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

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.

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.

Neuronal nicotinic acetylcholine receptor antibodies in autoimmune central nervous system disorders

Background

Neuronal nicotinic acetylcholine receptors (nAChRs) are abundant in the central nervous system (CNS), playing critical roles in brain function. Antigenicity of nAChRs has been well demonstrated with antibodies to ganglionic AChR subtypes (i.e., subunit α3 of α3β4-nAChR) and muscle AChR autoantibodies, thus making nAChRs candidate autoantigens in autoimmune CNS disorders. Antibodies to several membrane receptors, like NMDAR, have been identified in autoimmune encephalitis syndromes (AES), but many AES patients have yet to be unidentified for autoantibodies. This study aimed to develop of a cell-based assay (CBA) that selectively detects potentially pathogenic antibodies to subunits of the major nAChR subtypes (α4β2- and α7-nAChRs) and its use for the identification of such antibodies in "orphan" AES cases.

Methods

The study involved screening of sera derived from 1752 patients from Greece, Turkey and Italy, who requested testing for AES-associated antibodies, and from 1203 "control" patients with other neuropsychiatric diseases, from the same countries or from Germany. A sensitive live-CBA with α4β2-or α7-nAChR-transfected cells was developed to detect antibodies against extracellular domains of nAChR major subunits. Flow cytometry (FACS) was performed to confirm the CBA findings and indirect immunohistochemistry (IHC) to investigate serum autoantibodies' binding to rat brain tissue.

Results

Three patients were found to be positive for serum antibodies against nAChR α4 subunit by CBA and the presence of the specific antibodies was quantitatively confirmed by FACS. We detected specific binding of patient-derived serum anti-nAChR α4 subunit antibodies to rat cerebellum and hippocampus tissue. No serum antibodies bound to the α7-nAChR-transfected or control-transfected cells, and no control serum antibodies bound to the transfected cells. All patients positive for serum anti-nAChRs α4 subunit antibodies were negative for other AES-associated antibodies. All three of the anti-nAChR α4 subunit serum antibody-positive patients fall into the AES spectrum, with one having Rasmussen encephalitis, another autoimmune meningoencephalomyelitis and another being diagnosed with possible autoimmune encephalitis.

Conclusion

This study lends credence to the hypothesis that the major nAChR subunits are autoimmune targets in some cases of AES and establishes a sensitive live-CBA for the identification of such patients.

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.

Clinical analysis and literature review of two paediatric cases of anti-IgLON5 antibody-related encephalitis

Introduction

Anti-IgLON5 antibody-related encephalitis is a rare autoimmune disorder of the central nervous system, predominantly occurring in middle-aged elderly individuals, with paediatric cases being exceptionally rare. This study aims to enhance the understanding of paediatric anti-IgLON5 antibody-related encephalitis by summarising its clinical and therapeutic characteristics.

Method

A retrospective analysis was conducted on two paediatric patients diagnosed with anti-IgLON5 antibody-related encephalitis at Hunan Children's Hospital from August 2022 to November 2023. This involved reviewing their medical records and follow-up data, in addition to a literature review.

Results

The study involved two patients, one male and one female, aged between 2.5 and 9.6 years, both presenting with an acute/subacute course of illness. Clinically, both exhibited movement disorders (including dystonia, involuntary movements, and ataxia), cognitive impairments, sleep disturbances, and psychiatric symptoms. Patient 1 experienced epileptic seizures, while Patient 2 exhibited brainstem symptoms and abnormal eye movements. Neither patient showed autonomic dysfunction. Patient 1 had normal cerebrospinal fluid (CSF) and Brain MRI findings, whereas Patient 2 showed moderate leukocytosis and mild protein elevation in the CSF, and Brain MRI revealed symmetrical lesions in the basal ganglia and cerebellum. Oligoclonal bands in the CSF were positive in both cases. Both patients tested negative for HLA-DQB*05:01 and HLA-DRB*10:01. They received both first-line and second-line immunotherapies, with Patient 2 showing a poor response to treatment.

Discussion

Paediatric cases of anti-IgLON5 antibody-related encephalitis similarly present sleep disturbances as a core symptom, alongside various forms of movement disorders. Immunotherapy is partially effective. Compared to adult patients, these paediatric cases tend to exhibit more pronounced psychiatric symptoms, a more rapid onset, and more evident inflammatory changes in the CSF. The condition appears to have a limited association with HLA-DQB*05:01 and HLA-DRB*10:01 polymorphisms.

Genetic causes of infection induced encephalitis

INTRODUCTION

Patients with encephalitis following a viral infection are often thought to have a para infectious, inflammatory, or autoimmune cause for their presentation. These diagnoses usually result in treatments with immunosuppressant therapies which can have side effects. However, there is an increasing body of evidence demonstrating that patients can have a direct genetic cause mediating viral infection triggered encephalitis, where inflammation is a secondary response. These patients may benefit not from immunosuppressive therapies, but from protection from infection through dedicated immunisation programs and early antiviral therapies at times of infection.

METHODS

A small case series of paediatric neurology patients (n = 2) from a single institution with infection induced encephalitis and an underlying genetic cause, is presented. Patients with a confirmed genetic cause of infection induced encephalitis were identified and consented by their treating neurologist for inclusion in this case series. Ethics approval was gained for this case series and review of the surrounding literature.

CONCLUSION

A case of both DBR1 and NUP214 genetic changes resulting in infection induced encephalitis is presented. This case series raises awareness of this rare group of disorders and provides clues to their identification. Features to prompt clinician consideration of such genetic conditions are also highlighted. Although rare, identification of these patients is important due to implications on treatment, prognosis, and family planning.

Steroid-Responsive Involuntary Movements as a Remote Symptom of Febrile Infection-Related Epilepsy Syndrome

Febrile infection-related epilepsy syndrome (FIRES) is a rare epileptic encephalopathy that occurs in children or adolescents. To date, evidence for the management of the post-acute phase of FIRES is focused on drug-resistant epilepsy that continues from the acute phase. Information on involuntary movements, which are newly developed in the chronic phase, is limited. We report a 13-year-old boy, who had a history of FIRES at nine years of age and experienced worsening seizure control that was accompanied by unremitting involuntary　movements after two years of a fairly controlled period. The involuntary movements resulted in motor deterioration and forced him to be bedridden. Although no neuronal autoantibodies were detected, we hypothesized that the boy's neurological deterioration was triggered by an autoimmune response based on the elevation of serum anti-glutamic acid decarboxylase and serum anti-thyroid peroxidase antibodies and hypermetabolism of bilateral lenticular nuclei on 18-fluorodeoxyglucose positron emission tomography that resembled those reported in patients with other types of autoimmune encephalitis. Serial methylprednisolone pulse therapy and intravenous immunoglobulin therapy ameliorated involuntary movements and improved his activities of daily living. Late-onset involuntary movements, along with seizure exacerbation, may appear in the chronic phase of FIRES. Immunotherapy could be effective in treating these symptoms.

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 antibody profiles and clinical characteristics of children with suspected autoimmune encephalitis

AIM

To identify the spectrum of autoimmune encephalitis antibody biomarkers (AE-Abs) in children with suspected autoimmune encephalitis and explore the clinical features indicating AE-Abs presence.

METHOD

We included children with suspected autoimmune encephalitis who underwent AE-Abs tests at the Children's Hospital of Chongqing Medical University between June 2020 and June 2022. Clinical features suggestive of AE-Abs were analysed based on AE-Abs test results.

RESULTS

A total of 392 children were tested for AE-Abs with suspected autoimmune encephalitis. Of these, 49.5% were male, with a median age of 7 years 11 months (6 months-17 years 11 months); 93.6% (367/392) of all patients had both serum and cerebrospinal fluid (CSF) tests performed. The antibody-positive rate in the cohort was 23.7% (93/392), the serum antibody-positive rate was 21.9% (84/384), and the CSF antibody-positive rate was 20.8% (78/375). Eleven different AE-Abs were detected. Serum analysis revealed that N-methyl-D-aspartate receptor immunoglobulin-G (NMDAR-IgG) (15.1%) was greater than myelin oligodendrocyte glycoprotein (MOG)-IgG (14.6%) and glial fibrillary acidic protein (GFAP)-IgG (3.3%). CSF analysis revealed that NMDAR-IgG (16.3%) was greater than MOG-IgG (13.8%) and GFAP-IgG (3.3%). Compared with antibody-negative patients, antibody-positive patients were more often female (odds ratio [OR] 1.86, p = 0.03), with memory impairment (OR 2.91, p = 0.01) and sleep disorders (OR 2.08, p = 0.02).

