Anti-NMDA receptor encephalitis in Japan: long-term outcome without tumor removal

Successful Laparoscopic Resection of 7 mm Ovarian Mature Cystic Teratoma Associated with Anti-NMDAR Encephalitis

Anti-NMDAR (N-methyl-D-aspartate receptor) encephalitis is an immune-mediated encephalitis. It has been predominantly described in young women and is commonly associated with an ovarian teratoma. We report a case of anti-NMDAR encephalitis associated with a 7 mm ovarian teratoma that was completely resected by laparoscopic surgery. An 18-year-old woman suddenly presented with personality changes requiring her admission to the department of neurology. After that, she also showed involuntary movements, disturbance of consciousness, and central hypoventilation. As an abdominal image revealed the possibility of a right ovarian teratoma of 5 × 7 mm, a laparoscopic operation was performed. The macroscopic appearance of the right ovary did not show any abnormalities; nevertheless, we performed a partial resection of the right ovary, with reference to the image diagnosis, in order to spare the ovarian reserve. The 22 × 22 mm partially resected ovary contained an intact 5 × 7 mm cystic tumor. The pathological diagnosis was mature cystic teratoma with components of brain tissue. An anti-NMDAR-antibody test proved positive in both serum and cerebrospinal fluid 1 month after the surgery. From these results, she was diagnosed with anti-NMDAR encephalitis. By the administration of cyclophosphamide in addition to the operation, she recovered drastically without any of the symptoms shown before.

Electroencephalography of autoimmune limbic encephalopathy

There is an increasing recognition of autoimmune limbic encephalopathy with the hope for earlier diagnosis and expedited and improved treatment. Although antibody testing remains the definitive clinical diagnostic feature, the presentation of a rapid dementia, behavioral changes, and seizures leads to investigation using cerebral imaging, electroencephalography, and cerebrospinal fluid to confirm the diagnosis and also to exclude similar disorders. The electroencephalographer may be asked to comment on the types of electroencephalography abnormality and provide input toward the diagnosis of limbic encephalopathy. This article reviews the literature on limbic paraneoplastic and nonparaneoplastic encephalopathies, providing descriptions and examples of the electroencephalography findings. Typically, there are patterns of slow theta and delta activity and different patterns of temporal and frontal epileptic activity.

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis: an unusual cause of autistic regression in a toddler

Anti N-methyl-d-aspartate (NMDA) receptor encephalitis in children is associated with psychiatric changes, seizures, and dyskinesias. We present the first report of autistic regression in a toddler caused by this entity. A 33-month-old boy presented with decreased appetite, irritability, and insomnia following an upper respiratory tract infection. Over the next few weeks he lost language and social skills, and abnormal movements of his hand developed. Within a month, this patient came to fit the diagnostic criteria for autistic spectrum disorder. Upon investigation, anti-NMDA receptor antibodies were found in the boy's cerebrospinal fluid. He was treated with intravenous immunoglobulins and steroids, resulting in reacquisition of language and social skills and resolution of movements. Our case emphasizes the significance of suspecting anti-NMDA receptor encephalitis as the cause of autistic regression, even in an age group where the diagnosis of autistic spectrum disorder is typically made, and especially when presentation follows a febrile illness.

Pediatric anti-NMDA (N-methyl D-aspartate) receptor encephalitis

BACKGROUND

We report the clinical features and course of pediatric patients presenting with anti-N-methyl D-aspartate receptor (NMDA-R) encephalitis.

METHODS

Single-center 4-year observational study of pediatric encephalitis associated with NMDA-R antibodies in the serum and/or the cerebrospinal fluid.

RESULTS

Three girls with anti-NMDA-R encephalitis were identified. All presented with an acute hyperkinetic movement disorder and seizures, expressive aphasia, and emotional lability requiring inpatient treatment for 1-3 months. Imaging and electroencephalogram findings were nondiagnostic. None had an underlying tumor or ovarian teratoma. All received immune-modulatory therapy, including one or more of the following: high-dose methyl-prednisolone, plasma exchange, intravenous immunoglobulin or mycophenolate mofetil. Two of the three patients relapsed within 6 months of presentation and required retreatment with plasma exchange. All have remained in subsequent remission, with two of the three requiring second-line immunotherapy with rituximab.

CONCLUSIONS

Hyperkinetic movements in pediatric patients presenting with acute encephalopathy and prominent psychiatric symptoms should elicit a search for NMDA-R antibodies early in the evaluation. Relapses require aggressive immunomodulatory treatment for remission. This series highlights a unique positron emission tomography scan finding of hypermetabolism in one of the patients that correlated with her clinical symptoms. Recovery and rehabilitation can be prolonged, often taking years after the initial diagnosis. Early identification and treatment is likely to reduce relapses and limit morbidity associated with this potentially devastating but treatable encephalitis.

