Herpes simplex virus-induced anti-N-methyl-d-aspartate receptor encephalitis: a systematic literature review with analysis of 43 cases

The relevance of anti-N-methyl-D-aspartate receptor encephalitis for psychiatrists

Psychiatrists are often the first to be consulted in patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. While this disease is rare, psychiatrists need to be aware of its relevant fundamental, clinical and therapeutic aspects. We begin by reviewing the connection between anti-NMDAR encephalitis and the glutamate hypothesis of schizophrenia. Next, we focus on the profile of the patient typically afflicted with this disease. Then, we tackle the limited utility of current diagnostic criteria during the early stage of the disease. After reviewing the psychiatric features, we debate the quest for finding specific psychiatric phenotypes that could facilitate early-stage diagnosis. We conclude by discussing the treatment of psychiatric symptoms and disease outcomes. As follows, this paper presents the relevance of anti-NMDAR encephalitis for psychiatrists.

Unmasking bipolarity in recurrent depressive disorder following herpes simplex virus triggered n-methyl-D-aspartate encephalitis

OBJECTIVE

Herpes simplex virus (HSV) infection triggered n-methyl-D-aspartate (NMDA) encephalitis can lead to varied neuropsychiatric manifestations, including movement disorders and manic symptoms. HSV is known to affect the same brain regions as in secondary mania.

METHOD

We present a 35-year-old female diagnosed with recurrent depressive disorder (RDD) who developed NMDA encephalitis triggered by HSV infection.

RESULT

HSV-triggered NMDA encephalitis led to a manic switch in a woman with RDD on antidepressants, along with the new onset of dyskinetic movements.

CONCLUSION

A neurological insult predisposed our patient to the variable effects of antidepressant drugs.

Neuroinfectious Diseases in Children: Pathophysiology, Outcomes, and Global Challenges

Pathogens with affinity for the central nervous system (CNS) in children are diverse in their mechanisms of infecting and attacking the brain. Infections can reach the CNS via hematogenous routes, transneurally thereby avoiding the blood-brain barrier, and across mucosal or skin surfaces. Once transmission occurs, pathogens can wreak havoc both by direct action on host cells and via an intricate interplay between the protective and pathologic actions of the host's immune system. Pathogen prevalence varies depending on region, and susceptibility differs based on epidemiologic factors such as age, immune status, and genetics. In addition, some infectious diseases are monophasic, whereas others may lie dormant for years, thereby causing a dynamic effect on outcomes. Outcomes in survivors are highly variable for each particular pathogen and depend on the vaccination and immune status of the patient as well as the speed by which the patient receives evidence-based treatments. Given pathogens cause communicable diseases that can cause morbidity and mortality on a population level when spread, the burden is often the greatest and the outcomes the worst in low-resource settings. Here we will focus on the most common infections with a propensity to affect a child's brain, the pathologic mechanisms by which they do so, and what is known about the developmental outcomes in children who are affected by these infections.

Thymoma-associated autoimmune encephalitis with myasthenia gravis: Case series and literature review

OBJECTIVES

This comprehensive review aimed to compile cases of patients with thymoma diagnosed with both autoimmune encephalitis (AE) and myasthenia gravis (MG), and describe their clinical characteristics.

METHODS

Clinical records of 3 AE patients in the first affiliated hospital of Sun Yat-sen University were reviewed. All of them were diagnosed with AE between 1 November 2021 and 1 March 2022, and clinical evidence about thymoma and MG was found. All published case reports were searched for comprehensive literature from January 1990 to June 2022.

RESULTS

A total of 18 cases diagnosed with thymoma-associated autoimmune encephalitis (TAAE) and thymoma-associated myasthenia gravis (TAMG) were included in this complication, wherein 3 cases were in the first affiliated hospital of Sun Yat-sen University and the other 15 were published case reports. 5/18 patients had alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antibody (AMPAR-Ab) in their serum and cerebrospinal fluid (CSF). All of them had positive anti-acetylcholine receptor antibody (AChR-Ab). And 12/18 patients showed a positive response to thymectomy and immunotherapy. Besides, thymoma recurrences were detected because of AE onset. And the shortest interval between operation and AE onset was 2 years in patients with thymoma recurrence.

CONCLUSIONS

There was no significant difference in the clinical manifestations between these patients and others with only TAMG or TAAE. TAAE was commonly associated with AMPAR2-Ab. Significantly, AE more commonly heralded thymoma recurrences than MG onset. And the intervals of thymectomy and MG or AE onset had different meanings for thymoma recurrence and prognoses of patients.

Movement disorders associated with pediatric encephalitis

New onset movement disorders are a common clinical problem in pediatric neurology and can be infectious, inflammatory, metabolic, or functional in origin. Encephalitis is one of the more important causes of new onset movement disorders, and movement disorders are a common feature (~25%) of all encephalitis. However, all encephalitides are not the same, and movement disorders are a key diagnostic feature that can help the clinician identify the etiology of the encephalitis, and therefore appropriate treatment is required. Movement disorders are a characteristic feature of autoimmune encephalitis such as anti-NMDAR encephalitis, herpes simplex virus encephalitis-induced autoimmune encephalitis, and basal ganglia encephalitis. Other rarer autoantibody-associated encephalitis syndromes with movement disorder associations include encephalitis associated with glycine receptor, DPPX, and neurexin-3 alpha autoantibodies. In addition, movement disorders can accompany acute disseminated encephalomyelitis with and without myelin oligodendrocyte glycoprotein antibodies. Extremely important infectious encephalitides that have characteristic movement disorder associations include Japanese encephalitis, dengue fever, West Nile virus, subacute sclerosing panencephalitis (SSPE), and SARS-CoV-2 (COVID-19). This chapter discusses how specific movement disorder phenomenology can aid clinician diagnostic suspicion, such as stereotypy, perseveration, and catatonia in anti-NMDAR encephalitis, dystonia-Parkinsonism in basal ganglia encephalitis, and myoclonus in SSPE. In addition, the chapter discusses how the age of the patients can influence the movement disorder phenomenology, such as in anti-NMDAR encephalitis where chorea is typical in young children, even though catatonia and akinesia is more common in adolescents and adults.

Elevated serum levels of the NLRP3 inflammasome are associated with the severity of anti-NMDAR encephalitis in children

BACKGROUND

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most common autoimmune encephalitis, mainly impacting young females and children. The involvement of the Nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome and related cytokines in pediatric individuals with this condition remains unclear.

METHODS

We collected information from 27 children who had anti-NMDAR encephalitis and 12 individuals with non-inflammatory neurological disorders as controls. We used an enzyme-linked immunosorbent assay (ELISA) to identify NLRP3 inflammasome, interleukin (IL)-1β, and IL-18 expression in cerebrospinal fluid (CSF) and matching serum samples. The modified Rankin Scale (mRS) score was performed throughout the acute phase and at the 6-month follow-up to determine the severity of the disease. The area under the curve (AUC) of the receiver operating characteristic curve was utilized to calculate the prediction efficacy.

RESULTS

When compared to controls, individuals with anti-NMDAR encephalitis had significantly increased serum expression of the NLRP3 inflammasome (p < 0.001), IL-1β (p < 0.05), and IL-18 (p < 0.01). In the acute phase, mRS scores were correlated positively with serum levels of NLRP3 inflammasome (p = 0.008), IL-1β (p = 0.023), and IL-18 (p < 0.001). A positive connection was also found between serum levels of NLRP3 inflammasome and IL-1β (p = 0.005). Furthermore, the expression of IL-1β and IL-18 in serum correlated with the 6-month follow-up outcome. The AUC for NLRP3 inflammasome in distinguishing patients with severe neurologic impairments from those with moderate impairments was 0.808 (95 % CI: 0.645-0.972).