INTERPRETATION

In children, the most frequent AE-Abs detected were NMDAR-IgG and MOG-IgG. Female sex, memory impairment, and sleep disorders predict a higher likelihood of AE-Abs.

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 Autoimmune Encephalitis Post-COVID-19 Vaccination in a Pediatric Patient: A Case Report

Post-coronavirus disease 2019 (COVID-19) vaccination encephalitis is rarely reported particularly in the pediatric population. Herein, we report the first case of postvaccination anti-N-methyl-d-aspartate (NMDA) encephalitis in close temporal association with receiving COVID-19 vaccine in a pediatric patient. The patient is a 13-year-old female who received the first dose of the Pfizer-BioNTech COVID-19 vaccine and presented with subacute neurological and psychiatric symptoms and eventually confirmed the diagnosis of anti-NMDA autoimmune encephalitis. The patient recovered after receiving intravenous immunoglobulins and steroids.

Autoimmune central nervous system disorders: Antibody testing and its clinical utility

A rapidly expanding repertoire of neural antibody biomarkers exists for autoimmune central nervous system (CNS) disorders. Following clinical recognition of an autoimmune CNS disorder, the detection of a neural antibody facilitates diagnosis and informs prognosis and management. This review considers the phenotypes, diagnostic assay methodologies, and clinical utility of neural antibodies in autoimmune CNS disorders. Autoimmune CNS disorders may present with a diverse range of clinical features. Clinical phenotype should inform the neural antibodies selected for testing via the use of phenotype-specific panels. Both serum and cerebrospinal fluid (CSF) are preferred in the vast majority of cases but for some analytes either CSF (e.g. N-methyl-D-aspartate receptor [NMDA-R] IgG) or serum (e.g. aquaporin-4 [AQP4] IgG) specimens may be preferred. Screening using 2 methods is recommended for most analytes, particularly paraneoplastic antibodies. We utilize murine tissue-based indirect immunofluorescence assay (TIFA) with subsequent confirmatory protein-specific testing. The cellular location of the target antigen informs choice of confirmatory diagnostic assay (e.g. blot for intracellular antigens such as Hu; cell-based assay for cell surface targets such as leucine-rich glioma inactivated 1 [LGI1]). Titers of positive results have limited diagnostic utility with the exception of glutamic acid decarboxylase (GAD) 65 IgG autoimmunity, which is associated with neurological disease at higher values. While novel antibodies are typically discovered using established techniques such as TIFA and immunoprecipitation-mass spectrometry, more recent high-throughput molecular technologies (such as protein microarray and phage-display immunoprecipitation sequencing) may expedite the process of antibody discovery. Individual neural antibodies inform the clinician regarding the clinical associations, oncological risk stratification and tumor histology, the likely prognosis, and immunotherapy choice. In the era of neural antibody biomarkers for autoimmune CNS disorders, access to appropriate laboratory assays for neural antibodies is of critical importance in the diagnosis and management of these disorders.

Postacute Sequelae of SARS-CoV-2 in Children

The coronavirus disease 2019 (COVID-19) pandemic has caused significant medical, social, and economic impacts globally, both in the short and long term. Although most individuals recover within a few days or weeks from an acute infection, some experience longer lasting effects. Data regarding the postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection (PASC) in children, or long COVID, are only just emerging in the literature. These symptoms and conditions may reflect persistent symptoms from acute infection (eg, cough, headaches, fatigue, and loss of taste and smell), new symptoms like dizziness, or exacerbation of underlying conditions. Children may develop conditions de novo, including postural orthostatic tachycardia syndrome, myalgic encephalomyelitis/chronic fatigue syndrome, autoimmune conditions and multisystem inflammatory syndrome in children. This state-of-the-art narrative review provides a summary of our current knowledge about PASC in children, including prevalence, epidemiology, risk factors, clinical characteristics, underlying mechanisms, and functional outcomes, as well as a conceptual framework for PASC based on the current National Institutes of Health definition. We highlight the pediatric components of the National Institutes of Health-funded Researching COVID to Enhance Recovery Initiative, which seeks to characterize the natural history, mechanisms, and long-term health effects of PASC in children and young adults to inform future treatment and prevention efforts. These initiatives include electronic health record cohorts, which offer rapid assessments at scale with geographical and demographic diversity, as well as longitudinal prospective observational cohorts, to estimate disease burden, illness trajectory, pathobiology, and clinical manifestations and outcomes.

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.

Anti-NMDAR Encephalitis Clinical Practice Guideline: Improving Time to Diagnosis, Treatment, and Hospital Length of Stay

Background and Objectives

A clinical practice guideline (CPG) was created to standardize evaluation and treatment for patients with suspected anti-methyl-d-aspartate receptor (NMDAR) autoimmune encephalitis (AE), the most common AE in children. The objective of this study was to evaluate the CPG effect on time to diagnosis, treatment, and hospital length of stay (LOS).

Methods

Patients with an inpatient consult to pediatric rheumatology for AE during a 4-year period (period 2) after CPG implementation were identified. Data were extracted and compared with data over the preceding 4-year period (period 1).

Results

During period 1, fewer patients underwent diagnostic testing than during period 2 (34 vs 80). Number of patients diagnosed with AE did not differ from period 1 to that from period 2 (NMDAR AE 9 vs 8; seronegative AE 4 vs 5). The average time to diagnostic evaluation with lumbar puncture decreased from 5.4 to 1.5 days (p = 0.0082), and time to treatment decreased from 7.6 to 3.9 days (p = 0.018). LOS showed a trend toward improvement (40.4-29.2 days (p = 0.23)).

Discussion

Creation of a CPG for patients with suspected AE was associated with an improved time to diagnostic evaluation and treatment. With the CPG, more patients underwent AE testing, though total diagnoses remained the same.

Brain magnetic resonance imaging as predictors in pediatric anti-N-methyl-D-aspartate receptor encephalitis

OBJECTIVE

To investigate the associations between brain magnetic resonance imaging (MRI) changes and clinical profiles in children with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis.

METHODS

Clinical data and brain MRI results of children diagnosed with anti-NMDAR encephalitis in Guangzhou Women and Children's Medical Center from October 2014 to June 2022 were retrospectively studied.

RESULTS

A total of 143 children (Male: female 54:89) were enrolled, with a mean onset age of 6.8 years (6.8 ± 3.1). 40.6 % (58/143) of patients had abnormal initial brain MRI. Lesions in temporal lobe (34.5 %, 20/58) and frontal lobe (25.9 %, 15/58) were relatively common. Children with abnormal initial brain MRI were prone to have fever (P = 0.023), dystonia (P = 0.037), positive MOG antibodies (P = 0.015), higher cerebrospinal fluid (CSF) white blood cell count (WBC) (P = 0.019) and to receive rituximab treatment (P = 0.037). There were no significant differences in modified Rankin Scale (mRS) scores before immunotherapy, after immunotherapy and at last follow-up between the normal initial brain MRI group and abnormal group. No initial brain MRI changes were found to be associated with relapses. Brain MRI was reviewed in 72 patients at last follow-up with a median follow-up time of 25.5 months and 48.6 % (35/72) of patients had abnormal brain MRI. The mRS score of the group with normal brain MRI at last follow-up was significantly lower than that of the abnormal group.

CONCLUSIONS

About 40.0 % of children with anti-NMDAR encephalitis had abnormal initial brain MRI. Initial brain MRI was associated with certain clinical profiles, but not with relapse and prognosis. Around half of patients had abnormal brain MRI at last follow-up and were prone to have higher mRS score.

