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Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a recently identified auto-immune disorder characterised by severe memory deficit, a decreased level of consciousness, seizures, autonomic dysfunction and movement disorders. Three girls with the disorder are reported; they were aged 4 years, 5 years and 10 months. The 10-month-old infant who is one of the youngest patients reported with anti-NMDAR encephalitis worldwide, had MRI features suggestive of herpes simplex encephalitis (known to trigger anti-NMDAR encephalitis), but CSF PCR for herpes simplex was negative. All the patients presented with seizures, behavioural change, regression of speech, dystonia and choreo-athetosis. Anti-NMDAR antibodies were detected in all patients' sera and cerebrospinal fluid (CSF). Intravenous immunoglobulin, corticosteroids and rituximab were administered at different intervals. Cases 1 and 2 made a full recovery, but case 3 has mild motor and speech delay. Patients who present with encephalopathy, seizures and movement disorders should be tested for anti-NMDAR antibodies in serum and CSF in addition to being screened for herpes simplex encephalitis.

Anti-N-methyl-D-aspartate receptor (Anti-NMDAR) encephalitis can present with and without tumor. Tumor associations are less common in older patients. We report a 65-year-old gentleman who presented with one week history of cough, chills, rigor and altered behavior, followed by florid visual and auditory hallucinations. Mini mental status examination score was 16/30. Both cerebrospinal fluid and plasma anti-NMDA receptor antibodies were detected. A course of intravenous methylprednisolone was given with partial symptom improvement. A hepatic neuroendocrine carcinoma was detected and confirmed on biopsy. Unfortunately, he developed several medical complications: non-ST elevation myocardial infarction, infected foot gangrene and peripheral vascular disease, which made him unsuitable for both surgery and chemotherapy. He passed away 6months later due to the progression of the malignancy. This case illustrated that NMDAR encephalitis may be associated with an uncommon hepatic neuroendocrine carcinoma in an older person, which is responsive to early treatment., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Japanese encephalitis (JE) is usually a monophasic disease; however, in rare cases, patients with JE may have an early relapse after a partial recovery, giving rise to a biphasic pattern for the disease. In this study, we report three pediatric cases in which post-JE relapse was characterized by movement disorder and/or behavioral problems, and was related to anti-N-methyl-D-aspartate receptor (NMDAR) immunoglobulin G (IgG). Serum and cerebrospinal fluid were examined for anti-NMDAR IgG in three patients who had confirmed JE and then developed relapsing symptoms which were similar to those of anti-NMDAR encephalitis. The main symptoms of the two young children were choreoathetosis, irritability, and sleep disorder; while for the teenager, agitation, mutism, rigidity, and sleep disorder were the main symptoms. Samples of cerebrospinal fluid from all patients were positive for anti-NMDAR IgG, and all patients gradually improved with immunotherapy. Testing for NMDAR antibodies is highly recommend in patients with JE, especially those with a relapsing syndrome involving movement disorder and/or behavioral problems, as these patients may benefit from immunotherapy.

Objective: To analyze the clinical features of 13 pregnant patients with anti-N-Methyl-d-Aspartate receptor (NMDAR) encephalitis., Materials and Methods: Retrospective review of thirteen reported cases was conducted for anti-NMDAR encephalitis patients during pregnancy. The clinical data were collected from papers published in PubMed prior to 16 February 2016. Statistical analysis of the data was performed, which encompasses the patients' age, past medical history, onset of symptoms, concomitant with ovarian teratomas, immunotherapy, outcomes of mothers and newborns., Results: Thirteen cases were reported in 11 articles with a median age of 23 (interquartile range, 19-27) years old. There were eight cases in which the onset periods of gestation happened in the first trimester and five cases in the second trimester. Among 13 cases, five patients had a past medical history, one concomitant with autoimmune Graves' hyperthyroidism, one with bilateral ovarian teratomas removed history, one with anti-NMDAR encephalitis five years before pregnancy and two with psychiatric symptoms. Five patients were found with ovarian teratomas. Seven patients responded to first-line immunotherapy whereas all of two patients responded to second-line immunotherapy when the first-line immunotherapy failed. Following up all the 13 patients, most experienced a substantial recovery, except one had spasticity and dystonia in one hand, and one died of a superimposed infection. Three fetuses were miscarried or aborted in total. Most newborns were healthy, except two cases (2/10) with abnormal neurologic signs., Conclusions: Clinical analysis of the data indicates that most patients respond to first-line immunotherapy. A second-line immunotherapy is effective when first-line immunotherapy fails. It has also been found that most mothers and newborns can have good outcomes., (Copyright © 2017. Published by Elsevier B.V.)