CONCLUSION

In our investigation, children with anti-NMDAR encephalitis have more severe first clinical presentations when their serum concentrations of the NLRP3 inflammasome and related cytokines were higher. These findings provide a potential role for the NLRP3 inflammasome pathway in the pathogenesis of NMDAR encephalitis and provide a basis for targeted therapeutic interventions.

A case of new onset refractory status epilepticus in a U.S. traveler with Japanese encephalitis

New onset refractory status epilepticus (NORSE) is a rare but critical condition characterized by refractory status epilepticus (RSE) in an individual without prior history of epilepsy or known structural, toxic, or metabolic cause. Postinfectious immune activation is an important cause of NORSE. Early testing for autoimmune antibodies is strongly recommended (Wickstrom et al., 2022). We report a case of NORSE triggered by Japanese encephalitis (JE) in an unvaccinated US adult traveler. Her CSF later revealed positive anti-N-methyl-d-aspartate (NMDA)-receptor antibody. The patient responded well to first line immunotherapy with favorable functional outcome. This case highlights the diagnostic and treatment challenges in this rare presentation.

Neurologic complications in herpes simplex encephalitis: clinical, immunological and genetic studies

Patients with herpes simplex virus (HSV) encephalitis (HSE) often develop neuronal autoantibody-associated encephalitis (AE) post-infection. Risk factors of AE are unknown. We tested the hypotheses that predisposition for AE post-HSE may be involved, including genetic variants at specific loci, human leucocyte (HLA) haplotypes, or the blood innate immune response against HSV, including type I interferon (IFN) immunity. Patients of all ages with HSE diagnosed between 1 January 2014 and 31 December 2021 were included in one of two cohorts depending on whether the recruitment was at HSE onset (Spanish Cohort A) or by the time of new neurological manifestations (international Cohort B). Patients were assessed for the type of neurological syndromes; HLA haplotypes; blood type I-IFN signature [RNA quantification of 6 or 28 IFN-response genes (IRG)] and toll-like receptor (TLR3)-type I IFN-related gene mutations. Overall, 190 patients (52% male) were recruited, 93 in Cohort A and 97 in Cohort B. Thirty-nine (42%) patients from Cohort A developed neuronal autoantibodies, and 21 (54%) of them developed AE. Three syndromes (choreoathetosis, anti-NMDAR-like encephalitis and behavioural-psychiatric) showed a high (≥95% cases) association with neuronal autoantibodies. Patients who developed AE post-HSE were less likely to carry the allele HLA-A*02 (4/21, 19%) than those who did not develop AE (42/65, 65%, P = 0.0003) or the Spanish general population (2005/4335, 46%, P = 0.0145). Blood IFN signatures using 6 or 28 IRG were positive in 19/21 (91%) and 18/21 (86%) patients at HSE onset, and rapidly decreased during follow-up. At Day 21 after HSE onset, patients who later developed AE had higher median IFN signature compared with those who did not develop AE [median Zs-6-IRG 1.4 (0.6; 2.0) versus 0.2 (-0.4; 0.8), P = 0.03]. However, a very high median Zs-6-IRG (>4) or persistently increased IFN signature associated with uncontrolled viral infection. Whole exome sequencing showed that the percentage of TLR3-IFN-related mutations in patients who developed AE was not different from those who did not develop AE [3/37 (8%) versus 2/57 (4%), P = 0.379]. Multivariate logistic regression showed that a moderate increase of the blood IFN signature at Day 21 (median Zs-6-IRG >1.5 but <4) was the most important predictor of AE post-HSE [odds ratio 34.8, interquartile ratio (1.7-691.9)]. Altogether, these findings show that most AE post-HSE manifest with three distinct syndromes, and HLA-A*02, but not TLR3-IFN-related mutations, confer protection from developing AE. In addition to neuronal autoantibodies, the blood IFN signature in the context of HSE may be potentially useful for the diagnosis and monitoring of HSE complications.

Anti-N-methyl D-aspartate Receptor Encephalitis Following ChAdOx1 nCoV-19 Vaccination: A Case Report

As of December 2020, millions of people have been immunized using vaccines against SARS-CoV-2. A wide range of neurological adverse effects of SARS-CoV-2 vaccines have been reported so far. Here, we report a 23-year-old male who experienced psychiatric symptoms, loss of consciousness, language disintegration, and incontinency that happened 10 days after the first dosage of the COVID-19 AstraZeneca vaccine. Anti-NMDAR Encephalitis was diagnosed based on the results of the autoimmune panel. The patient responded to intravenous dexamethasone very well and experienced no other complications in 6 months of follow-up. Scientific reports of neurological side effects such as anti-NMDAR encephalitis after vaccination are necessary to optimize the safety and effectiveness of SARS-CoV-2 vaccines.

Anti-N-methyl-d-aspartate receptor encephalitis preceded by meningitis lasting up to 60 days

Long-lasting meningitis complicated by N-methyl-d-aspartate receptor (NMDAR) encephalitis has not been discussed widely in the literature. Herein, we present two cases of anti-NMDAR encephalitis preceded by meningitis. The patients had 60- and 22-day periods of preceding meningitis, which improved with intravenous methylprednisolone and plasmapheresis. No tumors were detected in either of the patients. Although meningitis preceding anti-NMDAR encephalitis is not rare, our patients, especially those who had it for a duration of 60 days, had longer durations of meningitis. This manuscript foregrounds that anti-NMDAR encephalitis might be included in the differential diagnosis of long-lasting meningitis.

Functional autoantibodies: Definition, mechanisms, origin and contributions to autoimmune and non-autoimmune disorders

A growing body of evidence underscores the relevance of functional autoantibodies in the development of various pathogenic conditions but also in the regulation of homeostasis. However, the definition of functional autoantibodies varies among studies and a comprehensive overview on this emerging topic is missing. Here, we do not only explain functional autoantibodies but also summarize the mechanisms underlying the effect of such autoantibodies including receptor activation or blockade, induction of receptor internalization, neutralization of ligands or other soluble extracellular antigens, and disruption of protein-protein interactions. In addition, in this review article we discuss potential triggers of production of functional autoantibodies, including infections, immune deficiency and tumor development. Finally, we describe the contribution of functional autoantibodies to autoimmune diseases including autoimmune thyroid diseases, myasthenia gravis, autoimmune pulmonary alveolar proteinosis, autoimmune autonomic ganglionopathy, pure red cell aplasia, autoimmune encephalitis, pemphigus, acquired thrombotic thrombocytopenic purpura, idiopathic dilated cardiomyopathy and systemic sclerosis, as well as non-autoimmune disorders such as allograft rejection, infectious diseases and asthma.

HSV-1 Encephalitis Presenting with Diplopia: Effects of Infection or Autoimmunity?

