Neuronal autoantigens--pathogenesis, associated disorders and antibody testing

Characterisation of a syndrome of autoimmune adult onset focal epilepsy and encephalitis

We report a series of patients with a clinical syndrome characterised by the explosive onset in adulthood of recurrent focal seizures of frontotemporal onset and features suggestive of autoimmune encephalitis. We propose that this presentation of "autoimmune adult onset focal epilepsy and encephalitis" is a recognisable clinical syndrome, and provide evidence it may be associated with heterogeneous immunological targets. Between 2008 and 2011 we encountered six patients with new-onset epilepsy in whom we suspected an autoimmune aetiology. We first characterised the clinical, electroencephalographic, cerebrospinal fluid (CSF), imaging, and pathological findings of this syndrome. We subsequently tested them for antibodies against both intracellular and neuronal cell surface antigens. All patients presented with recurrent seizures with focal frontotemporal onset, refractory to multiple anticonvulsants. Four had focal T2-weighted hyperintensities on MRI. CSF mononuclear cells were variably elevated with positive oligoclonal bands in four. Brain biopsy in one patient demonstrated perivascular lymphocytic infiltration. Two were treated with immunosuppression and went on to achieve complete seizure control and return to baseline cognition. Three of four patients who received only pulsed steroids or no treatment had ongoing frequent seizures, with two dying of sudden unexpected death in epilepsy. Subsequently, three had antibodies identified against neuronal cell surface antigens including N-methyl-D-aspartate receptor and leucine-rich glioma inactivated 1. We suggest that patients with such a presentation should be carefully evaluated for a suspected autoimmune aetiology targeting cell surface antigens and have a therapeutic trial of immunosuppression as this may improve their long-term outcome.

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.

Autoimmunity, seizures, and status epilepticus

The recent discovery of a category of autoimmune encephalitis associated with antibodies against neuronal cell-surface and synaptic proteins has renewed interest for autoimmune causes of epilepsy. The identification of autoimmune encephalitis has changed paradigms in the diagnosis and management of several novel and treatable syndromes that occur with seizures and status epilepticus previously attributed to viral or idiopathic etiologies. This review focuses on the novel group of autoimmune encephalitis and also discusses some classical paraneoplastic syndromes that constitute another group of autoimmune disorders that may result in seizures.

[Autoantibody diagnostics in neurology using native and recombinant antigenic substrates]

Modern diagnostics for the determination of neurologically relevant autoantibodies are based on indirect immunofluorescence using tissue sections of the hippocampus, cerebellum and other tissues. For monospecific detection human embryonic kidney (HEK) cells transfected with different neurological antigens are used. Biochip mosaics are designed to give a quick overview and contain 20 or more substances positioned next to each other on a reaction field, which are incubated with the serum or cerebrospinal fluid (CSF) sample. Western blots based on cerebellum or hippocampus extracts or line blots containing defined recombinant antigens are used additionally. Initial investigations should always comprise the parallel analysis of all major antineural autoantibodies instead of performing only single parameter tests. Up until a few years ago autoantibodies against intracellular neuronal antigens were mainly investigated. Antibodies against structures of the neural cell surface, however, are much more frequently found, especially those against glutamate receptors (type NMDA).

An optimized immunohistochemistry technique improves NMO-IgG detection: study comparison with cell-based assays

Cell-based assays (CBA) have increased the sensitivity of the neuromyelitis optica (NMO)-IgG/aquaporin-4-antibody detection compared to classical tissue-based indirect assays. We describe the sensitivity of an optimized immunohistochemistry (IHC-o) to detect NMO-IgG/aquaporin-4-antibody in comparison with that of two CBA: an in-house (CBA-ih) and a commercial (CBA-c) assay (Euroimmun, Germany). Coded serum from 103 patients with definite NMO and 122 inflammatory controls were studied by IHC-o, CBA-ih, and CBA-c. IHC-o used the same protocol described to detect antibodies against cell surface antigens. CBA-ih used live cells transfected with the aquaporin-4-M23-isoform. The sensitivity of the IHC-o was 74.8% (95% confidence interval [CI] 65-83) and was similar to that of the CBA-ih 75.7% (95% CI 66-84) and the CBA-c 73.8% (95% CI 64-82). The specificity of the three assays was 100% (95% CI 97-100). Interassay concordance was high, 100 of 103 samples were coincident in all techniques. The optimized immunohistochemistry proves to be as sensitive and specific as the cell-based assays. This assay extends the available tools for NMO-IgG/aquaporin-4-antibody detection.