Background: Anti-N-methyl d-aspartate receptor (NMDAR) encephalitis is a rare disorder characterized by seizures, neuropsychiatric symptoms, dyskinesia and autonomic instability., Objective: Aim of the present study was to evaluate the seizure phenotypes and electroencephalogram (EEG) features in children with anti-NMDAR encephalitis., Methods: Seizure types, electroclinical features and clinical characteristics of 17 children with anti-NMDAR encephalitis were analysed in a retrospective case series from nine centres in Europe., Results: Nearly half (8/17) of the children presented with psychiatric symptoms, whereas in 4/17 patients seizures were the first symptom and in 5/17 both symptoms occurred at the same time. During the following course seizures were reported in 16/17 children. The first EEG detected generalized slowing in 11/17 patients, focal slowing in 3/17 and normal background activity in only 3/17 children. The extreme delta brush (EDB) pattern was detected in 9/17 (53%) patients., Conclusion: In addition to psychiatric symptoms, children with anti-NMDAR encephalitis often show generalized slowing in EEG with or without seizures at initial presentation. EDB is present in half of all children and is potentially a helpful tool for early detection of this immune-mediated disease., (Copyright © 2016 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Anti-N-methyl-d-aspartate-type glutamate receptor autoimmune encephalitis can arise in the setting of ovarian teratoma and often responds to resection. When it occurs in the absence of tumor, failure to respond to treatment may be more likely, and affected patients often require intensive care. To further understand the mechanisms and potential management, we present findings from an autopsy conducted on a young woman who died of refractory autoimmune encephalitis of this type. Rituximab was administered 70 days before death, and both 37 and 14 days before death, CD19 + lymphocytes were only 0.1% of blood cells. Ten sessions of plasmapheresis were performed after rituximab treatment. Nonetheless, the autoantibodies were present in serum 4 days before death, demonstrating ongoing antibody production. The hippocampus and medial temporal lobe demonstrated inflammation with T cell and prominent microglial involvement, but no plasma cells or plasmablasts were found there, or anywhere in the brain, despite an extensive search. Examination of lymph node tissue identified many plasma cells along sinusoids. These findings demonstrate that the antibody-producing cells are long-lived and can reside in lymphoid tissue. Awareness of continuing antibody production, the extra-central nervous system site, the indication for cytotoxic therapy, and the potential for biopsy assessment may lead to more effective treatment., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Anti-N-Methyl-D-Aspartate receptor (NMDAR) encephalitis is an acute neurological disorder affecting children and adults. We aimed to compare the clinical characteristics, treatments, and outcomes between children and adults with anti-NMDAR encephalitis and to assess the probable risk factors. In this observational study, patients who tested positive for anti-NMDAR antibody in the cerebrospinal fluid were enrolled. The patients were divided into children and adults group on the basis of age (whether <16 or not). Clinical outcomes were assessed at onset, 1, 3, 6, 9, and 12 months after the patients received treatment and were scored based on whether they required hospitalization and intensive care. A total of 15 children and 14 adults were examined. The adults more likely manifested status epilepticus, central hypoventilation, and pneumonia but less likely exhibited movement disorder than the children did. All of the patients were subjected to corticosteroid treatment, 11 children and 9 adults were treated with intravenous immunoglobulin, and only the adults received plasma exchange or cyclophosphamide. The children recovered faster than the adults, especially in the first 6 months. Risk factors included age, status epilepticus, changes in consciousness, central hypoventilation, and pneumonia. Adults exhibit worse outcomes than children mostly because of status epilepticus.