This report describes a case in which diplopia was developed as a finding of postinfectious anti- N -methyl- d -aspartate receptor encephalitis. Infectious encephalitis, especially herpes simplex virus, is essential as it is one of the triggers of autoimmune encephalitis. Even if the cases present unexpected clinical findings, we should be vigilant in terms of autoimmune processes, such as diplopia seen in our case.

miRNAs in Neurological Manifestation in Patients Co-Infected with SARS-CoV-2 and Herpesvírus 6 (HHV-6)

Human herpesviruses (HHVs) can establish latency and be reactivated, also are neurotropic viruses that can trigger neurological disorders. HHV-6 is a herpesvirus that is associated with neurological disorders. Studies have reported the detection of HHV-6 in patients with COVID-19 and neurological manifestations. However, specific diagnoses of the neurological disorders caused by these viruses tend to be invasive or difficult to interpret. This study aimed to establish a relationship between miRNA and neurological manifestations in patients co-infected with COVID-19 and HHV-6 and evaluate miRNAs as potential biomarkers. Serum samples from COVID-19 patients in the three cohorts were analyzed. miRNA analysis by real-time polymerase chain reaction (qPCR) revealed miRNAs associated with neuroinflammation were highly expressed in patients with neurological disorders and HHV-6 detection. When compared with the group of patients without detection of HHVs DNA and without neurological alterations, the group with detection of HHV-6 DNA and neurological alteration, displayed significant differences in the expression of mir-21, mir-146a, miR-155 and miR-let-7b (p < 0.01). Our results reinforce the involvement of miRNAs in neurological disorders and provide insights into their use as biomarkers for neurological disorders triggered by HHV-6. Furthermore, understanding the expression of miRNAs may contribute to therapeutic strategies.

Infectious profiles in pediatric anti-N-methyl-d-aspartate receptor encephalitis

Anti-N-methyl-d-aspartate receptor autoimmune encephalitis (NMDAR AE) is an antibody-mediated neurological disorder that may be caused by post-herpes simplex virus-1 meningoencephalitis (HSV ME) and ovarian teratomas, although most pediatric cases are idiopathic. We sought to evaluate if other infections precede NMDAR AE by conducting a single-center, retrospective, case-control study of 86 pediatric cases presenting to Texas Children's Hospital between 2006 and 2022. HSV ME (HSV-1 and HSV-2) was a significantly more common preceding infection in the experimental group compared to control patients with idiopathic intracranial hypertension, while there was no difference in remote HSV infection between the two groups. Recent Epstein-Barr virus infection was evident in 8/42 (19%) tested experimental patients in comparison to 1/25 (4%) tested control patients which provided evidence for a genuine measure of effect but was not statistically significant due to small sample size (p = 0.07). The other 25 infectious etiologies were not different among the two groups and not all variables were clinically indicated or obtained in every subject, highlighting the need for future standardized, multi-institutional studies on underlying infectious precursors of autoimmune encephalitis.

Diagnostic Uncertainties: Chorea

Chorea is a hyperkinetic movement disorder with a multitude of potential etiologies, both acquired and inherited. Although the differential diagnosis for new-onset chorea is extensive, there are often clues in the history, exam, and basic testing that can help to narrow the options. Evaluation for treatable or reversible causes should take priority, as rapid diagnosis can lead to more favorable outcomes. While Huntington's disease is most common genetic cause of chorea, multiple phenocopies also exist and should be considered if Huntington gene testing is negative. The decision of what additional genetic testing to pursue should be based on both clinical and epidemiological factors. The following review provides an overview of the many possible etiologies as well as a practical approach for a patient presenting with new-onset chorea.

The presence of human respiratory syncytial virus in the cerebrospinal fluid of a child with Anti-N-methyl-D-aspartate receptor encephalitis of unknown trigger

BACKGROUND

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an important type of brain inflammation caused by autoantibody. As one of the primary agents responsible for respiratory tract infection, the human respiratory syncytial virus (hRSV) has also been reported to be capable of causing extrapulmonary diseases. Here, we first describe a case of anti-NMDAR encephalitis when hRSV was shown to be present in the cerebrospinal fluid.

CASE PRESENTATION

The child was noted to have ataxia and positive anti-NMDA receptors in the cerebrospinal fluid, diagnosed as anti-NMDA receptor encephalitis in combination with cranial MRI images. After high-dose hormone pulse therapy and medication, the disease improved, and he was discharged. However, a relapse occurred almost a year later, and the cranial MRI imaging showed progressive cerebellar atrophy. An hRSV strain from group B was detected in his cerebrospinal fluid, and the whole genome sequence was recovered using transcriptome sequencing.

CONCLUSIONS

To our knowledge, this is the first report of hRSV being found in the cerebrospinal fluid of a patient with anti-NMDAR encephalitis. Even though more clinical records and experimental evidence are needed for validation, this work expands the types of diseases linked to hRSV and the likely cause of anti-NMDAR encephalitis.

Immune Mechanisms in Epileptogenesis: Update on Diagnosis and Treatment of Autoimmune Epilepsy Syndromes

Seizures and epilepsy can result from various aetiologies, yet the underlying cause of several epileptic syndromes remains unclear. In that regard, autoimmune-mediated pathophysiological mechanisms have been gaining attention in the past years and were included as one of the six aetiologies of seizures in the most recent classification of the International League Against Epilepsy. The increasing number of anti-neuronal antibodies identified in patients with encephalitic disorders has contributed to the establishment of an immune-mediated pathophysiology in many cases of unclear aetiology of epileptic syndromes. Yet only a small number of patients with autoimmune encephalitis develop epilepsy in the proper sense where the brain transforms into a state where it will acquire the enduring propensity to produce seizures if it is not hindered by interventions. Hence, the term autoimmune epilepsy is often wrongfully used in the context of autoimmune encephalitis since most of the seizures are acute encephalitis-associated and will abate as soon as the encephalitis is in remission. Given the overlapping clinical presentation of immune-mediated seizures originating from different aetiologies, a clear distinction among the aetiological entities is crucial when it comes to discussing pathophysiological mechanisms, therapeutic options, and long-term prognosis of patients. Moreover, a rapid and accurate identification of patients with immune-mediated epilepsy syndromes is required to ensure an early targeted treatment and, thereby, improve clinical outcome. In this article, we review our current understanding of pathogenesis and critically discuss current and potential novel treatment options for seizures and epilepsy syndromes of underlying or suspected immune-mediated origin. We further outline the challenges in proper terminology.

Autoimmune Encephalitis with Autoantibodies to NMDAR1 following Herpes Encephalitis in Children and Adolescents

Herpes simplex virus (HSV) type 1 is a frequent pathogen causing infectious encephalitis (HSVE). Early treatment with intravenous acyclovir has led to a significant decrease in mortality. However, especially in children, deterioration during or after HSVE may occur without any evidence of HSV reactivation or improvement following repeated antiviral therapy. Here, we report 15 patients (age range 3 months to 15 years) who suffered from autoimmune encephalitis with autoantibodies to NMDAR1 following Herpes encephalitis, presenting with movement abnormalities (young children) or neuropsychiatric symptoms (older children) as major complaints, respectively. The diagnosis was based on positive cerebrospinal fluid (CSF) and/or serum anti-NMDAR-antibodies with two children showing only positive CSF antibody findings. The time lag between first symptoms and diagnosis of autoimmune encephalitis was significantly longer than between first symptoms and diagnosis of HSVE (p <0.01). All patients improved during immunosuppressive treatment, during which plasmapheresis or rituximab treatments were applied in 11 patients, irrespective of their age. Despite immunotherapy, no patients relapsed with HSVE. Early diagnosis and treatment of autoimmune encephalitis after HSVE may be associated with a better outcome so that high clinical awareness and routine testing for anti-NMDAR-antibodies after HSVE seems advisable. If autoimmune encephalitis is suspected, antibody testing should also be performed on CSF if negative in serum.