Non-length-dependent and length-dependent small-fiber neuropathies associated with tumor necrosis factor (TNF)-inhibitor therapy in patients with rheumatoid arthritis: expanding the spectrum of neurological disease associated with TNF-inhibitors

OBJECTIVE

Small-fiber neuropathy causes severe burning pain, requires diagnostic approaches such as skin biopsy, and encompasses two subtypes based on distribution of neuropathic pain. Such biopsy-proven subtypes of small-fiber neuropathies have not been previously described as complications of tumor necrosis factor (TNF)-inhibitor therapy.

METHODS

We therefore characterized clinical and skin biopsy findings in three rheumatoid arthritis (RA) patients who developed small-fiber neuropathies associated with TNF-inhibitors. We also conducted a systematic review of the literature to characterize subtypes of neuropathies previously reported in association with TNF-inhibitor therapy.

RESULTS

Two patients presented with a "non-length-dependent" small-fiber neuropathy, experiencing unorthodox patterns of burning pain affecting the face, torso, and proximal extremities. Abnormal skin biopsy findings were limited to the proximal thigh, which is a marker of proximal-most dorsal root ganglia degeneration. In contrast, one patient presented with a "length-dependent" small-fiber neuropathy, experiencing burning pain only in the feet. Abnormal skin biopsy findings were limited to the distal feet, which is a marker of distal-most axonal degeneration. One patient developed a small-fiber neuropathy in the context of TNF-inhibitor-induced lupus. In all patients, neuropathies occurred during TNF-inhibitor-induced remission of RA disease activity and improved on withdrawal of TNF-inhibitors.

CONCLUSIONS

We describe a spectrum of small-fiber neuropathies not previously reported in association with TNF-inhibitor therapy, with clinical and skin biopsy findings suggestive of dorsal root ganglia as well as axonal degeneration. The development of small-fiber neuropathies during inactive joint disease and improvement of neuropathic pain upon withdrawal of TNF-inhibitor suggest a causative role of TNF-inhibitors.

A novel autoantibody against ephrin type B receptor 2 in acute necrotizing encephalopathy

Acute necrotizing encephalopathy (ANE) is characterized by symmetrical brain necrosis, suggested to be due to breakdown of the blood–brain barrier (BBB). We experienced a rare case of ANE complicated with systemic lupus erythematosus (SLE), and found that the patient’s serum (V10-5) had binding activity to human umbilical vein endothelial cells (HUVECs). By SARF (Serological identification system for Autoantigens using a Retroviral vector and Flow cytometry) method using V10-5 IgG, a clone bound to V10-5 IgG was isolated. This cell clone was integrated with cDNA identical to EphB2, which plays critical roles in neuronal cells and endothelial cells. HUVECs and human brain microvascular endothelial cells expressed EphB2 and the V10-5 IgG bound specifically to EphB2-transfected cells. Anti-EphB2 antibody was not detected in other SLE patients without ANE. In this report, we identified EphB2 as a novel autoantigen, and anti-EphB2 antibody may define a novel group of brain disorders. Anti-EphB2 antibody can interfere not only with endothelial cells including those of the BBB (acting as an anti-endothelial cell antibody), but also neuronal cells (acting as an anti-neuronal antibody) if the BBB has been breached. Future studies should determine the clinical prevalence and specificity of anti-EphB2 antibody, and the molecular mechanisms by which anti-EphB2 antibody mediates neuronal and vascular pathological lesions.