Identification of the N-Methyl-D-aspartate receptor (NMDAR)-related epitope, NR2B, in the normal human ovary: implication for the pathogenesis of anti-NMDAR encephalitis

N-methyl-D-aspartate receptors (NMDARs) are one type of ionotropic glutamate receptors (GluRs) and are heterotetrametric cation channels composed of NMDAR1 (NR1), NMDAR2 (NR2A, 2B, 2C or 2D) and NMDAR3 (NR3A or NR3B) subunits. The main subunits are NR1 and NR2 and their combinations are classified into several diverse forms including NR1/NR1/NR2A/NR2A, NR1/NR1/NR2B/NR2B and NR1/NR1/NR2A/NR2B. NMDARs are physiologically related to synapse development and synaptic plasticity in the central nervous system. Anti-NMDAR encephalitis is a form of autoimmune limbic encephalitis mainly affecting young women, with various manifestations including initial psychiatric symptoms, subsequent unresponsiveness, intractable generalized seizure, dysautonomia and orofacial dyskinesia. This disorder is often accompanied by ovarian teratoma that is originated from oocytes. Anti-neural antibody for the NR1/NR2 heteromer of NMDAR has been identified as a disease-specific hallmark. It has been emphasized that neural components in ovarian teratoma act as a trigger to produce anti-NMDAR antibodies, although about half of the patients with anti-NMDAR encephalitis are not associated with ovarian teratoma. To identify NMDAR-related epitopes located outside of the brain, we performed immunohistochemical examinations of normal human ovary and testis using specific antibodies against NR1, NR2A and NR2B, respectively, and found expression of the NR2B epitope in the cytoplasm of oocytes. In contrast, the testis showed no immunohistochemical reactivity. Therefore, oocytes contain NMDAR-related epitopes including NR2B. The NMDAR-related epitopes in normal oocytes may cause an antigen-antibody reaction in certain pathological conditions. The presence of NR2B immunoreactivity in oocytes may account for the fact that anti-NMDAR encephalitis predominantly affects young females.

Molecular and cellular mechanisms underlying anti-neuronal antibody mediated disorders of the central nervous system

Over the last decade multiple autoantigens located on the plasma membrane of neurons have been identified. Neuronal surface antigens include molecules directly involved in neurotransmission and excitability. Binding of the antibody to the antigen may directly alter the target protein's function, resulting in neurological disorders. The often striking reversibility of symptoms following early aggressive immunotherapy supports a pathogenic role for autoantibodies to neuronal surface antigens. In order to better understand and treat these neurologic disorders it is important to gain insight in the underlying mechanisms of antibody pathogenicity. In this review we discuss the clinical, circumstantial, in vitro and in vivo evidence for neuronal surface antibody pathogenicity and the possible underlying cellular and molecular mechanisms. This review shows that antibodies to neuronal surface antigens are often directed at conformational epitopes located in the extracellular domain of the antigen. The conformation of the epitope can be affected by specific posttranslational modifications. This may explain the distinct clinical phenotypes that are seen in patients with antibodies to antigens that are expressed throughout the brain. Furthermore, it is likely that there is a heterogeneous antibody population, consisting of different IgG subtypes and directed at multiple epitopes located in an immunogenic region. Binding of these antibodies may result in different pathophysiological mechanisms occurring in the same patient, together contributing to the clinical syndrome. Unraveling the predominant mechanism in each distinct antigen could provide clues for therapeutic interventions.

[NMDA receptor encephalitis in the course of recurrent CNS demyelinating disorders: a case report]

We present the case of a 31-year-old woman who developed N-methyl-d-aspartate (NMDA) receptor encephalitis during the course of relapsing and remitting multiple brain lesions. The patient developed a tingling sensation in the left upper and lower extremities, and was first admitted to our hospital at age 27. She was tentatively diagnosed with multiple sclerosis on the basis of multiple lesions with Gd-enhancement in the brainstem, and 2 separate clinical relapses by age 28. At age 31, she developed a headache and pyrexia, followed by confusion and abnormal behavior. Her symptoms acutely progressed to stupor, and subsequently, she developed oral dyskinesia and athetosis-like involuntary movement of the left arm. The stupor state continued over 2 months. However, she had completely recovered by 3 months after the onset of psychiatric symptoms. Her serum and CSF samples tested positive for anti-NMDA receptor antibodies, and she was diagnosed with NMDA receptor encephalitis. Her serum was negative for anti-AQP4 antibody, but showed weak positivity for antinuclear antibody. Between ages 32 and 34, she experienced 2 clinical relapses, including right-hand clumsiness, confusion, aphasia, and dysphagia. FLAIR images showed a high-intensity area in the brain stem, thalamus, and subcortical white matter. No tumors were found throughout the course. A clinical entity of NMDA receptor encephalitis can include various neurologic disorders, such as the development of recurrent demyelinating brain lesions. Further investigation is required to clarify the pathophysiological role of anti-NMDA receptor antibody in our patient.

