Anti-NMDA receptor encephalitis: report of ten cases and comparison with viral encephalitis

Cortical atrophy in early-stage patients with anti-NMDA receptor encephalitis: a machine-learning MRI study with various feature extraction

Conventional brain magnetic resonance imaging (MRI) of anti-N-methyl-D-aspartate-receptor encephalitis (NMDARE) is non-specific, thus showing little differential diagnostic value, especially for MRI-negative patients. To characterize patterns of structural alterations and facilitate the diagnosis of MRI-negative NMDARE patients, we build two support vector machine models (NMDARE versus healthy controls [HC] model and NMDARE versus viral encephalitis [VE] model) based on radiomics features extracted from brain MRI. A total of 109 MRI-negative NMDARE patients in the acute phase, 108 HCs and 84 acute MRI-negative VE cases were included for training. Another 29 NMDARE patients, 28 HCs and 26 VE cases were included for validation. Eighty features discriminated NMDARE patients from HCs, with area under the receiver operating characteristic curve (AUC) of 0.963 in validation set. NMDARE patients presented with significantly lower thickness, area, and volume and higher mean curvature than HCs. Potential atrophy predominately presented in the frontal lobe (cumulative weight = 4.3725, contribution rate of 29.86%), and temporal lobe (cumulative weight = 2.573, contribution rate of 17.57%). The NMDARE versus VE model achieved certain diagnostic power, with AUC of 0.879 in validation set. Our research shows potential atrophy across the entire cerebral cortex in acute NMDARE patients, and MRI machine learning model has a potential to facilitate the diagnosis MRI-negative NMDARE.

Temporal transformer-spatial graph convolutional network: an intelligent classification model for anti N-methyl-D-aspartate receptor encephalitis based on electroencephalogram signal

Encephalitis is a disease typically caused by viral infections or autoimmunity. The most common type of autoimmune encephalitis is anti-N-methyl-D-aspartate receptor (NMDAR) antibody-mediated, known as anti-NMDA receptor encephalitis, which is a rare disease. Specific EEG patterns, including "extreme delta brush" (EDB), have been reported in patients with anti-NMDA receptor encephalitis. The aim of this study was to develop an intelligent diagnostic model for encephalitis based on EEG signals. A total of 131 Participants were selected based on reasonable inclusion criteria and divided into three groups: health control (35 participants), viral encephalitis (58 participants), and anti NMDAR receptor encephalitis (55 participants). Due to the low prevalence of anti-NMDAR receptor encephalitis, it took several years to collect participants' EEG signals while they were in an awake state. EEG signals were collected and analyzed following the international 10-20 system layout. We proposed a model called Temporal Transformer-Spatial Graph Convolutional Network (TT-SGCN), which consists of a Preprocess Module, a Temporal Transformer Module (TTM), and a Spatial Graph Convolutional Module (SGCM). The raw EEG signal was preprocessed according to traditional procedures, including filtering, averaging, and Independent Component Analysis (ICA) method. The EEG signal was then segmented and transformed using short-time Fourier transform (STFT) to produce concatenated power density (CPD) maps, which served as inputs for the proposed model. TTM extracted the time-frequency features of each channel, and SGCM fused these features using graph convolutional methods based on the location of electrodes. The model was evaluated in two experiments: classification of the three groups and pairwise classification among the three groups. The model was trained using two stages and achieved the performance, with an accuracy of 82.23%, recall of 80.75%, precision of 82.51%, and F1 score of 81.23% in the classification of the three groups. The proposed model has the potential to become an intelligent auxiliary diagnostic tool for encephalitis.

Anti-N-methyl-D-aspartate receptor encephalitis and positive human herpesvirus-7 deoxyribonucleic acid in cerebrospinal fluid: a case report

BACKGROUND

Anti-N-methyl-D-aspartate receptor encephalitis is a neuroautoimmune syndrome typically presenting with seizures, psychiatric symptoms, and autonomic dysfunction. Human herpesvirus-7 is often found with human herpesvirus-6 and infects leukocytes such as T-cells, monocytes-macrophages, epithelial cells, and central nervous system cells. The pathogenicity of human herpesvirus-7 is unclear. Cases of anti-N-methyl-D-aspartate receptor encephalitis with human herpesvirus-7 present in cerebrospinal fluid have been documented, but the clinical significance of this finding remains unclear.

CASE PRESENTATION

An 11-year-old Caucasian boy was admitted to hospital after a generalized tonic-clonic seizure. Generalized tonic seizures repeated three more times during the day of hospitalization. Blood tests showed minor ongoing inflammation, while brain computed tomography yielded normal results. Brain magnetic resonance imaging showed hyperintense focal alterations in both temporal lobes, hippocampi, and at the base of the right frontal lobe. Positive anti-N-methyl-D-aspartate receptor antibodies were found in both serum and cerebrospinal fluid. Positive novel coronavirus 2 (severe acute respiratory syndrome coronavirus 2) immunoglobulin G antibodies were found in serum. Polymerase chain reaction test for severe acute respiratory syndrome coronavirus 2 was negative. Furthermore, positive human herpesvirus-7 deoxyribonucleic acid was found in cerebrospinal fluid. The patient was treated with acyclovir, human immunoglobulin, and methylprednisolone. The seizures did not repeat, and no psychiatric symptoms were present. The patient made a full recovery.

CONCLUSIONS

We present a pediatric case of anti-N-methyl-D-aspartate receptor encephalitis with atypical clinical presentation. The role of human herpesvirus-7 in neurological disorders remains unclear in immunocompetent patients.

Long COVID and the Neuroendocrinology of Microbial Translocation Outside the GI Tract: Some Treatment Strategies

Similar to previous pandemics, COVID-19 has been succeeded by well-documented post-infectious sequelae, including chronic fatigue, cough, shortness of breath, myalgia, and concentration difficulties, which may last 5 to 12 weeks or longer after the acute phase of illness. Both the psychological stress of SARS-CoV-2 infection and being diagnosed with COVID-19 can upregulate cortisol, a stress hormone that disrupts the efferocytosis effectors, macrophages, and natural killer cells, leading to the excessive accumulation of senescent cells and disruption of biological barriers. This has been well-established in cancer patients who often experience unrelenting fatigue as well as gut and blood–brain barrier dysfunction upon treatment with senescence-inducing radiation or chemotherapy. In our previous research from 2020 and 2021, we linked COVID-19 to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) via angiotensin II upregulation, premature endothelial senescence, intestinal barrier dysfunction, and microbial translocation from the gastrointestinal tract into the systemic circulation. In 2021 and 2022, these hypotheses were validated and SARS-CoV-2-induced cellular senescence as well as microbial translocation were documented in both acute SARS-CoV-2 infection, long COVID, and ME/CFS, connecting intestinal barrier dysfunction to disabling fatigue and specific infectious events. The purpose of this narrative review is to summarize what is currently known about host immune responses to translocated gut microbes and how these responses relate to fatiguing illnesses, including long COVID. To accomplish this goal, we examine the role of intestinal and blood–brain barriers in long COVID and other illnesses typified by chronic fatigue, with a special emphasis on commensal microbes functioning as viral reservoirs. Furthermore, we discuss the role of SARS-CoV-2/Mycoplasma coinfection in dysfunctional efferocytosis, emphasizing some potential novel treatment strategies, including the use of senotherapeutic drugs, HMGB1 inhibitors, Toll-like receptor 4 (TLR4) blockers, and membrane lipid replacement.

