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

Anti-NMDA-receptor encephalitis: a severe, multistage, treatable disorder presenting with psychosis

Anti-NMDA-receptor encephalitis is a severe, treatable and potentially reversible disorder presenting with memory deficits, psychiatric symptoms and seizures. Initially described in young patients with ovarian teratoma, the disease is meanwhile increasingly recognized also in women without tumours, in men and in children. The presence of anti-glutamate receptor (type NMDA) autoantibodies in serum or cerebrospinal fluid is specific for this novel and widely underdiagnosed disorder. Early recognition is crucial since prognosis largely depends on adequate immunotherapy and, in paraneoplastic cases, complete tumour removal. Indirect immunofluorescence using NMDA-type glutamate receptors recombinantly expressed in human cells is a highly competent method for diagnosing anti-NMDA-receptor encephalitis.

Anti-NMDA-receptor encephalitis: an adolescent with an ovarian teratoma

BACKGROUND

Anti-N-methyl-D-aspartate (NMDA) receptor encephalitis has been reported to be associated with ovarian teratomas. In many patients, surgical excision has resulted in improvement.

CASE

A previously healthy 14-year-old girl presented with confusion which later evolved into a comatose state. Imaging revealed an adnexal mass which was surgically removed and confirmed to be a mature teratoma. Her cerebral spinal fluid was positive for antibodies to NR1/NR2 heteromers of NMDA receptors.

COMMENTS

Cystic teratomas are one of the most common benign ovarian lesions in children and young women. While an association of ovarian teratomas and paraneoplastic encephalitis is published in the neurologic literature, this association needs to be clarified for the practicing gynecologist who may be asked to consult on these patients.

[Unique clinical features and pathophysiology of anti-NMDA receptor encephalitis]

Recently a new category of treatment-responsive encephalitis has been proposed associated with antibodies against neuronal cell membrane antigens, including VGKC, NMDA receptor (NMDAR) and AMPA receptor. Anti-NMDAR encephalitis is caused by the antibodies, which bind to extracellular conformal epitope in the NR1/NR2 heteromers of the NMDAR. The antibodies are usually detected in CSF/serum of young women with ovarian teratoma (OT), who typically developed schizophrenia-like psychiatric symptoms. Most patients developed seizures, followed by unresponsive/catatonic state, central hypoventilation, and bizarre orofacial-limb dyskinesias. Based on symptomatology and current NMDAR hypofunction hypothesis in schizophrenia, we speculated that the antibodies might cause inhibition of NMDAR in presynaptic GABAergic interneurons, causing a reduction of release of GABA. This results in disinhibition of postsynaptic glutamatergic transmission, excessive release of glutamate in the prefrontal/subcortical structures, and glutamate/dopamine dysregulation. Recent studies demonstrated that the antibodies cause reversible reduction in the numbers of cell-surface NMDAR and NMDAR clusters in postsynaptic dendrites, suggesting antibodies-mediated decreased function of NMDAR. Early tumor resection with immunotherapy is recommended in OT-positive cases but not in OT-negative cases. However, exploratory laparotomy may increase the chance to identify microscopic teratoma and improve the outcome if patients who were refractory to immunotherapy had anti-NMDAR antibodies and ovarian cyst.

Cortical hypometabolism demonstrated by PET in relapsing NMDA receptor encephalitis

N-methyl-d-aspartate (NMDA) receptor encephalitis is a newly defined type of autoimmune encephalitis. Two girls (age 3 years, case 1, and 7 years, case 2) with relapsing NMDA receptor encephalitis each had the classic clinical features of encephalopathy, movement disorders, psychiatric symptoms, seizures, insomnia, and mild autonomic dysfunction. Both patients had persistent neuropsychiatric disability, despite immune therapies. Positron emission tomography (PET) scans were performed during clinical relapse at 6 weeks (case 1) and 5 months (case 2). In both cases, the scans demonstrated reduced fluorodeoxyglucose metabolism in the cerebral cortex, with the temporal regions being most affected. PET imaging was more sensitive than magnetic resonance imaging in these patients. In contrast, the one previous report of acute NMDA receptor encephalitis indicated cortical hypermetabolism. Thus, NMDA receptor encephalitis may be associated with variable PET findings, possibly dependent upon the timing of the study, or other factors. Future studies should investigate whether cortical hypometabolism is associated with a relapsing course, and whether it is predictive of a poorer outcome in NMDA receptor encephalitis.

[Differential diagnosis of encephalitis due to anti-NMDA receptor antibodies]

INTRODUCTION

Anti-NMDA receptor (NMDAR) encephalitis usually develops as a multistage syndrome with a broad differential diagnosis.

PATIENTS

We report 2 patients with anti-NMDAR encephalitis and a clinical picture typical of this disorder but whose initial evaluation suggested other aetiologies.

DISCUSSION

The frequent development of this disorder in young individuals presenting with psychiatric manifestations often suggests other diagnostic possibilities, most commonly viral encephalitis, psychiatric disorders, and neuroleptic malignant syndrome. In addition, several less clearly defined syndromes or descriptively reported disorders in adult and paediatric patients were likely cases of anti-NMDAR encephalitis.

CONCLUSIONS

Anti-NMDAR encephalitis should be considered in young individuals with subacute presentation of psychiatric symptoms, abnormal movements, and autonomic dysfunction. The clinical and immunological characterization of this disorder has lead to the identification of new antibodies that affect memory, learning, behaviour and psychosis.