VGKC-complex/LGI1-antibody encephalitis: clinical manifestations and response to immunotherapy

Leucine-rich glioma inactivated 1 (LGI1) was recently identified as a target protein in autoimmune synaptic encephalitis, a rare condition associated with autoantibodies against structures in the neuronal synapse. Studies dealing with LGI1 are small in number and the various outcomes of different therapeutic regimens are not well studied. Here, we analyzed clinical characteristics of 14 patients with LGI1 antibodies, and outcomes according to therapeutic strategies. Most patients exhibited abnormal brain positron emission tomography and that patients treated with steroids alone were more likely to relapse and had less favorable outcomes than those treated with steroids and intravenous immunoglobulins.

Encephalitis and GABAB receptor antibodies: novel findings in a new case series of 20 patients

OBJECTIVE

To report the clinical features of 20 newly diagnosed patients with GABAB receptor (GABABR) antibodies and determine the frequency of associated tumors and concurrent neuronal autoantibodies.

METHODS

Clinical data were retrospectively obtained and evaluated. Serum and CSF samples were examined for additional antibodies using methods previously reported.

RESULTS

Seventeen patients presented with seizures, memory loss, and confusion, compatible with limbic encephalitis (LE), one patient presented with ataxia, one patient presented with status epilepticus, and one patient presented with opsoclonus-myoclonus syndrome (OMS). Nineteen (95%) patients eventually developed LE during the course of the disease. Small-cell lung cancer (SCLC) was identified in 10 (50%) patients, all with LE. Treatment and outcome was available from 19 patients: 15 showed complete (n = 7) or partial (n = 8) neurologic improvement after steroids, IV immunoglobulins, or plasma exchange and oncologic treatment when indicated; 1 patient died of tumor progression shortly after the first cycle of immunotherapy, and 3 were not treated. Five patients with SCLC had additional onconeuronal antibodies (Ri, amphiphysin, or SOX1), and 2 without tumor had GAD65 and NMDAR antibodies, respectively. GABABR antibodies were not detected in serum of 116 patients with SCLC without neurologic symptoms.

CONCLUSION

Our study confirms GABABR as an autoantigen of paraneoplastic and nonparaneoplastic LE and expands the phenotype of GABABR antibodies to ataxia, OMS, and status epilepticus. The long-term prognosis is dictated by the presence of a tumor. Recognition of syndromes associated with GABABR antibodies is important because they usually respond to treatment.

Priorities in pediatric epilepsy research: improving children's futures today

The Priorities in Pediatric Epilepsy Research workshop was held in the spirit of patient-centered and patient-driven mandates for developing best practices in care, particularly for epilepsy beginning under age 3 years. The workshop brought together parents, representatives of voluntary advocacy organizations, physicians, allied health professionals, researchers, and administrators to identify priority areas for pediatric epilepsy care and research including implementation and testing of interventions designed to improve care processes and outcomes. Priorities highlighted were 1) patient outcomes, especially seizure control but also behavioral, academic, and social functioning; 2) early and accurate diagnosis and optimal treatment; 3) role and involvement of parents (communication and shared decision-making); and 4) integration of school and community organizations with epilepsy care delivery. Key factors influencing pediatric epilepsy care included the child's impairments and seizure presentation, parents, providers, the health care system, and community systems. Care was represented as a sequential process from initial onset of seizures to referral for comprehensive evaluation when needed. We considered an alternative model in which comprehensive care would be utilized from onset, proactively, rather than reactively after pharmacoresistance became obvious. Barriers, including limited levels of evidence about many aspects of diagnosis and management, access to care--particularly epilepsy specialty and behavioral health care--and implementation, were identified. Progress hinges on coordinated research efforts that systematically address gaps in knowledge and overcoming barriers to access and implementation. The stakes are considerable, and the potential benefits for reduced burden of refractory epilepsy and lifelong disabilities may be enormous.