Younger Age at Onset Is Associated With Worse Long-term Behavioral Outcomes in Anti-NMDA Receptor Encephalitis

BACKGROUND AND OBJECTIVES

Anti-NMDA receptor encephalitis (anti-NMDARE) is one of the most common causes of encephalitis. It typically presents in adolescence and young adulthood, but little is known about its potential long-term consequences across the lifespan. Adaptive behavior describes an individual's ability to respond and adapt to environmental demands and unanticipated changes in daily routines. In this study, we evaluate the relationship between features from clinical presentation, including age, and long-term adaptive behavior in participants with anti-NMDARE.

METHODS

Cross-sectional informant-reported data were collected between 2017 and 2019 from 41 individuals/caregivers of individuals with anti-NMDARE treated at 3 major academic hospitals. Neurologic disability was assessed by record review using the modified Rankin Scale (mRS). Functional outcomes were assessed using the validated Adaptive Behavior Assessment System, Third Edition (ABAS-3).

RESULTS

The mean age at the time of study enrollment was 23.4 years (SD 17.0 years), and the mean time from symptom onset to study enrollment was 4.0 years. Seventeen participants were aged <12 years at symptom onset, 19 participants were aged 12-30 years, and 5 participants were aged >30 years. Mean ABAS-3 scores at study enrollment for all participants were in the average range (mean general adaptive composite standard score 92.5, SD 18.7). Individuals aged <12 years at symptom onset had lower mean ABAS-3 scores and were in the below average range compared with those aged 12-30 years at symptom onset, whose mean scores were in the average range (87 vs 99, p < 0.05). Similar differences were seen in 3 of the individual subscales (functional academics, health and safety, and self-care). There were no significant differences in mRS scores between age groups (p > 0.05).

DISCUSSION

Although anti-NMDARE is associated with an overall favorable outcome, younger age at onset associates with worse long-term adaptive behavior despite no differences in neurologic disability. These findings suggest that the disease may have distinct consequences on the early developing brain. Future studies should evaluate behavioral recovery and quality of life after anti-NMDARE and identify additional factors associated with differential recovery.

Severity of Hospitalized Children with Anti-NMDAR Autoimmune Encephalitis

Background: Information on the clinical characteristics and severity of autoimmune encephalitis with antibodies against the N-methyl-d-aspartate receptor (NMDAR) in children is attracting more and more attention in the field of pediatric research. Methods: In this retrospective cohort study, all cases (n = 67) were enrolled from a tertiary children's hospital, from 2017 to 2020. We compared severe cases that received intensive care unit (ICU) care with nonsevere cases that did not receive ICU care and used machine learning algorithm to predict the severity of children, as well as using immunologic and viral nucleic acid tests to identify possible pathogenic triggers. Results: Mean age of children was 8.29 (standard deviation 4.09) years, and 41 (61.19%) were girls. Eleven (16.42%) were admitted to the ICU, and 56 (83.58%) were admitted to neurology ward. Ten individual parameters were statistically significant differences between severe cases and nonsevere cases (P < .05), including headache, abnormal mental behavior or cognitive impairment, seizures, concomitant tumors, sputum/blood pathogens, blood globulin, blood urea nitrogen, blood immunoglobulin G, blood immunoglobulin M, and number of polynucleated cells in cerebrospinal fluid. Random forest regression model presented that the overall prediction power of severity reached 0.806, among which the number of polynucleated cells in cerebrospinal fluid contributed the most. Potential pathogenic causes exhibited that the proportion of mycoplasma was the highest, followed by Epstein-Barr virus. Conclusion: Our findings provided evidence for early identification of autoimmune encephalitis in children, especially in severe cases.

Contemporary advances in anti-NMDAR antibody (Ab)-mediated encephalitis

The study of antibody (Ab)-mediated encephalitis has advanced dramatically since the discovery of antibodies directed against the N-methyl-D-aspartate receptor (NMDAR) in association with a unique neuro-psychiatric syndrome, over a decade-and-a-half ago. Anti-NMDAR Ab-mediated encephalitis now represents the most well characterised form of autoimmune encephalitis. The disease most commonly manifests in young women, but all ages and both sexes can be affected. Autoantibodies may arise in the context of two well-recognised disease triggers in a proportion of patients, and ultimately facilitate NMDAR displacement from synapses. Various CSF cytokines, chemokines, and other molecules have been explored as candidate biomarkers but are limited in sensitivity and specificity. The clinical spectrum is diverse, with evolution and a combination of neuro-psychiatric abnormalities at disease nadir common. Anti-NMDAR Ab-mediated encephalitis is immunotherapy responsive, and a near-majority ultimately acquire a broadly favourable clinical outcome. The diagnosis, and more particularly, the management of the disease can still hold considerable challenges. Moreover, well-defined biomarkers remain elusive. The present review will therefore delineate pathogenic and clinical advances to date in anti-NMDAR antibody-mediated encephalitis.

Diagnostic approach and treatment regimens in adult patients suffering from antibody-mediated or paraneoplastic encephalitis

Identification of patients with antibody-mediated encephalitis poses a diagnostic challenge and any delay in that respect will increase the interval until initiation of immunotherapy and may negatively affect the patient´s clinical outcome. Within this review we focus on therapeutic strategies in antibody-mediated encephalitis and propose how to proceed with patients, who are suspected to have encephalitis of unknown origin. We further briefly outline differences in treatment of paraneoplastic and antibody-mediated encephalitis according to its pathomechanisms.

Inflammatory Disease Affecting the Central Nervous System in Dogs: A Retrospective Study in England (2010–2019)

The epidemiology of inflammatory diseases affecting the central nervous system (CNS) in dogs is largely unknown. We aimed to report the relative proportion of different causes of inflammatory disease affecting the CNS in dogs and identify predictors for infectious vs. immune-mediated conditions and predictors for the most common diseases affecting the brain and the spinal cord. This was a retrospective cohort study over a 10-year period in 2 referral institutions using multivariable and multinomial logistic regression for identification of risk factors. In total, 1,140 client-owned dogs diagnosed with inflammatory disease affecting the CNS were included. Fifteen different diagnoses were identified, with immune-mediated (83.6%) disease being more common than infectious conditions (16.4%). The most common immune-mediated conditions diagnosed were meningoencephalitis of unknown origin (47.5%) and steroid-responsive meningitis–arteritis (30.7%), and the most common infectious conditions were discospondylitis (9.3%) and otogenic intracranial infection (2.2%). Older age (p < 0.001, OR = 1.019, 95% CI: 1.014–1.024), higher body weight (p < 0.001, OR = 1.049, 95% CI: 1.025–1.074), male sex (p = 0.009, OR = 1.685, 95% CI: 1.141–2.488), longer duration of the clinical signs before presentation (p < 0.001, OR = 1.011, 95% CI: 1.006–1.017), progressive nature of the clinical signs (p < 0.001, OR = 2.295, 95% CI: 1.463–3.599), identification of a possibly associated preceding event (p = 0.0012, OR = 1.93, 95% CI: 1.159–3.213), and hyperesthesia on presentation (p < 0.001, OR = 2.303, 95% CI: 1.528–3.473) were associated with a diagnosis of infectious diseases. Our data shows that immune-mediated diseases are more common than infectious conditions as a cause for inflammatory CNS disease in dogs. The risk factors for the most common diagnoses were identified from signalment, history, and findings of the physical and neurological examinations to give valuable information that can guide clinicians with their investigations.