Brain immunohistopathological study in a patient with anti-NMDAR encephalitis

BACKGROUND AND PURPOSE

Anti-N-methyl-D-asparate (NMDA) receptor encephalitis is thought to be antibody-mediated. To perform an immunohistopathological study of the inflammatory reaction in a brain biopsy performed before immunomodulatory treatments in a patient with anti-NMDA receptor encephalitis.

METHODS

An immunohistochemical study was performed using CD3, CD68, CD20, CD138 and CD1a antibodies.

RESULTS

Prominent B-cell cuffing was present around brain vessels accompanied by some plasma cells, while macrophages and T cells were scattered throughout the brain parenchyma.

CONCLUSION

These findings suggest that the B cells interact with the T cells and are involved in antibody secretion by the plasma cells.

[Anti-NMDA-receptor encephalitis. An interdisciplinary clinical picture]

Anti-NMDA-receptor encephalitis is a severe and considerably underdiagnosed form of encephalitis with characteristic clinical features including psychiatric symptoms, decreased levels of consciousness, hypoventilation, epileptic seizures, autonomic dysfunction and dyskinesias. Most patients are primarily seen by psychiatrists, often on the assumption of a drug-induced psychosis. Anti-NMDA-receptor encephalitis had initially been described in young women with ovarian teratoma, but is also common in women without tumour, in men and in children. The diagnosis is based on the characteristic clinical picture, supporting findings of brain MRI, electroencephalogram and cerebrospinal fluid (CSF), and the presence of highly specific autoantibodies directed against the NR1 subunit of NMDA-type glutamate receptors in the serum or CSF. In particular, anti-NMDA-receptor encephalitis must be excluded in patients with 'encephalitis of unknown cause'. In principle, the prognosis is favourable and recovery from symptoms can be expected even after prolonged intensive care treatment and mechanical ventilation. However, improvement correlates with prompt identification of the disorder, early immunotherapy and - in the case of a malignancy - with complete tumour removal. Patient care requires an interdisciplinary approach including neurologists, psychiatrists, paediatricians, oncologists and gynaecologists.

Reduced NMDAR1 expression in the Sp4 hypomorphic mouse may contribute to endophenotypes of human psychiatric disorders

The reduced expression of the Sp4 gene in Sp4 hypomorphic mice resulted in subtle vacuolization in the hippocampus as well as deficits in sensorimotor gating and contextual memory, putative endophenotypes for schizophrenia and other psychiatric disorders. In this study, we examined both spatial learning/memory and hippocampal long-term potentiation (LTP) of Sp4 hypomorphic mice. Impaired spatial learning/memory and markedly reduced LTP were found. To corroborate the functional studies, the expression of N-methyl-D-aspartate (NMDA) glutamate receptors was investigated with both western blot and immunohistochemical analyses. The reduced expression of the Sp4 gene decreased the level of the NR1 subunit of NMDA receptors in Sp4 hypomorphic mice. In human, SP4 gene was found to be deleted sporadically in schizophrenia patients, corroborating evidence that polymorphisms of human SP4 gene are associated with schizophrenia and other psychiatric disorders. Impaired NMDA neurotransmission has been implicated in several human psychiatric disorders. As yet, it remains unclear how mutations of candidate susceptibility genes for these disorders may contribute to the disruption of NMDA neurotransmission. Sp4 hypomorphic mice could therefore serve as a genetic model to investigate impaired NMDA functions resulting from loss-of-function mutations of human SP4 gene in schizophrenia and/or other psychiatric disorders. Furthermore, aberrant expression of additional genes, besides NMDAR1, likely also contributes to the behavioral abnormalities in Sp4 hypomorphic mice. Thus, further investigation of the Sp4 pathway may provide novel insights in our understanding of a variety of neuropsychiatric disorders.

Mechanisms underlying autoimmune synaptic encephalitis leading to disorders of memory, behavior and cognition: insights from molecular, cellular and synaptic studies

Recently, several novel, potentially lethal and treatment-responsive syndromes that affect hippocampal and cortical function have been shown to be associated with auto-antibodies against synaptic antigens, notably glutamate or GABA-B receptors. Patients with these auto-antibodies, sometimes associated with teratomas and other neoplasms, present with psychiatric symptoms, seizures, memory deficits and decreased levels of consciousness. These symptoms often improve dramatically after immunotherapy or tumor resection. Here we review studies of the cellular and synaptic effects of these antibodies in hippocampal neurons in vitro and preliminary work in rodent models. Our work suggests that patient antibodies lead to rapid and reversible removal of neurotransmitter receptors from synaptic sites, leading to changes in synaptic and circuit function that in turn are likely to lead to behavioral deficits. We also discuss several of the many questions raised by these and related disorders. Determining the mechanisms underlying these novel anti-neurotransmitter receptor encephalopathies will provide insights into the cellular and synaptic bases of the memory and cognitive deficits that are hallmarks of these disorders, and potentially suggest avenues for therapeutic intervention.