Rehabilitation for a child with recalcitrant anti-N-methyl-d-aspartate receptor encephalitis: case report and literature review

Anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis is a newly recognized, potentially fatal, but treatable autoimmune disease. Good outcome predictors include milder severity of symptoms, no need for intensive care unit admission, early aggressive immunotherapy, and prompt tumor removal. We report a case of a young girl aged 3 years 2 months and diagnosed as recalcitrant anti-NMDA receptor encephalitis without any underlying neoplasm. The patient had initial symptoms of behavioral changes that progressed to generalized choreoathetosis and orofacial dyskinesia, which resulted in 6 months of hospitalization in the pediatric intensive care unit. One year after initial onset of the disease, she had only achieved the developmental age of an infant aged 6-8 months in terms of gross and fine motor skills, but she resumed total independence in activities of daily living after receiving extensive immunotherapy and 28 months of rehabilitation. Our brief review will help clinical practitioners become more familiar with this disease and the unique rehabilitation programs.

Inflammation and the two-hit hypothesis of schizophrenia

The high societal and individual cost of schizophrenia necessitates finding better, more effective treatment, diagnosis, and prevention strategies. One of the obstacles in this endeavor is the diverse set of etiologies that comprises schizophrenia. A substantial body of evidence has grown over the last few decades to suggest that schizophrenia is a heterogeneous syndrome with overlapping symptoms and etiologies. At the same time, an increasing number of clinical, epidemiological, and experimental studies have shown links between schizophrenia and inflammatory conditions. In this review, we analyze the literature on inflammation and schizophrenia, with a particular focus on comorbidity, biomarkers, and environmental insults. We then identify several mechanisms by which inflammation could influence the development of schizophrenia via the two-hit hypothesis. Lastly, we note the relevance of these findings to clinical applications in the diagnosis, prevention, and treatment of schizophrenia.

Paraneoplastic limbic encephalitis resembling acute herpetic encephalitis

Introduction. Paraneoplastic limbic encephalitis (PLE) is a rare disorder that typically follows a chronic or subacute course of personality changes, memory loss, seizures, and hallucinations. Early diagnosis is difficult and characteristic symptoms can be mimicked by a variety of conditions. We present a case of PLE, initially presenting as acute herpetic encephalitis. Case Presentation. A 56-year-old male was admitted for evaluation of acute onset headache, fever, and confusion. On neurological examination he was confused with MMSE score of 15/30. CSF analysis revealed marked lymphocytic pleocytosis. A possible diagnosis of acute herpetic encephalitis was rendered and patient was treated with acyclovir. CSF PCR was negative. Cranial MRI revealed bilateral hyperintense lesions in medial temporal lobes with contrast enhancement. Despite treatment with acyclovir patient was deteriorated; thus, a paraneoplastic syndrome was suspected. Chest CT showed a right paratracheal lymph node mass, while a biopsy revealed neuroendocrine lung cancer. Auto antibodies to Hu were also detected. The patient was treated with steroids and chemotherapy. Six months later, he had complete tumour remission and marked neurological improvement. Discussion. PLE can rarely invade acutely, being indistinguishable from herpetic encephalitis. Inclusion of PLE in the differential diagnosis of acute encephalitis is of great clinical significance.

Anti-NMDAR encephalitis misdiagnosed as Hashimoto's encephalopathy

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a well-defined autoimmune disorder. Hashimoto's encephalopathy (HE) is a still controversial entity, lacking definite diagnostic criteria. We described a 14-year-old-girl presenting with a clinical picture consistent with the diagnosis of anti-NMDAR encephalitis, confirmed by NMDAR antibody testing. Four years earlier, she had presented a similar episode of acute encephalopathy diagnosed as HE. Anti-NMDAR encephalitis and HE share similar clinical features so that the differential diagnosis can be difficult if specific antibodies are not tested. The correct diagnosis of anti-NMDAR encephalitis is crucial to plan the appropriate management and follow-up, namely in term of oncological screening, since it can be paraneoplastic in origin. We suggest to re-evaluate the clinical history of all subjects with previous HE diagnosis in order to evaluate the possible diagnosis of anti-NMDAR encephalitis and plan the appropriate management of these patients.

Antibody titres at diagnosis and during follow-up of anti-NMDA receptor encephalitis: a retrospective study

BACKGROUND

Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis is a severe but treatable autoimmune disorder which diagnosis depends on sensitive and specific antibody testing. We aimed to assess the sensitivity and specificity of serum and CSF antibody testing in patients with anti-NMDA receptor encephalitis, and the relation between titres, relapses, outcome, and epitope repertoire.