Paraneoplastic and Other Autoimmune Encephalitides: Antineuronal Antibodies, T Lymphocytes, and Questions of Pathogenesis

Autoimmune and paraneoplastic encephalitides represent an increasingly recognized cause of devastating human illness as well as an emerging area of neurological injury associated with immune checkpoint inhibitors. Two groups of antibodies have been detected in affected patients. Antibodies in the first group are directed against neuronal cell surface membrane proteins and are exemplified by antibodies directed against the N-methyl-D-aspartate receptor (anti-NMDAR), found in patients with autoimmune encephalitis, and antibodies directed against the leucine-rich glioma-inactivated 1 protein (anti-LGI1), associated with faciobrachial dystonic seizures and limbic encephalitis. Antibodies in this group produce non-lethal neuronal dysfunction, and their associated conditions often respond to treatment. Antibodies in the second group, as exemplified by anti-Yo antibody, found in patients with rapidly progressive cerebellar syndrome, and anti-Hu antibody, associated with encephalomyelitis, react with intracellular neuronal antigens. These antibodies are characteristically found in patients with underlying malignancy, and neurological impairment is the result of neuronal death. Within the last few years, major advances have been made in understanding the pathogenesis of neurological disorders associated with antibodies against neuronal cell surface antigens. In contrast, the events that lead to neuronal death in conditions associated with antibodies directed against intracellular antigens, such as anti-Yo and anti-Hu, remain poorly understood, and the respective roles of antibodies and T lymphocytes in causing neuronal injury have not been defined in an animal model. In this review, we discuss current knowledge of these two groups of antibodies in terms of their discovery, how they arise, the interaction of both types of antibodies with their molecular targets, and the attempts that have been made to reproduce human neuronal injury in tissue culture models and experimental animals. We then discuss the emerging area of autoimmune neuronal injury associated with immune checkpoint inhibitors and the implications of current research for the treatment of affected patients.

Etiological and Clinical Profile of Acute Nonbacterial Encephalitis in Children: A Single-Center Prospective Study

Encephalitis is a serious neurological syndrome caused by inflammation of the brain. The diagnosis can be challenging and etiology remains unidentified in about half of the pediatric cases. We aimed to investigate demographic, clinical, laboratory, electroencephalographic and neuroimaging findings, and outcome of acute encephalitis of nonbacterial etiology. This prospective study included children hospitalized with the diagnosis of acute encephalitis between 2017 and 2019. Microbiological investigations of the cerebrospinal fluid (CSF) were recorded. All CSF specimens were tested for anti-N methyl D-aspartate receptor (NMDAR) antibodies. In total, 31 children aged 10 months to 17 years (median = 6 years) were included. Pathogens were confirmed in CSF in three patients (9.7%): varicella zoster virus, herpes simplex virus type 1 (HSV-1), and both HSV-1 and NMDAR antibodies. Presenting features included encephalopathy (100%), fever (80.6%), seizure (45.2%), focal neurological signs (29%), and ataxia (19.4%). On clinical follow-up of median 9 (6-24) months, six patients showed neurological deficits: together with two patients who died in hospital, total eight (25.8%) patients were considered to have unfavorable outcome. Need for intubation, receiving immunomodulatory treatment, prolonged hospitalization, and high erythrocyte sedimentation rate at admission were associated with unfavorable outcome. The etiology of encephalitis remains unexplained in the majority of children. HSV-1 is the most frequently detected virus, consistent with the literature. The fact that anti-NMDAR encephalitis was detected in one child suggests autoimmune encephalitis not being rare in our center. The outcome is favorable in the majority while about one-fifth of cases suffer from sequelae.

Pediatric Autoimmune Encephalitis and Its Relationship With Infection

Autoimmune encephalitis (AE) is an increasingly recognized inflammatory disorder of the central nervous system and is most often characterized by antibodies against intracellular and neuronal surface antigens. AE is a devastating disease that may result in developmental delay or regression in children. However, the pathogenesis of AE is not clear, and immune system disorders after infection likely play an important role in AE. Many studies have reported that patients with herpes simplex virus encephalitis develop anti-N-methyl-d-aspartate receptor encephalitis after antiviral treatment. It is critical to recognize pediatric AE early and to distinguish it from infectious forms because AE is treatable and responsive to immunotherapies. In this review, we discuss the clinical features of pediatric AE and focus on the relationship between AE and postinfection status. In addition, we review the probable mechanisms underlying infection-triggered AE, which include molecular mimicry, bystander activation, epitope spreading, immune system disorder, and genetic susceptibility.

Encephalitis in Previously Healthy Children

Encephalitis is defined as altered mental status for more than 24 hours accompanied by 2 or more findings concerning for inflammation of the brain parenchyma: fever, seizures or other focal neurologic disorders, cerebrospinal fluid pleocytosis, and abnormal neuroimaging and electroencephalographic findings. Herpes simplex virus causes the most severe form of virus-induced encephalitis; the early administration of acyclovir can improve the prognosis of this disease. The rising interest in autoimmune causes of encephalitis, most notably anti-N-methyl-d-aspartate receptor, should prompt the clinician to consider immunomodulatory treatments, which may improve outcomes. A broad testing panel may be necessary to detect the etiologic agent; a few published pediatric cases suggest that infectious and autoimmune causes may occur concurrently in the same patient with encephalitis. More than 40% of children diagnosed as having encephalitis will not return to their previous level of neurologic function after resolution of their disease, although outcomes are highly variable depending on the etiologic agent.

A narrative review of pharmacologic approaches to symptom management of pediatric patients diagnosed with anti-NMDA receptor encephalitis

Anti-N-Methyl-D-Aspartate Receptor Encephalitis (ANMDARE) is one of the most common autoimmune encephalitis in the pediatric population. Patients with ANMDARE initially present with a prodrome of neuropsychiatric symptoms followed by progressively worsening seizures, agitation, and movement disorders. Complications can include problems such as aggression, insomnia, catatonia, and autonomic instability. Due to the complexity of this disease process, symptom management can be complex and may lead to significant polypharmacy. The goal of this review is to educate clinicians about the challenges of managing this disorder and providing guidance in symptom management.

Differential Diagnosis and Hospital Emergency Management for Fastlane Treatment of Central Nervous System Infection Under the COVID-19 Epidemic in Changsha, China

Importance: Corona virus disease 2019 (COVID-19) has long latent period, strong infectivity, and non-specific symptoms and signs in the upper respiratory tract. Some initial neurological symptoms appear, including dizziness, headache, seizures, slurred speech, disturbance of consciousness, and limb paralysis among a few COVID-19 patients, which share similar manifestations with central nervous system (CNS) infection. Improving the diagnostic efficiency of suspected CNS infection patients on the basis of preventing and controlling COVID-19 plays a key role in preventing nosocomial and cross infections. This study intends to formulate a hospital emergency management system of fastlane treatment of CNS infection for epidemic prevention and control, aiming at providing references and guidelines for the government and medical institutions to improve the efficiency of treating CNS infection patients in the clinical practice during COVID-19.

Observations: This study formulated a framework of a fastlane treatment of CNS infection based on the cooperation of resources and experience, aiming at the key and difficult problems faced by the hospital emergency management system during the COVID-19 outbreak in Changsha, China. The main problem of formulating the hospital emergency management system is efficiently identifying whether CNS infection was caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The framework improves the efficiency of diagnosing and treating CNS infections by standardizing the diagnosis and treatment process of patients in emergency observation and strengthening the management of inpatient wards, aiming at assisting medical staff during clinical practice.

Conclusions and Relevance: The hospital emergency management system of a fastlane treatment of CNS infection for epidemic prevention and control of the COVID-19 outbreak is a professional and multisystem project, which needs the cooperation of various resources and the experience of clinical leadership.