Brain MRI features of anti-N-methyl-D-aspartate (anti-NMDA) receptor encephalitis secondary to central nervous system infection in adult patients

BACKGROUND

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis secondary to central nervous system (CNS) infection is a unique subtype of the autoimmune-mediated disease, of which the imaging features are unclear.

PURPOSE

To compare the brain magnetic resonance imaging (MRI) features between the anti-NMDAR encephalitis secondary to CNS infection and that without initial infection.

MATERIAL AND METHODS

A total of 70 adult patients with anti-NMDAR encephalitis were retrospectively enrolled (24 in the post-infection group, 46 in the non-infection-related group). Their clinical and imaging features (lesion distribution, lesion shape, enhancement pattern, brain atrophy) were reviewed and summarized. Lesion distributions were compared between the two groups on lesion probability maps.

RESULTS

The patients with normal brain MRI scans in the post-infection group were less than those in the non-infection related group (29% vs. 63%; P = 0.0113). Among the 24 patients in the post-infection group, visible lesions were shown at the anti-NMDAR encephalitis onset in 17 patients; lesion distribution was more diffuse than the non-infection-related group, showing higher lesion peak probabilities in the bilateral hippocampus, frontal lobe, temporal lobe, insula, and cingulate. The lesions with contrast enhancement were also more common in the post-infection group than the non-infection-related group (7/13 vs. 2/10). Brain atrophy was observed in eight patients in the post-infection group and three in the non-infection-related group.

CONCLUSION

Anti-NMDAR encephalitis secondary to CNS infection has its imaging features-extensive lesion distribution, leptomeningeal enhancement, early atrophy, and necrosis-that could deepen the understanding of the pathophysiology and manifestation of the autoimmune encephalitis besides the classic type.

When herpes simplex virus encephalitis meets antiviral innate immunity

Herpes simplex virus (HSV) is the most common pathogen of infectious encephalitis, accounting for nearly half of the confirmed cases of encephalitis. Its clinical symptoms are often atypical. HSV PCR in cerebrospinal fluid is helpful for diagnosis, and the prognosis is usually satisfactory after regular antiviral treatment. Interestingly, some patients with recurrent encephalitis have little antiviral effect. HSV PCR in cerebrospinal fluid is negative, but glucocorticoid has a significant effect after treatment. Specific antibodies, such as the NMDA receptor antibody, the GABA receptor antibody, and even some unknown antibodies, can be isolated from cerebrospinal fluid, proving that the immune system contributes to recurrent encephalitis, but the specific mechanism is still unclear. Based on recent studies, we attempt to summarize the relationship between herpes simplex encephalitis and innate immunity, providing more clues for researchers to explore this field further.

Long-Term Outcome of Pediatric Patients with Anti-NMDA Receptor Encephalitis in a Single Center

BACKGROUND

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is the most common autoimmune encephalitis in children. There is a high probability of recovery if treated promptly. We aimed to analyze the clinical features and long-term outcomes of pediatric patients with anti-NMDA receptor encephalitis.

METHOD

We conducted a retrospective study with definite diagnoses of anti-NMDA receptor encephalitis in 11 children treated in a tertiary referral center between March 2012 and March 2022. Clinical features, ancillary tests, treatment, and outcomes were reviewed.

RESULTS

The median age at disease onset was 7.9 years. There were eight females (72.7%) and three males (27.3%). Three (27.3%) patients initially presented with focal and/or generalized seizures and eight (72.7%) with behavioral change. Seven patients (63.6%) revealed normal brain MRI scans. Seven (63.6%) had abnormal EEG results. Ten patients (90.1%) received intravenous immunoglobulin, corticosteroid, and/or plasmapheresis. After a median follow-up duration of 3.5 years, one patient was lost to follow-up at the acute stage, nine (90%) had an mRS ≤ 2, and only one had an mRS of 3.

CONCLUSIONS

With the early recognition of anti-NMDA receptor encephalitis based on its clinical features and ancillary tests, we were able to treat patients promptly with first-line treatment and achieve favorable neurological outcomes.

Overlapping anti-NMDAR encephalitis and multiple sclerosis: A case report and literature review

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune-mediated disease characterized by complicated neuropsychiatric symptoms and the detection of cerebrospinal fluid antibodies against the GluN1 subunit of the NMDAR. With the proposed clinical method, more anti-NMDAR encephalitis patients have been discovered since its first report. However, anti-NMDAR encephalitis overlapping with multiple sclerosis (MS) is rare. Herein we report a male patient with anti-NMDAR encephalitis who developed MS in mainland China. Furthermore, we summarized the characteristics of patients who were diagnosed with overlapping MS and anti-NMDAR encephalitis in previous studies. Additionally, we pioneered the use of mycophenolate mofetil in immunosuppressive therapy, providing a novel therapeutic alternative for overlapping anti-NMDAR encephalitis and MS.

Single-cell transcriptomics reveals cell type-specific immune regulation associated with anti-NMDA receptor encephalitis in humans

Introduction

Anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) is a rare autoimmune disease, and the peripheral immune characteristics associated with anti-NMDARE antibodies remain unclear.

Methods

Herein, we characterized peripheral blood mononuclear cells from patients with anti-NMDARE and healthy individuals by single-cell RNA sequencing (scRNA-seq).

Results

The transcriptional profiles of 129,217 cells were assessed, and 21 major cell clusters were identified. B-cell activation and differentiation, plasma cell expansion, and excessive inflammatory responses in innate immunity were all identified. Patients with anti-NMDARE showed higher expression levels of CXCL8, IL1B, IL6, TNF, TNFSF13, TNFSF13B, and NLRP3. We observed that anti-NMDARE patients in the acute phase expressed high levels of DC_CCR7 in human myeloid cells. Moreover, we observed that anti-NMDARE effects include oligoclonal expansions in response to immunizing agents. Strong humoral immunity and positive regulation of lymphocyte activation were observed in acute stage anti-NMDARE patients.

Discussion

This high-dimensional single-cell profiling of the peripheral immune microenvironment suggests that potential mechanisms are involved in the pathogenesis and recovery of anti-NMDAREs.

Autoimmune encephalitis after herpes simplex encephalitis: A still undefined condition

Herpes simplex encephalitis (HSE) is one of the most common sporadic viral encephalitis. Generally, HSE is characterized by a monophasic short course, although in some patients neurological relapses or worsening of deficits can develop some weeks later, when viral therapy has been discontinued and signs and symptoms of the central nervous system (CNS) damage seem to have stabilized. The second HSE stage is generally identified as autoimmune encephalitis after HSE (AEaHSE). Aim of this paper is to discuss which are the present knowledge in this regard. Literature analysis showed that AEaHSE exists, it is more common in younger children and it has different clinical manifestations according to age. All the patients with AEaHSE are positive for one or more neuronal cell-surface and synaptic antibodies, mainly anti-NMDAR antibodies, and the earlier the appearance of the antibodies the greater the risk of AEaHSE development. This means that a careful monitoring of antibody production starting from anti-NMDAR antibodies in all HSE cases could lead to the early identification of AEaHSE and the prompt administration of a potentially effective therapy. Further studies are needed to clarify which are the main pathogenetic mechanisms, whether there are differences in risk of development and clinical course of AEaHSE according to the type of antibody production, why response to immunosuppressive therapy significantly varies and whether administration of steroids to patients with HSE during the first phase of disease can play a role for reducing the risk of AEaHSE development.