METHODS

In this observational study, we used rat brain immunohistochemistry and cell-based assays (CBA) with fixed or live NMDA receptor-expressing cells to determine the sensitivity and specificity of antibody testing in paired serum and CSF samples. Samples were obtained at diagnosis from patients with anti-NMDA receptor encephalitis and from control participants worldwide. We deemed a patient to be antibody positive if their serum, their CSF, or both tested positive with both immunohistochemistry and CBA techniques; we determined titres with serial sample dilution using brain immunohistochemistry. We examined samples from 45 patients (25 with good outcome [modified Rankin Scale, mRS 0-2], ten with poor outcome [mRS 3-6], and ten with relapses) at three or more timepoints. We determined the epitope repertoire in the samples of 23 patients with CBA expressing GluN1-NMDA receptor mutants.

FINDINGS

We analysed samples from 250 patients with anti-NMDA receptor encephalitis and 100 control participants. All 250 patients had NMDA receptor antibodies in CSF but only 214 had antibodies in serum (sensitivity 100.0% [98.5-1000%] vs 85.6% [80.7-89.4%], p<0.0001). Serum immunohistochemistry testing was more often in agreement with CBA with fixed cells (77 [71%] of 108) than with CBA with live cells (63 [58%] of 108, p=0.0056). In multivariable analysis, CSF and serum titres were higher in patients with poor outcome than in those with good outcome (CSF dilution 340 vs 129, difference 211, [95% CI 1-421], p=0.049; serum dilution 7370 vs 1243, difference 6127 [2369-9885], p=0.0025), and in patients with teratoma than in those without teratoma (CSF 395 vs 110, difference 285 [134-437], p=0.0079; serum 5515 vs 1644, difference 3870 [548-7193], p=0.024). Over time there was a decrease of antibody titres in the 35 patients with good or poor outcome and samples followed at three timepoints regardless of outcome (from diagnosis to last follow-up: CSF 614 to 76, difference 538 [288-788]; serum 5460 to 1564, difference 3896 [2428-5362]; both p<0.0001). Relapses were associated with a change in titre more often in CSF than in serum (14 of 19 vs seven of 16, p=0.037). After recovery, 24 of 28 CSF samples and 17 of 23 serum samples from patients remained antibody positive. Patients' antibodies targeted a main epitope region at GluN1 aminoacid 369; the epitope repertoire did not differ between patients with different outcomes, and did not change during relapses.

INTERPRETATION

The sensitivity of NMDA receptor antibody testing is higher in CSF than in serum. Antibody titres in CSF and serum were higher in patients with poor outcome or teratoma than in patients with good outcome or no tumour. The titre change in CSF was more closely related with relapses than was that in serum. These findings emphasise the importance of including CSF in antibody studies, and that antibody titres can complement clinical assessments.

FUNDING

Dutch Cancer Society, National Institutes of Health, McKnight Neuroscience of Brain Disorders award, the Fondo de Investigaciones Sanitarias, ErasmusMC fellowship, and Fundació la Marató de TV3.

Autoimmune-induced glutamatergic receptor dysfunctions: conceptual and psychiatric practice implications

Glutamatergic neurotransmission is mediated via complex receptorial systems including N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolpropionic acid (AMPA) and metabotropic receptor subtypes and plays a critical role in the modulation of synaptic plasticity, mood, cognitive processes and motor behavior. Glutamatergic function deficits are hypothesized to contribute to the pathogenesis of neuropsychiatric disorders, including schizophrenia, mood and movement disorders. Accumulating data are rapidly leading to the characterization of specific types of autoimmune encephalitis in which the receptors and proteins critically involved in glutamatergic neurotransmission, e.g., NMDA, AMPA receptors, are antigen targets. Characteristic of these syndromes, antibodies alter the structure and/or function of the corresponding neuronal antigen resulting in clinical pictures that resemble pharmacological disease models. Presently the best characterized autoimmune glutamatergic disorder is anti-NMDA receptor encephalitis. This disorder manifests with intertwined psychiatric and neurological features, defines a new syndrome, reclassifies poorly defined clinical states and extends previous hypotheses, such as hypo-NMDA receptor function in schizophrenia. The characterization of autoimmune-induced glutamatergic receptor dysfunctions (AGRD) is likely to have a substantial conceptual impact upon our understanding of neuropsychiatric disorders including schizophrenia, affective and movement dysfunctions. Further definition of AGRD will provide additional guidelines for psychiatric diagnoses, identification of homogeneous patient subtypes within broad phenomenological classifications and will contribute to the development of personalized treatments. The body of knowledge already accumulated on anti-NMDA receptor encephalitis highlights the need for wide dissemination of these concepts among psychiatrists, and in suspected cases, for early recognition, prompt clinical and laboratory investigation and efficient interface between mental health and medical teams.