Enhanced Detection of DNA Viruses in the Cerebrospinal Fluid of Encephalitis Patients Using Metagenomic Next-Generation Sequencing

The long and expanding list of viral pathogens associated with causing encephalitis confounds current diagnostic procedures, and in up to 50% of cases, the etiology remains undetermined. Sequence-agnostic metagenomic next-generation sequencing (mNGS) obviates the need to specify targets in advance and thus has great potential in encephalitis diagnostics. However, the low relative abundance of viral nucleic acids in clinical specimens poses a significant challenge. Our protocol employs two novel techniques to selectively remove human material at two stages, significantly increasing the representation of viral material. Our bioinformatic workflow using open source protein- and nucleotide sequence-matching software balances sensitivity and specificity in diagnosing and characterizing any DNA viruses present. A panel of 12 cerebrospinal fluid (CSFs) from encephalitis cases was retrospectively interrogated by mNGS, with concordant results in seven of nine samples with a definitive DNA virus diagnosis, and a different herpesvirus was identified in the other two. In two samples with an inconclusive diagnosis, DNA viruses were detected and in a virus-negative sample, no viruses were detected. This assay has the potential to detect DNA virus infections in cases of encephalitis of unknown etiology and to improve the current screening tests by identifying new and emerging agents.

Neuroimmunological antibody-mediated encephalitis and implications for diagnosis and therapy in neuropsychiatry

The past decade has seen a surge of reports and investigations into cases of autoimmune-mediated encephalitis. The increasing recognition of these disorders is especially of relevance to the fields of neurology and psychiatry. Autoimmune encephalitis involves antibodies against synaptic receptors, neuronal cell surface proteins and intracellular targets. These disorders feature prominent symptoms of cognitive impairment and behavioural changes, often associated with the presence of seizures. Early in the clinical course, autoimmune encephalitis may manifest as psychiatric symptoms of psychosis and involve psychiatry as an initial point of contact. Although commonly associated with malignancy, these disorders can present in the absence of an inciting neoplasm. The identification of autoimmune encephalitis is of clinical importance as a large proportion of individuals experience a response to immunotherapy. This review focuses on the current state of knowledge on n-methyl-d-aspartate (NMDA) receptor-associated encephalitis and limbic encephalitis, the latter predominantly involving antibodies against the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, the γ-aminobutyric acid (GABA)B receptor and leucine-rich glioma-inactivated 1 (LGI1) protein. In addition, we briefly describe anti-dopamine D2 receptor encephalitis. A summary of the literature will focus on common clinical presentations and course, diagnostic approaches and response to treatment. Since a substantial proportion of patients with autoimmune encephalitis exhibit symptoms of psychosis, the relevance of this disorder to theories of psychosis and schizophrenia will also be discussed.

Immune-mediated encephalitis for the infectious disease specialist

PURPOSE OF REVIEW

Autoimmune encephalitis is increasingly recognized and must be distinguished from infectious forms of encephalitis. Moreover, physicians should be aware of infectious triggers of autoimmune encephalitis and of infectious complications associated with treatment.

RECENT FINDINGS

Recent epidemiological studies suggest that the incidence of autoimmune encephalitis may rival that of infectious encephalitis. Although distinguishing autoimmune from infectious forms of encephalitis on clinical grounds can be challenging, recently proposed diagnostic criteria can provide some assistance. There has been an explosion in our knowledge of autoimmune encephalitis associated with antibodies to neuronal cell surface antigens, and two of the most common forms, anti-NMDA receptor encephalitis and anti-LGI1 encephalitis, are typically associated with distinctive clinical features. Although tumors have long been known to trigger autoimmune encephalitis, it has been recently recognized that herpes simplex encephalitis may trigger the generation of antineuronal autoantibodies resulting in an autoimmune neurologic relapse. Both first and second-line therapies for autoimmune encephalitis are associated with infectious complications, whereas emerging treatments, including anakinra and tocilizumab, may also result in increased susceptibility to certain infections.

SUMMARY

The diagnosis and management of autoimmune encephalitis is complex, and awareness of diagnostic criteria and modalities, typical clinical syndromes, infectious triggers of disease, and infectious complications of therapies is critical in optimizing care for affected patients.

Compliance with international guidelines in adults with encephalitis

Background

Encephalitis is associated with significant neurological disability and mortality. Many guidelines are published for encephalitis management but compliance with them is unknown.

Objectives

To evaluate the appropriate management and compliance to the current guidelines in adults with encephalitis.

Study design

A retrospective multicenter study at 17 hospitals in the Greater Houston area from August 1, 2008 through September 30, 2017. All cases met the definition for possible or probable encephalitis as per the international encephalitis consortium guidelines.

Results

A total of 241 adults (age >17 years) with encephalitis were enrolled. The most common etiologies were unknown (41.9 %), viral (27.8 %) and autoimmune (21.2 %). An adverse clinical outcome was seen in 49 % with 12.4 % in hospital mortality. A high compliance with guidelines (>90 %) was only seen in obtaining a brain computerized tomography (CT) scan, blood cultures and cerebrospinal fluid (CSF) gram stain and culture. A CSF herpes virus simplex (HSV) polymerase chain reaction (PCR) was done in 84 % and only repeated in 14.2 % of patients with an initial negative result. Furthermore, only two-thirds of patients were started empirically on intravenous acyclovir and antibiotics. Evaluation for other etiologies were not uniformly performed: arboviral serologies (57.3 %), CSF anti-N-Methyl-d-Aspartate Receptor (NMDA) receptor antibody (35.7 %), and CSF varicella zoster virus (VZV) PCR (32 %). The highest yield for the tests were arboviral serologies (42 %), anti-NMDA antibodies (41.2 %) and VZV PCR (16.4 %).

Conclusion

The management of encephalitis as per current guidelines is suboptimal leading to underutilization of currently available diagnostic tests and empirical therapy.

Drebrin Autoantibodies in Patients with Seizures and Suspected Encephalitis

OBJECTIVE

Assess occurrence of the dendritic spine scaffolding protein Drebrin as a pathophysiologically relevant autoantibody target in patients with recurrent seizures and suspected encephalitis as leading symptoms.

METHODS

Sera of 4 patients with adult onset epilepsy and suspected encephalitis of unresolved etiology and equivalent results in autoantibody screening were subjected to epitope identification. We combined a wide array of approaches, ranging from immunoblotting, immunoprecipitation, mass spectrometry, subcellular binding pattern analyses in primary neuronal cultures, and immunohistochemistry in brains of wild-type and Drebrin knockout mice to in vitro analyses of impaired synapse formation, morphology, and aberrant neuronal excitability by antibody exposure.

RESULTS

In the serum of a patient with adult onset epilepsy and suspected encephalitis, a strong signal at ∼70kDa was detected by immunoblotting, for which mass spectrometry revealed Drebrin as the putative antigen. Three other patients whose sera also showed strong immunoreactivity around 70kDa on Western blotting were also anti-Drebrin-positive. Seizures, memory impairment, and increased protein content in cerebrospinal fluid occurred in anti-Drebrin-seropositive patients. Alterations in cerebral magnetic resonance imaging comprised amygdalohippocampal T2-signal increase and hippocampal sclerosis. Diagnostic biopsy revealed T-lymphocytic encephalitis in an anti-Drebrin-seropositive patient. Exposure of primary hippocampal neurons to anti-Drebrin autoantibodies resulted in aberrant synapse composition and Drebrin distribution as well as increased spike rates and the emergence of burst discharges reflecting network hyperexcitability.

INTERPRETATION

Anti-Drebrin autoantibodies define a chronic syndrome of recurrent seizures and neuropsychiatric impairment as well as inflammation of limbic and occasionally cortical structures. Immunosuppressant therapies should be considered in this disorder. ANN NEUROL 2020;87:869-884.

First report of concomitant cryptococcal meningitis and anti-NMDAR encephalitis

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disorder, seen most often in young adults and children, triggered by tumors or infections. We report a case of cryptococcal meningitis in a patient with sarcoidosis, presenting prominent neuropsychiatric symptoms, electroencephalographic features of autoimmune encephalitis and positive anti-NMDAR antibodies in the cerebrospinal fluid, raising the hypothesis of an infectious immune-mediated mechanism triggering the production of anti-NMDAR antibodies. Since anti-NMDAR encephalitis is potentially fatal and has significant morbidity, further descriptions of its etiological associations are essential to early identification and prompt treatment.