Purpose: Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a recently discovered paraneoplastic limbic encephalitis. Ovarian teratoma is the only tumor clearly related to anti-NMDAR encephalitis occurrence. This study aimed to assess ovarian teratoma for neurological and mental symptoms highly related with anti-NMDAR encephalitis, treatment principles, and prognosis., Methods: Between June 2011 and October 2014, in Peking Union Medical College Hospital, ten patients with ovarian teratoma associated with anti-NMDAR encephalitis were enrolled. All patients underwent laparoscopic oophorocystectomy followed by immunotherapy., Results: In nine patients, mental and neurological symptoms were significantly relieved 13.7 ± 5.5 days after surgery; however, symptoms persisted in one patient, who was still hospitalized when writing this paper. During the postoperative follow-up period, seven patients showed no mental symptoms or tumor recurrence; one subject had symptom recurrence 28 days after surgery, while another patient showed suspected tumor recurrence 273 days after operation., Conclusions: Ovarian teratoma associated with anti-NMDAR encephalitis is usually associated with neurological and mental symptoms at onset. Its manifestations are complex, and nursing care is difficult. Laparoscopic oophorocystectomy followed by immunotherapy led to symptom resolution in most patients.

We describe neurological and cognitive/neuropsychological changes from symptom onset in 13 consecutive children (8 females and 5 males; median age 11 years, range 3-17) with anti-NMDAR-encephalitis. We assessed neurological status using the modified Rankin Scale for children and cognitive/neuropsychological status using a standardized battery that was administered serially in 10 prospective patients, and at latest follow-up in three retrospective patients diagnosed before study initiation. Symptom onset was marked by neurological or psychiatric/behavioural manifestations, which became severe but regressed at variable rates after starting immunotherapy. The 10 prospective patients were able to undergo first standardized cognitive/neuropsychological assessment a median of 3 months (range 1-12) after symptom onset: they had extensive deficits, although severity varied. Subsequent assessment showed marked improvements although the timescale varied. At latest evaluation (median 31 months, range 3-112, after symptom onset), seven patients had no neurological disability, five had improved substantially, and one had persistent behavioural problems. Latest cognitive/neuropsychological assessment in 11 patients with at least a year of follow-up showed normal general intellectual abilities, but over half had residual deficits indicating frontal lobe dysfunction. All patients had resumed normal activities. Our findings suggest that early installation of immunotherapy results in good long-term recovery in most paediatric patients with anti-NMDAR-encephalitis, however, recovery is incomplete and the disease leaves subtle lasting defects that impact quality of life, social relationships, and academic achievement.

We are reporting on a case of pediatric anti-NMDAR encephalitis with autonomic instability. The patient showed little response to first-line treatment of steroid and IVIG. We initiated plasma exchange, also a first-line treatment. This worsened his autonomic instability, resulting in hypotensive shock. He responded well to rituximab and cyclophosphamide, second-line therapies. Anti-NMDAR encephalitis is often accompanied by autonomic instability. Our and other reported cases, raise the question of plasma exchange as a first-line therapy for pediatric NMDAR encephalitis, which is frequently accompanied by autonomic instability. Plasma exchange should be performed cautiously in such patients., (Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

We report a case of a 17-year-old man presenting with new onset psychiatric symptoms. Magnetic resonance imaging (MRI) and proton magnetic resonance (MR) spectroscopy revealed some lesions in the right cerebellar hemisphere and ipsilateral cerebellar tonsil suggestive of encephalitis. An extensive workup was negative for both infectious and neoplastic diseases and he was afterward diagnosed with anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis. This disorder is an autoimmune encephalitis, highly lethal but curable, predominantly found in young female with ovarian teratoma. He received methylprednisolone. His clinical findings gradually improve and he made a complete recovery. Accordingly, repeated brain MRI and proton MR spectroscopy showed a gradual reduction of the lesions; MRI taken six months after starting therapy showed complete resolution of the lesions. Our case shows that, although rare, anti-NMDAR encephalitis should be considered also in young men for whom a rapid onset of psychiatric neurological disorders cannot be explained by more frequent causes. Our report underlines also the usefulness of MRI and proton MR spectroscopic findings in the diagnosis and follow-up of this disease., (© The Author(s) 2015.)

Autoimmune encephalitis causes subacute deficits of memory and cognition, often followed by suppressed level of consciousness or coma. A careful history and examination may show early clues to particular autoimmune causes, such as neuromyotonia, hyperekplexia, psychosis, dystonia, or the presence of particular tumors. Ancillary testing with MRI and EEG may be helpful for excluding other causes, managing seizures, and, rarely, for identifying characteristic findings. Appropriate autoantibody testing can confirm specific diagnoses, although this is often done in parallel with exclusion of infectious and other causes. Autoimmune encephalitis may be divided into several groups of diseases: those with pathogenic antibodies to cell surface proteins, those with antibodies to intracellular synaptic proteins, T-cell diseases associated with antibodies to intracellular antigens, and those associated with other autoimmune disorders. Many forms of autoimmune encephalitis are paraneoplastic, and each of these conveys a distinct risk profile for various tumors. Tumor screening and, if necessary, treatment is essential to proper management. Most forms of autoimmune encephalitis respond to immune therapies, although powerful immune suppression for weeks or months may be needed in difficult cases. Autoimmune encephalitis may relapse, so follow-up care is important.

