Pediatric autoimmune encephalitis: Recognition and diagnosis

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.

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.

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.

Anti-GluK2 Encephalitis in an Asian Child: A Case Report and Literature Review

Background

Anti-glutamate kainate receptor subunit 2 (anti-GluK2) antibodies mediated encephalitis is very rare in both children and adults. This study aimed to describe the second report of the anti-GluK2 encephalitis worldwide, the first youngest patient worldwide, and the first case ever in Asia. Besides, this study provides a summary of the clinical manifestations of all previous reported cases.

Methods

The patient was attended at the Department of Pediatrics, Xiangya Hospital, Central South University. Anti-GluK2 antibodies were tested in the serum and cerebrospinal fluid (CSF) by the indirect immunofluorescence on cell-based assays. The clinical information of the patient was collected. In addition, a literature search was carried out in the PubMed.

Results

Our patient was a male who presented with lethargy, recurrent dizziness and vomiting, headache and cerebellar ataxia at the age of 13 years. Prodromal illnesses included Herpes Zoster infection and Mycoplasma pneumonia. The anti-GluK2 antibodies and elevated IL-6 levels were detected in serum while high oligoclonal bands levels were found in the CSF. The intravenous methylprednisolone, immunoglobulin, antibiotics and other symptomatic treatments helped the patient to recover full. We could only find one previous report in the literature (from Barcelona). The literature review plus our report unveiled eight patients with pure anti-GluK2 antibodies related encephalitis. The median age of onset was 28.50 years and majority were males (75.00%). Most of the cases (87.50%) presented with acute cerebellitis symptoms and signs. Preceding or concurrent infection was observed in two patients, while paraneoplastic tumors were observed in two patients. Patients had non-parenchymal brain lesions; the commonest anomalies were those localized in the cerebellum (62.50%).

Conclusion

Our report provides more evidence that anti-GluK2 antibodies may be pathogenic for the autoimmune encephalitis (cerebellitis). Immunotherapy can be used to treat it with good outcome.

Autoimmune Psychosis as a Differential Diagnosis of Primary Schizophreniform Psychosis in Children and Adolescents

Objective: Autoimmune psychosis (AP), defined as an isolated schizophreniform psychosis with no or only minimal neurological abnormalities stemming from autoantibody-associated cerebral processes, is a very rare and potentially underdiagnosed disorder in children and adolescents. Methods: This article reports the case of a 13-year-old boy who became acutely ill with a psychotic disorder following a respiratory infection. We describe the diagnosis and course of treatment in detail. Results: Following an extensive interdisciplinary workup, a probable glutamic acid decarboxylase (GAD)-associated AP was diagnosed that ultimately remitted completely with treatment. Conclusions: Autoimmune psychoses remain a relatively uncharted territory for the specialty of child and adolescent psychiatry. Good interdisciplinary cooperation is essential for patients with somewhat atypical psychotic symptoms, both in terms of diagnosis and treatment.

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.

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.

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.

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.

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.

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.

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.

MRI-Based Machine Learning Fusion Models to Distinguish Encephalitis and Gliomas

This paper aims to compare the performance of the classical machine learning (CML) model and the deep learning (DL) model, and to assess the effectiveness of utilizing fusion radiomics from both CML and DL in distinguishing encephalitis from glioma in atypical cases. We analysed the axial FLAIR images of preoperative MRI in 116 patients pathologically confirmed as gliomas and clinically diagnosed with encephalitis. The 3 CML models (logistic regression (LR), support vector machine (SVM) and multi-layer perceptron (MLP)), 3 DL models (DenseNet 121, ResNet 50 and ResNet 18) and a deep learning radiomic (DLR) model were established, respectively. The area under the receiver operating curve (AUC) and sensitivity, specificity, accuracy, negative predictive value (NPV) and positive predictive value (PPV) were calculated for the training and validation sets. In addition, a deep learning radiomic nomogram (DLRN) and a web calculator were designed as a tool to aid clinical decision-making. The best DL model (ResNet50) consistently outperformed the best CML model (LR). The DLR model had the best predictive performance, with AUC, sensitivity, specificity, accuracy, NPV and PPV of 0.879, 0.929, 0.800, 0.875, 0.867 and 0.889 in the validation sets, respectively. Calibration curve of DLR model shows good agreement between prediction and observation, and the decision curve analysis (DCA) indicated that the DLR model had higher overall net benefit than the other two models (ResNet50 and LR). Meanwhile, the DLRN and web calculator can provide dynamic assessments. Machine learning (ML) models have the potential to non-invasively differentiate between encephalitis and glioma in atypical cases. Furthermore, combining DL and CML techniques could enhance the performance of the ML models.