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Cryptococcal meningitis is a rare complication of sarcoidosis and CD4 lymphopenia.

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Anti-NMDAR encephalitis is an autoimmune disorder triggered by tumors or infection.

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A case of concomitant cryptococcosis and anti-NMDAR encephalitis is presented.

Frequency and temporal sequence of clinical features in adults with anti-NMDA receptor encephalitis presenting with psychiatric symptoms

BACKGROUND

Anti-NMDA receptor (NMDAr) encephalitis is the most common autoimmune encephalitis in adults. It mimics psychiatric disorders so often that most patients are initially referred to a psychiatrist, and many are misdiagnosed. Without prompt and effective treatment, patients are likely to suffer a protracted course with significant residual disability, or death. This study focuses on the frequency and chronology of salient clinical features in adults with anti-NMDAr encephalitis who are likely to be first evaluated by a psychiatrist because their presentation suggests a primary psychiatric disorder.

METHODS

A systematic search of PubMed and EMBASE databases identified published reports of anti-NMDAr encephalitis associated with prominent behavioral or psychiatric symptoms. After eliminating redundancies, the frequencies and relative timing of clinical features were tabulated. Signs and symptoms were assigned temporal ranks based on the timing of their first appearance relative to the first appearance of other signs and symptoms in each patient; median ranks were used to compare temporal sequencing of both individual features and major symptom domains.

RESULTS

Two hundred thirty unique cases (185 female) met study inclusion criteria. The most common features were seizures (60.4%), disorientation/confusion (42.6%), orofacial dyskinesias (39.1%), and mutism/staring (37.4%). Seizures, fever, and cognitive dysfunction were often the earliest features to emerge, but psychiatric features predominated and sequencing varied greatly between individuals.

CONCLUSIONS

Clinicians should consider anti-NMDAr encephalitis when new psychiatric symptoms are accompanied by a recent viral prodrome, seizures or unexplained fever, or when the quality of the psychiatric symptoms is unusual (e.g. non-verbal auditory hallucinations).

Differences and diversity of autoimmune encephalitis in 77 cases from a single tertiary care center

Background

The incidence of autoimmune encephalitis has risen globally. There are two general categories of disease-associated antibodies that can be tested for: neuronal surface and intracellular. However, testing both groups of autoantibodies are costly. This study aims to identify differences between groups by comparing clinical presentations, radiological findings and CSF profile of patients, and determine if any parameters are indicative of one group of autoantibodies over another. Additionally, we aim to report the local incidence of less common groups of disease-associated antibodies as well.

Methods

Seventy-seven records of autoimmune encephalitis/encephalomyelitis patients admitted to King Chulalongkorn Memorial Hospital, Bangkok, Thailand, between October 2010 and February 2017 were reviewed. Patients with infections or those with classic central nervous system demyelinating features were excluded.

Results

Of 77 patients, 40% presented with neuronal surface antibodies and 33% had intracellular antibodies. The most common autoantibody detected in each group was anti-NMDAr antibody (25/31, 81%) and anti-Ri antibody (7/25, 28%) respectively. In the neuronal surface antibody group, behavioral change was the most common complaint (45%), followed by seizures (39%) and abnormal movements (29%). In the latter group, seizure was the most common presenting symptom (32%), followed by motor weakness (20%), behavioural change (16%) and abnormal movements (16%). Patients with neuronal surface antibodies were younger (35 vs 48 years old, p = 0.04) and more likely to present with behavioral change (45% vs 16%, p = 0.02). Mortality rate was higher in the intracellular group (16% vs 3.2%, p = 0.09). No differences were detected in magnetic resonance imaging (MRI) and CSF profile.

Conclusions

In the early stages of the disease, both groups have comparable clinical outcomes. Although there were significant differences in age and percentage of patients with behavioral change, both groups of autoimmune encephalitis still shared many clinical features and could not be distinguished based on MRI and CSF profiles. Therefore, we recommend that patients with features of autoimmune encephalitis should be screened for both the neuronal surface and intracellular antibodies regardless of clinical presentation.

Clinical variants of limbic encephalitis

The clinical picture of immunomediator disorders of the central nervous system resulting from autoimmune or paraneoplastic processes is often represented by the limbic symptom complex or limbic encephalitis. The article gives a brief description of these conditions, allocated to a separate nosological group in 2007. The symptoms of limbic encephalitis include mental disorders and epileptic seizures of both convulsive and non-convulsive spectrum, up to epileptic status. Four clinical cases representative of different variants of limbic encephalitis are presented in this study, along with the discussion of epidemiology, differential diagnostics, and generally accepted patient management strategies. The diagnosis of limbic encephalitis was made on clinical grounds alone in three cases and on the presence of antibodies to N-Methyl-d-aspartic acid receptors in one case. A combination of glucocorticoid pulse therapy with prolonged use of valproic acid was successfully applied for the treatment of limbic encephalitis with non-convulsive epileptic status. Plasmapheresis was used for the treatment of limbic encephalitis with recurrent focal non-motor attacks with and without loss of consciousness, as well as for limbic encephalitis with focal motor attacks. Presented cases emphasize the need to increase the awareness of physicians of various specialties to autoimmune disorders of the nervous system. In addition, it highlights the necessity of complete diagnostic workup for a patient with impaired consciousness of unclear etiology.

Clinical Features and Inflammatory Markers in Autoimmune Encephalitis Associated With Antibodies Against Neuronal Surface in Brazilian Patients

Acute encephalitis is a debilitating neurological disorder associated with brain inflammation and rapidly progressive encephalopathy. Autoimmune encephalitis (AE) is increasingly recognized as one of the most frequent causes of encephalitis, however signs of inflammation are not always present at the onset which may delay the diagnosis. We retrospectively assessed patients with AE associated with antibodies against neuronal surface diagnosed in reference centers in Northeast of Brazil between 2014 to 2017. CNS inflammatory markers were defined as altered CSF (pleocytosis >5 cells/mm³) and/or any brain parenchymal MRI signal abnormality. Thirteen patients were evaluated, anti-NMDAR was the most common antibody found (10/13, 77%), followed by anti-LGI1 (2/13, 15%), and anti-AMPAR (1/13, 7%). Median time to diagnosis was 4 months (range 2–9 months). Among these 13 patients, 6 (46.1%) had inflammatory markers and when compared to those who did not present signs of inflammation, there were no significant differences regarding the age of onset, time to diagnosis and modified Rankin scale score at the last visit. Most of the patients presented partial or complete response to immunotherapy during follow-up. Our findings suggest that the presence of inflammatory markers may not correlate with clinical presentation or prognosis in patients with AE associated with antibodies against neuronal surface. Neurologists should be aware to recognize clinical features of AE and promptly request antibody testing even without evidence of inflammation in CSF or MRI studies.

Recognizing psychiatric presentations of anti-NMDA receptor encephalitis in children and adolescents: A synthesis of published reports

AIM

The aim of this study was to improve early recognition of anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDArE) in children and adolescents by identifying characteristic temporal patterns of clinical features in patients likely to be referred for psychiatric evaluation. In this form of autoimmune encephalitis, NMDAr hypofunction is caused by autoantibodies to receptor surface components. Clinical outcomes following prompt immunotherapy are usually good, but delayed treatment often results in a protracted course with significant residual disability or death. Anti-NMDArE frequently mimics psychiatric disorders, so most patients are referred initially to a psychiatrist and treated for days or weeks before being correctly diagnosed.