Co-existence of anti-glutamic acid decarboxylase-65 and anti-sry-like high-mobility group box receptor antibody-associated autoimmune encephalitis: A rare case report

Autoimmune encephalitis (AE) has been increasingly recognized in children. An 11-year-old Saudi boy presented with prodromal symptoms of fever and headache followed by behavioral changes, cognitive impairment, and focal seizures. Cerebrospinal fluid (CSF) analysis showed pleocytosis. Brain magnetic resonance imaging showed T2/fluid-attenuated inversion recovery hyperintensities involving the temporal, parietal and frontal lobes. Electroencephalography revealed diffuse encephalopathy and electrographic seizures. AE was suspected; intravenous methylprednisolone and immunoglobulin were administered. Autoantibodies against glutamic acid decarboxylase-65 were detected in his serum and CSF and against Sry-like high- mobility group box 1 in his serum only. The patient was diagnosed with seropositive AE and favorably responded to intensive immunosuppressive therapy.

Electroencephalography in encephalopathy and encephalitis

Electroencephalography (EEG) is a useful adjunct to clinical neurological examination, particularly as it may detect subtle or subclinical disturbance of cerebral function and it allows monitoring of cerebral activity over time. Continuous EEG combined with quantitative analysis and machine learning may help identify changes in real time, before the emergence of clinical signs and response to interventions. EEG is rarely pathognomonic in encephalopathy/encephalitis but when interpreted correctly and within the clinical context, certain phenotypes may indicate a specific pathophysiology (eg, lateralised periodic discharges in HSV-1, generalised periodic discharges in sporadic Creutzfeldt-Jakob disease, and extreme delta brushes in anti-n-methyl-D-aspartate receptor autoimmune encephalitis). EEG is included in some specialist guidelines for disease assessment, monitoring and prognostication (ie, hepatic, cancer immunotherapy, viral, prion, autoimmune encephalitis and hypoxic ischaemic encephalopathy). EEG is invaluable for confirming or excluding non-convulsive seizures or status epilepticus, particularly in critically ill patients, and in understanding new concepts such as epileptic encephalopathy and the ictal-interictal continuum.

Sudden-Onset Acute Obsessive-Compulsive Disorder Associated with Streptococcus and Brain MRI Hyperintensity in a Young Adult

BACKGROUND

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal (strep) infections (PANDAS) are a recognized medical entity among children. But evidence for strep-mediated sudden-onset obsessive-compulsive disorder (OCD) in young adults is very limited. Delayed strep assessment and treatment may negatively impact clinical outcomes.

METHODS

We describe a young adult with acute sudden-onset OCD (age 24), treated unsuccessfully with medication and therapy for 3 years. At age 27, antistreptolysin-O (ASO) was tested, based on extensive pediatric history of strep infections. Antibiotic treatment was initiated.

RESULTS

Magnetic resonance imaging (MRI) identified a new temporal lobe hyperintensity at OCD onset (age 24), which persisted at ages 25 and 30. ASO titers were elevated from age 27 through 29. Following Amoxicillin treatment, ASO initially increased. Subsequent Amoxicillin + Clavulin treatment produced improved OCD symptoms and treatment response, with no adverse effects.

CONCLUSION

These results strongly suggest an association among strep infection, neuro-inflammation and sudden-onset OCD in this young adult whose response to medication and therapy was successful only after high-dose antibiotic intervention. Greater OCD remission potential may be possible with earlier identification and antibiotic treatment than 3 years post OCD onset. These findings add to the limited literature on strep as an etiology of the sudden-onset of OCD in young adults. They also lend urgency to increased frontline awareness for early strep and ASO assessment in sudden-onset acute OCD among young adults.

Rituximab for Pediatric Central Nervous System Inflammatory Disorders in Alberta, Canada

BACKGROUND

Early and effective treatment of central nervous system (CNS) inflammatory disorders is vital to reduce neurologic morbidity and improve long-term outcomes in affected children. Rituximab is a B-cell-depleting monoclonal antibody whose off-label use for these disorders is funded in the province of Alberta, Canada, by the Short-Term Exceptional Drug Therapy (STEDT) program. This study describes the use of rituximab for pediatric CNS inflammatory disorders in Alberta.

METHODS

Rituximab applications for CNS inflammatory indications in patients <18 years of age were identified from the STEDT database between January 1, 2012, and December 31, 2019. Patient information was linked to other provincial datasets including the Discharge Abstract Database, Pharmaceutical Information Network, and Provincial Laboratory data. Analysis was descriptive.

RESULTS

Fifty-one unique rituximab applications were identified, of which 50 were approved. New applications increased from one in 2012 to a high of 12 in 2018. The most common indication was autoimmune encephalitis without a specified antibody (n = 16, 31%). Most children were approved for a two-dose (n = 33, 66%) or four-dose (n = 16, 32%) induction regimen. Physician-reported outcomes were available for 24 patients, of whom 14 (58%) were felt to have fully met outcome targets.

CONCLUSION

The use of rituximab for pediatric CNS inflammatory disorders has increased, particularly for the indication of autoimmune encephalitis. This study identified significant heterogeneity in dosing practices and laboratory monitoring. Standardized protocols for the use of rituximab in these disorders and more robust outcome reporting will help better define the safety and efficacy of rituximab in this population.

Consultation-Liaison Case Conference: Systemic Challenges in Management of Aggression in a Pediatric Patient With Seronegative Autoimmune Encephalitis

We present the case of a 9-year-old girl who presented to a tertiary-care academic children's hospital with acute onset of severe obsessive-compulsive symptoms, perseveration, grimacing, and personality changes with resultant agitation. Extensive multidisciplinary workup led to a diagnosis of seronegative autoimmune encephalitis. The clinical course included multiple general pediatric and inpatient psychiatric unit admissions that were complicated by severe affective dysregulation with physical aggression towards staff and family. Top experts in the consultation-liaison field provide guidance for this commonly encountered clinical case based on their experience and a review of available literature. Key teaching points include assessment and management of seronegative autoimmune encephalitis and catatonia. We discuss the system-level challenges of management of aggression in health care settings and ways to improve care for patients presenting with behavioral manifestations (aggression) of physical illness.

Antibody Investigations in 2,750 Children With Suspected Autoimmune Encephalitis

OBJECTIVES

To assess the frequency and types of neuronal and glial (neural) antibodies in children with suspected autoimmune encephalitis (AE).

METHODS

Patients younger than 18 years with suspected AE other than acute disseminated encephalomyelitis, whose serum or CSF samples were examined in our center between January 1, 2011, and April 30, 2022, were included in this study. Samples were systematically examined using brain immunohistochemistry; positive immunostaining was further investigated with cell-based assays (CBA), immunoblot, or live neuronal immunofluorescence.

RESULTS

Of 2,750 children, serum or CSF samples of 542 (20%) showed brain immunoreactivity, mostly (>90%) against neural cell surface antigens, and 19 had antibodies only identified by CBA. The most frequent targets were N-methyl-d-aspartate receptor (NMDAR, 76%) and myelin oligodendrocyte glycoprotein (MOG, 5%), followed by glutamic acid decarboxylase 65 (2%) and γ-aminobutyric acid A receptor (2%). Antibodies against other known cell surface or intracellular neural antigens (altogether 6% of positive cases) and unknown antigens (9%) were very infrequent.

DISCUSSION

The repertoire of antibodies in children with AE is different from that of the adults. Except for NMDAR and MOG antibodies, many of the antibodies included in diagnostic panels are rarely positive and their up-front testing in children seems unneeded.

Disease Course and Response to Immunotherapy in Children With Childhood Disintegrative Disorder: A Retrospective Case Series

Childhood disintegrative disorder is a poorly understood neurobehavioral disorder of early childhood characterized by acute to subacute profound regression in previously developed language, social behavior, and adaptive functions. The etiology of childhood disintegrative disorder remains unknown and treatment is focused on symptomatic management. Interest in neuroinflammatory mechanisms has grown with the increased recognition of autoimmune brain diseases and similarities between the presenting symptoms of childhood disintegrative disorder and pediatric autoimmune encephalitis. Importantly, a diagnosis of pediatric autoimmune encephalitis requires evidence of inflammation on paraclinical testing, which is absent in childhood disintegrative disorder. Here we report 5 children with childhood disintegrative disorder who were initially diagnosed with possible autoimmune encephalitis and treated with immunotherapy. Two children had provocative improvements, whereas 3 did not change significantly on immunotherapy. Additionally, a sixth patient with childhood disintegrative disorder evaluated in our Autoimmune Brain Disease Clinic showed spontaneous improvement and is included to highlight the variable natural history of childhood disintegrative disorder that may mimic treatment responsiveness.