Autoimmune status epilepticus

OPINION STATEMENT

Autoimmune status epilepticus is a rare condition but one that has been increasingly recognized by neurologists and clinicians in the intensive care unit. As more cases are described in the literature and more antibody tests become commercially available, diagnosis is now feasible; however, early diagnosis remains a challenge. For practical purposes, status epilepticus may be considered as possibly autoimmune if it is refractory to anticonvulsant treatment and there is no other known cause; this may then lead to empiric immunomodulatory therapy. Major factors that raise the index of suspicion are recent cognitive or behavioral alterations, a history of malignancy or tumor, or presence of other neurological features. There is a lack of high level evidence in the literature for treatment of status epilepticus, and almost none for autoimmune encephalitis. Patients with autoimmune status epilepticus may be treated with immunomodulatory therapy, including steroids, intravenous immunoglobulin (IVIG), plasmapheresis (PLEX), and other immunosuppressive agents while maximizing their anticonvulsant therapy. For some patients, resective surgery may be necessary, such as hemispherectomy for Rasmussen's encephalopathy. In the case of status epilepticus due to paraneoplastic autoantibodies, urgent and aggressive testing and treatment of a primary malignancy is needed. Importantly, any suspicion of autoimmune mediated status epilepticus should prompt the transfer of the patient to a specialized center with experience in refractory status epilepticus whenever possible.

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.

N-methyl-D-aspartate receptor antibodies in post-herpes simplex virus encephalitis neurological relapse

Herpes simplex virus encephalitis (HSVE) is a devastating condition that relapses, often with a chorea in children, despite adequate antiviral treatment. At relapse, evidence of viral replication is frequently absent, suggesting that the relapse may be immune-mediated. Seven children who had a neurological relapse following their initial encephalitis, identified from 20 cases of pediatric HSVE, were studied. Serum and/or cerebrospinal fluid (CSF) were tested for N-methyl-D-aspartate receptor (NMDAR) and other antibodies previously reported in central nervous system autoimmunity. Five of the 7 relapsing children had choreoathetosis; 2 of these were NMDAR antibody-positive, 2 were negative (1 with HSV-positive CSF), and 1 was not available for testing. An additional patient, who relapsed with cognitive regression but with no movement disorder, was also NMDAR antibody-positive. In 2 of the NMDAR antibody-positive patients who were treated at relapse and in 1 who was treated only after 10 years of having a relapsing encephalopathy, a beneficial response was observed. Neurological relapses after HSVE may frequently be immune-mediated, particularly in children with chorea. NMDAR antibodies are common, and immunotherapy may be beneficial.

Distinction and temporal stability of conformational epitopes on myelin oligodendrocyte glycoprotein recognized by patients with different inflammatory central nervous system diseases

Autoantibodies targeting conformationally intact myelin oligodendrocyte glycoprotein (MOG) are found in different inflammatory diseases of the CNS, but their antigenic epitopes have not been mapped. We expressed mutants of MOG on human HeLa cells and analyzed sera from 111 patients (104 children, 7 adults) who recognized cell-bound human MOG, but had different diseases, including acute disseminated encephalomyelitis (ADEM), one episode of transverse myelitis or optic neuritis, multiple sclerosis (MS), anti-aquaporin-4 (AQP4)-negative neuromyelitis optica (NMO), and chronic relapsing inflammatory optic neuritis (CRION). We obtained insight into the recognition of epitopes in 98 patients. All epitopes identified were located at loops connecting the β strands of MOG. The most frequently recognized MOG epitope was revealed by the P42S mutation positioned in the CC'-loop. Overall, we distinguished seven epitope patterns, including the one mainly recognized by mouse mAbs. In half of the patients, the anti-MOG response was directed to a single epitope. The epitope specificity was not linked to certain disease entities. Longitudinal analysis of 11 patients for up to 5 y indicated constant epitope recognition without evidence for intramolecular epitope spreading. Patients who rapidly lost their anti-MOG IgG still generated a long-lasting IgG response to vaccines, indicating that their loss of anti-MOG reactivity did not reflect a general lack of capacity for long-standing IgG responses. The majority of human anti-MOG Abs did not recognize rodent MOG, which has implications for animal studies. Our findings might assist in future detection of potential mimotopes and pave the way to Ag-specific depletion.