METHODS

A systematic search of PubMed and EMBASE electronic databases identified all published reports of antibody-confirmed anti-NMDArE associated with psychiatric symptoms in patients <19 years old. Redundant reports were eliminated manually. For each patient, the order in which each feature was first observed was ranked relative to others. Median temporal ranks were used to compare the sequencing of individual features and major symptom domains.

RESULTS

One hundred and sixty seven cases (121 females) met the inclusion criteria. The most common features were dyskinesias (77.8%), seizures (72.5%), mutism or staring (40.7%), insomnia (39.5%), language dysfunction (36.5%), fever (31.1%), disorientation/confusion (28.7%), reduced arousal (28.1%), and memory disturbance (26.9%). The configuration and temporal sequencing of features were highly variable between individuals.

CONCLUSION

Clinicians need to suspect this disorder: if new behavioral symptoms arise in the context of a recent viral prodrome; if they are accompanied by dyskinesias, seizures or insomnia; or if psychiatric symptoms are unusual (e.g., non-verbal auditory hallucinations).

Anti-N-methyl-D-aspartate receptor encephalitis associated with reactivated Epstein-Barr virus infection in pediatric patients: Three case reports

RATIONALE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most frequent autoimmune encephalitis in children, and its presentation is various. The disease can be triggered by various infections.

PATIENT CONCERNS

Case 1 was a 7-year-old female with the presentation of seizure, repeated fever, language disorder, and decreased muscle strength of the right limbs; Case 2 was a 7-year-old male with the manifestation of repeated emesis, headache, involuntary movement, altered personality, seizures, and cognitive impairment; Case 3 was a 2-year-old female with repeated fever, emesis, seizures, coma, and decreased muscle strength of limbs. Anti-NMDAR antibody was identified in cerebrospinal fluid (CSF) in the 3 cases, confirming the diagnosis of anti-NMDAR encephalitis. Pathogenic examinations revealed positive serum Epstein-Barr virus (EBV)-nuclear antigen and EBV-capsid antigen (CA)-IgG antibodies in the 3 cases, as well as positive EBV-early antigen (EA)-IgG antibody in CSF. Case 1 also had positive EBV-CA-IgA antibody; Case 3 also had positive EBV-CA-IgA and EBV-CA-IgG antibodies.

DIAGNOSES

Anti-NMDAR antibody and EBV-EA-IgG antibody in CSF were tested positive in the 3 cases. Thus, they were diagnosed as anti-NMDAR encephalitis associated with reactivated EBV infection.

INTERVENTIONS

All of the 3 cases received immunoglobulin, corticosteroid, and ganciclovir treatment. Cases 2 and 3 also received antiepileptic drugs due to repeated seizures. In addition, Case 3 also received assistant respiration, plasma exchange, and rituximab.

OUTCOMES

The 3 cases were substantially recovered after treatment. Repeat CSF analysis showed decreased titer of the anti-NMDAR antibody.

LESSONS

Reactivated EBV infection may trigger anti-NMDAR encephalitis in children, which has not been reported previously. Related possible virology tests should be completed while diagnosing the disease.

Anti-NMDAR encephalitis preceded by non-herpetic central nervous system infection: Systematic literature review and first case of tick-borne encephalitis triggering anti-NMDAR encephalitis

After the recent description of biphasic disease with herpes simplex virus (HSV) encephalitis followed by anti-N-methyl-d-aspartate receptor encephalitis (anti-NMDARE), anti-NMDARE preceded by non-HSV central nervous system (CNS) infection has been more rarely reported. We report the first case of TBE followed by anti-NMDARE and carry out a systematic literature review on anti-NMDARE preceded by non-HSV CNS infection.

Environmental Exposures and Neuropsychiatric Disorders: What Role Does the Gut-Immune-Brain Axis Play?

PURPOSE OF REVIEW

Evidence is growing that environmental exposures-including xenobiotics as well as microbes-play a role in the pathogenesis of many neuropsychiatric disorders. Underlying mechanisms are likely to be complex, involving the developmentally sensitive interplay of genetic/epigenetic, detoxification, and immune factors. Here, we review evidence supporting a role for environmental factors and disrupted gut-immune-brain axis function in some neuropsychiatric conditions.

RECENT FINDINGS

Studies suggesting the involvement of an altered microbiome in triggering CNS-directed autoimmunity and neuropsychiatric disturbances are presented as an intriguing example of the varied mechanisms by which environmentally induced gut-immune-brain axis dysfunction may contribute to adverse brain outcomes. The gut-immune-brain axis is a burgeoning frontier for investigation of neuropsychiatric illness. Future translational research to define individual responses to exogenous exposures in terms of microbiome-dependent skew of the metabolome, immunity, and brain function may serve as a lens for illumination of pathways involved in the development of CNS disease and fuel discovery of novel interventions.

Glutamate Receptor Antibodies in Autoimmune Central Nervous System Disease: Basic Mechanisms, Clinical Features, and Antibody Detection

Immune-mediated inflammation of the brain has been recognized for more than 50 years, although the initial descriptions were mainly thought to be secondary to an underlying neoplasm. Some of these paraneoplastic encephalitides express serum antibodies, but these were not thought to be pathogenic but instead have a T-cell-mediated pathophysiology. Over the last two decades, several pathogenic antibodies against neuronal surface antigens have been described in autoimmune encephalitis, which are amenable to immunotherapy. Several of these antibodies are directed against glutamate receptors (GluRs). NMDAR encephalitis (NMDARE) is the most common of these antibodies, and patients often present with psychosis, hallucinations, and reduced consciousness. Patients often progress on to develop confusion, seizures, movement disorders, autonomic instability, and respiratory depression. Although initially described as exclusively occurring secondary to ovarian teratoma (and later other tumors), non-paraneoplastic forms are increasingly common, and other triggers like viral infections are now well recognized. AMPAR encephalitis is relatively less common than NMDARE but is more likely to paraneoplastic. AMPAR antibodies typically cause limbic encephalitis, with patients presenting with confusion, disorientation, memory loss, and often seizures. The syndromes associated with the metabotropic receptor antibodies are much rarer and often can be paraneoplastic-mGluR1 (cerebellar degeneration) and mGluR5 (Ophelia syndrome) being the ones described in literature.With the advance in molecular biology techniques, it is now possible to detect these antibodies using cell-based assays with high sensitivity and specificity, especially when coupled with brain tissue immunohistochemistry and binding to live cell-based neurons. The rapid and reliable identification of these antibodies aids in the timely treatment (either in the form of identifying/removing the underlying tumor or instituting immunomodulatory therapy) and has significantly improved clinical outcome in this otherwise devastating group of conditions.

Limbic Encephalitis following Guillain-Barré Syndrome Associated with <b><i>Mycoplasma</i></b> Infection

A 12-year-old girl was admitted to the authors’ hospital due to muscle weakness, gait disturbance, dysarthria, dysphagia, and diplopia. She experienced prodromal fever 10 days before admission. On examination, deep tendon reflex was absent in the extremities, and nerve conduction velocity was decreased in the ulnar nerve. She was diagnosed with Guillain-Barré syndrome (GBS). Despite steroid pulse therapy following administration of intravenous high-dose γ-globulin, clinical manifestations remained unchanged. Therefore, plasma exchange was performed on day 10 of the illness. The titer of serum <i>Mycoplasma</i> immunoglobulin M level was increased. Immunological testing was positive for serum anti-galactocerebroside C antibody. On day 18 of the illness, however, she developed generalized convulsion. Brain magnetic resonance imaging revealed high intensity in the medial temporal lobes, including the hippocampus and thalamus on T2-weighted intensity imaging, which was consistent with limbic encephalitis. Further immunological tests revealed positivity for anti-N-methyl-D-aspartate-type glutamate receptor antibody in the cerebrospinal fluid. She was treated with additional plasma exchange; however, she exhibited residual manifestations including short-term memory disorder, emotional incontinence, and convulsions. This article describes a notable case of limbic encephalitis following GBS associated with prodromal <i>Mycoplasma</i> infection. It is interesting that autoimmune encephalopathy is concomitant with autoimmune polyneuropathy subsequent to <i>Mycoplasma</i> infection.