N-methyl-D-aspartate antibody encephalitis: temporal progression of clinical and paraclinical observations in a predominantly non-paraneoplastic disorder of both sexes

Antibodies to the N-methyl-d-aspartate subtype of glutamate receptor have been associated with a newly-described encephalopathy that has been mainly identified in young females with ovarian tumours. However, the full clinical spectrum and treatment responses are not yet clear. We established a sensitive cell-based assay for detection of N-methyl-d-aspartate receptor antibodies in serum or cerebrospinal fluid, and a quantitative fluorescent immunoprecipitation assay for serial studies. Although there was marked intrathecal synthesis of N-methyl-d-aspartate receptor antibodies, the absolute levels of N-methyl-d-aspartate receptor antibodies were higher in serum than in cerebrospinal fluid. N-methyl-d-aspartate receptor antibodies were of the immunoglobulin G1 subclass and were able to activate complement on N-methyl d-aspartate receptor-expressing human embryonic kidney cells. From questionnaires returned on 44 N-methyl-d-aspartate receptor antibody-positive patients, we identified a high proportion without a detected tumour (35/44, 80%: follow-up 3.6–121 months, median 16 months). Among the latter were 15 adult females (43%), 10 adult males (29%) and 10 children (29%), with four in the first decade of life. Overall, there was a high proportion (29%) of non-Caucasians. Good clinical outcomes, as defined by reductions in modified Rankin scores, correlated with decreased N-methyl-d-aspartate receptor antibody levels and were associated with early (<40 days) administration of immunotherapies in non-paraneoplastic patients (P < 0.0001) and earlier tumour removal in paraneoplastic patients (P = 0.02). Ten patients (23%) who were first diagnosed during relapses had no evidence of tumours but had received minimal or no immunotherapy during earlier episodes. Temporal analysis of the onset of the neurological features suggested progression through two main stages. The time of onset of the early features, characterized by neuropsychiatric symptoms and seizures preceded by a median of 10–20 days, the onset of movement disorders, reduction in consciousness and dysautonomia. This temporal dichotomy was also seen in the timing of cerebrospinal fluid, electroencephalographic and in the rather infrequent cerebral imaging changes. Overall, our data support a model in which the early features are associated with cerebrospinal fluid lymphocytosis, and the later features with appearance of oligoclonal bands. The immunological events and neuronal mechanisms underlying these observations need to be explored further, but one possibility is that the early stage represents diffusion of serum antibodies into the cortical grey matter, whereas the later stage results from secondary expansion of the immunological repertoire within the intrathecal compartment acting on subcortical neurons. Four patients, who only had temporal lobe epilepsy without oligoclonal bands, may represent restriction to the first stage.

A modern perspective on the differential diagnosis between encephalitis lethargica or anti-NMDA-receptor encephalitis

Two cases initially diagnosed as "encephalitis lethargica" are discussed. Both cases satisfied the published diagnostic criteria for encephalitis lethargica, with neuropsychiatric features including complex movement disorder, hypoventilation and altered conscious state. On later investigation N-methyl-D-aspartate receptor antibodies were detected in both cases. With the recent descriptions of tumour related antibodies to neuronal surface antigens in NMDA-receptor encephalitis, we highlight the importance of revisiting a diagnosis which may have prognostic significance.

Reversible brain atrophy in anti-NMDA receptor encephalitis: a long-term observational study

The long-term neuroimaging correlates of clinical recovery have not been described in anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. The aim of the study is to evaluate the long-term outcome of brain atrophy in anti-NMDAR encephalitis. Patients were two women (ages 17 and 33 years) with severe anti-NMDAR encephalitis resulting in decreased level of consciousness, autonomic instability, hypoventilation, and dyskinesias requiring continuous infusion of anesthetic agents for 6-7 months. Brain MRI and cerebral blood flow SPECT obtained at the time of maximal neurological disability were compared with similar studies obtained 5-7 years later. Both patients were hospitalized for 9-14 months and developed frontotemporal atrophy and hypoperfusion 7-12 months after symptom presentation. In both patients, cognitive functions gradually improved over the next 4-5 years. Comparative neuroimaging studies obtained 5-7 years after symptom presentation showed dramatic improvement of the atrophy and frontotemporal hypoperfusion. The severe and protracted deficits and the frontotemporal atrophy that occur in some patients with anti-NMDAR encephalitis are potentially reversible. This suggests that a functional rather than a structural neuronal damage underlies the pathogenesis of this disorder.

Expanding spectrum of encephalitis with NMDA receptor antibodies in young children

The authors report here 2 cases of subacute-onset encephalitis with N-methyl-D-aspartate (NMDA) receptor antibodies. One had a paraneoplastic syndrome associated with a neuroblastoma, whereas the other had no primary tumor. This disease was originally described as a paraneoplastic syndrome in young women with ovarian teratoma. The clinical features of both children resembled the typical symptoms reported for older patients with this disease: psychomotor deterioration, movement disorders, and seizures. One of the reported cases is the first known case of paraneoplastic encephalitis with NMDA antibodies in a child with neuroblastoma. Both cases described here were younger than any of the previously reported cases. Consistent with recently published series, this report suggests that the spectrum of symptoms of encephalitis with NMDA receptor antibodies is probably wider than previously thought.