Autoantibodies and the immune hypothesis in psychotic brain diseases: challenges and perspectives

The pathophysiology of psychosis is poorly understood, with both the cognitive and cellular changes of the disease process remaining mysterious. There is a growing body of evidence that points to dysfunction of the immune system in a subgroup of patients with psychosis. Recently, autoantibodies directed against neuronal cell surface targets have been identified in a range of syndromes that feature psychosis. Of interest is the detection of autoantibodies in patients whose presentations are purely psychiatric, such as those suffering from schizophrenia. Autoantibodies have been identified in a minority of patients, suggesting that antibody-associated mechanisms of psychiatric disease likely only account for a subgroup of cases. Recent work has been based on the application of cell-based assays-a paradigm whose strength lies in the expression of putative antigens in their natural conformation on the surface of live cells. The responsiveness of some of these newly described clinical syndromes to immune therapy supports the hypothesis that antibody-associated mechanisms play a role in the pathogenesis of psychotic disease. However, further investigation is required to establish the scope and significance of antibody pathology in psychosis. The identification of a subgroup of patients with antibody-mediated disease would promise more effective approaches to the treatment of these high-morbidity conditions.

Intracellular and circulating neuronal antinuclear antibodies in human epilepsy

There are overwhelming data supporting the inflammatory origin of some epilepsies (e.g., Rasmussen's encephalitis and limbic encephalitis). Inflammatory epilepsies with an autoimmune component are characterized by autoantibodies against membrane-bound, intracellular or secreted proteins (e.g., voltage gated potassium channels). Comparably, little is known regarding autoantibodies targeting nuclear antigen. We tested the hypothesis that in addition to known epilepsy-related autoantigens, the human brain tissue and serum from patients with epilepsy contain autoantibodies recognizing nuclear targets. We also determined the specific nuclear proteins acting as autoantigen in patients with epilepsy. Brain tissue samples were obtained from patients undergoing brain resections to treat refractory seizures, from the brain with arteriovenous malformations or from post-mortem multiple sclerosis brain. Patients with epilepsy had no known history of autoimmune disease and were not diagnosed with autoimmune epilepsy. Tissue was processed for immunohistochemical staining. We also obtained subcellular fractions to extract intracellular IgGs. After separating nuclear antibody-antigen complexes, the purified autoantigen was analyzed by mass spectrometry. Western blots using autoantigen or total histones were probed to detect the presence of antinuclear antibodies in the serum of patients with epilepsy. Additionally, HEp-2 assays and antinuclear antibody ELISA were used to detect the staining pattern and specific presence of antinuclear antibodies in the serum of patients with epilepsy. Brain regions from patients with epilepsy characterized by blood-brain barrier disruption (visualized by extravasated albumin) contained extravasated IgGs. Intracellular antibodies were found in epilepsy (n=13/13) but not in multiple sclerosis brain (n=4/4). In the brain from patients with epilepsy, neurons displayed higher levels of nuclear IgGs compared to glia. IgG colocalized with extravasated albumin. All subcellular fractions from brain resections of patients with epilepsy contained extravasated IgGs (n=10/10), but epileptogenic cortex, where seizures originated from, displayed the highest levels of chromatin-bound IgGs. In the nuclear IgG pool, anti-histone autoantibodies were identified by two independent immunodetection methods. HEp-2 assay and ELISA confirmed the presence of anti-histone (n=5/8) and anti-chromatin antibodies in the serum from patients with epilepsy. We developed a multi-step approach to unmask autoantigens in the brain and sera of patients with epilepsy. This approach revealed antigen-bound antinuclear antibodies in neurons and free antinuclear IgGs in the serum of patients with epilepsy. Conditions with blood-brain barrier disruption but not seizures, were characterized by extravasated but not chromatin-bound IgGs. Our results show that the pool of intracellular IgG in the brain of patients with epilepsy consists of nucleus-specific autoantibodies targeting chromatin and histones. Seizures may be the trigger of neuronal uptake of antinuclear antibodies.