Optic neuritis as the initial clinical presentation of limbic encephalitis: a case report

BACKGROUND

Limbic encephalitis is characterized by rapid onset of working memory deficit, mood changes, and often seizures. The condition has a strong paraneoplastic association, but not all cases are invariably due to tumors.

CASE PRESENTATION

We present a case of limbic encephalitis in a Chinese patient who initially presented to our hospital with optic neuritis and no other neurological symptoms. The diagnosis was made radiologically, and cognitive and neurological symptoms did not occur until 5 months later. Extensive investigations for autoimmune, infective, and neoplastic causes were all negative. A working diagnosis of paraneoplastic neurological syndrome was made, and the patient is being managed with high-dose steroid therapy according to the Optic Neuritis Treatment Trial protocol during relapses, as well as with tumor surveillance.

CONCLUSIONS

This case highlights ocular symptoms as important clues for diagnosing neurological diseases, as well as autoimmune encephalitis as an important differential diagnosis in the management of "idiopathic" optic neuritis in the Chinese population.

Dysfunction of the blood-cerebrospinal fluid-barrier and N-methyl-D-aspartate glutamate receptor antibodies in dementias

N-Methyl-D-aspartate glutamate receptor (NMDA-R) antibodies (Abs) could play a role in neurodegenerative disorders. Since, in these diseases, NMDA-R Abs were detected in serum, but only sporadic in cerebrospinal fluid (CSF), the origin and impact of the Abs are still unresolved. We examined the presence of NMDA-R Abs in serum and CSF using a cell-based immunofluorescence assay as well as the function of the blood-CSF-barrier (B-CSF-B) by determination of Q albumin (ratio of albumin in CSF and serum) in patients with mild cognitive impairment (MCI; N = 59) and different types of dementia, Alzheimer's disease (AD; N = 156), subcortical ischemic vascular dementia (SIVD; N = 61), and frontotemporal dementia (FTD; N = 34). Serum IgA/IgM NMDA-R Abs and/or a disturbed B-CSF-B were sporadically present in all investigated patients' groups. In AD, these Abs often developed during the disease course. Patients with either no hippocampal atrophy and/or no AD-related characteristic changes in CSF, referred to "non-classical" AD, were characterized by seropositivity at diagnosis and loss of function of the B-CSF-B showed a progressive decline in cognitive functions and a poor prognosis. Our data indicate that NMDA-R Abs are present in different types of dementia and elderly healthy individuals. In combination with disturbed B-CSF-B integrity, they seem to promote their pathological potential on cognitive decline, and thus, a subgroup of dementia patients with these unique characteristics might inform clinicians.

Clinical diagnosis and treatment of pediatric anti-N-methyl-D-aspartate receptor encephalitis: A single center retrospective study

The aim of the present retrospective study was to investigate the diagnosis, treatment and prognosis of pediatric anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis. A total of 23 pediatric patients with anti-NMDAR encephalitis were included in the present study. The clinical data, laboratory test results, imaging examination, treatment outcomes, and follow-up records were reviewed and analyzed. A total of 8 patients exhibited prodromal symptoms, including fever, cough, and vomiting. Clinical symptoms included epilepsy, convulsions, ataxia, coma, dyskinesia, personal behavior change and hallucinations. A total of 20 cases had the initial neurologic symptoms of dyskinesia or seizure, whereas 3 cases exhibited psychiatric symptoms of personal behavior change and hallucinations. Furthermore, pediatric patients >6 years old had more psychiatric symptoms than those ≤6 years. A total of 20 cases exhibited abnormal electroencephalography records, with 1 case of extreme δ brush. A total of 10 cases exhibited abnormal brain magnetic resonance imaging detection. Furthermore, the CSF protein contents for pediatric patients ≤6 years old was significantly higher than those >6 years. For treatment, 18 pediatric patients received the first-line treatment of methylprednisone and intravenous injection of immunoglobulin, and 6 cases were subjected to the second-line treatment of rituximab. A total of 2 patients underwent plasma exchange and/or cyclophosphamide treatment. In follow-up, 12 cases reported no convulsion, whereas 11 cases had moderate or severe neurological and psychiatric sequelae. The recovery rate for pediatric patients ≤6 years old was significantly higher than those >6 years. Anti-NMDAR encephalitis is commonly seen in pediatric patients, mainly with initial neurological symptoms. These patients could respond to immunotherapy, and younger pediatric patients typically have a better prognosis.

Evaluation of Clinical and Paraclinical Findings for the Differential Diagnosis of Autoimmune and Infectious Encephalitis

Background: The differential diagnosis of autoimmune and infectious encephalitis is notoriously difficult. For this study, we compare the presenting clinical symptoms and paraclinical test results of autoimmune and infectious encephalitis patients. A clinical algorithm for the diagnosis of autoimmune encephalitis has recently been published. We test these Graus criteria on our cohort for diagnostic sensitivity and specificity within the first week of presentation. Methods: We included all patients seen at our department within a 10-year-period who were diagnosed with encephalitis. The discharge diagnoses served as the reference standard for testing the clinical algorithm for two conditions: use of all the clinical information available on a patient during the first week of hospital admission assuming undefined autoantibody status and microbiological test results (C1) vs. consideration of all the information available on a patient, including the results of serological and microbiological testing (C2). Results: Eighty-four patients (33 autoimmune, 51 infectious encephalitis) were included in the study. Fifty-one (17 autoimmune, 34 infectious) had a definite clinical diagnosis. The two groups differed significantly for the presence of headache, fever, epileptic seizures, and CSF cell-count at presentation. Application of the clinical algorithm resulted in a low sensitivity (58%) and very low specificity (8%) for the diagnosis of possible autoimmune encephalitis. The latter increased considerably in the subgroups of probable and definite autoimmune encephalitis. Whereas the sensitivity of the individual diagnostic categories was clearly time-dependent, the specificity rested foremost on the knowledge of the results of microbiological testing. Anti-CASPR2- and -LGI1-associated autoimmune encephalitis and tick-borne virus encephalitis presented particular diagnostic pitfalls. Conclusions: We define clinical symptoms and paraclinical test results which prove valuable for the differentiation between infectious and autoimmune encephalitis. Sensitivity and specificity of the clinical algorithm clearly depended on the amount of time passed after hospital admission and knowledge of microbiological test results. Accepting this limitation for the acute setting, the algorithm remains a valuable diagnostic aid for antibody-negative autoimmune encephalitis or in resource-poor settings. The initiation of immune therapy however should not be delayed if an autoimmune etiology is considered likely, even if the diagnostic criteria of the algorithm are not (yet) fulfilled.