Cellular and synaptic mechanisms of anti-NMDA receptor encephalitis

We recently described a severe, potentially lethal, but treatment-responsive encephalitis that associates with autoantibodies to the NMDA receptor (NMDAR) and results in behavioral symptoms similar to those obtained with models of genetic or pharmacologic attenuation of NMDAR function. Here, we demonstrate that patients' NMDAR antibodies cause a selective and reversible decrease in NMDAR surface density and synaptic localization that correlates with patients' antibody titers. The mechanism of this decrease is selective antibody-mediated capping and internalization of surface NMDARs, as Fab fragments prepared from patients' antibodies did not decrease surface receptor density, but subsequent cross-linking with anti-Fab antibodies recapitulated the decrease caused by intact patient NMDAR antibodies. Moreover, whole-cell patch-clamp recordings of miniature EPSCs in cultured rat hippocampal neurons showed that patients' antibodies specifically decreased synaptic NMDAR-mediated currents, without affecting AMPA receptor-mediated currents. In contrast to these profound effects on NMDARs, patients' antibodies did not alter the localization or expression of other glutamate receptors or synaptic proteins, number of synapses, dendritic spines, dendritic complexity, or cell survival. In addition, NMDAR density was dramatically reduced in the hippocampus of female Lewis rats infused with patients' antibodies, similar to the decrease observed in the hippocampus of autopsied patients. These studies establish the cellular mechanisms through which antibodies of patients with anti-NMDAR encephalitis cause a specific, titer-dependent, and reversible loss of NMDARs. The loss of this subtype of glutamate receptors eliminates NMDAR-mediated synaptic function, resulting in the learning, memory, and other behavioral deficits observed in patients with anti-NMDAR encephalitis.

Anti-N-methyl-D-aspartate receptor encephalitis: early treatment is beneficial

Anti-N-methyl-D-aspartate receptor antibody has been associated with a severe stereotypic form of subacute encephalitis, often found in women with ovarian teratoma. Reported here is the diagnosis of anti-N-methyl-D-aspartate receptor encephalitis in a 5-year-old girl who presented with subacute encephalopathy and movement disorder without evidence of malignancy. Early diagnosis and treatment with immune globulin and steroids resulted in near-complete recovery.

Anti-N-methyl-D-aspartate receptor antibodies: a potentially treatable cause of encephalitis in the intensive care unit

OBJECTIVE

To report the occurrence of an unusual neurologic disorder requiring admission to the intensive care unit.

DESIGN

Analysis of an observational cohort study of 31 patients with encephalitis admitted over a 4-yr period.

SETTING

Neurologic intensive care unit in a tertiary referral center.

PATIENTS

We identified N-methyl-D-aspartate receptor antibodies in six patients (two male and four female). All seropositive patients presented with a psychiatric prodrome, before developing seizures and obtundation requiring intensive care unit admission. They exhibited limb and truncal stereotypies and orofacial dyskinesias upon weaning sedation. Two patients had ovarian tumors.

INTERVENTIONS

Patients were treated with sedation, antiepileptic drugs, and immunotherapy. One patient received a magnesium infusion and ketamine.

MEASUREMENTS AND MAIN RESULTS

N-methyl-D-aspartate receptor antibodies were identified in serum samples by an immunofluorescent cell-based assay. Three patients made a good but slow recovery; two were left with severe neurologic deficits; and one died after return to the referring hospital. These patients accounted for approximately 20% of all patients admitted with encephalitis to this referral center.

CONCLUSIONS

N-methyl-D-aspartate receptor antibodies should be tested in patients with hyperkinetic encephalitis and neuropsychiatric prodrome admitted to the intensive care unit. The disorder is probably not rare and is potentially treatable.

[Anti-NMDA receptor encephalitis during pregnancy]

A 19-year-old female in her 2nd trimester (17 weeks) of pregnancy became irritable a few days before admission. She became unable to open her mouth and could not talk. She was admitted to the psychiatric hospital due to a rapid change in behavior and a consciousness disturbance. She was diagnosed as having schizophrenia by a psychiatrist. Her EEG showed diffuse high voltage and slow waves. Acute encephalitis was then suspected. Her past and family histories were not suggestive of viral infection. On physical examination, she had a low grade fever. She had hyperhidrosis, autophagia, and repeated oral dyskinesia. Her consciousness level fluctuated from somnolence to stupor. Although her blood CRP level was mildly elevated and she had mild pleocytosis, HSV-PCR was negative in the cerebrospinal fluid (CSF). Abdominal ultrasound examination and MRI showed no ovarian teratoma. Computed tomography (CT) and magnetic resonance imaging (MRI) showed no brain abnormalities. Before analysis for specific nervous system antibodies, the initial diagnosis was non-herpetic limbic encephalitis. She was twice treated with a 6-day course of methylprednisolone (500 mg/day) infusion. She was also given phenobarbital since she had a tonic-clonic seizure about 1 month after admission. Finally, she had a normal delivery at 37 weeks. The baby was healthy, and the patient was discharged without sequelae. We concluded that her diagnosis was anti-N-methyl-D-aspartate (NMDA) receptor (anti-NMDAR) encephalitis based on the presence of anti-NMDAR antibody in the CSF. This report is the first description of a patient with anti-NMDAR antibody encephalitis. The precise mechanism of this encephalitis is not clear, although there have been several reports of autoimmune encephalitis during pregnancy. The patient's CSF anti-NMDAR antibody titer during treatment was measured. Before treatment, the CSF anti-NMDAR antibody titer was strongly positive, but it decreased during treatment and then disappeared after delivery. We hypothesized that the presence of the embryo or placenta may have triggered an antigenic signal and/or antibody through inappropriate immunological modulation.