[Complications of presumed benign ovarian tumors]

The main risk factor of adnexal torsion is a previous adnexal torsion (LE3). There is no clinical, biological or radiological sign that may exclude the diagnosis of adnexal torsion (LE3). The presence of flow at color Doppler imaging does not allow exclusion of the diagnosis (LE2). An emergent laparoscopy is recommended for adnexal untwisting (Grade B), except in postmenopausal women where oophorectomy is recommended (grade C). A persistent black color of the adnexa after untwisting is not an indication for systematic oophorectomy (grade C), since a functional recovery is possible (LE3). Ovariopexy is not routinely recommended following adnexal untwisting (grade C). The clinical signs of intra-cystic hemorrhage and those of rupture of the corpus luteum are not specific (LE4). MRI is not recommended to confirm the diagnosis of intra-cystic hemorrhage (grade C). Malignant transformation of an ovarian cyst is very rare. The presence of a benign ovarian cyst is not associated with an increased risk of ovarian cancer at long-term follow-up (LE2). For these women, an ultrasound follow-up is not recommended (grade C). Dermoid ovarian cyst containing nerve tissue can trigger the production of pathogenic auto-antibody-anti-NMDA, leading to encephalitis. A high proportion of thyroid tissue in a mature teratoma (struma ovarii) may cause hyperthyroidism.

Pediatric anti-N methyl D aspartate receptor encephalitis

Anti-N Methyl D Aspartate Receptor encephalitis (anti-NMDARE) is a recently defined disease, which is probably more under-recognized than rare. We report a case of anti-NMDARE in a 13-years-old girl, who presented with intractable seizures. To the best of our knowledge, this is the second case of pediatric anti-NMDARE being reported from India. The need for a greater awareness of this disease and the subtle differences in clinical presentation between pediatric and adult patients are highlighted.

Autoimmune encephalitis: recent updates and emerging challenges

The knowledge of immune dysregulation and autoimmunity in neurological disorders has expanded considerably in recent times. Recognition of clinical syndromes, reliable methods of diagnosis, and early targeted immunotherapy can lead to a favourable outcome in acute and subacute neurological disorders that may be associated with significant morbidity and mortality if left untreated. This review focuses on the rapidly expanding field of autoimmune encephalitis. We describe the differences between limbic encephalitis associated with antibodies targeting intracellular antigens, and neuronal surface antibody syndromes (NSAS) where the antigens are primarily receptors or synaptic proteins located on the neuronal cell surface. We chronologically highlight important developments in NSAS by focusing on voltage gated potassium channel complex-associated antibody mediated encephalitis, anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis, and anti-dopamine 2 receptor antibody-associated basal ganglia encephalitis. Contentious issues such as the complexities of using serum antibodies as biomarkers, the initiation of central nervous system autoimmunity, and possible pathogenic mechanisms of these antibodies will be reviewed. The therapeutic challenges that clinicians face such as the timing of therapy and the role of second-line therapy will be discussed, with crucial concepts highlighted in the form of clinical vignettes. Future directions will involve the identification of novel antigens and methods to establish their pathogenicity, as well as evaluation of the most efficacious therapeutic strategies in patients with established NSAS.

Anti-NMDA-R encephalitis: follow-up of 24 months

Anti-N-methyl-D-aspartate receptor (anti-NMDA-R) encephalitis is the second-most-common cause of autoimmune encephalitis, based on epidemiological studies.It has been predominantly described in young females, with prominent psychiatric symptoms, memory loss, decrease in level of consciousness, epilepsy, and central hypoventilation. The condition is commonly associated with mature ovarian teratomas. We describe a video report with a classic presentation of anti-NMDA-R encephalitis in a young patient with no identifiable tumor. Anti-NMDA encephalitis is a recognizable and treatable illness. The prognosis of patients depends on early diagnosis, implementation of appropriate immunomodulatory therapy and, in paraneoplastic cases, complete tumor removal. Clinicians should be wary of this condition, especially when assessing patients with recent onset of psychiatric symptoms unresponsive to antipsychotic treatment.

Young girl with abnormal behavior: Anti-N-Methyl-D-Aspartate receptor immune encephalitis

Anti N Methyl D Aspartate receptor immune encephalitis (Anti NMDARE) is a recently defined, under-recognized and often misdiagnosed disease, which typically occurs in young females and may be associated with an underlying tumor, usually ovarian teratoma. If diagnosed early, initiation of immunotherapy and tumor removal (if present) may result in recovery. We report a case of a 17 years old girl with Anti NMDARE who was initially misdiagnosed as Functional psychosis, Neuroleptic Malignant Syndrome and Sepsis syndrome. To the best of our knowledge, this is only the second case of anti NMDARE being reported from India. This case report underscores the need for a greater awareness of this entity across multiple specialties, e.g., general medicine, psychiatry and neurology, to ensure a heightened diagnostic suspicion, which can lead to timely diagnosis and adequate therapy of this treatable disease.

Functional and structural brain changes in anti-N-methyl-D-aspartate receptor encephalitis

OBJECTIVE

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune encephalitis with a characteristic neuropsychiatric syndrome and severe and prolonged clinical courses. In contrast, standard clinical magnetic resonance imaging (MRI) remains normal in the majority of patients. Here, we investigated structural and functional brain changes in a cohort of patients with anti-NMDAR encephalitis.