Gut Microbiota Profiling and Gut-Brain Crosstalk in Children Affected by Pediatric Acute-Onset Neuropsychiatric Syndrome and Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcal Infections

Pediatric acute-onset neuropsychiatric syndrome (PANS) and pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections syndrome (PANDAS) are conditions that impair brain normal neurologic function, resulting in the sudden onset of tics, obsessive-compulsive disorder, and other behavioral symptoms. Recent studies have emphasized the crosstalk between gut and brain, highlighting how gut composition can influence behavior and brain functions. Thus, the present study investigates the relationship between PANS/PANDAS and gut microbiota ecology. The gut composition of a cohort of 30 patients with PANS/PANDAS was analyzed and compared to control subjects using 16S rRNA-based metagenomics. Data were analyzed for their α- and β-diversity; differences in bacterial distribution were detected by Wilcoxon and LEfSe tests, while metabolic profile was predicted via PICRUSt software. These analyses demonstrate the presence of an altered bacterial community structure in PANS/PANDAS patients with respect to controls. In particular, ecological analysis revealed the presence of two main clusters of subjects based on age range. Thus, to avoid age bias, data from patients and controls were split into two groups: 4-8 years old and >9 years old. The younger PANS/PANDAS group was characterized by a strong increase in Bacteroidetes; in particular, Bacteroides, Odoribacter, and Oscillospira were identified as potential microbial biomarkers of this composition type. Moreover, this group exhibited an increase of several pathways concerning the modulation of the antibody response to inflammation within the gut as well as a decrease in pathways involved in brain function (i.e., SCFA, D-alanine and tyrosine metabolism, and the dopamine pathway). The older group of patients displayed a less uniform bacterial profile, thus impairing the identification of distinct biomarkers. Finally, Pearson's analysis between bacteria and anti-streptolysin O titer reveled a negative correlation between genera belonging to Firmicutes phylum and anti-streptolysin O while a positive correlation was observed with Odoribacter. In conclusion, this study suggests that streptococcal infections alter gut bacterial communities leading to a pro-inflammatory status through the selection of specific bacterial strains associated with gut inflammation and immune response activation. These findings highlight the possibility of studying bacterial biomarkers associated with this disorder and might led to novel potential therapeutic strategies.

Autoimmune Movement Disorders in Children

Over the last decade, there have been significant advances in the identification, characterization, and treatment of autoimmune neurologic disorders in children. Many of these diseases include a typical movement disorder that can be a powerful aid to diagnosis. Frequently, movement disorders in autoimmune conditions are the sole or among a few presenting symptoms, allowing for earlier diagnosis of an underlying malignancy or systemic autoimmune disease. Given that early detection and treatment with immunotherapy may confer improved outcomes, recognizing these patterns of abnormal movements is essential for child neurologists. The purpose of this review is to summarize the clinical characteristics, diagnosis, and treatment of movement disorders that occur in pediatric autoimmune disorders.

Anti-N-methyl-D-aspartate receptor encephalitis associated with acute Toxoplasma gondii infection: A case report

RATIONALE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis has been recognized as the most frequent autoimmune encephalitis in children. Several infectious agents have been implicated in anti-NMDA encephalitis.

PATIENT CONCERNS

A previously healthy immunocompetent 9-year-old girl first presented with seizures, headaches and vomiting. Cerebrospinal fluid and brain magnetic resonance imaging were normal. After one week onset, the patient gradually developed unexplained personality and behavior changes, accompanied by fever and seizures again. Repeated CSF analysis revealed a slightly lymphocytic predominant pleocytosis and positive anti-NMDAR antibody. A variety of pathogenic examinations were negative, except for positive toxoplasma IgM and IgG.

DIAGNOSES

The patient was diagnoses for anti-NMDA encephalitis associated with acute acquired toxoplasma gondii infection.

INTERVENTIONS

The patient received 10 days azithromycin for treatment of acquired toxoplasma infection. The parents refuse immunotherapy because substantial recovery from clinical symptoms.

OUTCOMES

The patient was substantially recovered with residual mild agitation after therapy for acquired toxoplasma gondii infection. Two months later, the patient was completely devoid of symptoms, and the levels of serum IgM and IgG of toxoplasma gondii were decreased.

LESSONS

Acquired toxoplasma gondii infection may trigger anti-NMDAR encephalitis in children, which has not been reported previously. Clinicians should assess the possibility of toxoplasma gondii infection when evaluating a patient with anti-NMDA encephalitis.

Phencyclidine-Based New Psychoactive Substances

The serendipitous discovery of phencyclidine (PCP) in 1956 sets the stage for significant research efforts that resulted in a plethora of analogs and derivatives designed to explore the biological effects of this class. PCP soon became the prototypical dissociative agent that eventually sneaked through the doors of clinical laboratories and became an established street drug. Estimations suggest that around 14 PCP analogs were identified as "street drugs" in the period between the 1960s and 1990s. Fast forward to the 2000s, and largely facilitated by advancements in electronic forms of communication made possible through the Internet, a variety of new PCP analogs began to attract the attention of communities interested in the collaborative exploration of these substances. Traditionally, as was the case with the first-generation analogs identified in previous decades, the substances explored represented compounds already known in the scientific literature. As the decade of the noughties unfolded, a number of new PCP-derived substances appeared on the scene, which included some analogs that have not been previously recorded in the published literature. The aim of this chapter is to present a brief introductory overview of substances that have materialized as PCP-derived new psychoactive substances (NPS) in recent years and their known pharmacology. Since N-methyl-D-aspartate receptor (NMDAR) antagonism is implicated in mediating the subjective and mind-altering effects of many dissociative drugs, additional data are included from other analogs not presently identified as NPS.

Anti-NMDA-Receptor Encephalitis: From Bench to Clinic

NMDAR encephalitis is a common cause of autoimmune encephalitis, predominantly affecting young adults. Current data supports the idea that autoantibodies targeting NMDARs are responsible for disease pathogenesis. While these autoantibodies occur in the setting of underlying malignancy in approximately half of all patients, initiating factors for the autoimmune response in the remainder of patients are unclear. While there is increasing evidence supporting viral triggers such as herpes simplex encephalitis, this association and the mechanism of action have not yet been fully described. Although the majority of patients achieve good outcomes, those without an underlying tumor consistently show worse outcomes, prolonged recovery, and more frequent relapses. The cloning of patient-specific autoantibodies from affected individuals has raised important questions as to disease pathophysiology and clinical heterogeneity. Further advances in our understanding of this disease and underlying triggers are necessary to develop treatments which improve outcomes in patients presenting in the absence of tumors.

Status epilepticus and anti-NMDA receptor encephalitis after resection of an ovarian teratoma

Anti-N-methyl-D-aspartate receptor encephalitis is a recently recognised autoimmune, paraneoplastic syndrome that typically presents with psychiatric disturbance, reduced conscious level and seizures. The disorder has been previously associated with ovarian teratomas. We present the case of a 35-year-old female, with a previous surgical history for resection of an ovarian teratoma, who later developed status epilepticus and anti-N-methyl-D-aspartate receptor encephalitis requiring intensive care management. Her presentation, treatment and early follow-up are described, alongside an overview of anti-N-methyl-D-aspartate receptor encephalitis pathophysiology and intensive care management.

Comparative Outcomes in Children and Adults With Anti- N-Methyl-D-Aspartate (anti-NMDA) Receptor Encephalitis

This study compared neurologic disability and adaptive function in children and adults >1 year following anti- N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis diagnosis. Retrospective record review identified 12 patients with anti-NMDAR encephalitis. At last follow-up, all surviving patients had "good" modified Rankin Score (0-2). Four children, 6 adults, and their families participated in a telephone interview. Median duration since diagnosis was similar for children (2.42 years, interquartile range 2.12-3.32) and adults (3.55 years, interquartile range 2.08-5.50 years). 3/4 (75%) pediatric and 3/5 (60%) adult patients reported neuropsychiatric symptoms (fatigue, emotional lability, short-term memory deficits or concentration deficits). On the Adaptive Behavior Assessment System (ABAS-3), although overall adaptive function was intact for adults (general adaptive composite standard score: median 104.5, interquartile range 98.8-112.5), the median for children was below average (General Adaptive Composite Standard Score: median 82.0, interquartile range 79.0-89.0). Children with anti-NDMAR encephalitis may have long-term effects impacting daily life while adults regain normal function.