Survival Analysis of Immunotherapy Effects on Relapse Rate in Pediatric and Adult Autoimmune Encephalitis

BACKGROUND AND OBJECTIVES

Prior observational studies for autoimmune encephalitis (AE) have mostly focused on outcomes after acute immunotherapies with better outcomes associated with earlier immunotherapy use. However, the impact of long-term immunotherapy and its association with clinical relapse is not well known.

METHODS

We conducted a retrospective study of consecutive patients meeting published clinical criteria for AE evaluated at UC San Diego and Rady Children's Hospital from January 2007 to November 2021. Survival analysis and Cox multivariable regression models were used to evaluate relapse risk using rituximab exposure as a time-dependent variable. Pooled and age-stratified analyses were performed.

RESULTS

A total of 204 pediatric and 380 adult participants were screened of which 30 pediatric and 75 adult participants were included. The most common antibody subtype in both cohorts was anti-NMDA receptor (76% in pediatric, 34% in adult). Relapses occurred in 31% of pediatric antibody-positive, 40% of adult antibody-positive, and 20% of adult antibody-negative cases. Times to first relapse (TTFR) were 10.6 ± 7.4 months (pediatric antibody-positive), 13.1 ± 24.5 months (adult antibody-positive), and 6.9 ± 3.8 months (adult antibody-negative). Rituximab was the most common second-line immunotherapy used. Combining pediatric and adult data, rituximab use was associated with a 71% lower hazard for time to first relapse (hazard ratio [HR] 0.29, 95% CI 0.09-0.85) and 51% lower hazard for recurring relapses (HR 0.49, 95% CI 0.9-1.26). The HR for TTFR with rituximab use in children was 0.30 (95% CI 0.05-1.69), 0.29 (95% CI 0.07-1.29) in adults, 0.32 in non-NMDA antibody-positive encephalitis (95% CI 0.07-1.39), and 0.42 (95% CI 0.07-2.67) for anti-NMDAR.

DISCUSSION

Relapses are common in pediatric and adult patients with AE, although less frequently in anti-NMDARE. Using a rigorous survival model, we demonstrate a substantial benefit of rituximab use for reducing relapse rates in AE, especially for the adult population.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that rituximab is associated with a lower hazard to relapse in patients with AE.

Social network size and mental health outcomes in youth with neuroinflammatory disorders

BACKGROUND

75 % of youth with MS report symptoms of fatigue, depression, and anxiety. Social network size (number of people in an individual's network) is known to have positive impacts on health and health behavior in pediatric populations and in individuals with multiple sclerosis.

OBJECTIVES

To estimate associations between social network size (SNS) and depression, anxiety, symptoms of post-traumatic stress disorder (PTSD), and quality of life among youth with recurrent neuroinflammatory disorders (RNI) in comparison to that of youth with monophasic acquired demyelinating syndrome (mono-ADS).

METHODS

Youth with RNI and mono-ADS were recruited from the Pediatric Neuroinflammatory Disorders Clinic at the Hospital for Sick Children between September 2020 and August 2022. After consent, participants completed the questionnaires on social network composition, depression, anxiety, PTSD, and quality of life. Descriptive and inferential analyses were conducted for differences between cohorts and correlations.

RESULTS

Youth with RNI (n = 37, Female= 22, Median age= 15, IQR= 3) and mono-ADS (n = 23, Female= 12, Median age= 14, IQR= 4.5) did not differ in: SNS, depression, anxiety, PTSD, and quality of life. Larger SNS was associated with lower anxiety (rs= -0.350, p<0.05) in youth with RNI and youth with RNI who presented anxiety disorder had significantly lower number of social contacts than those who did not (t = 2.23, p = 0.033, ES= 0.90) but not in mono-ADS. When analyzing the two cohorts grouped together, all youth who screened for anxiety had significantly smaller network size than those who did not (t = 2.06, p = 0.045, ES= 0.66). This was similar with those who screened for depression (t = 2.05, p = 0.046, ES= 0.58).

CONCLUSIONS

In youth with RNI, SNS was associated with anxiety. SNS is one important aspect of social networks that have the potential to shape mental health in youth with neuroinflammatory disorders. Future studies should focus on social network composition, strength of ties, and types of support in shaping health outcomes.

Mechanisms and Emerging Therapies for Treatment of Seizures in Pediatric Autoimmune Encephalitis and Autoinflammatory/Autoimmune-Associated Epilepsy

There has been increasing understanding of the role of inflammation in seizures and epilepsy, as well as targeted immunomodulatory treatments. In children, immune-mediated seizures often present acutely in the setting of autoimmune encephalitis and are very responsive to immunotherapy with low rates of subsequent epilepsy. Conversely, seizures in autoimmune-associated epilepsies, such as Rasmussen syndrome, can remain refractory to multimodal therapy, including immunomodulation. In this review, the authors discuss the presentations of immune-mediated seizures in children, underlying mechanisms, and emerging therapies.

Antibody-Negative Autoimmune Encephalitis: A Single-Center Retrospective Analysis

BACKGROUND AND OBJECTIVES

Autoimmune encephalitis (AE) refers to a heterogenous group of inflammatory CNS diseases. Subgroups with specified neural autoantibodies are more homogeneous in presentation, trigger factors, outcome, and response to therapy. However, a considerable fraction of patients has AE features but does not harbor detectable autoantibodies and is referred to as antibody-negative AE. Our aim was to describe clinical features, trigger factors, treatments, and outcome of a cohort of comprehensively tested antibody-negative AE patients.

METHODS

This retrospective monocentric study recruited adult patients whose serum and/or CSF was sent to our tertiary center for neural antibody testing between 2011 and 2020, who entered the diagnostic algorithm as possible antibody-negative AE and had the following: (1) probable antibody-negative AE, definite antibody-negative acute disseminated encephalomyelitis (ADEM), or definite autoimmune limbic encephalitis (LE) according to diagnostic criteria; (2) available data on MRI of the brain, CSF, and EEG; and (3) stored serum and/or CSF samples. These samples were reanalyzed using a comprehensive combination of cell-based and tissue-based assays.

RESULTS

Of 2,250 patients tested, 33 (1.5%) were classified as possible antibody-negative AE. Of these, 5 were found to have antibodies by comprehensive testing, 5 fulfilled the criteria of probable AE (3F:2M, median age 67, range 42-67), 4 of definite autoimmune LE (2F:2M, median age 45.5, range 27-60 years), one of definite antibody-negative ADEM, 2 of Hashimoto encephalopathy, one had no samples available for additional testing, and 15 had no further categorization. Of 10 probable/definite AE/LE/ADEM, one had a malignancy and none of them received an alternative diagnosis until the end of follow-up (median 18 months). In total, 80% (8/10) of patients received immunotherapy including corticosteroids, and 6/10 (60%) patients received rituximab, azathioprine, cyclophosphamide, plasma exchange, or IV immunoglobulins. Five (50%) patients improved, one (10%) stabilized, one (10%) worsened, and 3 (30%) died. All deaths were considered to be related to encephalitis. We did not observe differences of immunotherapy-treated patients in likelihood of improvement with or without nonsteroidal immunotherapy (with 2/6, without 1/2).

DISCUSSION

Antibody-negative AE should be diagnosed only after comprehensive testing. Diagnostic effort is important because many patients benefit from immunotherapy and some have malignancies.

Mimics of Autoimmune Encephalitis: Validation of the 2016 Clinical Autoimmune Encephalitis Criteria

BACKGROUND AND OBJECTIVES

The clinical criteria for autoimmune encephalitis (AE) were proposed by Graus et al. in 2016. In this study, the AE criteria were validated in the real world, and common AE mimics were described. In addition, criteria for probable anti-LGI1 encephalitis were proposed and validated.