Developing therapeutic antibodies for neurodegenerative disease

The central nervous system has been considered off-limits to antibody therapeutics. However, recent advances in preclinical and clinical drug development suggest that antibodies can cross the blood-brain barrier in limited quantities and act centrally to mediate their effects. In particular, immunotherapy for Alzheimer's disease has shown that targeting beta amyloid with antibodies can reduce pathology in both mouse models and the human brain, with strong evidence supporting a central mechanism of action. These findings have fueled substantial efforts to raise antibodies against other central nervous system targets, particularly neurodegenerative targets, such as tau, beta-secretase, and alpha-synuclein. Nevertheless, it is also apparent that antibody penetration across the blood-brain barrier is limited, with an estimated 0.1-0.2 % of circulating antibodies found in brain at steady-state concentrations. Thus, technologies designed to improve antibody uptake in brain are receiving increased attention and are likely going to represent the future of antibody therapy for neurologic diseases, if proven safe and effective. Herein we review briefly the progress and limitations of traditional antibody drug development for neurodegenerative diseases, with a focus on passive immunotherapy. We also take a more in-depth look at new technologies for improved delivery of antibodies to the brain.

Advances in pediatric neurocritical care

Because pediatric intensive care units (PICUs) improve survival for a range of acute diseases, attention has turned toward ensuring the best possible functional outcomes after critical illness. The neurocritical care of children is of increasing interest. However, the pediatric population encompasses a heterogeneous set of neurologic conditions, with several possible models of how best to address them. This article reviews the special challenges faced by PICUs with regards to diseases, technologies, and skills and the progress that has been made in treatment, monitoring, and prognostication. Recent advances in translational research expected to modify the field in the near-term are described.

The 2010 revised classification of seizures and epilepsy

PURPOSE OF REVIEW

Classifications of epilepsies (1989) and seizures (1981) took a central role in epilepsy care and research. Based on nearly century-old concepts, they were abandoned in 2010, and recommendations for new concepts and terminology were made in accordance with a vision of what a future classification would entail. This review outlines the major changes, the ways these changes relate to the earlier systems, the implications for the practicing health care provider, and some of the recommendations for future classification systems.

RECENT FINDINGS

New terminology for underlying causes (genetic, structural-metabolic, and unknown) was introduced to replace the old (idiopathic, symptomatic, and cryptogenic) in 2010. The use of generalized and focal to refer to the underlying epilepsy was largely abandoned, but the terms were retained in reference to mode of seizure initiation and presentation. The terms "complex" and "simple partial" for focal seizures were abandoned in favor of more descriptive terms. Electroclinical syndromes were highlighted as specific epilepsy diagnoses and distinguished from nonsyndromic-nonspecific diagnoses. The importance of diagnosis (a clinical goal focused on the individual patient) over classification (an intellectual system for organizing information) was emphasized.

SUMMARY

Accurate description and diagnosis of the seizures, causes, and specific type of epilepsy remain the goal in clinical epilepsy care. While terminology and concepts are being revised, the implications for patient care currently are minimal; however, the gains in the future of clear, accurate terminology and a multidomain classification system could potentially be considerable.

Psychiatric phenomena as initial manifestation of encephalitis by anti-NMDAR antibodies

OBJECTIVE

Autoimmune encephalitis associated with autoantibodies against the N-methyl-d-aspartate receptor (NMDAR) often presents with behavioural change. Our objective was to describe in detail the psychiatric presentation and pathways to care in order to aid the early diagnosis of NMDAR encephalitis.

METHODS

Sera and cerebrospinal fluid (CSF) from patients with suspected NMDAR encephalitis were tested on HEK 293 cells transfected with the NR1 subunit of the NMDAR. Clinical information was obtained from the referring psychiatrists and neurologists and by review of the clinical records.