Pathophysiology of stroke-like episodes in MELAS: neuron–astrocyte uncoupling in neuronal hyperexcitability

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) is a distinct clinical syndrome characterized by fluctuated encephalopathy, migraineous headache, seizure and stroke-like episodes. The molecular mechanism of MELAS mutations has been elucidated; however, the pathogenesis of stroke-like episodes remains largely unknown. Three main hypotheses include ischemic, metabolic and neuronal hyperexcitability hypotheses. Recently, emerging hypotheses include alterations in nitric oxide homeostasis and over-reduction/oxidative stress mechanisms. Although neuron–astrocyte communication is crucial in various physiological functions, it has not been seriously considered in the pathophysiology of stroke-like episodes. This review summarizes what is known about the molecular mechanisms of gene mutation, clinico-radiological, clinico-physiological and pathological features of stroke-like episodes, as well as its pathogenesis. We finally discuss potential mechanisms involved in the pathogenesis of stroke-like episodes based on currently available clinical data and the current understanding of the mechanisms of neuron–astrocyte communications. We propose that neuron–astrocyte uncoupling is a new target of research in mitochondrial disorders.

Expression of various glutamate receptors including N-methyl-D-aspartate receptor (NMDAR) in an ovarian teratoma removed from a young woman with anti-NMDAR encephalitis

A 21-year-old woman developed psychiatric symptoms, progressive unresponsiveness, generalized seizures, severe dyskinesia, marked fluctuation of blood pressure, and hypersalivation after a flu-like episode. Anti-glutamate receptor (GluR)ε2 and anti-N-methyl-D-aspartate receptor (NMDAR) antibodies were positive in both her serum and CSF. After she recovered five months later she underwent surgery to remove a right ovarian teratoma. Immunohistochemical examinations of her teratoma disclosed abundant expression of various GluRs including NR2B subunit of NMDAR, GluR1, and GluR2/3. These immunoreactivities of GluRs were seen not only in small areas of neural tissue identified as anti-glial fibrillary acidic protein (GFAP)-immunoreactive areas but also in other large areas of undifferentiated neuroepithelial tissue without GFAP immunoreactivity. Our findings strongly support the recent idea that neural elements in ovarian teratoma play an important role in the production of antibodies to NMDARs in anti-NMDAR encephalitis. Additionally, the study of control ovaries clearly showed NR2B-related immunoreactivity in the cytoplasm of oocytes, indicating that the normal ovary itself has expression of NMDARs. This finding might provide a clue to understand the pathogenesis of this disease in female patients without ovarian teratoma.

Evidence for antibody-mediated pathogenesis in anti-NMDAR encephalitis associated with ovarian teratoma

We report the immunopathological analysis of the brain and tumor of two patients who died of anti-NMDAR-associated encephalitis, and of the tumor of nine patients who recovered. Findings included prominent microgliosis and deposits of IgG with rare inflammatory infiltrates in the hippocampus, forebrain, basal ganglia, and spinal cord. Detection of cells expressing markers of cytotoxicity (TIA, granzyme B, perforin and Fas/Fas ligand) was extremely uncommon. All tumors showed NMDAR-expressing neurons and inflammatory infiltrates. All patients’ NMDAR antibodies were IgG1, IgG2, or IgG3. No complement deposits were observed in any of the central nervous system regions examined. Overall, these findings coupled with recently reported in vitro data showing that antibodies downregulate the levels of NMDA receptors suggest that the antibody immune-response is more relevant than cytotoxic T-cell mechanisms in the pathogenesis of anti-NMDAR-associated encephalitis.

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

The California Encephalitis Project (CEP), established in 1998 to explore encephalitic etiologies, has identified patients with N-methyl-D-aspartate receptor (NMDAR) antibodies, the likely etiology of their encephalitis. This study compares the presentation of such patients to those with viral encephalitis, so that infectious disease clinicians may identify individuals with this treatable disorder. Patients were physician-referred, and standardized forms were used to gather demographic, clinical, and laboratory data. Features of anti-NMDAR+ patients were compared with the viral encephalitides of enteroviral (EV), rabies, and herpes simplex-1 (HSV-1) origins. Sixteen cases with confirmed viral etiologies were all negative on NMDAR antibody testing. Ten anti-NMDAR+ patients were profiled with a median age of 18.5 years (range 11-31 years). None were Caucasian. They had a characteristic progression with prominent psychiatric symptoms, autonomic instability, significant neurologic abnormalities, and seizures. Two had a teratoma, and, of the remaining eight, four had serologic evidence of acute Mycoplasma infection. The clinical and imaging features of anti-NMDAR+ patients served to differentiate this autoimmune disorder from HSV-1, EV, and rabies. Unlike classic paraneoplastic encephalitis, anti-NMDAR encephalitis affects younger patients and is often treatable. The association of NMDAR antibodies in patients with possible Mycoplasma pneumoniae infection warrants further study.