METHODS

In this retrospective cohort study, patients referred to our national referral center with suspicion of AE and specific neuroinflammatory disorders with similar clinical presentations were included from July 2016 to December 2019. Exclusion criteria were pure cerebellar or peripheral nerve system disorders. All patients were evaluated according to the AE criteria.

RESULTS

In total, 239 patients were included (56% female; median age 42 years, range 1-85). AE was diagnosed in 104 patients (44%) and AE mimics in 109 patients (46%). The most common AE mimics and misdiagnoses were neuroinflammatory CNS disorders (26%), psychiatric disorders (19%), epilepsy with a noninflammatory cause (13%), CNS infections (7%), neurodegenerative diseases (7%), and CNS neoplasms (6%). Common confounding factors were mesiotemporal lesions on brain MRI (17%) and false-positive antibodies in serum (12%). Additional mesiotemporal features (involvement extralimbic structures, enhancement, diffusion restriction) were observed more frequently in AE mimics compared with AE (61% vs 24%; p = 0.005). AE criteria showed the following sensitivity and specificity: possible AE, 83% (95% CI 74-89) and 27% (95% CI 20-36); definite autoimmune limbic encephalitis (LE), 10% (95% CI 5-17) and 98% (95% CI 94-100); and probable anti-NMDAR encephalitis, 50% (95% CI 26-74) and 96% (95% CI 92-98), respectively. Specificity of the criteria for probable seronegative AE was 99% (95% CI 96-100). The newly proposed criteria for probable anti-LGI1 encephalitis showed a sensitivity of 66% (95% CI 47-81) and specificity of 96% (95% CI 93-98).

DISCUSSION

AE mimics occur frequently. Common pitfalls in AE misdiagnosis are mesiotemporal lesions (predominantly with atypical features) and false-positive serum antibodies. As expected, the specificity of the criteria for possible AE is low because these criteria represent the minimal requirements for entry in the diagnostic algorithm for AE. Criteria for probable AE (-LGI1, -NMDAR, seronegative) and definite autoimmune LE are applicable for decisions on immunotherapy in early disease stage, as specificity is high.

The Impact of Neuroimmunologic Disease and Developing Nervous System

Over the last two decades, neuroimmunologic disorders of childhood have been increasingly described, phenotyped, and treated. These disorders remain rare in the general population and while sharing common therapeutic interventions due to their immune pathophysiology, are heterogeneous with regard to presentation and risk of recurrence. As such, the impact of these disorders on the developing brain has come into the forefront of emerging research in pediatric neuroimmunology. Investigations into the singular impact of monophasic disease on long-term development and the impact of early and aggressive disease-modifying therapy in relapsing conditions are quickly becoming areas of ripe investigation as the field's most optimal way to treat and monitor these conditions over time. Although critically important in evaluating the developing brain, research has been heterogeneous among these diseases and limited by small cohort size. This narrative review details the role of common neuroimmunologic disorders in long-term neurological and cognitive outcomes in children as they develop.

Brazilian autoimmune encephalitis network (BrAIN): antibody profile and clinical characteristics from a multicenter study

Background

The frequency of antibodies in autoimmune encephalitis (AIE) may vary in different populations, however, data from developing countries are lacking. To describe the clinical profile of AIE in Brazil, and to evaluate seasonality and predictors of AIE in adult and pediatric patients.

Methods

We evaluated patients with possible AIE from 17 centers of the Brazilian Autoimmune Encephalitis Network (BrAIN) between 2018 and 2022. CSF and serum were tested with TBAs and CBAs. Data on clinical presentation, complementary investigation, and treatment were compiled. Seasonality and predictors of AIE in adult and pediatric populations were analyzed.

Results

Of the 564 patients, 145 (25.7%) were confirmed as seropositive, 69 (12.23%) were seronegative according to Graus, and 58% received immunotherapy. The median delay to diagnosis confirmation was 5.97 ± 10.3 months. No seasonality variation was observed after 55 months of enrolment. The following antibodies were found: anti-NMDAR (n=79, 54%), anti-MOG (n=14, 9%), anti-LGI1(n=12, 8%), anti-GAD (n=11, 7%), anti-GlyR (n=7, 4%), anti-Caspr2 (n=6, 4%), anti-AMPAR (n=4, 2%), anti-GABA-BR (n=4, 2%), anti-GABA-AR (n=2, 1%), anti-IgLON5 (n=1, 1%), and others (n=5, 3%). Predictors of seropositive AIE in the pediatric population (n=42) were decreased level of consciousness (p=0.04), and chorea (p=0.002). Among adults (n=103), predictors of seropositive AIE were movement disorders (p=0.0001), seizures (p=0.0001), autonomic instability (p=0.026), and memory impairment (p=0.001).

Conclusion

Most common antibodies in Brazilian patients are anti-NMDAR, followed by anti-MOG and anti-LGI1. Only 26% of the possible AIE patients harbor antibodies, and 12% were seronegative AIE. Patients had a 6-month delay in diagnosis and no seasonality was found. Findings highlight the barriers to treating AIE in developing countries and indicate an opportunity for cost-effect analysis. In this scenario, some clinical manifestations help predict seropositive AIE such as decreased level of consciousness, chorea, and dystonia among children, and movement disorders and memory impairment among adults.

A not so incidental 'incidentaloma' - pediatric ganglioneuroma-associated cerebellar degeneration and super-refractory status epilepticus: case report and literature review

Paraneoplastic neurological disorders are rare in children, with paraneoplastic cerebellar degeneration (PCD) considered highly atypical. We describe a 13-year-old girl with progressive neurobehavioral regression, cerebellar ataxia, and intractable epilepsy presenting in super-refractory status epilepticus. After an extensive evaluation, her clinical picture was suggestive of probable autoimmune encephalitis (AE). Further diagnostic testing revealed a molecularly undefined neural-restricted autoantibody in both serum and CSF, raising suspicion over an adrenal mass previously considered incidental. Surgical resection led to a robust clinical improvement, and pathology revealed a benign ganglioneuroma. This report widens the spectrum of paraneoplastic manifestations of ganglioneuroma, reviews the diagnostic approach to antibody-negative pediatric AE, and raises important clinical considerations regarding benign and incidentally found tumors in the setting of a suspected paraneoplastic neurologic syndrome.

Anti-Inflammatory and Immunomodulatory Effect of High-Dose Immunoglobulins in Children: From Approved Indications to Off-Label Use

BACKGROUND

The large-scale utilization of immunoglobulins in patients with inborn errors of immunity (IEIs) since 1952 prompted the discovery of their key role at high doses as immunomodulatory and anti-inflammatory therapy, in the treatment of IEI-related immune dysregulation disorders, according to labelled and off-label indications. Recent years have been dominated by a progressive imbalance between the gradual but constant increase in the use of immunoglobulins and their availability, exacerbated by the SARS-CoV-2 pandemic.

OBJECTIVES

To provide pragmatic indications for a need-based application of high-dose immunoglobulins in the pediatric context.

SOURCES

A literature search was performed using PubMed, from inception until 1st August 2023, including the following keywords: anti-inflammatory; children; high dose gammaglobulin; high dose immunoglobulin; immune dysregulation; immunomodulation; immunomodulatory; inflammation; intravenous gammaglobulin; intravenous immunoglobulin; off-label; pediatric; subcutaneous gammaglobulin; subcutaneous immunoglobulin. All article types were considered.

IMPLICATIONS

In the light of the current imbalance between gammaglobulins' demand and availability, this review advocates the urgency of a more conscious utilization of this medical product, giving indications about benefits, risks, cost-effectiveness, and administration routes of high-dose immunoglobulins in children with hematologic, neurologic, and inflammatory immune dysregulation disorders, prompting further research towards a responsible employment of gammaglobulins and improving the therapeutical decisional process.

Contactin-associated protein-like 2 antibody-associated autoimmune encephalitis in children: case reports and systematic review of literature

OBJECTIVES

To ascertain the clinical characteristics of pediatric patients with contactin-associated protein-like 2 (CASPR2) antibody-associated autoimmune encephalitis (AEs).

METHODS

Two cases of CASPR2 antibody-associated AEs have been reported. In addition, a systematic search of literature published between January 2010 and March 2022 through six online databases was conducted to identify the pediatric patients with CASPR2 antibody-associated AEs. Data on demographics, clinical symptoms, laboratory examinations, imaging, treatment, and outcome were collected.