CD8 Encephalitis: A Diagnostic Dilemma

CD8+ encephalitis is a subacute encephalopathy associated with HIV infection. Pathophysiology is thought to be auto-reactive CD8+ cells attacking on HIV infected CD4+ cells and ‘viral escape’ phenomena (replication of CD8+ cells in CSF). We present a case of a 45-year-old man with well controlled HIV who developed CD8 encephalitis following Herpes simplex encephalitis. He had persistent encephalopathy for several weeks with status epilepticus and agitated delirium, and diagnosis remained elusive until a brain biopsy confirmed the diagnosis.

Psychiatric Illness or Immune Dysfunction-Brain Perfusion Imaging Providing the Answer in a Case of Anti-NMDAR Encephalitis

BACKGROUND

We investigated the potential use of SPECT quantification in addition to qualitative brain perfusion analysis for the detection of anti-NMDAR encephalitis. The question is how to normalize brain activity to be able to quantitatively detect perfusion patterns. Usually, brain activity is normalized to a structure considered unaffected by the disease.

METHODS

Brain [99mTc]-HMPAO SPECT was performed as a method to detect brain perfusion patterns. The patterns of abnormal brain perfusion cannot always be reliably and qualitatively assessed when dealing with rare diseases. Recent advances in SPECT quantification using commercial software have enabled more objective and detailed analysis of brain perfusion. The cerebellum and whole brain were used as the normalization structures and were compared with visual analysis.

RESULTS

The quantification analysis performed with whole brain normalization confirmed right parietal lobe hypoperfusion while also detecting statistically significant left-to-right perfusion differences between the temporal lobe and thalamus. Whole brain normalization further described bilateral frontal lobe hyperperfusion, predominantly of the left lobe, and was in accordance with visual analysis.

CONCLUSION

SPECT quantitative brain perfusion analysis, using the whole brain as the normalization structure rather than the cerebellum, in this case, improved confidence in the visual detection of anti-NMDAR encephalitis and provided unexpected solutions to atypical psychiatric dilemmas.

Targeting NMDA Receptors at the Neurovascular Unit: Past and Future Treatments for Central Nervous System Diseases

The excitatory neurotransmission of the central nervous system (CNS) mainly involves glutamate and its receptors, especially N-methyl-D-Aspartate receptors (NMDARs). These receptors have been extensively described on neurons and, more recently, also on other cell types. Nowadays, the study of their differential expression and function is taking a growing place in preclinical and clinical research. The diversity of NMDAR subtypes and their signaling pathways give rise to pleiotropic functions such as brain development, neuronal plasticity, maturation along with excitotoxicity, blood-brain barrier integrity, and inflammation. NMDARs have thus emerged as key targets for the treatment of neurological disorders. By their large extracellular regions and complex intracellular structures, NMDARs are modulated by a variety of endogenous and pharmacological compounds. Here, we will present an overview of NMDAR functions on neurons and other important cell types involved in the pathophysiology of neurodegenerative, neurovascular, mental, autoimmune, and neurodevelopmental diseases. We will then discuss past and future development of NMDAR targeting drugs, including innovative and promising new approaches.

Immunity, Ion Channels and Epilepsy

Epilepsy is a common chronic neurological disorder in modern society. One of the major unmet challenges is that current antiseizure medications are basically not disease-modifying. Among the multifaceted etiologies of epilepsy, the role of the immune system has attracted considerable attention in recent years. It is known that both innate and adaptive immunity can be activated in response to insults to the central nervous system, leading to seizures. Moreover, the interaction between ion channels, which have a well-established role in epileptogenesis and epilepsy, and the immune system is complex and is being actively investigated. Some examples, including the interaction between ion channels and mTOR pathways, will be discussed in this paper. Furthermore, there has been substantial progress in our understanding of the pathophysiology of epilepsy associated with autoimmune encephalitis, and numerous neural-specific autoantibodies have been found and documented. Early recognition of immune-mediated epilepsy is important, especially in cases of pharmacoresistant epilepsy and in the presence of signs of autoimmune encephalitis, as early intervention with immunotherapy shows promise.

Clinical Characteristics of Children With Anti-N-Methyl-d-Aspartate Receptor Encephalitis After Japanese Encephalitis

BACKGROUND

Viral encephalitis is an important trigger for anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. We analyzed the clinical characteristics of anti-NMDAR encephalitis after Japanese encephalitis (JE) in children.

METHODS

Clinical data of 185 children with anti-NMDAR encephalitis were retrospectively reviewed. Patients with a history of viral encephalitis other than JE or who were identified with other autoantibodies were excluded.

RESULTS

Twenty children with anti-NMDAR encephalitis after JE were enrolled with a median age of 6 years and 10 months (interquartile range [IQR]: 3 years to 11 years and 5 months). The median time from JE to anti-NMDAR encephalitis was 29 (IQR: 25 to 32) days. At 12 months, most patients (17 of 18) recovered to at least their baseline modified Rankin scale (mRS) scores caused by JE. One hundred forty two children with classical anti-NMDAR encephalitis were enrolled. Compared with classical anti-NMDAR encephalitis, patients after JE had significantly more decreased level of consciousness (50% vs 18.3%, P = 0.003), more autonomic dysfunction (30.0% vs 9.9%, P = 0.021), fewer psychiatric or behavioral symptoms (70.0% vs 90.8%, P = 0.016), fewer seizures (25.0% vs 68.3%, P < 0.001), lesser improvement 4 weeks after immunotherapy (35.0% vs 73.2%, P = 0.001), and worse outcomes at 12 months (median mRS: 1 vs 0, P < 0.001).

CONCLUSIONS

Anti-NMDAR encephalitis after JE in children mainly occurred within two months. Their clinical manifestation may differ from classical anti-NMDAR encephalitis. The prognosis of children with anti-NMDAR encephalitis after JE probably depends on the neurological sequelae after JE.

Post-Infectious Autoimmunity in the Central (CNS) and Peripheral (PNS) Nervous Systems: An African Perspective

The direct impact and sequelae of infections in children and adults result in significant morbidity and mortality especially when they involve the central (CNS) or peripheral nervous system (PNS). The historical understanding of the pathophysiology has been mostly focused on the direct impact of the various pathogens through neural tissue invasion. However, with the better understanding of neuroimmunology, there is a rapidly growing realization of the contribution of the innate and adaptive host immune responses in the pathogenesis of many CNS and PNS diseases. The balance between the protective and pathologic sequelae of immunity is fragile and can easily be tipped towards harm for the host. The matter of immune privilege and surveillance of the CNS/PNS compartments and the role of the blood-brain barrier (BBB) and blood nerve barrier (BNB) makes this even more complex. Our understanding of the pathogenesis of many post-infectious manifestations of various microbial agents remains elusive, especially in the diverse African setting. Our exploration and better understanding of the neuroimmunology of some of the infectious diseases that we encounter in the continent will go a long way into helping us to improve their management and therefore lessen the burden. Africa is diverse and uniquely poised because of the mix of the classic, well described, autoimmune disease entities and the specifically "tropical" conditions. This review explores the current understanding of some of the para- and post-infectious autoimmune manifestations of CNS and PNS diseases in the African context. We highlight the clinical presentations, diagnosis and treatment of these neurological disorders and underscore the knowledge gaps and perspectives for future research using disease models of conditions that we see in the continent, some of which are not uniquely African and, where relevant, include discussion of the proposed mechanisms underlying pathogen-induced autoimmunity. This review covers the following conditions as models and highlight those in which a relationship with COVID-19 infection has been reported: a) Acute Necrotizing Encephalopathy; b) Measles-associated encephalopathies; c) Human Immunodeficiency Virus (HIV) neuroimmune disorders, and particularly the difficulties associated with classical post-infectious autoimmune disorders such as the Guillain-Barré syndrome in the context of HIV and other infections. Finally, we describe NMDA-R encephalitis, which can be post-HSV encephalitis, summarise other antibody-mediated CNS diseases and describe myasthenia gravis as the classic antibody-mediated disease but with special features in Africa.