Pediatric anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis: Exploring psychosis, related risk factors, and hospital outcomes in a nationwide inpatient sample: A cross-sectional study

OBJECTIVE

Our study aims to examine the risk factors for comorbid psychosis in pediatric patients hospitalized for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis and its impact on hospital outcomes.

METHODS

We conducted a cross-sectional study using the nationwide inpatient sample (NIS 2018-2019). We included 3,405 pediatric inpatients (age 6-17 years) with a primary discharge diagnosis of anti-NMDAR encephalitis. We used binomial logistic regression model to evaluate the odds ratio (OR) of variables (demographic and comorbidities) associated with comorbid psychosis.

RESULTS

The prevalence of comorbid psychosis in anti-NMDAR encephalitis inpatients was 5.3%, and majorly constituted of adolescents (72.2%) and females (58.3%). In terms of race, Blacks (OR 2.41), and Hispanics (OR 1.80) had a higher risk of comorbid psychosis compared to Whites. Among comorbidities, encephalitis inpatients with depressive disorders (OR 4.60), sleep-wake disorders (OR 3.16), anxiety disorders (OR 2.11), neurodevelopmental disorders (OR 1.95), and disruptive behavior disorders (OR 2.15) had a higher risk of comorbid psychosis. Anti-NMDAR encephalitis inpatients with comorbid psychosis had a longer median length of stay at 24.6 days (vs. 9.8 days) and higher median charges at $262,796 (vs. $135,323) compared to those without psychotic presentation.

CONCLUSION

Adolescents, females, and Blacks with encephalitis have a higher risk of psychotic presentation leading to hospitalization for anti-NMDAR encephalitis. Identification of demographic predictors and comorbidities can aid in early recognition and intervention to optimize care and potentially reduce the healthcare burden.

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.

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.

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.

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.

Evaluation, Treatment, and Outcomes of Viral and Autoimmune Encephalitis in Children

Viral encephalitis and autoimmune encephalitis are currently the most common causes of encephalitis. Determining the causative agent is helpful in initiating medical treatment that may help reduce long-term sequelae. Cerebrospinal fluid, neuroimaging, serologic, and electroencephalogram in combination with clinical manifestations play a role in determining the cause of the encephalitis. Although motor dysfunction tends to improve, there is a significant risk of long-term neurologic and cognitive sequelae. These persistent deficits that occur in childhood indicate the importance for ongoing rehabilitative services to maximize functional skills, improve cognitive deficits, and assist with community integration.

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.

Neuroinflammation in Obsessive-Compulsive Disorder: Sydenham Chorea, Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections, and Pediatric Acute Onset Neuropsychiatric Syndrome

Sydenham chorea (SC), pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) and pediatric acute-onset neuropsychiatric syndrome (PANS) are postinfectious neuroinflammatory diseases that involve the basal ganglia and have obsessive-compulsive disorder as a major manifestation. As is true for many childhood rheumatological diseases and neuroinflammatory diseases, SC, PANDAS and PANS lack clinically available, rigorous diagnostic biomarkers and randomized clinical trials. Research on the treatment of these disorders depend on three complementary modes of intervention including: treating the symptoms, treating the source of inflammation, and treating disturbances of the immune system. Future studies should aim to integrate neuroimaging, inflammation, immunogenetic, and clinical data (noting the stage in the clinical course) to increase our understanding and treatment of SC, PANDAS, PANS, and all other postinfectious/immune-mediated behavioral disorders.

Determination of Clinical, Electrophysiological, and Radiological Characteristics of Pediatric Autoimmune Encephalopathy

Autoimmune encephalopathy (AE) is a group of diseases with subacute onset, that represents a wide clinical spectrum, manifested by complex neuropsychiatric symptoms and signs. In this study, the data of 27 patients diagnosed and followed up in our clinic with the diagnosis of AE between 2011 and 2021 were evaluated retrospectively. Out of 27 patients, 6 were definite seropositive AE, 2 of them met the diagnostic criteria for limbic encephalitis, and the remaining 19 were probable AE. Nowadays, we see AEs with increasing frequency. While there is a generally established approach in the diagnosis and treatment of seropositive patients, there are still hesitations and diagnostic difficulties in seronegative AEs. In this study, clinical, radiological, and prognostic features of definite and probable AE patients diagnosed in a tertiary pediatric neurology clinic were documented. It is thought that pediatric neurologists have an important responsibility to increase awareness about AE in pediatricians. In the future, it is predicted that AE will be diagnosed more frequently with new antibodies and one has to differentiate it from viral encephalitis and neuropsychiatric syndromes and diseases.