RESULTS

Our updated literature search yielded 1,837 publications, of which 21 were selected, and 40 patients in this study met the diagnostic criteria for AE. There were 25 males and 15 females with a mean age of 9.2 years. The most common presenting symptoms are psychiatric symptoms (72.5%), sleep changes (62.5%), and movement disorders (60%). The psychiatric symptoms included mood changes (39.1%), behavior changes (25%), and hallucination (7.5%). In total, 23 cases (57.5%) combined with autonomic dysfunction, such as gastrointestinal dysmotility, cardiovascular-related symptoms, and sweating. No tumors were observed in children. Thirty-eight patients received first-line immunotherapy, and eight received first-line and second-line immunotherapy. All patients had a good clinical response to immune therapy. Mean mRS at onset was 3.4; It was 0.88 at the last follow-up. There was no recurrence during follow-up.

CONCLUSION

Psychiatric symptoms, sleep disorders, movement disorders, and cardiovascular-related symptoms are the most common presentation in pediatric patients with CASPR2 antibody-associated AEs. Tumor, particularly with thymoma, is uncommon in children diagnosed with CASPR2 antibody-associated AEs. In addition, prompt diagnosis and immunotherapy can relieve symptoms and improve the prognosis.

Acute pediatric encephalitis: etiology, course, and outcome of a 12-year single-center immunocompetent cohort

BACKGROUND

Encephalitis is an uncommon but severe disorder due to an inflammation of the brain parenchyma, usually diagnosed on clinical, laboratory, electroencephalographic, and neuroradiological features. New causes of encephalitis have been reported in recent years, so diagnostic criteria have changed over time. We report on a single-center experience of a pediatric Hospital, the hub of its region, over 12 years (2008-2021), with the evaluation of all children managed for acute encephalitis.

METHODS

We retrospectively reviewed clinical, laboratory, neuroradiological, and EEG data from the acute phase and outcome of all immunocompetent patients diagnosed with acute encephalitis. According to the newly proposed criteria for pediatric autoimmune encephalitis, we divided patients into infectious, definite autoimmune, probable autoimmune, and possible autoimmune, and performed a comparison between the different groups.

RESULTS

48 patients (26 females, mean age 4.4 years), 19 with infections, and 29 with autoimmune encephalitis, were included. Herpes simplex virus 1 encephalitis was the most frequently identified etiology followed by anti-NMDA receptor encephalitis. Movement disorders at onset and a longer hospital stay were observed more frequently in autoimmune compared to infectious encephalitis (p p < 0.001 and p = 0.001, respectively). Among the autoimmune group, children who started immunomodulatory treatment earlier (within 7 days from onset) had more frequent complete functional recovery (p = 0.002).

CONCLUSIONS

Herpes virus and anti-NMDAR encephalitis are the most frequent etiologies within our cohort. Clinical onset and course are extremely variable. Since early immunomodulatory treatment was associated with a better functional outcome, our data confirm that a timely diagnostic classification in definite, probable, or possible autoimmune encephalitis can help the clinician in a successful therapeutic approach.

A juvenile mouse model of anti-N-methyl-D-aspartate receptor encephalitis by active immunization

INTRODUCTION

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a common autoimmune encephalitis, and it is associated with psychosis, dyskinesia, and seizures. Anti-NMDAR encephalitis (NMDARE) in juveniles and adults presents different clinical charactreistics. However, the pathogenesis of juvenile anti-NMDAR encephalitis remains unclear, partly because of a lack of suitable animal models.

METHODS

We developed a model of juvenile anti-NMDAR encephalitis using active immunization with an amino terminal domain peptide from the GluN1 subunit (GluN1356 - 385) against NMDARs in 3-week-old female C57BL/6J mice.

RESULTS

Immunofluorescence staining suggested that autoantibody levels in the hippocampus increased, and HEK-293T cells staining identified the target of the autoantibodies as GluN1, suggesting that GluN1-specific immunoglobulin G was successfully induced. Behavior assessment showed that the mice suffered significant cognition impairment and sociability reduction, which is similar to what is observed in patients affected by anti-NMDAR encephalitis. The mice also exhibited impaired long-term potentiation in hippocampal CA1. Pilocarpine-induced epilepsy was more severe and had a longer duration, while no spontaneous seizures were observed.

CONCLUSION

The juvenile mouse model for anti-NMDAR encephalitis is of great importance to investigate the pathological mechanism and therapeutic strategies for the disease, and could accelerate the study of autoimmune encephalitis.

Antibody response to SARS-CoV-2 vaccination or infection in a prospective cohort of children with neuroinflammatory diseases

INTRODUCTION

Immune medications affect antibody responses to SARS-CoV-2 vaccination in adults with neuroinflammatory disorders, but little is known about antibody responses in children with neuroinflammation and on immune treatments. Here we measure antibody levels in response to SARS-CoV-2 vaccination in children receiving anti-CD20 monoclonal antibodies, or fingolimod.

METHODS

Children under 18 years of age with pediatric-onset neuroinflammatory disorders who received at least two mRNA vaccines were included. Plasma samples were assayed for SARS-CoV-2 antibodies (spike, spike receptor binding domain-RBD, nucleocapsid) and neutralization antibodies.

RESULTS

Seventeen participants with pediatric onset neuroinflammatory diseases were included: 12 multiple sclerosis, one neuromyelitis optica spectrum disorder, two MOG-associated disease, and two autoimmune encephalitis. Fourteen were on medications (11 on CD20 monoclonal antibodies-mAbs, one on fingolimod, one on steroids, one on intravenous immunoglobulin) and three were untreated. Nine patients also had pre-vaccination samples available. All participants had seropositivity to spike or spike RBD antibodies except for those receiving CD20 mAbs. However, this proportion was higher in children than in an adult MS patient cohort. The most significant contributor to antibody levels was duration of DMT.

CONCLUSION

SARS-CoV-2 antibodies are decreased in children on CD20 monoclonal antibodies than on other treatments. Treatment duration associated with vaccination responses.

Alternative Diagnoses in the Work Up of Down Syndrome Regression Disorder

PURPOSE

Down Syndrome Regression Disorder (DSRD) is a diagnosis of exclusion. Psychiatric and neuroimmunologic etiologies have been proposed although the exact etiology remains unknown. This study sought to review non-DSRD diagnoses at a large quaternary medical center specializing in the diagnosis of DSRD and compare clinical characteristics between those diagnosed with DSRD and those with non-DSRD diagnoses.

METHODS

The authors performed a single-center retrospective, chart-based, review of referrals for developmental regression in individuals with Down syndrome.

RESULTS

Two hundred and sixty-six individuals were evaluated for DSRD and of these, 54 (20%) ultimately had alternative diagnoses. Individuals with DSRD were more likely to have shorter nadir to clinical symptoms (p = 0.01, 95% CI: 0.36-0.47) and have preceding triggers (p < 0.001, 95% CI: 1.13-1.43) compared to those with alternative diagnoses. Individuals with non-DSRD diagnoses were more likely to be born premature (p = 0.01, 95% CI: 0.51-0.87) and have a history of epilepsy (p = 0.01, 95% CI: 0.23-0.77) but were also less likely to have a history of cytokine abnormalities on bloodwork (p < 0.001, 95% CI: 1.19-1.43) and have catatonia (p < 0.001, 95% CI: 1.54-2.17). The majority of alternative diagnoses (41/54, 76%) were autism spectrum disorder. In these cases, symptoms were more likely to be longstanding (symptoms > 12 months) and earlier onset (median 8 years, IQR: 6-11). Other diagnoses included epilepsy (5/54, 9%), Celiac disease (5/54, 9%), cerebrovascular disease (3/54, 6%).

CONCLUSIONS

This study identifies that 20% of individuals referred with concerns for DSRD have alternative diagnoses. The majority of these diagnoses were autism, but rare treatable conditions were also identified, highlighting the importance of a thorough neurodiagnostic assessment.