Granulomatous Herpetic Encephalitis A Possible Role for Inflammasomes

BACKGROUND

Granulomatous herpetic encephalitis is a rare inflammatory complication of acute herpes simplex encephalitis.

METHODS

We describe 3 cases of granulomatous herpetic encephalitis in children arising between 1 to 10 years after the initial presentation with acute herpes simplex encephalitis. We focus on the clinical course and neuroimaging phenotype with a discussion of possible mechanisms underpinning this entity.

RESULTS

The clinical course was highly variable. However, the dominant neuroimaging phenotype in each of our cases was that of confluent gyriform cortical enhancement with predominantly solid foci of enhancement in the subjacent white matter +/- deep gray nuclei. Cerebrospinal fluid was negative for herpes simplex virus DNA in all cases. All 3 cases required brain biopsy to help establish the diagnosis.

CONCLUSIONS

Increased recognition of granulomatous herpetic encephalitis in children will facilitate earlier diagnosis and treatment. Although the exact role played by the host immune response, genetics, and environment in determining the different outcomes of herpes simplex encephalitis remains to be determined, we postulate a role for inflammasome dysregulation in this entity.

Anti-NMDAR Encephalitis in the Netherlands, Focusing on Late-Onset Patients and Antibody Test Accuracy

Background and Objectives

To describe the clinical features of anti-NMDAR encephalitis, emphasizing on late-onset patients and antibody test characteristics in serum and CSF.

Methods

Nationwide observational Dutch cohort study, in patients diagnosed with anti-NMDAR encephalitis between 2007 and 2019.

Results

One hundred twenty-six patients with anti-NMDAR encephalitis were included with a median age of 24 years (range 1–86 years). The mean annual incidence was 1.00/million (95% CI 0.62–1.59). Patients ≥45 years of age at onset (19%) had fewer seizures (46% vs 71%, p = 0.021), fewer symptoms during disease course (3 vs 6 symptoms, p = 0.020), and more often undetectable serum antibodies compared with younger patients (p = 0.031). In the late-onset group, outcome was worse, and all tumors were carcinomas (both p < 0.0001). CSF was more accurate than serum to detect anti-NMDAR encephalitis (sensitivity 99% vs 68%, p < 0.0001). Using cell-based assay (CBA), CSF provided an unconfirmed positive test result in 11/2,600 patients (0.4%); 6/11 had a neuroinflammatory disease (other than anti-NMDAR encephalitis). Patients with anti-NMDAR encephalitis, who tested positive in CSF only, had lower CSF antibody titers (p = 0.003), but appeared to have an equally severe disease course.

Discussion

Anti-NMDAR encephalitis occurs at all ages and is less rare in the elderly patients than initially anticipated. In older patients, the clinical phenotype is less outspoken, has different tumor association, and a less favorable recovery. Detection of antibodies in CSF is the gold standard, and although the CBA has very good validity, it is not perfect. The clinical phenotype should be leading, and confirmation in a research laboratory is recommended, when in doubt.

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.

Seventeen-Year-Old Female With History of Depression Presented With Mania and Enuresis

A 17-year-old girl with a history of depression was referred by her psychologist to the emergency department (ED) because of concerning behavioral changes for the past 2 weeks. She was engaging in erratic behaviors, including excessive baking, handling broken glass, mixing chemicals, and swimming alone while clothed. She denied any intention to harm herself or others. She was feeling energized in the morning despite only sleeping a few hours at night. She also urinated on herself the day before her ED visit. Her examination and preliminary testing findings in the ED were largely normal. Her initial presentation was concerning for a psychiatric etiology, such as new-onset bipolar disorder given previous history of depression and recent impulsive symptoms suggestive of mania. As her clinical course evolved and urinary incontinence continued, her definitive diagnosis was made by an interdisciplinary team that included child psychiatry and pediatric neurology.

Low high-density lipoprotein cholesterol and apolipoprotein A-I levels are associated with poor outcome and relapse in autoimmune encephalitis

BACKGROUND

Growing evidence suggests an association between dyslipidemia and autoimmune diseases. This study aimed to investigate the relationship between lipid profiles and prognosis of autoimmune encephalitis (AE) patients.

METHODS

This retrospective study consisted of 114 AE patients from September 2014 to September 2020. Data of clinical parameters, including age, sex, body mass index (BMI), clinical features, comorbidities, therapeutic management, lipid profiles, modified Rankin scale (mRS) scores, outcomes, and relapses were collected. Logistic regression models were used to examine the associations between lipid profiles and outcomes of AE. Correlations between lipid profiles and C-reactive protein (CRP), which is an inflammatory marker, were assessed.

RESULTS

In the univariate logistic analysis, sex (P = 0.030), mental behavior disorder (P = 0.004), disturbance of consciousness (P = 0.002), mRS at study entry (P = 0.020), tumor comorbidity (P = 0.028), high-density lipoprotein cholesterol (HDL-C) (P = 0.029), apolipoprotein A-I (apoA-I) (P = 0.012), apolipoprotein B (apoB) (P = 0.036) and apoA-I/apoB (P = 0.001) levels were all associated with the unfavorable outcomes of patients. After adjustment for age, sex and mRS at study entry, lower apoA-I and apoA-I /apoB levels were still significantly associated with the unfavorable outcomes of patients. Low HDL-C (P = 0.048) and apoA-I levels (P = 0.026) were also significantly associated with the relapse of AE patients. HDL-C and apoA-I levels were negatively correlated with CRP levels in correlation analysis.

CONCLUSIONS

Lipid profiles, especially low HDL-C and apoA-I levels, are significantly associated with the poor outcomes and relapse of AE patients, and seem associated with inflammatory responses. HDL-C and apoA-I levels may be good candidates for predicting prognosis of AE patients.

NMDA Autoimmune Encephalitis and Severe Persistent Hypokalemia in a Pregnant Woman

Introduction: For more than a decade, NMDAR autoimmune encephalitis has been studied and treated as a neurological condition, and good results have been achieve through immune therapies. Apart from being well represented in the CNS, NMDA receptors are currently known of and being studied in multiple non-neuronal cells with potential clinical significance. The association of NMDAR autoimmune encephalitis with pregnancy is rare, and hypokalemia is not mentioned. Methods: We present the case of a 30-year-old woman with NMDAR autoimmune encephalitis in her 17th week of pregnancy associated with persistent hypokalemia that had no apparent cause and resisted Kalium chloride supplementation. A diagnostic work-up including clinical, laboratory, and imagistic examinations, was performed. The case was monitored between May and September 2016 at Neurology, SCJUT. Results: Severe hypokalemia with normal serum sodium levels persisted throughout the course of clinical manifestation of anti-NMDAR autoimmune encephalitis. Conclusions: NMDAR autoimmune encephalitis is under-diagnosed in its atypical clinical variants, and this disease’s association with hypokalemia is not mentioned in the literature. Still, it is of clinical importance because it attests to the implications of other organs/systems in the general autoimmune process of NMDAR encephalitis, and it might change the way we address certain psychiatric disorders by searching underlying organic conditions.