METHODS

Twenty-four patients with established diagnosis of anti-NMDAR encephalitis and age- and gender-matched controls underwent neuropsychological testing and multimodal MRI, including T1w/T2w structural imaging, analysis of resting state functional connectivity, analysis of white matter using diffusion tensor imaging, and analysis of gray matter using voxel-based morphometry.

RESULTS

Patients showed significantly reduced functional connectivity of the left and right hippocampus with the anterior default mode network. Connectivity of both hippocampi predicted memory performance in patients. Diffusion tensor imaging revealed extensive white matter changes, which were most prominent in the cingulum and which correlated with disease severity. In contrast, no differences in T1w/T2w structural imaging and gray matter morphology were observed between patients and controls.

INTERPRETATION

Anti-NMDAR encephalitis is associated with characteristic alterations of functional connectivity and widespread changes of white matter integrity despite normal findings in routine clinical MRI. These results may help to explain the clinicoradiological paradox in anti-NMDAR encephalitis and advance the pathophysiological understanding of the disease. Correlation of imaging abnormalities with disease symptoms and severity suggests that these changes play an important role in the symptomatology of anti-NMDAR encephalitis.

Prolonged Ketamine Effects in Sp4 Hypomorphic Mice: Mimicking Phenotypes of Schizophrenia

It has been well established that schizophrenia patients display impaired NMDA receptor (NMDAR) functions as well as exacerbation of symptoms in response to NMDAR antagonists. Abnormal NMDAR signaling presumably contributes to cognitive deficits which substantially contribute to functional disability in schizophrenia. Establishing a mouse genetic model will help investigate molecular mechanisms of hypoglutmatergic neurotransmission in schizophrenia. Here, we examined the responses of Sp4 hypomorphic mice to NMDAR antagonists in electroencephalography and various behavioral paradigms. Sp4 hypomorphic mice, previously reported to have reduced NMDAR1 expression and LTP deficit in hippocampal CA1, displayed increased sensitivity and prolonged responses to NMDAR antagonists. Molecular studies demonstrated reduced expression of glutamic acid decarboxylase 67 (GAD67) in both cortex and hippocampus, consistent with abnormal gamma oscillations in Sp4 hypomorphic mice. On the other hand, human SP4 gene was reported to be deleted in schizophrenia. Several human genetic studies suggested the association of SP4 gene with schizophrenia and other psychiatric disorders. Therefore, elucidation of the Sp4 molecular pathway in Sp4 hypomorphic mice may provide novel insights to our understanding of abnormal NMDAR signaling in schizophrenia.

What should you know about limbic encephalitis?

Autoimmune encephalitis is an inflammatory disorder characterized by a subacute impairment of short-term memory, psychiatric features and seizures. It is often associated with a variety of other neurological symptoms, and its differential diagnosis is wide, leading to challenges in its recognition. It used to be regarded as a rare disease, usually paraneoplastic and with poor prognosis. However, with the recent recognition of membrane-surface directed antibodies, it is now known that in a substantial proportion of cases there is no association with any malignancy and there is a good prognosis if treated. Hence, early recognition and prompt initiation of immunotherapies are of great importance.

Anti-NMDAR encephalitis: a new, severe and challenging enduring entity

Two girls, 15- and 17-year-old, were consecutively and involuntarily admitted to the local child and adolescent psychiatric hospital with severe first onset psychosis. Due to refractory agitation, ongoing psychosis and insomnia, catatonic features, autonomic instability and the need for one-on-one guidance, the first girl was transferred to the PICU of an academic tertiary hospital and anti-NMDA receptor encephalitis was diagnosed. Given this experience nursing staff suspected, due to similarities in the clinical presentation and course, anti-NMDA receptor encephalitis in the second girl also and this proved to be true. The main clinical features, pharmacological and non-pharmacological treatment strategies and outcomes are presented and discussed. Perhaps, one ought to suspect anti-NMDA receptor encephalitis in every case of severe first onset psychosis with catatonic features.

Pediatric anti-N-methyl-D-aspartate receptor encephalitis-clinical analysis and novel findings in a series of 20 patients

OBJECTIVE

To report the clinical features of 20 pediatric patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis.

STUDY DESIGN

Review of clinical data, long-term follow-up, and immunologic studies performed in a single center in Spain in the last 4 years.

RESULTS

The median age of the patients was 13 years (range, 8 months-18 years), 70% were female. In 12 patients (60%), the initial symptoms were neurologic, usually dyskinesias or seizures, and in the other 40% psychiatric. One month into the disease, all patients had involuntary movements and alterations of behavior and speech. All patients received steroids, intravenous immunoglobulin or plasma exchange, and 7 rituximab or cyclophosphamide. With a median follow up of 17.5 months, 85% had substantial recovery, 10% moderate or severe deficits, and 1 died. Three patients had previous episodes compatible with anti-NMDAR encephalitis, 2 of them with additional relapses after the diagnosis of the disorder. Ovarian teratoma was identified in 2 patients, 1 at onset of encephalitis and the other 1 year later. Two novel observations (1 patient each) include, the identification of an electroencephalographic pattern ("extreme delta brush") considered characteristic of this disorder, and the development of anti-NMDAR encephalitis as post herpes simplex encephalitis choreoathetosis.