Autoimmune Encephalitis with Antibodies: Anti-NMDAR, Anti-AMPAR, Anti-GQ1b, Anti-DPPX, Anti-CASPR2, Anti-LGI1, Anti-RI, Anti-Yo, Anti-Hu, Anti-CV2 and Anti-GABAAR, in the Course of Psychoses, Neoplastic Diseases, and Paraneoplastic Syndromes

Encephalitis is a condition with a variety of etiologies, clinical presentations, and degrees of severity. The causes of these disorders include both neuroinfections and autoimmune diseases in which host antibodies are pathologically directed against self-antigens. In autoimmune encephalitis, autoantibodies are expressed in the central nervous system. The incidence of this disease is approximately 4% of all reported cases of encephalitis. Autoimmune encephalitis can be induced by antibodies against neuronal surface antigens such as N-methyl-D-aspartate-activated glutamate receptors (NMDAR), α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (AMPAR) or gangliosides GQ1b, DPPX, CASPR2, LGI1, as well as by antibodies against neuronal intracellular antigens. The paper presents a number of both mental and neurological symptoms of autoimmune encephalitis. Moreover, the coexistence of psychoses, neoplastic diseases, and the methods of diagnosing autoimmune encephalitis are discussed. Attention was also drawn to the fact that early diagnosis, as well as early initiation of targeted treatment, increases the chance of a successful course of the therapeutic process. Strategy and Methodology: The articles on which the following paper was based were searched using search engines such as PubMed and Medline. Considering that anti-NMDAR antibodies were first described in 2007, the articles were from 2007 to 2023. The selection of papers was made by entering the phrases "autoimmune encephalitis and psychosis/paraneplastic syndromes or cancer". The total number of articles that could be searched was 747, of which 100 items were selected, the most recent reports illustrating the presented topic. Thirty-four of them were rejected in connection with case reports or papers that could not be accessed.

Multimodal Management of Febrile Infection-Related Epilepsy Syndrome in a 17-Year-Old Male

New-onset refractory status epilepticus (NORSE) is a clinical presentation, not a specific diagnosis, in which healthy people are suddenly struck by prolonged seizures that do not respond to at least two anti-seizure drugs and do not have a clear structural, toxic, or metabolic cause.Febrile infection-related epilepsy syndrome (FIRES) is considered a sub-category of NORSE. Our patient is a 17-year-old male admitted to the pediatric ward after a self-limited convulsive episode at home, noted to occur following five days of upper respiratory infection symptoms accompanied by fever. After multiple generalized tonic-clonic seizures necessitating treatment, he went into status epilepticus despite multiple antiepileptic drugs. The possibility of FIRES had been considered from the onset of refractory status epilepticus; as a result, an intensive multimodal treatment regimen was proactively implemented with some clinical improvement.

Retrospective Comparison of Patients Evaluated for Pediatric Autoimmune Encephalitis with Typical and Atypical Premorbid Neuropsychiatric Development

PURPOSE

Patients with neurodevelopmental disorders (NDD) (i.e. autism, developmental delay, early-onset psychiatric or seizure disorders) increasingly seek evaluation of new or exacerbated symptoms concerning for autoimmune encephalitis (AE). Clinical AE evaluation can be challenging in NDD patients with symptom overlap between anti-neuronal autoimmunity and baseline atypical neurodevelopment. This study sought to explore differences in AE features by neurodevelopmental status.

METHODS

This retrospective chart review included 67 children with typical development (TD) or NDD evaluated for AE at the authors' institution. AE diagnosis included seronegative AE or seropositive AE with anti-NMDAR or anti-GAD antibodies. Reported AE clinical domains, symptom onset acuity, and treatment response were compared between three groups: (1) TD children with AE (TD-AE, N = 24); (2) NDD children with AE (NDD-AE, N = 21); and (3) NDD children with a non-AE diagnosis following appropriate workup (NDD-nonAE, N = 22).

RESULTS

Children with AE had a greater number of reported clinical domains than non-AE children with NDD (p < 0.0001) regardless of baseline developmental status. There were no observed differences in reported domains between TD-AE and NDD-AE groups. Onset acuity differed across the three groups (p = 0.04). No treatment response differences were observed between groups.

CONCLUSION

NDD children with AE had a comparable number of reported clinical domains relative to TD children and a similar treatment response. NDD patients with AE had a greater number of reported clinical domains than their NDD peers without an AE diagnosis. These findings suggest that AE is a multi-domain process in both TD and NDD children.

Case report: Evolution of catatonic mutism and psychotic symptoms in an adolescent with Down syndrome: transition from Down syndrome disintegrative disorder to anti-N-methyl-D-aspartate receptor encephalitis

During her first year of junior high school, a 12-year-old Japanese girl with Down syndrome experienced dizziness, gait disruption, paroxysmal weakness in her hands, and sluggish speaking. Regular blood tests and a brain MRI revealed no abnormalities, and she was tentatively diagnosed with adjustment disorder. Nine months later, the patient experienced a subacute sickness of chest pain, nausea, sleep problem with night terrors, and delusion of observation. Rapid deterioration then developed with simultaneous fever, akinetic mutism, loss of facial expression, and urine incontinence. These catatonic symptoms improved after a few weeks after admission and treatment with lorazepam, escitalopram, and aripiprazole. After discharge, nonetheless, daytime slumber, empty eyes, paradoxical laughter, and declined verbal communication persisted. Upon confirmation of the cerebrospinal N-methyl-D-aspartate (NMDA) receptor autoantibody, methylprednisolone pulse therapy was tried, but it had little effect. Visual hallucinations and cenesthopathy, as well as suicidal thoughts and delusions of death, have predominated in the following years. Cerebrospinal IL-1ra, IL-5, IL-15, CCL5, G-CSF, PDGFbb, and VFGF were raised in the early stage of initial medical attention with nonspecific complaints, but were less prominent in the later stages of catatonic mutism and psychotic symptoms. We suggest a disease concept of progression from Down syndrome disintegrative disorder to NMDA receptor encephalitis, based on this experience.

Diagnostic criteria for autoimmune encephalitis: utility and pitfalls for antibody-negative disease

Increased awareness of autoimmune encephalitis has led to two unintended consequences: a high frequency of misdiagnoses and the inappropriate use of diagnostic criteria for antibody-negative disease. Misdiagnoses typically occur for three reasons: first, non-adherence to reported clinical requirements for considering a disorder as possible autoimmune encephalitis; second, inadequate assessment of inflammatory changes in brain MRI and CSF; and third, absent or limited use of brain tissue assays along with use of cell-based assays that include only a narrow range of antigens. For diagnosis of possible autoimmune encephalitis and probable antibody-negative autoimmune encephalitis, clinicians should adhere to published criteria for adults and children, focusing particularly on exclusion of alternative disorders. Moreover, for diagnosis of probable antibody-negative autoimmune encephalitis, the absence of neural antibodies in CSF and serum should be well substantiated. Neural antibody testing should use tissue assays along with cell-based assays that include a broad range of antigens. Live neuronal studies in specialised centres can assist in resolving inconsistencies with respect to syndrome-antibody associations. Accurate diagnosis of probable antibody-negative autoimmune encephalitis will identify patients with similar syndromes and biomarkers, which will provide homogeneous populations for future assessments of treatment response and outcome.

Pediatric Acute-Onset Neuropsychiatric Syndrome: Current Perspectives

Pediatric acute-onset neuropsychiatric syndrome (PANS) features a heterogeneous constellation of acute obsessive-compulsive disorder (OCD), eating restriction, cognitive, behavioral and/or affective symptoms, often followed by a chronic course with cognitive deterioration. An immune-mediated etiology is advocated in which the CNS is hit by different pathogen-driven (auto)immune responses. This narrative review focused on recent clinical (ie, diagnostic criteria, pre-existing neurodevelopmental disorders, neuroimaging) and pathophysiological (ie, CSF, serum, genetic and autoimmune findings) aspects of PANS. We also summarized recent points to facilitate practitioners with the disease management. Relevant literature was obtained from PubMed database which included only English-written, full-text clinical studies, case reports, and reviews. Among a total of 1005 articles, 205 were pertinent to study inclusion. Expert opinions are converging on PANS as the effect of post-infectious events or stressors leading to "brain inflammation", as it is well-established for anti-neuronal psychosis. Interestingly, differentiating PANS from either autoimmune encephalitides and Sydenham's chorea or from alleged "pure" psychiatric disorders (OCD, tics, Tourette's syndrome), reveals several overlaps and more analogies than differences. Our review highlights the need for a comprehensive algorithm to help both patients during their acute distressing phase and physicians during their treatment decision. A full agreement on the hierarchy of each therapeutical intervention is missing owing to the limited number of randomized controlled trials. The current approach to PANS treatment emphasizes immunomodulation/anti-inflammatory treatments in association with both psychotropic and cognitive-behavioral therapies, while antibiotics are suggested when an active bacterial infection is established. A dimensional view, taking into account the multifactorial origin of psychiatric disorders, should suggest neuro-inflammation as a possible shared substrate of different psychiatric phenotypes. Hence, PANS and PANS-related disorders should be considered as a conceptual framework describing the etiological and phenotypical complexity of many psychiatric disorders.