Acute psychiatric illness in a young woman: an unusual form of encephalitis

A 21-year-old woman was admitted to hospital with a diagnosis of acute psychotic mania, but developed, over approximately 6 weeks, seizures, delirium, catatonia, movement disorder and autonomic dysfunction. She was found to have antibodies to N-methyl-D-aspartate (NMDA) NR1-NR2 receptors in both serum and cerebrospinal fluid, consistent with anti-NMDA-receptor encephalitis, a severe, potentially lethal but treatment-responsive encephalitis often associated with ovarian tumour. With aggressive immunotherapy and bilateral oophorectomy, she recovered over a period of 14 months from her initial presentation. No ovarian tumour was identified.

Limbic encephalitis associated with systemic lupus erythematosus

A 34-year-old woman with systemic lupus erythematosus (SLE) presented with general fatigue, seizures and memory loss. Magnetic resonance imaging of the brain showed a high signal area in the mesial temporal lobe bilaterally. Computed tomography scan of the chest and abdomen and ultrasound of pelvis detected no malignancy and tumour marker, antibodies to antineuronal antibodies (anti-Hu, anti-Ta and anti-Ma) and antibodies to voltage-gated potassium channels were all negative. The present case is limbic encephalitis (LE) associated with SLE and the pathogenesis may include autoimmunity shared. Our experience indicates that the immunologic spectrum of LE will expand to include additional immune mechanisms. Lupus (2009) 18, 1316—1319.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis in children and adolescents

OBJECTIVE

To report the clinical features of anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis in patients < or = 18 years old.

METHODS

Information was obtained by the authors or referring physicians. Antibodies were determined by immunocytochemistry and enzyme-linked immunosorbent assay (ELISA) using HEK293 cells ectopically expressing NR1.

RESULTS

Over an 8-month period, 81 patients (12 male) with anti-NMDAR encephalitis were identified. Thirty-two (40%) were < or =18 years old (youngest 23 months, median 14 years); 6 were male. The frequency of ovarian teratomas was 56% in women >18 years old, 31% in girls < or =18 years old (p = 0.05), and 9% in girls < or =14 years old (p = 0.008). None of the male patients had tumors. Of 32 patients < or =18 years old, 87.5% presented with behavioral or personality change, sometimes associated with seizures and frequent sleep dysfunction; 9.5% with dyskinesias or dystonia; and 3% with speech reduction. On admission, 53% had severe speech deficits. Eventually, 77% developed seizures, 84% stereotyped movements, 86% autonomic instability, and 23% hypoventilation. Responses to immunotherapy were slow and variable. Overall, 74% had full or substantial recovery after immunotherapy or tumor removal. Neurological relapses occurred in 25%. At the last follow-up, full recovery occurred more frequently in patients who had a teratoma that was removed (5/8) than in those without a teratoma (4/23; p = 0.03).

INTERPRETATION

Anti-NMDAR encephalitis is increasingly recognized in children, comprising 40% of all cases. Younger patients are less likely to have tumors. Behavioral and speech problems, seizures, and abnormal movements are common early symptoms. The phenotype resembles that of the adults, although dysautonomia and hypoventilation are less frequent or severe in children. Ann Neurol 2009;66:11-18.

AMPA receptor antibodies in limbic encephalitis alter synaptic receptor location

OBJECTIVE

To report the clinical and immunological features of a novel autoantigen related to limbic encephalitis (LE) and the effect of patients' antibodies on neuronal cultures.

METHODS

We conducted clinical analyses of 10 patients with LE. Immunoprecipitation and mass spectrometry were used to identify the antigens. Human embryonic kidney 293 cells expressing the antigens were used in immunocytochemistry and enzyme-linked immunoabsorption assay. The effect of patients' antibodies on cultures of live rat hippocampal neurons was determined with confocal microscopy.

RESULTS

Median age was 60 (38-87) years; 9 were women. Seven had tumors of the lung, breast, or thymus. Nine patients responded to immunotherapy or oncological therapy, but neurological relapses, without tumor recurrence, were frequent and influenced the long-term outcome. One untreated patient died of LE. All patients had antibodies against neuronal cell surface antigens that by immunoprecipitation were found to be the glutamate receptor 1 (GluR1) and GluR2 subunits of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR). Human embryonic kidney 293 cells expressing GluR1/2 reacted with all patients' sera or cerebrospinal fluid, providing a diagnostic test for the disorder. Application of antibodies to cultures of neurons significantly decreased the number of GluR2-containing AMPAR clusters at synapses with a smaller decrease in overall AMPAR cluster density; these effects were reversed after antibody removal.

INTERPRETATION

Antibodies to GluR1/2 associate with LE that is often paraneoplastic, treatment responsive, and has a tendency to relapse. Our findings support an antibody-mediated pathogenesis in which patients' antibodies alter the synaptic localization and number of AMPARs.