Autoimmune encephalitis and CSF anti-AMPA GluR3 antibodies in childhood: a case report and literature review

Acute autoimmune encephalitis is a severe neurological disorder presenting with altered level of consciousness, confusion, irritability, headache, vomiting, and in some cases seizures. An infective event precedes by 1-2 weeks the onset of the symptoms. Cognitive impairment is considered the cardinal symptom. The autoimmune encephalitis comprises an increasingly group of inflammatory brain disorder caused by an underlying abnormal immune response to the CNS to the infective agent. In children, several antibodies have been recorded as causative agent. Among these, GAD65, MOG, and NMDAR antibodies are more commonly reported and with less frequency, the Dopamine-2 receptor, GABA A receptor, GABA B receptor, and Glycinereceptorandm-GluR5. We report here a 10-year-old male with acute autoimmune encephalitis with altered status of consciousness and severe cerebral involvement at the brain-MRI. Serum and cerebrospinal fluid disclosed the presence of anti-AMPA-GluR3 antibodies suggesting a possible pathogenetic correlation with the disorder presented by the proband. Precocious treatment with intravenous methylprednisolone and immunoglobulin resulted in progressive but constant improvement. At 3-month follow-up, the clinical condition of the child and the neuro-radiological brain anomalies returned to the normal. At the 2-year follow-up, no recurrence or other disturbances were reported.

Childhood encephalitis in the Greater Mekong region (the SouthEast Asia Encephalitis Project): a multicentre prospective study

BACKGROUND

Encephalitis is a worldwide public health issue, with a substantially high burden among children in southeast Asia. We aimed to determine the causes of encephalitis in children admitted to hospitals across the Greater Mekong region by implementing a comprehensive state-of-the-art diagnostic procedure harmonised across all centres, and identifying clinical characteristics related to patients' conditions.

METHODS

In this multicentre, observational, prospective study of childhood encephalitis, four referral hospitals in Cambodia, Vietnam, Laos, and Myanmar recruited children (aged 28 days to 16 years) who presented with altered mental status lasting more than 24 h and two of the following minor criteria: fever (within the 72 h before or after presentation), one or more generalised or partial seizures (excluding febrile seizures), a new-onset focal neurological deficit, cerebrospinal fluid (CSF) white blood cell count of 5 per mL or higher, or brain imaging (CT or MRI) suggestive of lesions of encephalitis. Comprehensive diagnostic procedures were harmonised across all centres, with first-line testing was done on samples taken at inclusion and results delivered within 24 h of inclusion for main treatable causes of disease and second-line testing was done thereafter for mostly non-treatable causes. An independent expert medical panel reviewed the charts and attribution of causes of all the included children. Using multivariate analyses, we assessed risk factors associated with unfavourable outcomes (ie, severe neurological sequelae and death) at discharge using data from baseline and day 2 after inclusion. This study is registered with ClinicalTrials.gov, NCT04089436, and is now complete.

FINDINGS

Between July 28, 2014, and Dec 31, 2017, 664 children with encephalitis were enrolled. Median age was 4·3 years (1·8-8·8), 295 (44%) children were female, and 369 (56%) were male. A confirmed or probable cause of encephalitis was identified in 425 (64%) patients: 216 (33%) of 664 cases were due to Japanese encephalitis virus, 27 (4%) were due to dengue virus, 26 (4%) were due to influenza virus, 24 (4%) were due to herpes simplex virus 1, 18 (3%) were due to Mycobacterium tuberculosis, 17 (3%) were due to Streptococcus pneumoniae, 17 (3%) were due to enterovirus A71, 74 (9%) were due to other pathogens, and six (1%) were due to autoimmune encephalitis. Diagnosis was made within 24 h of admission to hospital for 83 (13%) of 664 children. 119 (18%) children had treatable conditions and 276 (42%) had conditions that could have been preventable by vaccination. At time of discharge, 153 (23%) of 664 children had severe neurological sequelae and 83 (13%) had died. In multivariate analyses, risk factors for unfavourable outcome were diagnosis of M tuberculosis infection upon admission (odds ratio 3·23 [95% CI 1·04-10·03]), coma on day 2 (2·90 [1·78-4·72]), supplementary oxygen requirement (1·89 [1·25-2·86]), and more than 1 week duration between symptom onset and admission to hospital (3·03 [1·68-5·48]). At 1 year after inclusion, of 432 children who were discharged alive from hospital with follow-up data, 24 (5%) had died, 129 (30%) had neurological sequelae, and 279 (65%) had completely recovered.

