowledge on ISTs, potential biomarkers of disease activity, outcome measures, and long-term sequelae. Further research is needed to answer questions regarding optimal IST, biomarker validity, and sequelae of disease.

Identification of etiologies according to baseline clinical features of pediatric new-onset refractory status epilepticus in single center retrospective study

PURPOSE

New-onset refractory status epilepticus (NORSE) is defined as a state of prolonged seizure activity that does not improve despite the appropriate administration of medications, with underlying causes unknown after the initial diagnosis of status epilepticus. Because episodes of NORSE are accompanied by severe complications and a high risk of mortality, the prompt identification of the underlying cause is crucial for effective treatment and outcome prediction. This study assessed the relationship of NORSE etiologies with baseline clinical features in pediatric population.

METHODS

Seventy-one pediatric patients, under 18 years of age at the initial diagnosis (4.50 ± 4.04, mean ± standard deviation), who experienced at least one episode of NORSE and underwent a comprehensive diagnostic evaluation between January 2005 and June 2020 at our center, were retrospectively selected. We reviewed clinical features at disease onset and long-term follow-up data. Uniform manifold approximation and projection (UMAP) was used to distinguish etiological clusters according to baseline clinical characteristics, and further analysis was performed based on underlying etiologies.

RESULTS

Two distinct etiological groups-genetic and non-genetic-were identified based on the UMAP of clinical characteristics. Dravet syndrome (12/15, 80%) was more predominant in patients with a genetic diagnosis, whereas cryptogenic NORSE and encephalitis were prevalent in patients without a genetic diagnosis. The analysis of etiological categories revealed that age at the onset of status epilepticus (P=0.021) and progression to super refractory status epilepticus (SRSE) (P=0.038) were independently associated with differences in etiologies.

CONCLUSION

Several clinical features in patients with NORSE, including the age of onset and the development of SRSE, can help identify underlying causes, which necessitate prompt and adequate treatment.

Autoimmune-associated seizure disorders

With the discovery of an expanding number of neural autoantibodies, autoimmune etiologies of seizures have been increasingly recognized. Clinical phenotypes have been identified in association with specific underlying antibodies, allowing an earlier diagnosis. These phenotypes include faciobrachial dystonic seizures with LGI1 encephalitis, neuropsychiatric presentations associated with movement disorders and seizures in NMDA-receptor encephalitis, and chronic temporal lobe epilepsy in GAD65 neurologic autoimmunity. Prompt recognition of these disorders is important, as some of them are highly responsive to immunotherapy. The response to immunotherapy is highest in patients with encephalitis secondary to antibodies targeting cell surface synaptic antigens. However, the response is less effective in conditions involving antibodies binding intracellular antigens or in Rasmussen syndrome, which are predominantly mediated by cytotoxic T-cell processes that are associated with irreversible cellular destruction. Autoimmune encephalitides also may have a paraneoplastic etiology, further emphasizing the importance of recognizing these disorders. Finally, autoimmune processes and responses to novel immunotherapies have been reported in new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES), warranting their inclusion in any current review of autoimmune-associated seizure disorders.

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.

Autoimmune glial fibrillary acidic protein astrocytopathy with anti-NMDAR and sulfatide-IgG-positive encephalitis overlap syndrome: A case report and literature review

RATIONALE

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a rare autoimmune disease of the central nervous system that affects the meninges, brain, spinal cord, and optic nerves. GFAP astrocytopathy can coexist with a variety of antibodies, which is known as overlap syndrome. Anti-NMDAR-positive encephalitis overlap syndrome has been reported; however, encephalitis overlap syndrome with both anti-NMDAR and sulfatide-IgG positivity has not been reported.

PATIENT CONCERNS

The patient was a 50-year-old male who was drowsy and had chills and weak limbs for 6 months. His symptoms worsened after admission to our hospital with persistent high fever, dysphoria, gibberish, and disturbance of consciousness. Positive cerebrospinal fluid NMDA, GFAP antibodies, and serum sulfatide antibody IgG were positive.

DIAGNOSES

Autoimmune GFAP astrocytopathy with anti-NMDAR and sulfatide-IgG-positive encephalitis overlap syndrome.

INTERVENTIONS

In addition to ventilator support and symptomatic supportive treatment, step-down therapy with methylprednisolone (1000 mg/d, halved every 3 days) and pulse therapy with human immunoglobulin (0.4 g/(kg d) for 5 days) were used.

OUTCOMES

After 6 days of treatment, the patient condition did not improve, and the family signed up to give up the treatment and left the hospital.

CONCLUSIONS

Patients with autoimmune GFAP astrocytopathy may be positive for anti-NMDAR and sulfatide-IgG, and immunotherapy may be effective in patients with severe conditions.

LESSONS

Autoimmune GFAP astrocytopathy with nonspecific symptoms is rarely reported and is easy to be missed and misdiagnosed. GFAP astrocytopathy should be considered in patients with fever, headache, disturbance of consciousness, convulsions, and central infections that do not respond to antibacterial and viral agents. Autoimmune encephalopathy-related antibody testing should be performed as soon as possible, early diagnosis should be confirmed, and immunomodulatory therapy should be administered promptly.

A systematic review of the epidemiology of pediatric autoimmune encephalitis: disease burden and clinical decision-making

Background

Autoimmune encephalitis (AIE) comprises a group of rare, immune system-mediated conditions. Clinical manifestations among children are not well-characterized, and there are challenges in testing and diagnosis. This can result in treatment delays, which has been found to correlate with poorer long-term outcomes. This challenge is exacerbated by the scarcity of epidemiological reporting of AIE. The objective of this systematic literature review (SLR) was to identify studies reporting epidemiological data on AIE in children.

Methods

MEDLINE, Embase, the Cochrane Library, and the University of York Centre for Reviews and Dissemination (CRD) were searched in May 2023 for studies reporting on the epidemiology of AIE in children. These were supplemented with additional searches of conference proceedings, gray literature, and the reference lists of identified SLRs. Quality of studies was assessed using a modified version of the Joanna Briggs Institute (JBI) Checklist for Prevalence Studies.

Results

Forty-three publications reporting on 41 unique studies were included. Nine studies reported incidence estimates of different subtypes of AIE, with only one reporting the incidence of overall AIE in children ≤ 18 years, estimated at 1.54 per million children per year in the Netherlands. Three studies reported the incidence of pediatric N-methyl-D-aspartate receptor (NMDAR)-AIE [in United Kingdom (UK), Hong Kong, and Denmark]. The other studies reported incidence data for selected populations.

Conclusion

This SLR highlights a paucity of epidemiology data for AIE in children, which is likely reflective of difficulties in testing and diagnosis. There is a clear need for further research and awareness of these challenges in clinical practice to avoid treatment delays and improve patient outcomes. A deeper understanding of the epidemiology of AIE will help determine the worldwide burden of disease and inform research, health policies and clinical decision-making.