[Clinical features and pathogenesis of anti-NMDA receptor encephalitis]

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a new category of treatment-responsive encephalitis associated with "anti-NMDAR antibodies," which bind to extracellular conformal epitope in the NR1/NR 2 heteromers of the NMDAR. The antibodies are usually detected in CSF/serum of young women with ovarian teratoma, who typically developed schizophrenia-like psychiatric symptoms, usually preceded by viral infection-like illness. Most cases developed seizures, followed by unresponsive/catatonic state, decreased level of consciousness, central hypoventilation, orofacial-limb dyskinesias, and autonomic symptoms. Brain MRI is often unremarkable. CSF reveals nonspecific changes. EEG shows diffuse delta slowing. The pathogenesis remains unknown, however this disorder is considered as an antibodies-mediated encephalitis. The prodromal "viral-like" disorder by itself or in combination with a teratoma sets off the autoimmune response. The antibodies bind to the common autoantigens expressed on the cell membrane of the neurons in the forebrain/hippocampus. Based on the current NMDAR hypofunction hypothesis of schizophrenia, we speculate that the antibodies may cause inhibition of NMDAR, rather than stimulation, in presynaptic GABAergic interneurons, causing a reduction of release of GABA. This results in disinhibition of postsynaptic glutamatergic transmission, excessive release of glutamate in the prefrontal/subcortical structures, and glutamate and dopamine dysregulation that might contribute to development of schizophrenia-like psychosis and bizarre dyskinesias.

[Limbic encephalitis and variants related to neuronal cell membrane autoantigens]

Limbic encephalitis refers to an inflammatory process involving the hippocampi. amygdala and less frequently frontobasal and insular regions. This disorder used to be considered extremely rare, invariably associated with cancer, and unresponsive to treatment. However, recent studies suggest that limbic encephalitis is more frequent than it was previously thought, and a substantial number of patients may recover. This is due in part to the development of clinical diagnostic criteria and identification of antibodies directed against two broad categories of antigens: (1) intracellular or classical paraneoplastic antigens, including Hu, Ma2, and CV2 CRMP5, among others, and (2) cell surface antigens including, voltage-gated potassium channels (VGKC), N-methyl-D-aspartate receptor (NMDAR), and others expressed in the neuropil of the hippocampus. While the disorders related to the first category of antibodies associate with cancer (lung, testis and other), prominent brain infiltrates of T-cells, and limited response to treatment, the disorders related to the second category of antibodies associate with other tumors (thymoma. teratoma, Hodgkin's lymphoma), appear to be antibody-mediated, and respond better to immunotherapy. Of particular interest in the later group is the disorder that associates with antibodies to extracellular epitopes of NR1/NR2 heteromers of the NMDA receptor. Patients with this syndrome may present as limbic encephalitis but more frequently manifest severe psychiatric symptoms, seizures, dyskinesias, autonomic instability or hypoventilation. In all, the study of these disorders provides a link between immunologic processes and neuronal events involved in memory, cognition, seizures, and neuronal degeneration.

Acquired hepatocerebral degeneration

Cirrhosis and its co-morbidities may cause a variety of neurological complications, the most common being bouts of toxic metabolic encephalopathy. A proportion of patients with chronic liver disease develop acquired hepatocerebral degeneration (AHD), a chronic progressive neurological syndrome characterized by parkinsonism, ataxia and other movement disorders. This article reviews the clinical spectrum, pathophysiology, neuroimaging features and differential diagnosis of AHD along with emerging treatment options.

The distinctive movement disorder of ovarian teratoma-associated encephalitis

The movement disorder observed in four cases of ovarian teratoma associated encephalitis is described. The illness began with neuropsychiatric symptoms and was followed by prolonged unresponsiveness, respiratory failure, and autonomic instability. The movement disorder consisted of semirhythmic repetitive bulbar and limb movements and persisted during prolonged periods of unresponsiveness, diminishing as awareness returned. The characteristics of the movement disorder differed from recognized dyskinesias. It is suggested that interruption of forebrain corticostriatal inputs by anti-N-methyl-D-aspartate (NMDA) receptor antibodies removes tonic inhibition of brainstem pattern generators releasing primitive patterns of bulbar and limb movement. Recognition of the distinctive movements should prompt a search for an ovarian teratoma since the condition is responsive to tumor resection and immunomodulation.

Nationwide survey of acute juvenile female non-herpetic encephalitis in Japan: relationship to anti-N-methyl-D-aspartate receptor encephalitis

OBJECTIVE

To study the incidence and clinical features of acute juvenile female non-herpetic encephalitis (AJFNHE) in Japan.

METHODS

A nationwide questionnaire on patients with severe non-herpetic encephalitis of unknown etiology with a prolonged clinical course or death was sent to the departments of Internal Medicine, Neurology, Pediatrics, and Emergency and Critical Care at all hospitals with 200 beds or more in Japan.

RESULTS

The recovery rate was 25% (1,279 out of 5,030 departments) and 90 patients were enrolled in this study. The annual incidence was 0.33/10(6) population. 85% of patients were female. The means and standard deviations of age at onset and hospital stay were 26+/-10 years and 180+/-228 days. As first symptoms, fever and psychosis were presented in 90%. Among the neurological symptoms, disturbance of consciousness was presented in 92%, convulsions in 65%, and involuntary movements in 55%. Respiratory failure during hospitalization was observed in 71% and required care with mechanical ventilation. The detection rate of anti-GluR epsilon2 and/or delta1 antibodies was 67% of patients. Anti-N-methyl-D-aspartate receptor NR1/NR2 antibody was detected in all four examined patients with anti-GluR epsilon2 antibody, and also detected in both of the two examined patients without anti-GluR epsilon2 antibody. As for outcome, 46% returned to work and 37% returned home, but 7% died. Associated tumors were demonstrated in 39%. All reported patients had ovarian tumors, among which teratoma was the most frequent.

CONCLUSION

A nationwide survey provided data for the annual incidence and clinical features of AJFNHE in Japan.