COVID-19 and neurologic manifestations: a synthesis from the child neurologist's corner

BACKGROUND

Since December 2019, the SARS-CoV-2 virus has been a global health issue. The main clinical presentation of this virus is a flu-like disease; however, patients with diverse neurologic manifestations have also been reported. In this review, we attempt to summarize, discuss and update the knowledge of the neurologic manifestations in the pediatric population affected by SARS-CoV-2 infection and the pandemic's effects in children with neurologic diseases.

DATA SOURCES

This review analyzes studies found on the PubMed database using the following keywords: Neurologic manifestations COVID-19, Neurological COVID-19, coronavirus, SARS-CoV-2, pediatric COVID-19, COVID-19 in children, MIS-C, Pediatric Inflammatory Multisystem Syndrome, Guillain Barré Syndrome, Stroke, ADEM, and Anti-NMDA encephalitis. All studies cited were published between 2004 and 2022, and represent the most relevant articles in the field. The World Health Organization COVID-19 online dashboard was assessed to obtain updated epidemiological data.

RESULTS

The most common neurologic symptoms in the pediatric population are headache, seizures, encephalopathy, and muscle weakness. These can be present during COVID-19 or weeks after recovering from it. Children who presented with multi-system inflammatory syndrome had a higher incidence of neurologic manifestations, which conferred a greater risk of morbidity and mortality. Several neuro-pathophysiological mechanisms have been proposed, including direct virus invasion, hyper-inflammatory reactions, multi-systemic failure, prothrombotic states, and immune-mediated processes. On the other hand, the COVID-19 pandemic has affected patients with neurologic diseases, making it challenging to access controls, treatment, and therapies.

CONCLUSIONS

Various neurologic manifestations have been associated with children's SARS-CoV-2 infection. It is important to identify and give them proper and opportune treatment because they can be potentially grave and life-threatening; some can lead to long-lasting sequelae. Different neuro-pathophysiological mechanisms have been proposed, however, a causal relationship between SARS-CoV-2 infection and neurologic manifestations remains to be proven. Patients with neurologic diseases are especially affected by COVID-19, not only by the disease itself but also by its complications and pandemic management measures.

Case Report: HSV-2 Encephalitis Presenting With Chorea; Effects of Infection Alone or Combination of Infection and Autoimmunity?

Background: Chorea as a symptom of late-onset post-infectious autoimmune encephalitis has been reported with HSV-1 but not HSV-2 encephalitis. Extrapyramidal symptoms are typically associated with the presence of anti-NMDA receptor antibodies but may also exist in antibody-negative individuals.

Case: This case highlights a patient who presented with mental status changes and chorea as the initial manifestation of HSV-2 encephalitis. The choreiform movements failed to respond to antiviral medications but were rapidly responsive to plasmapheresis, which, together with abnormal intrathecal immunoglobulin synthesis, suggests a potential contribution of parainfectious immune-mediated process. The patient made a full recovery and a complete resolution of the chorea.

Discussion: This is the first case associating HSV-2 encephalitis presentation with chorea. The neurological complications, including chorea, are largely related to active CNS HSV-2 infection, possibly together with triggered CNS autoimmunity despite undetectable CSF neuronal autoantibodies and normal neuroimaging. Early diagnosis and treatment with antiviral agent and immune therapies might be pivotal to optimize the clinical outcome.

Treatable Hyperkinetic Movement Disorders Not to Be Missed

Hyperkinetic movement disorders are characterized by the presence of abnormal involuntary movements, comprising most notably dystonia, chorea, myoclonus, and tremor. Possible causes are numerous, including autoimmune disorders, infections of the central nervous system, metabolic disturbances, genetic diseases, drug-related causes and functional disorders, making the diagnostic process difficult for clinicians. Some diagnoses may be delayed without serious consequences, but diagnosis delays may prove detrimental in treatable disorders, ranging from functional disabilities, as in dopa-responsive dystonia, to death, as in Whipple's disease. In this review, we focus on treatable disorders that may present with prominent hyperkinetic movement disorders.

Acute Psychosis Due to Anti-N-Methyl D-Aspartate Receptor Encephalitis Following COVID-19 Vaccination: A Case Report

Anti-N-methyl D-aspartate (NMDA) receptor (anti-NMDAR) encephalitis has been reported after SARS-CoV-2 infection, but not after SARS-CoV-2 vaccination. We report the first known case of anti-NMDAR encephalitis after SARS-CoV-2 immunization in a young female presenting with acute psychosis, highlighting a rare potential immunological complication of vaccination against SARS-CoV-2 that is currently being distributed worldwide. The patient presented initially with anxiety and hypochondriacal delusions which progressed to psychosis and catatonia but returned to baseline with aggressive immunomodulatory therapy consisting of intravenous immunoglobulin, high-dose glucocorticoids, and rituximab. This study highlights that the workup of acute psychosis should include establishing a history of recent vaccination followed by a thorough neurological assessment, including for anti-NMDAR antibodies in blood and cerebrospinal fluid.

Virus reactivation after immunotherapy of anti-NMDAR encephalitis secondary to herpes simplex encephalitis: A case report

Herpes simplex encephalitis is the most common cause of sporadic fatal encephalitis. More than half of patients with herpes simplex encephalitis will die and the vast majority of survivors have severe neurologic sequelae without effective antiviral therapy. Some people experience relapses such as secondary anti-N-methyl-d-aspartate receptor encephalitis despite appropriate antiviral treatment. It is rare that virus reactivation after immunotherapy of anti-N-methyl-d-aspartate receptor encephalitis after herpes simplex encephalitis. In the present study, we retrospectively review one patient who showed this rare situation.

Anti-N-methyl-D-aspartate receptor encephalitis: An observational and comparative study in Mexican children and adults

OBJECTIVE

To present a case series of encephalitis patients with anti-N-methyl-D-aspartate receptor antibodies, attending two neurological referral centers in a three-year period.

METHODS

A retrospective, descriptive, comparative study included child and adult patients in two neurological populations, positive for antibodies against the NR1 and NR2 subunits of the glutamate (NMDA) receptor in serum and CSF, as determined during a three-year period.

RESULTS

Sixty-six patients were included (40 children and 26 adults). Male patients were more affected (M: F ratio was 1:0.6). No differences in progression or hospitalization time were observed between groups. In children, 35% of patients showed herpetic infection before autoimmune encephalitis (P = 0.01). Among viral prodromal symptoms, upper respiratory tract infection (P = 0.02) and fever (P = 0.001) predominated in children, while infectious gastroenteritis was more frequent in adults (P = 0.03). Among neuropsychiatric signs, mental confusion (P = 0.0001) and orofacial dyskinesia/oromandibular dystonia (P = 0.0001) were frequent in children, while emotional lability (P = 0.03), catatonia (P = 0.0001), and headache (P = 0.005) predominated in adults. The score in the modified Rankin scale on admission was higher in children (4.3 ± 0.8 vs. 2.2 ± 1.3, P = 0.0001), but at one-year of clinical follow up no significant differences were found.

CONCLUSIONS

Male patients were predominantly affected in our population. One-third of all patients developed prodromal infection. Neuropsychiatric clinical complaints were different in children and adults. However, post-hospitalization recovery was similar between groups.