INTERPRETATION

In southeast Asia, most causes of childhood encephalitis are either preventable or treatable, with Japanese encephalitis virus being the most common cause. We provide crucial information that could guide public health policy to improve diagnostic, vaccination, and early therapeutic guidelines on childhood encephalitis in the Greater Mekong region.

FUNDING

Institut Pasteur, Institut Pasteur International Network, Fondation Merieux, Aviesan Sud, INSERM, Wellcome Trust, Institut de Recherche pour le Développement (IRD), and Fondation Total.

Autoimmune Encephalitis in Children

Autoimmune encephalitis is a group of central nervous system (CNS) inflammatory disorders that most commonly affect young adults and children. These disorders are closely associated with antibodies against neuronal cell-surface proteins, receptors, and ion channels; however, some forms of the disorder have no known antibody at this time. In children, neurological manifestations such as seizure, movement disorders, and focal neurological deficits are more prominent at initial presentation than psychiatric or behavioral symptoms. When psychiatric symptoms do occur, they often manifest as temper tantrums, aggression, agitation, and rarely psychosis. Prompt diagnosis and early treatment can lead to improved outcomes and decreased relapses. First-line therapies include intravenous steroids, intravenous immunoglobulin, and plasmapheresis, whereas rituximab and cyclophosphamide are utilized for refractory or relapsing disease. This review highlights the different forms of this disorder, discusses approach to diagnosis and treatment, and reviews the outcome and prognosis of children diagnosed with different forms of autoimmune encephalitis.

Rare antibody-mediated and seronegative autoimmune encephalitis: An update

Paralleling advances with respect to more common antibody-mediated encephalitides, such as anti-N-methyl-D-aspartate receptor (NMDAR) and anti-leucine-rich glioma-inactivated 1 (LGI1) Ab-mediated encephalitis, the discovery and characterisation of novel antibody-mediated encephalitides accelerated over the past decade, adding further depth etiologically to the spectrum of antibody-mediated encephalitis. Herein, we review the major mechanistic, clinical features and management considerations with respect to anti-γ-aminobutyric acid B (GABA_B)-, anti-α-amino-3-hydroxy-5-methyl-4-isoxazolepropinoic receptor- (AMPAR), anti-GABA_A-, anti-dipeptidyl-peptidase-like protein-6 (DPPX) Ab-mediated encephalitides, delineate rarer subtypes and summarise findings to date regarding seronegative autoimmune encephalitis.

Neurological and cognitive outcomes after antibody-negative autoimmune encephalitis in children

AIM

To characterize the neurological and cognitive outcomes in children with antibody-negative autoimmune encephalitis (Ab-negative AE).

METHOD

A cohort of children presenting to our institution over a 10-year period with autoimmune encephalitis was identified by structured retrospective review of medical records. Clinical features at presentation and final follow-up were recorded. Neuropsychological testing was performed in a subset of patients. Outcomes after Ab-negative AE were compared with outcomes after N-methyl-D-aspartate receptor antibody encephalitis (NMDARE).

RESULTS

Forty-four patients (26 females, 18 males, median age 9y 2mo [interquartile range 4y 5mo-11y 8mo], 23 with NMDARE) with a diagnosis of autoimmune encephalitis were included. Postencephalitic epilepsy was more frequent after Ab-negative AE compared to NMDARE (61% vs 14%, p=0.002). Cognitive testing was performed in a subset of patients (n=21; Ab-negative AE=11, NMDARE=10). Full-scale IQ was lower after Ab-negative AE than NMDARE (mean IQ 75 vs 92, p=0.02), primarily because of reduced verbal comprehension index (80 vs 98, p=0.01) and working memory index (77 vs 95, p=0.09). The cognitive function most commonly impaired was executive function (80% [8/10] vs 22% [2/9]).

INTERPRETATION

Ab-negative AE was associated with poorer cognitive outcomes than NMDARE at 1-year follow-up. Further studies are required to evaluate if immunotherapy can be optimized to improve outcome.