CONCLUSIONS

The initial symptoms of pediatric anti-NMDAR encephalitis vary from those of the adults (more neurologic and less psychiatric in children), the development of a mono-symptomatic illness is extremely rare (except in relapses), and most patients respond to treatment. Our study suggests a link between post herpes simplex encephalitis choreoathetosis and anti-NMDAR encephalitis.

Anti-N-methyl-d-aspartate encephalitis with ovarian cystadenofibroma

We report the case of an adolescent girl with anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis who presented with focal seizures and hemichorea, followed by agitation, speech disturbance, mutism, and autonomic dysfunction. The institution of immunotherapy and removal of an ovarian cystadenofibroma led to full resolution of her symptoms with disappearance of serum NMDAR antibodies. This is the first report linking ovarian cystadenofibroma to anti-NMDAR encephalitis.

Anti-NMDA receptor encephalitis: a cause of acute psychosis and catatonia

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a newly described form of encephalitis associated with prominent psychiatric symptoms at onset. Recognition of the symptom complex is the key to diagnosis. Most patients with anti-NMDAR encephalitis develop a multistage illness that progresses from initial psychiatric symptoms to memory disturbance, seizures, dyskinesia, and catatonia. Psychiatric manifestations include anxiety, mania, social withdrawal, and psychosis (i.e., delusions, hallucinations, disorganized behavior). The disorder is more common in females (80%), in approximately half of whom it is associated with an underlying ovarian teratoma. Treatment involves immunosuppression, with steroids and intravenous immunoglobulin considered first line. The disorder is particularly relevant to psychiatrists, because most patients are initially seen by psychiatric services. Psychiatrists should consider anti-NMDAR encephalitis in patients presenting with psychosis as well as dyskinesia, seizures, and/or catatonia, especially if there is no history of a psychiatric disorder. We present the case of a 37-year-old woman who demonstrated many of the key clinical features of this potentially treatable disorder.

Anti-NMDA Receptor Encephalitis

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis is a severe but potentially reversible neurologic disorder that is clinically recognizable in children and adolescents. Prompt diagnosis and treatment are essential to facilitate recovery. Treatment consists of corticosteroids, intravenous immunoglobulin, or plasma exchange as first-line therapy followed by cyclophosphamide or rituximab, if necessary, as second-line immunotherapy. Patients with tumor-associated encephalitis benefit from tumor resection. More than 75% of patients make a substantial recovery, which occurs in the reverse order of symptom presentation associated with a decline in antibody titers.

Immune-mediated pediatric epilepsies

Apart from Rasmussen encephalitis, other immune-mediated brain disorders have emerged that are frequently associated with recurrent epileptic seizures: (1) limbic encephalitis, (2) anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis, and (3) steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT, formerly called Hashimoto encephalopathy). Limbic encephalitis mainly affects the mediotemporal aspect of the cortex giving rise to temporal lobe seizures and memory and affective disturbances. It can occur as a paraneoplastic or, even more frequently, a nonparaneoplastic condition. Detection of specific autoantibodies may suggest underlying cancer (onconeural antibodies) and may give hints regarding the long-term prognosis. VGKC-complex or GAD antibodies have been identified in children. Anti-NMDAR encephalitis is a disorder mainly of female adolescents and young adults. Patients present with seizures in around one-third of cases, and 80% of patients develop recurrent, mainly extratemporal seizures at some stage of their disorder. The clinical course is that of a mostly monophasic, but sometimes multiphasic, severe cortico-subcortical encephalopathy. Ovarian teratomas underlie the disorder in 30-60% of adult cases but are rare in young children. Tumor removal and early intense immunotherapy are predictors for a favorable outcome. SREAT is not a disorder with definite pathogenesis but rather a "catch all" for encephalopathic immune-mediated brain diseases (often with seizures) which have in common thyroid antibodies and a good response to steroid therapy.

Uncommon cause of psychotic behavior in a 9-year-old girl: a case report

Anti-N-methyl-D-aspartate receptors encephalitis (ANMDARE) is a well-defined, life threatening, but treatable disorder that often occurs as a paraneoplastic manifestation of ovarian teratomas in adult women. We report a child with this disorder who displayed a subacute onset of delirium, seizures, and autonomic instability. Antibodies against NMDA receptor were detectable in the serum and in the cerebrospinal fluid. No teratoma or other tumour was detected. We speculate that the previous viral/mycoplasma infection may be the trigger of this encephalitis. This patient showed a reversal of the neurological symptoms after intravenous immunoglobulin. Prompt recognition of this disorder followed by immunotherapy results in full neurological recovery.