The Association of Ovarian Teratoma and Anti-N-Methyl-D-Aspartate Receptor Encephalitis: An Updated Integrative Review

Ovarian teratomas are by far the most common ovarian germ cell tumor. Most teratomas are benign unless a somatic transformation occurs. The designation of teratoma refers to a neoplasm that differentiates toward somatic-type cell populations. Recent research shows a striking association between ovarian teratomas and anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, a rare and understudied paraneoplastic neurological syndrome (PNS). Among teratomas, mature teratomas are thought to have a greater relevance with those neurological impairments. PNS is described as a neurologic deficit triggered by an underlying remote tumor, whereas anti-NMDAR encephalitis is characterized by a complex neuropsychiatric syndrome and the presence of autoantibodies in cerebral spinal fluid against the GluN1 subunit of the NMDAR. This review aims to summarize recent reports on the association between anti-NMDAR encephalitis and ovarian teratoma. In particular, the molecular pathway of pathogenesis and the updated mechanism and disease models would be discussed. We hope to provide an in-depth review of this issue and, therefore, to better understand its epidemiology, diagnostic approach, and treatment strategies.

Differentiation of viral and autoimmune central nervous system inflammation by kynurenine pathway

Objective

To determine whether the metabolites of Kynurenine pathway (KP) could serve as biomarkers for distinguishing between viral CNS infections and autoimmune neuroinflammatory diseases, especially anti‐N‐methyl‐D‐aspartate receptor encephalitis (NMDARE) and herpes virus encephalitis (HSE).

Methods

This study enrolled CSF samples from 76 patients with viral CNS infections, autoimmune neuroinflammatory, and non‐inflammatory neurological diseases. We measured cerebrospinal fluid (CSF) concentrations of tryptophan (Trp) and kynurenine (Kyn) by ELISA.

Results

Kyn concentrations and Kyn/Trp ratios were highly increased (p < 0.001, viral vs. autoimmune) in viral CNS infections, whereas patients with autoimmune neuroinflammatory and non‐inflammatory diseases exhibited low concentrations. Furthermore, Kyn concentrations and Kyn/Trp ratio turned out to be excellent biomarkers to distinguish between herpes simplex encephalitis (HSE) and NMDARE (AUC 0.920 and AUC 0.906), whereas Trp concentrations were similar in all three groups.

Interpretation

The results suggest that elevated CSF Kyn concentrations and Kyn/Trp ratio may serve as biomarkers for distinguishing viral CNS infections from autoimmune neuroinflammatory diseases. In particular, the distinction between HSE and NMDARE is of great clinical relevance. Further studies are warranted to investigate the potential of CSF Kyn levels and Kyn/Trp ratio as routine parameters in patients with CNS diseases.

Lyme Disease and Associated NMDAR Encephalitis: A Case Report and Literature Review

We present a case of a patient with positive N-methyl-D-aspartate receptor (NMDAR) IgG antibodies in their serum and cerebrospinal fluid (CSF) associated with neuroborreliosis. Clinically, the patient presented with symptoms of confusion, as well as behavioral and speech impairments. Regardless of antibacterial treatment, no significant improvement was achieved. Methylprednisolone provided a marked improvement in the patient’s clinical signs and CSF findings. The screening did not reveal any underlying neoplasm. Taking into account the marked clinical improvement after treatment with glucocorticosteroids, we suggest that NMDAR encephalitis is a possible autoimmune complication in neuroborreliosis patients requiring additional immunotherapy.

Expanding the clinical spectrum of anti-IgLON5 disease: A multicenter retrospective study

BACKGROUND

We conducted this study to describe detailed the clinical characteristics, ancillary test results and treatment response of a group of Chinese patients with anti-IgLON5 disease.

METHODS

We recruited 13 patients with positive IgLON5 antibodies in serum and/or cerebrospinal fluid from nine tertiary referral centers. Patients were enrolled from February 2017 to July 2021. We retrospectively collected information on the presenting and main symptoms, treatment response and follow-up outcomes.

RESULTS

The median age of onset for symptoms was 60 (range: 33-73) years and six of the 13 patients were females. The predominant clinical presentations included sleep disturbance (eight patients) and cognitive impairment (seven patients), followed by movement disorders (six patients). Parainfectious cause seemed plausible. Notably, we identified the first case of possible Epstein-Barr virus (EBV)-related anti-IgLON5 disease. Coexisting neural autoantibodies were identified in two patients. Furthermore, two patients had other autoimmune diseases. The IgG subclass was determined in four patients, including two with dominant IgG4 subtype and two with dominant IgG1 subtype. Additionally, 10 patients were treated with immunotherapy and four patients exhibited improvement. Overall, six of 10 patients for whom follow-up results were assessable had favorable clinical outcomes (modified Rankin Scale score ≤2).

CONCLUSIONS

The clinical spectrum of anti-IgLON5 disease is variable. Our results highlight a boarder spectrum of anti-IgLON5 disease.

Intrathecal Antibody Production Against Epstein-Barr, Herpes Simplex, and Other Neurotropic Viruses in Autoimmune Encephalitis

Background and Objectives

Neurotropic viruses are suspected to play a role in the pathogenesis of autoimmune diseases of the CNS such as the association between the Epstein-Barr virus (EBV) and multiple sclerosis (MS). A group of autoimmune encephalitis (AE) is linked to antibodies against neuronal cell surface proteins. Because CNS infection with the herpes simplex virus can trigger anti–NMDA receptor (NMDAR) encephalitis, a similar mechanism for EBV and other neurotropic viruses could be postulated. To investigate for previous viral infections of the CNS, intrathecally produced virus-specific antibody synthesis was determined in patients with AE.

Methods

Antibody-specific indices (AIs) against EBV and measles, rubella, varicella zoster, herpes simplex virus, and cytomegalovirus were determined in 27 patients having AE (anti-NMDAR encephalitis, n = 21, and LGI1 encephalitis, n = 6) and in 2 control groups comprising of 30 patients with MS and 21 patients with noninflammatory CNS diseases (NIND), which were sex and age matched.

Results

An intrathecal synthesis of antibodies against EBV was found in 5/27 (19%) patients with AE and 2/30 (7%) of the patients with MS. All these patients had also at least 1 additional elevated virus-specific AI. In contrast, in none of the patients with NIND, an elevated virus-specific AI was detected.

Discussion

Intrathecally produced antibodies against EBV can be found in patients with AE and MS but only together with antibodies against different neurotropic viruses. Evidence of these antibodies is the result of a polyspecific immune response similar yet distinct from MS response rather than an elapsed infection of the CNS.

Video Anthology of Movement Disorders Due to Infections in South Asia

South Asia, encompassing many populous countries including India, Pakistan, and Bangladesh, is home to a wide variety of infectious diseases several of which are disproportionately prevalent, endemic or distinctive to the region. These result in considerable morbidity and mortality, which can be greatly reduced through public-health measures, timely diagnosis and treatment. Some of these infectious diseases have neurological manifestations including movement disorders either due to the pathogen being neuroinvasive or via an immune-mediated response. For diseases such as Japanese encephalitis, movement disorders are the primary manifestation while for others, they can be a presenting feature. Thus, recognizing these movement disorders is often crucial to the diagnosis of the particular infection, and/or to exclude infection as a cause and arrive at the correct alternate diagnosis. Once diagnosed, the infection-related movement disorders are treated by targeting the infectious agent, or symptomatically. In this article, we describe and illustrate a variety of movement disorders that are seen in patients infected by viruses, bacteria and parasites in South Asia. This would be of value to neurologists practicing in the region and, with the increasing ease in movement of people and pathogens, those practicing elsewhere.