Characterizing the features and course of psychiatric symptoms in children and adolescents with autoimmune encephalitis

Autoimmune encephalitis (AE) can present like a psychiatric disorder. We aimed to illustrate the psychiatric manifestations, course and management of AE in a paediatric cohort. Neuropsychiatric symptoms, investigations and treatment were retrospectively retrieved in 16 patients (mean age 11.31, SD 2.98) with an AE diagnosis at the liaison psychiatry services in two UK tertiary paediatric centres. Psychiatric presentation was characterised by an acute polysymptomatic (predominantly agitation, anger outbursts/aggressiveness, hallucinations, and emotional lability) onset. Antipsychotics produced side effects and significant worsening of symptoms in four cases, and benzodiazepines were commonly used. This psychiatric phenotype should make clinicians suspect the diagnosis of AE and carefully consider use of treatments.

Autoimmune Encephalitis

Autoimmune encephalitis is a common and treatable cause of encephalitis in children and adults. Individuals present with a variety of symptoms, including altered mental status, behavioral changes, irritability, insomnia, developmental regression, seizures, dyskinetic movements, and autonomic instability. Evaluation includes electroencephalography, magnetic resonance imaging, and lumbar puncture. Once infectious and other causes are reasonably ruled out, treatment should be started empirically without waiting for antibody confirmation. Early clinical suspicion is key, as the outcome depends on early initiation of immunotherapy, including corticosteroids, intravenous immunoglobulin, and/or plasmapheresis. Severe or refractory cases require other treatments, such as rituximab, cyclophosphamide, or other immunotherapies using novel monoclonal antibodies. Psychiatry should be involved early for the management of behavioral issues. Additional considerations include management of seizures and dyskinesias. ICU admission may be required for management of hypoventilation necessitating mechanical ventilation (either intrinsic or iatrogenic, eg, from sedatives), refractory seizures, and dysautonomia. Anti-N-methyl-d-aspartate receptor and other forms of autoimmune encephalitis are less often associated with neoplasia (such as ovarian teratoma) in children compared with adults, but screening and removal of tumor if present should be performed.

Diagnosis and Management of Suspected Pediatric Autoimmune Encephalitis: A Comprehensive, Multidisciplinary Approach and Review of Literature

Autoimmune encephalitis is an increasingly recognized entity in children. When treated promptly, favorable outcomes are seen in a majority of pediatric patients. However, recognition of autoimmune encephalitis in young patients is challenging. Once autoimmune encephalitis is suspected, additional difficulties exist regarding timing of treatment initiation and duration of treatment, as evidence to guide management of these patients is emerging. Here, we review available literature regarding pediatric autoimmune encephalitis and present our institution's comprehensive approach to the evaluation and management of the disease. These guidelines were developed through an iterative process involving both pediatric neurologists and rheumatologists.

Case Report: Anti-NMDAR Encephalitis Presenting With Catatonic Symptoms in an Adolescent Female Patient With a History of Traumatic Exposure

INTRODUCTION

Catatonia is a severe syndrome associated with a high proportion of underlying organic conditions including autoimmune encephalitis. The link between catatonia and psychiatric conditions such as mood disorders and schizophrenia spectrum disorders is well established while the causative effect of Post-Traumatic Stress Disorders and stress related disorders remains speculative.

CASE REPORT

Here we describe the clinical case of a 14-year-old female patient presenting to the Emergency Department of a Pediatric University Hospital with acute changes in behavior five days after a sexual abuse. Acute stress reaction was suspected. Afterwards she developed catatonic symptoms alternating from stupor to excitement, resistant to the usual treatment with benzodiazepines. The first line examinations (PE, MRI, EEG) were inconclusive. The final diagnosis of anti-NMDARE was made 22 days after her admission in a University Department of Child and Adolescent Psychiatry. Her state improved after first- and second-line immunotherapy, with no signs of relapse at this day (8 months of clinical follow-up).

DISCUSSION

The diagnosis of anti-NMDARE is challenging, involving a multidisciplinary approach. The neuropsychiatric features are complex, with no specific psychiatric phenotype. Several hypotheses are discussed to determine the role of an acute environmental stressors in the emergence of such complex neuropsychiatric clinical presentation (i.e., shared vulnerability, precipitators, consequences of preexisting psychiatric symptoms).

CONCLUSION

Child and adolescent psychiatrists and pediatricians should be aware of the overlap between neurological and psychiatric features in the setting of anti-NMDARE. Catatonia should not be dismissed as a primary psychiatric disorder even in the context of recent traumatic exposure.