RESULTS

Samples from 15 patients (13 female, 2 male, mean age 24 years, range 5-56 years) tested anti-NMDAR positive. Twelve of the 15 patients (80%) presented with prominent psychiatric symptoms and 8 were initially referred to a psychiatric service. The most prominent initial psychiatric symptoms were anxiety in seven (47%), behavioural change (often bizarre) in six (40%) and agitation in five (33%). All patients developed psychiatric symptoms in the first 6 weeks of illness. Thirteen patients received psychotropic medications: antipsychotics in 12 and benzodiazepines in 11. Treating physicians considered the psychotropic medication not effective in 11 patients resulting in many drug switches. At nadir, all patients were in a very poor condition. However, eight patients (53%) recovered (almost) completely. Outcome tended to be better in patients who had received early immunotherapy or tumour removal.

CONCLUSIONS

Autoimmune encephalitis and anti-NMDAR testing in serum and CSF should be considered in patients, especially young females, presenting with atypical psychiatric phenomena. Early diagnosis and treatment will likely improve the prognosis of NMDAR encephalitis.

Paraneoplastic neurological syndromes: general treatment overview

OPINION STATEMENT

Major recent discoveries have bringing out a revised definition of paraneoplastic neurological syndromes (PNS), bringing out the concept of antibody-mediated neurological disorders, triggered or not by cancer. Classification of these diseases is not based anymore on the clinical pattern or an underlying tumor, but on the location of the targeted antigens. Indeed, evolution, response to treatment, and pathophysiology are radically different according to the associated antibodies. In some patients with newly described antibodies targeting cell-surface antigens, humoral immunity seems to play a direct role and a dramatic improvement is observed with immunomodulator treatments. In these patients, an associated tumor is less frequent. Conversely, patients with antibodies directed against intracellular targets are, in most cases, characterized by a high degree of irreversible neuronal death mediated by cytotoxic T-cells and do not improve after immunomodulator treatments. In these patients, an associated tumor is highly frequent and must be cured as soon as possible. A third group of patients can be identified with anti-GAD65 and anti-Amphiphysin antibodies. In patients with these antibodies, the efficiency of immunomodulator treatments is less clear as well as the type of immune response that could be a mix between humoral and cellular. In this last group, the antigen is intracellular, but patients may improve with immunomodulator treatments and associated tumors are rare. Thus, identification of associated antibodies should be prompt and the treatment guided according the identified antibody. Mainstream of treatment include the quest of a tumor and its cure. Immunotherapy must be promptly initiated, targeting humoral, or cellular immune response, or both, according to the associated antibodies. Furthermore, in some situations such as Lambert-Eaton Myasthenic Syndromes and Stiff-Person Syndromes, symptomatic drugs can be useful to control the symptoms.

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.

Treatment and prognostic factors for long-term outcome in patients with anti-NMDA receptor encephalitis: an observational cohort study

BACKGROUND

Anti-NMDA receptor (NMDAR) encephalitis is an autoimmune disorder in which the use of immunotherapy and the long-term outcome have not been defined. We aimed to assess the presentation of the disease, the spectrum of symptoms, immunotherapies used, timing of improvement, and long-term outcome.

METHODS

In this multi-institutional observational study, we tested for the presence of NMDAR antibodies in serum or CSF samples of patients with encephalitis between Jan 1, 2007, and Jan 1, 2012. All patients who tested positive for NMDAR antibodies were included in the study; patients were assessed at symptom onset and at months 4, 8, 12, 18, and 24, by use of the modified Rankin scale (mRS). Treatment included first-line immunotherapy (steroids, intravenous immunoglobulin, plasmapheresis), second-line immunotherapy (rituximab, cyclophosphamide), and tumour removal. Predictors of outcome were determined at the Universities of Pennsylvania (PA, USA) and Barcelona (Spain) by use of a generalised linear mixed model with binary distribution.