Clinical spectrum of contactin-associated protein 2 autoimmune encephalitis in children

Objective

Anti-contactin-associated protein 2 (CASPR2)-related autoimmune encephalitis (AE) is more common in adults than in children. Clinical understanding of anti-CASPR2-antibody (Ab)-related AE, diagnosis and treatment standards are lacking in children. Therefore, this retrospective study on clinical symptoms and treatment outcomes in children with anti-CASPR2-Ab-related AE was conducted, to improve the clinical understanding of the disease, its diagnosis and treatment.

Methods

This study retrospectively assessed children with anti-CASPR2-Ab-related AE from January 1, 2020, to June 30, 2022, in the Department of Neurology at Hunan Children's Hospital. Data regarding demographics, clinical symptoms, laboratory examinations, electroencephalography (EEG), imaging, and curative were collected.

Results

Thirteen patients were positive for serum anti-CASPR2-Ab (age at manifestation, 25 months to 13 years old; median, 8.1 years old; male-to-female ratio, 8/5). One patient (P1) had dual Abs, including anti-CASPR2 and anti-N-methyl-D-aspartate receptor Abs; his symptoms were more severe than those of children with anti-CASPR2 Abs alone. The clinical symptoms of the 13 patients with anti-CASPR2 Ab were movement disorders (9/13), consciousness disorders (9/13), abnormal demeanor (8/13), seizures (7/13), language disorders (6/13), fever (6/13), pain (4/13), involuntary exercise (4/13), poor diet (4/13), vomiting (3/13), sleep disorders (3/13), mood disorders (3/13), eczema/itching/redness (2/13), sweating (P8), urinary disorders (P13), and cognitive disorders (P9). No tumors were found in any patient. Additionally, EEG results of six patients were abnormal and imaging findings such as abnormal signals were found in 10 patients. Moreover, all except one patient recovered well after treatment; P1 with overlapping syndrome underwent recovery for more than 2 years. None of the patients who recovered have had a relapse.

Discussion and conclusion

Anti-CASPR2-Ab-related AE has several clinical manifestations. Anti-CASPR2-Ab levels were higher in male patients than in female patients. Moreover, related tumors are relatively rare. Most patients benefit from immunotherapy and have a lower chance of recurrence in the short term. Furthermore, different from patients who had anti-CASPR2-Ab AE alone, those with overlapping syndrome had a severe and complex condition requiring lengthy treatment and rehabilitation. Additional studies are needed to evaluate the long-term prognosis of these patients.

Retrospective Pediatric Cohort Study Validates NEOS Score and Demonstrates Applicability in Children With Anti-NMDAR Encephalitis

BACKGROUND AND OBJECTIVES

Anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) is the most common form of autoimmune encephalitis in children and adults. Although our understanding of the disease mechanisms has progressed, little is known about estimating patient outcomes. Therefore, the NEOS (anti-NMDAR Encephalitis One-Year Functional Status) score was introduced as a tool to predict disease progression in NMDARE. Developed in a mixed-age cohort, it currently remains unclear whether NEOS can be optimized for pediatric NMDARE.

METHODS

This retrospective observational study aimed to validate NEOS in a large pediatric-only cohort of 59 patients (median age of 8 years). We reconstructed the original score, adapted it, evaluated additional variables, and assessed its predictive power (median follow-up of 20 months). Generalized linear regression models were used to examine predictability of binary outcomes based on the modified Rankin Scale (mRS). In addition, neuropsychological test results were investigated as alternative cognitive outcome.

RESULTS

The NEOS score reliably predicted poor clinical outcome (mRS ≥3) in children in the first year after diagnosis (p = 0.0014) and beyond (p = 0.036, 16 months after diagnosis). A score adapted to the pediatric cohort by adjusting the cutoffs of the 5 NEOS components did not improve predictive power. In addition to these 5 variables, further patient characteristics such as the "Herpes simplex virus encephalitis (HSE) status" and "age at disease onset" influenced predictability and could potentially be useful to define risk groups. NEOS also predicted cognitive outcome with higher scores associated with deficits of executive function (p = 0.048) and memory (p = 0.043).

DISCUSSION

Our data support the applicability of the NEOS score in children with NMDARE. Although not yet validated in prospective studies, NEOS also predicted cognitive impairment in our cohort. Consequently, the score could help identify patients at risk of poor overall clinical outcome and poor cognitive outcome and thus aid in selecting not only optimized initial therapies for these patients but also cognitive rehabilitation to improve long-term outcomes.

Autoimmune encephalitis : Part 1 (Epidemiology, Pathophysiology and Clinical spectrum)

Since the identification of anti-N-methyl-D-aspartate (NMDA) receptor antibodies about 15 years ago, many patients with rapidly progressing psychiatric symptoms, abnormal movements, seizures or unexplained coma, have been diagnosed with autoimmune encephalitis (AE). The symptom onset is often unspecific and might mimic psychiatric disease, but the later course is frequently characterized by severe disease, often requiring intensive care. Clinical and immunological criteria are helpful in identifying the patients, but no biomarkers exist to guide the clinician in therapy or predict outcome. While persons of all ages can be affected by AE, some types of AE affect more children and young adults and are more prevalent in women. This review will focus on encephalitides associated with neuronal cell-surface or synaptic antibodies, which can result in characteristic syndromes, and are often recognizable on clinical grounds. AE subtypes associated with antibodies against extracellular epitopes can occur with or without tumours. Because the antibodies bind and alter the function of the antigen, the effects are often reversible if immunotherapy is initiated, and the prognosis is favourable in most instances. The first part of this series will introduce the topic, provide an overview of current neuronal surface antibodies and how they present, describe the most common subtype, anti-NMDA receptor encephalitis, and discuss the difficulties in recognizing patients with underlying AE amongst patients with new onset psychiatric disorders.

Neuroinflammatory syndromes in children

PURPOSE OF REVIEW

Neuropsychiatric symptoms due to paediatric neuroinflammatory diseases are increasingly recognized and reported. Psychiatrists are crucial in front-lines identification, diagnosis and care of individuals with disorders such as autoimmune encephalitis and management of long-term neurobehavioral sequelae. This review summarizes recent literature on autoimmune and post-infectious encephalitis, discusses special considerations in children with neurodevelopmental conditions and presents a paradigm for evaluation and management.

RECENT FINDINGS

There is a growing body of evidence on neuropsychiatric symptom burdens of paediatric neuroinflammatory diseases. A particular development is the evolution of diagnostic and treatment guidelines for conditions such as autoimmune encephalitis, which take into account phenotypes of acute, short-term and long-term sequelae. Interest in inflammatory sequelae of viral illness, such as SARS-CoV-2, in children remains in early development.

SUMMARY

Neuroimmunological disease data are constantly evolving. New recommendations exist for multiple common neuroimmunological disorders with behavioural, emotional, cognitive and neurological sequelae. Anti-NMDA receptor encephalitis now has well-recognized patterns of symptom semiology, diagnostic and treatment recommendations, and outcome patterns. Recognizing psychiatric symptoms heralding autoimmune brain disease and understanding neuropsychiatric sequelae are now a crucial skill set for paediatric psychiatrists. Exploration of inflammatory features of other diseases, such as genetic syndromes, is a burgeoning research area.