Clinical features, investigations, and outcomes of pediatric limbic encephalitis: A multicenter study

OBJECTIVES

To describe the clinical presentation, investigations, management, and disease course in pediatric autoimmune limbic encephalitis (LE).

METHODS

In this retrospective observational study, from the UK Childhood Neuroinflammatory Disease network, we identified children from six tertiary centers with LE <18 years old between 2008 and 2021. Clinical and paraclinical data were retrieved from medical records.

RESULTS

Twenty-five children fulfilling LE criteria were identified, with median age of 11 years (IQR 8, 14) and median follow-up of 24 months (IQR 18, 48). All children presented with seizures; 15/25 (60%) were admitted to intensive care. Neuroimaging demonstrated asymmetric mesial temporal changes in 8/25 (32%), and extra-limbic changes with claustrum involvement in 9/25 (38%). None were positive for LGI1/CASPR2 antibodies (Abs), 2/25 were positive for serum anti-NMDAR Abs, and 2/15 positive for anti-Hu Abs; one died from relapsing neuroblastoma. Two children had serum and CSF anti-GAD antibodies. Initial immune therapy included steroids in 23/25 (92%), intravenous immunoglobulin (IVIg) in 14/25 (56%), and plasma exchange in 7/25 (28%). The commonest second-line treatment was rituximab in 15/25 (60%). Median duration of hospital admission was 21 days (IQR 11, 30). At last follow-up, 13/25 (52%) had refractory seizures and 16/25 (64%) had memory impairment. Six children (24%) had modified Rankin Scale (mRS) scores ≥3. There was no significant difference in mRS, or long-term cognitive and epilepsy outcomes in those who received rituximab versus those who did not.

INTERPRETATION

A diagnosis of autoimmune LE was associated with significant morbidity and adverse outcomes in this pediatric cohort.

Autoimmune Encephalitis and Autism Spectrum Disorder

The concept of "acquired autism" refers to the hypothesis that amongst the massive heterogeneity that encompasses autism spectrum disorder (ASD) there may be several phenotypes that are neither syndromic nor innate. Strong and consistent evidence has linked exposure to various pharmacological and infective agents with an elevated risk of a diagnosis of ASD including maternal valproate use, rubella and herpes encephalitis. Autoimmune encephalitis (AE) describes a group of conditions characterised by the body's immune system mounting an attack on healthy brain cells causing brain inflammation. The resultant cognitive, psychiatric and neurological symptoms that follow AE have also included ASD or autism-like traits and states. We review the current literature on AE and ASD. Drawing also on associated literature on autoimmune psychosis (AP) and preliminary evidence of a psychosis-linked subtype of ASD, we conclude that AE may either act as a potentially causative agent for ASD, and/or produce symptoms that could easily be mistaken for or misdiagnosed as autism. Further studies are required to discern the connection between AE and autism. Where autism is accompanied by regression and atypical onset patterns, it may be prudent to investigate whether a differential diagnosis of AE would be more appropriate.

Pediatric Autoimmune Encephalitis in Sri Lanka: A Single-Center Experience over 7 Years

Pediatric autoimmune encephalitis (AE) remains a diagnostic and therapeutic challenge in resource-poor settings. Minimizing delay in diagnosis and appropriate escalation of treatment will help reduce both the short- and long-term neurodisabilities. A retrospective observational study was performed on children consecutively diagnosed with possible AE and then prospectively followed up in a single tertiary care children's hospital in Sri Lanka. Serum and cerebrospinal fluid were tested for neuroglial surface-binding autoantibodies using cell-based assays in majority of these children. Twenty-five children (mean age 7.6 years, standard deviation = 4) were recruited. In these children, presenting symptom was psychiatric in 11 children (44%), seizures in 10 (40%), language regression in 2 (8%), and combination of psychosis and convulsions in 2 (8%). Psychiatric presentations were more common in older (>6 years) compared with young children (p = 0.001), while neurological presentations were more common in children aged ≤6 years (p = 0.001). N-methyl-D-aspartate receptor (NMDAR) antibodies were detected in 9 (45%) and unspecified voltage-gated potassium channel antibodies in 1 (5%) of the 20 tested. All received intravenous steroids and immunoglobulins; 19 (76%) plasma exchange; 7 (29%) rituximab. Complete/substantial improvement at 3 months occurred in 64%. Pediatric Cerebral Performance Category score at last review was 1 (normal function for age) in 43%. Higher proportion of younger children required less intense therapy and had better recovery (56%). Death (8%), incomplete recovery (71%), and relapses (8%) were more in older children. Clinical presentation and disease outcomes were different in children aged <6 years compared with older age group. NMDAR antibody encephalitis was the commonest AE syndrome identified in this cohort.