RESULTS

We enrolled 577 patients (median age 21 years, range 8 months to 85 years), 211 of whom were children (<18 years). Treatment effects and outcome were assessable in 501 (median follow-up 24 months, range 4-186): 472 (94%) underwent first-line immunotherapy or tumour removal, resulting in improvement within 4 weeks in 251 (53%). Of 221 patients who did not improve with first-line treatment, 125 (57%) received second-line immunotherapy that resulted in a better outcome (mRS 0-2) than those who did not (odds ratio [OR] 2·69, CI 1·24-5·80; p=0·012). During the first 24 months, 394 of 501 patients achieved a good outcome (mRS 0-2; median 6 months, IQR 2-12) and 30 died. At 24 months' follow-up, 203 (81%) of 252 patients had good outcome. Outcomes continued to improve for up to 18 months after symptom onset. Predictors of good outcome were early treatment (0·62, 0·50-0·76; p<0·0001) and no admission to an intensive care unit (0·12, 0·06-0·22; p<0·0001). 45 patients had one or multiple relapses (representing a 12% risk within 2 years); 46 (67%) of 69 relapses were less severe than initial episodes (p<0·0001). In 177 children, predictors of good outcome and the magnitude of effect of second-line immunotherapy were similar to those of the entire cohort.

INTERPRETATION

Most patients with anti-NMDAR encephalitis respond to immunotherapy. Second-line immunotherapy is usually effective when first-line treatments fail. In this cohort, the recovery of some patients took up to 18 months.

FUNDING

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

Antibodies to contactin-1 in chronic inflammatory demyelinating polyneuropathy

OBJECTIVE

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a frequent autoimmune neuropathy with a heterogeneous clinical spectrum. Clinical and experimental evidence suggests that autoantibodies may be involved in its pathogenesis, but the target antigens are unknown. Axoglial junction proteins have been proposed as candidate antigens. We examined the reactivity of CIDP patients' sera against neuronal antigens and used immunoprecipitation for antigen unraveling.

METHODS

Primary cultures of hippocampal neurons were used to select patients' sera that showed robust reactivity with the cell surface of neurons. The identity of the antigens was established by immunoprecipitation and mass spectrometry, and subsequently confirmed with cell-based assays, immunohistochemistry with teased rat sciatic nerve, and immunoabsorption experiments.

RESULTS

Four of 46 sera from patients with CIDP reacted strongly against hippocampal neurons (8.6%) and paranodal structures on peripheral nerve. Two patients' sera precipitated contactin-1 (CNTN1), and 1 precipitated both CNTN1 and contactin-associated protein 1 (CASPR1). Reactivity against CNTN1 was confirmed in 2 cases, whereas the third reacted only when CNTN1 and CASPR1 were cotransfected. No other CIDP patient or any of the 104 controls with other neurological diseases tested positive. All 3 patients shared common clinical features, including advanced age, predominantly motor involvement, aggressive symptom onset, early axonal involvement, and poor response to intravenous immunoglobulin.

INTERPRETATION

Antibodies against the CNTN1/CASPR1 complex occur in a subset of patients with CIDP who share common clinical features. The finding of this biomarker may help to explain the symptoms of these patients and the heterogeneous response to therapy in CIDP.

Paraneoplastic syndromes and autoimmune encephalitis: Five new things

We review novel findings in paraneoplastic syndromes including the Lambert-Eaton myasthenic syndrome, and then focus on the novel disorders associated with antibodies against cell surface antigens, discussing the importance and caveats of antibody testing, and providing an algorithm for interpretation of results. In anti-NMDAR encephalitis 2 novel findings include the recognition of a characteristic EEG pattern ("extreme delta brush") in 30% of patients and the demonstration of a fronto-temporo-occipital gradient of glucose metabolism that correlates with disease activity. In limbic encephalitis, antibodies to GABA(B) receptor are the most frequently detected in patients with small-cell lung cancer who are anti-Hu negative, and antibodies to mGluR5 distinctively associate with Hodgkin lymphoma (Ophelia syndrome). We also address the syndromes associated with "VGKC-complex antibodies," a problematic term that groups well-characterized immune-mediated disorders (LGI1, Caspr2) with others that lack syndrome specificity, are less responsive to treatment, and for which the target antigens are unknown.