[Relationship between anti-NMDAR encephalitis and acute juvenile female non-herpetic encephalitis (AJFNHE)]

The relationships between AJFNHE (Kamei S: 2004) and anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis (Dalmau J et al: 2007) is discussed. The comparative clinical features in both reports revealed that most were young adult women, a prodrome was presented in 80%, the first neurological symptom was psychosis, the main symptoms included convulsions, consciousness disturbance, and involuntary movements, and mechanical ventilation was required in 80%. Dalmau reported that ovarian teratoma was demonstrated in 11 out of 12 patients, and mediastinal teratoma in 1 patient. We had yet to examine these conditions at the time of publication. AJFNHE and anti-NMDAR encephalitis are thus considered to be the same condition. AJFNHE represents a clinical concept based on the specific clinical features, and anti-NMDAR encephalitis represents a clinical entity based on the neuro-oncological findings. A nationwide survey of AJFNHE was undertaken in Japan. Collected patients predominantly were young adult women. Their clinical features were uniform and also in concordance with those previously reported as AJFNHE. This survey revealed that the annual incidence was 0.33/10(6) population, respiratory failure was observed in 70% and required care with mechanical ventilation, associated tumors were demonstrated in 40% and ovarian teratoma was the most frequent.

[Anti-NMDAR encephalopathy: treatment]

Anti-NMDAR encephalopathy is included in paraneoplastic limbic encephalopathy and show the good response to treatment compared to other paraneoplastic syndromes. Treatment of anti-NMDAR encephalopathy includes immunotherapy and/or tumor removal. About 65% of patients with anti-NMDAR encephalopathy had fully or near-full recovery. Immunotherapy is principally necessary and effective in patients with and without tumor. Corticosteroids and intravenous immunoglobulin are most frequently used. It is likely that patients who do not respond to one form of immunotherapy might respond to others regimens including plasmapheresis, cyclophosphamide, and rituximab. A tumor was found in 58% of patients with anti-NMDAR encephalopathy. Early removal of tumor should be considered based on following reasons. First, patients with ovarian teratoma showed higher mortality and higher titer of anti-NMDAR antibody compared with those without. Second, relapsing neurological symptoms occurred in 13% of patients, usually related to a delay in tumor diagnosis. Third, when a tumor was found and removed, recovery was faster and predictable. However, early removal of tumor cannot be conducted because of unstable conditions such as hypoventilation and dyskinesias. In supportive cares, severe central hypoventilation requires mechanical ventilation. The involuntary movements and facial dyskinesias are refractory to anti-epileptic drugs. In conclusion, search for and removal of an ovarian teratoma should be promptly considered after the diagnosis of anti-NMDAR encephalopathy.

Anti-NMDA-receptor encephalitis: case series and analysis of the effects of antibodies

BACKGROUND

A severe form of encephalitis associated with antibodies against NR1-NR2 heteromers of the NMDA receptor was recently identified. We aimed to analyse the clinical and immunological features of patients with the disorder and examine the effects of antibodies against NMDA receptors in neuronal cultures.

METHODS

We describe the clinical characteristics of 100 patients with encephalitis and NR1-NR2 antibodies. HEK293 cells ectopically expressing single or assembled NR1-NR2 subunits were used to determine the epitope targeted by the antibodies. Antibody titres were measured with ELISA. The effect of antibodies on neuronal cultures was determined by quantitative analysis of NMDA-receptor clusters.

FINDINGS

Median age of patients was 23 years (range 5-76 years); 91 were women. All patients presented with psychiatric symptoms or memory problems; 76 had seizures, 88 unresponsiveness (decreased consciousness), 86 dyskinesias, 69 autonomic instability, and 66 hypoventilation. 58 (59%) of 98 patients for whom results of oncological assessments were available had tumours, most commonly ovarian teratoma. Patients who received early tumour treatment (usually with immunotherapy) had better outcome (p=0.004) and fewer neurological relapses (p=0.009) than the rest of the patients. 75 patients recovered or had mild deficits and 25 had severe deficits or died. Improvement was associated with a decrease of serum antibody titres. The main epitope targeted by the antibodies is in the extracellular N-terminal domain of the NR1 subunit. Patients' antibodies decreased the numbers of cell-surface NMDA receptors and NMDA-receptor clusters in postsynaptic dendrites, an effect that could be reversed by antibody removal.

INTERPRETATION

A well-defined set of clinical characteristics are associated with anti-NMDA-receptor encephalitis. The pathogenesis of the disorder seems to be mediated by antibodies.

Psychosis associated with anti-N-methyl-D-aspartate receptor antibodies

We describe the eighth case study of a female diagnosed with anti-N-methyl-D-aspartate receptor encephalitis without an identified tumor who presented with floridly psychotic symptoms following a 2-week prodromal phase with new-onset headaches and presyncopal episodes. While hospitalized, the patient had seizures, autonomic dysfunction, involuntary movements, and a decline in mental status. A subsequent assay was positive for anti-N-methyl-D-aspartate receptor receptor antibodies. In contrast to most reported cases, an initial trial with corticosteroids was therapeutically unsuccessful. Subsequent treatment with intravenous immunoglobulins, however, resulted in a prompt, robust clinical response and enabled the patient to be rapidly discharged from the hospital, with minimal neuropsychiatric sequelae.