Anti-NMDAR Encephalitis After Neonatal HSV-1 Infection in a Child With Low TLR-3 Function

Neonatal herpes simplex virus encephalitis (HSVE) often results in long-lasting neuro-disability in affected children. In addition to primary HSVE and HSVE relapses, children with herpes simplex virus are at increased risk of developing anti-N-methyl-d-aspartate receptor encephalitis (NMDARe), an autoimmune encephalitis. In this study, we describe a patient with neonatal disseminated herpes infection, who developed HSVE after discontinuation of 2 years of acyclovir suppressive therapy. After resolution of HSVE, the patient rapidly deteriorated with significant behavioral and neurologic changes including emotional outbursts, fearfulness, involuntary movements, and focal seizures. The patient was diagnosed with anti-NMDARe and was later found to have low toll-like receptor-3 function. In this study, we review published pediatric cases of anti-NMDARe after HSVE as well as previous literature and primary data examining the presentation, predisposing risk factors, predictive outcomes, future directions, and the role of immunodeficiency in HSVE-mediated anti-NMDARe. The neonatal immune system and developing brain are disproportionately vulnerable to early viral exposure; therefore, it is important to recognize the value of early immunodeficiency screening in patients with neonatal herpes simplex virus. By understanding the immune landscape within this patient population, we can mitigate long-term neurologic disability and improve the quality of life of affected children.

Thalamic Lesions in a Toddler with Glutamic Acid Decarboxylase Autoimmune Encephalitis

We present a child with glutamic acid decarboxylase (GAD) autoimmune encephalitis (AE) with bilateral thalamic lesions on magnetic resonance imaging (MRI) of the brain. A healthy 21-month-old girl, after superrefractory status epilepticus (SE) and fever developed dyskinesia and ataxia, which we subsequently diagnosed as GAD AE. She showed remarkable response to treatment with methylprednisolone and intravenous immunoglobulin (IVIg). Following an initial normal MRI of her brain, a further brain imaging showed bilateral thalamic lesions. This is an unusual finding since brain imaging abnormalities, when found in GAD AE, mostly involve the mesial temporal lobe structures. Thalamic lesions in GAD AE have not been reported previously.

Pediatric auto-immune encephalitis

Pediatric Auto-Immune Encephalitis (PAE) is a neuro-inflammatory disorder with a varied presentation. The discovery of the Anti NMDA receptor and other antibodies as the causative agents of PAE, has led to an increased need for guidelines for diagnosis and management of these disorders. PAE remains a challenging group of disorders due to their varying presentations and etiology with a prolonged clinical course. The wide spectrum of clinical symptoms involves altered mental status, movement disorders, acute behavioral changes, psychosis, delirium, seizures, and insomnia. This group of disorders was recently recognized in the children. This review provides clinicians with information on the most common PAE disorders, the spectrum of their clinical presentation, diagnostic tests and treatment protocols based on the current literature.

High incidence of NMDAR encephalitis among Austronesians: A population-based study in Sabah, Malaysia

NMDAR encephalitis may be more common among non-Caucasians. A population-based study was conducted to estimate its incidence in Sabah, Malaysia, where the population consists predominantly of Austronesians (84%), and with a Chinese minority. Registries of NMDAR encephalitis at neurology referral centers were reviewed for case ascertainment. The annual incidence was 2.29/million (Austronesians: 2.56/million, Chinese: 1.31/million). Among pediatric population, the incidence was: Austronesians: 3.63/million, Chinese: 2.59/million. Our study demonstrated a higher incidence of NMDAR encephalitis among Austronesians than the predominantly Caucasian populations in Europe (0.5-0.9/million; pediatric: 0.7-1.5/million). Racial and genetic factors may contribute to risks of developing NMDAR encephalitis.

Clinical Features and Treatment Outcomes of Seronegative Pediatric Autoimmune Encephalitis

BACKGROUND AND PURPOSE

New diagnostic criteria for pediatric autoimmune encephalitis (AIE) have been introduced recently. A substantial proportion of cases of pediatric AIE are diagnosed as seronegative based on these criteria, and so the clinical characteristics of this group remain to be investigated.

METHODS

This study included 46 pediatric patients younger than 18 years with suspected AIE. Clinical features, laboratory or radiological findings, and treatment outcomes were compared between seronegative and seropositive patients.