Autoimmune encephalitis in children

The causes of encephalitis are numerous, and extensive investigations for infectious agents and other etiologies are often negative. The discovery that many of these encephalitis are immune mediated has changed the approach to the diagnosis and treatment of these disorders. Moreover, the broad spectrum of symptoms including, psychosis, catatonia, alterations of behavior and memory, seizures, abnormal movements, and autonomic dysregulation usually requires a multidisciplinary treatment approach. This review focuses in several forms of encephalitis that occur in children, and for which an autoimmune etiology has been demonstrated (eg, anti-N-methyl-d-aspartate receptor encephalitis) or is strongly suspected (eg, Rasmussen encephalitis, limbic encephalitis, opsoclonus-myoclonus). The authors also review several disorders that may be immune mediated, such as the rapid onset obesity with hypothalamic dysfunction, hypoventilation and autonomic dysregulation (ROHHAD) syndrome and some encephalopathies with fever and status epilepticus. Recognition of novel immune-mediated encephalitis is important because some of these disorders are highly responsive to immunotherapy.

Low-voltage EEG activity presenting from psychotic stage in a patient with anti-NMDA receptor encephalitis

EEG in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis shows generalised or predominantly frontotemporal δ-θ activity, and epileptiform potentials are less frequent than slowness. The voltage of EEG activity in this disorder is uncertain. We studied the voltage pattern of EEG of two patients. Both patients had psychiatric symptoms, central hypoventilation requiring prolonged ventilatory support, seizures, involuntary movements and autonomic instability. No patient showed abnormal findings on conventional MRI. Mature teratoma was diagnosed in one patient after ovarian tumour resection. Both patients received corticosteroids and intravenous immunoglobulins, and plasmapheresis. One patient recovered completely. In one patient, teratoma was not found, and ventilatory support or sedative drugs were given for about 35 months. The EEG voltages in both patients were decreased in all brain areas as compared with those of the healthy controls. Low-voltage EEG activity in all brain areas was evident from the psychotic stage.

Pathogenic and physiological autoantibodies in the central nervous system

In this article, we review the current knowledge on pathological and physiological autoantibodies directed toward structures in the central nervous system (CNS) with an emphasis on their regulation and origin. Pathological autoantibodies in the CNS that are associated with autoimmunity often lead to severe neurological deficits via inflammatory processes such as encephalitis. In some instances, however, autoantibodies function as a marker for diagnostic purposes without contributing to the pathological process and/or disease progression. The existence of naturally occurring physiological autoantibodies has been known for a long time, and their role in maintaining homeostasis is well established. Within the brain, naturally occurring autoantibodies targeting aggregated proteins have been detected and might be promising candidates for new therapeutic approaches for neurodegenerative disorders. Further evidence has demonstrated the existence of naturally occurring antibodies targeting antigens on neurons and oligodendrocytes that promote axonal outgrowth and remyelination. The numerous actions of physiological autoantibodies as well as their regulation and origin are summarized in this review.

Young girl with psychosis, cognitive failure and seizures

Psychiatric symptoms combined with neurological disturbances should always arouse suspicion that the cause may be organic. We describe a young patient whose examination revealed a recently described condition for which there are precise diagnostics and in many cases effective treatment.

[Anti-NMDA receptor encephalitis - case report]

We present a patient with multiple sclerosis, diagnosed at the age of 16.5, in whom mental and orientation disturbances, strange behaviour as well as bizarre dyskinesias of the face and extremities occurred at age 20. After several days, tonic-clonic status epilepticus developed. Head computed tomography showed no abnormalities. Lumbar puncture revealed a pleocytosis of 20/3, which became normal after treatment. Seizures were brought under control, but the psychiatric symptoms persisted; they subsided after a dozen or so weeks. Magnetic resonance of the head and cervical spinal cord did not show any new abnormalities. After another several months, all symptoms recurred. A wide range of laboratory tests, as well as positron emission tomography, did not reveal any abnormalities. Suspicion of autoimmune encephalitis led to a test for serum anti-NMDA-receptor antibodies that confirmed the diagnosis. After immunotherapy, our patient improved and was transferred for rehabilitation.

An update on diagnostic imaging studies for viral encephalitis

Viral encephalitis is still a life-threatening disease occurring at any age. It is critical to make a rapid and correct diagnosis for a better outcome of the disease. Accumulating evidence has suggested that MRI is a powerful tool for the detection of any lesion of the CNS caused by viral infections and helps to initiate the timely treatment. In this review, we summarize the current understanding of MRI findings of viral encephalitis, especially related to HSV, HIV, varicella zoster, Japanese encephalitis, John Cunningham, and influenza viruses. With these considerations, we learnt that the inclusion of diffusion-weighted image sequences on routine MRI examination would have a significant value in detecting the pathologic changes that occur following viral invasion of the CNS.