RESULTS

Nine (19.6%) of the 46 patients were diagnosed as seropositive AIE. All of the patients with seropositive AIE had anti-N-methyl-D-aspartate receptor antibodies. Commonly identified neuropsychiatric symptoms were altered mental status, cognitive dysfunction, seizure, speech dysfunction, and psychotic disorder in both the seronegative and seropositive groups. Immunotherapy produced favorable treatment outcomes in both the seropositive (n=7, 77.8%) and seronegative (n=35, 94.6%) AIE patients. Treatment outcomes for first-line immunotherapy were better in seronegative AIE than seropositive AIE patients (p=0.003), and hence a smaller proportion of seronegative patients required second-line treatment (p=0.015).

CONCLUSIONS

Pediatric seronegative AIE patients showed clinical presentations similar to those of seropositive AIE patients, with favorable treatment outcomes after immunotherapy.

Antibody-Mediated Encephalitis in Children: Focus on Diagnostic Clues and Acute Symptom Management

Antibody-mediated encephalitis is a treatable cause of encephalitis that manifests over days to weeks as changes in behavior and cognition, seizures, movement disorders, and autonomic dysfunction. Patients with autoimmune encephalitis develop a variety of symptoms. As such, they require a multidisciplinary approach to care. In this review we summarize the clinical presentation and practical diagnostic approach to pediatric autoimmune encephalitis, review treatments of the autoimmune process, and discuss the management of the acute symptoms encountered in children.

Autoimmune Encephalitis in Children: From Suspicion to Diagnosis

There are several well-described and studied autoimmune diseases that affect different organ systems, and a limited number of these affect the central nervous system. Autoimmune encephalitis represents a disease with a wide spectrum of clinical manifestations and different levels of severity, from mild cognitive impairment to complex encephalopathy. Immune-mediated encephalitis refers to a diverse and rare group of conditions in children associated with nonspecific symptomatology, altered mental state, and recalcitrant seizures. Infectious etiology must be excluded. Immune-mediated encephalitis syndromes could be associated with paraneoplastic or primarily autoimmune mechanisms. The newest scientific advantages have concluded that autoimmune encephalitis may be further divided into different groups of diseases depending on the immune response; examples are antibodies to cell surface proteins, antibodies to intracellular synaptic proteins, T-cell response with antibodies to intracellular antigens, among others. Treatment consists of supportive therapy, ranging from supplemental oxygen, fluid restriction to mechanical circulatory support. Specific treatment includes immunoglobulin infusion, plasmapheresis, and pulse steroid treatment. Prognosis is poor if specific treatment is not timely instituted. The diagnosis of autoimmune encephalitis could be challenging to clinicians due to its diverse clinical features, which can mimic a variety of other pathologic processes. Screening for cancer and proper management that includes immune therapy are fundamental, although some patients will need immune suppression for weeks or months as autoimmune encephalitis may relapse; therefore, follow-up is always necessary.

Electroencephalographic findings in antileucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis: A systematic review

BACKGROUND

Antileucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis is a distinct syndrome of early onset faciobrachial dystonic seizures (FBDS) and other focal seizures followed by neuropsychiatric symptoms. The electroclinical syndrome of this condition is yet to be fully understood. The main objective of this study was to determine the frequencies of electroencephalogram (EEG) findings in patients diagnosed with anti-LGI1 autoimmune encephalitis through a systematic review of published relevant articles.

METHODS

Major electronic healthcare databases were searched for relevant published articles until July 2020.

RESULTS

From 327 articles, 23 case reports and 14 case series were included in the review after satisfying the eligibility criteria. Data from a total of 151 cases of definite anti-LGI1 encephalitis were analyzed in this systematic review. Epileptiform discharges were the most frequent finding at 57.3%. Focal electroencephalographic abnormalities including slow wave (59.3%) and epileptiform activities (53.5%) most commonly arise from the temporal region. Faciobrachial dystonic seizures often have no ictal electroencephalographic correlate but would show electrodecremental events when seizure duration is prolonged.

CONCLUSION

Electroencephalogram abnormalities are seen in anti-LGI1 autoimmune encephalitis with epileptiform discharges as the most common finding followed by focal slowing. These findings were most frequently seen arising in the temporal region. Further studies using a standardized protocol focusing on electroencephalographic findings in anti-LGI1 encephalitis with clinical correlation to disease stage and treatment outcomes in terms of seizure control and memory and cognitive function are needed. Particular attention on ictal electrodecremental activity during FBDS should be done in studies with a larger sample size.