Patients with anti-NMDA receptor (anti-NMDAR) encephalitis frequently suffer from autonomic dysfunctions, which can cause substantial morbidity. This study assessed cardiac autonomic functions in patients with anti-NMDAR encephalitis using heart rate variability (HRV) analysis. This was a retrospective single-center case-control study. Eleven patients with anti-NMDAR encephalitis and 15 age- and sex-matched controls were included in this study. To ensure that autonomic dysfunction does not occur in any encephalitis, we additionally analyzed HRV of 9 patients with herpes encephalitis (HSE) and compared with that of NMDAR encephalitis patients and controls. Five minute resting stationary electrocardiogram was collected from each subject, and HRV was analyzed. Total power and low frequency (LF) power were lower in anti-NMDAR encephalitis patients than those in controls (p=0.005, 0.001 respectively), indicating cardiac autonomic dysfunction especially in sympathetic system. Patients with HSE showed no significant difference in HRV parameters compared with that of controls. Cardiac autonomic dysfunction was associated with 3 month functional outcome in anti-NMDAR encephalitis patients., (Copyright © 2015 Elsevier B.V. All rights reserved.)

In recent years, autoantibodies to proteins or receptors expressed on the surface of neurons have been detected in movement and psychiatric disorders. These autoantibodies can assist in better recognition of clinical syndromes and offer novel treatment opportunities via immunotherapies, potentially leading to improved patient outcome. In this review, we describe several autoimmune syndromes associated with movement and psychiatric disorders, including anti-N-methyl-d-aspartate receptor encephalitis, basal ganglia encephalitis, Sydenham chorea, and autoantibody-associated psychosis and schizophrenia. However, rather than focusing on clinical aspects of these diseases, as they have been reviewed in detail elsewhere, we mainly focus on the scientific aspects of the different methodologies for detecting antibodies, with an emphasis on the current gold standard in the field, the cell-based assay, and on issues related to the use of live versus permeabilized cells. We also reflect on the implications associated with the choice of patient serum and cerebrospinal fluid for antibody testing, on the mechanism of antibody entry into the central nervous system through the blood-brain barrier, and the essential issue of antibody pathogenicity., (© 2015 New York Academy of Sciences.)

Anti-neuronal autoimmune encephalitis (AIE) comprises a recently characterized group of immune-mediated disorders that result in limbic, multifocal, or diffuse encephalitis due to direct interaction of autoantibodies with neuronal surface or synaptic proteins. The pathological effects of the autoantibodies vary according to the target antigen but when they are removed, neuronal dysfunction is commonly reversed. Ongoing research on AIE constantly increases the number of novel autoantibodies and expands the spectrum of neurological syndromes that are important in the differential diagnosis of psychiatric illness, dementia, or viral encephalitis. This review summarizes recent advances in AIE, focusing on pathogenetic mechanisms and novel associations with other CNS disorders such as neurodegeneration, relapsing symptoms post-herpes simplex virus encephalitis, and demyelinating diseases. In addition, an algorithmic approach to detect and characterize neuronal cell surface autoantibodies is proposed.

To contribute to characterize electroencephalographic (EEG) activity in pediatric anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis, we reviewed electroclinical data of 5 children with anti-NMDA receptor encephalitis diagnosed in our department. We identified 4 longitudinal electroencephalographic phases: in the early phase, background activity was normal, with intermixed nonreactive slow waves; in the florid phase, background activity deteriorated with appearance of sequences of peculiar rhythmic theta and/or delta activity unrelated to clinical changes, unresponsive to stimuli and antiepileptic medications; in the recovery phase, these sequences decreased and reactive posterior rhythm re-emerged; electroencephalogram normalized 2 to 5 months after onset. In conclusion, in the presence of evocative clinical history, recognizing a characteristic longitudinal electroencephalographic activity could provide ancillary aspects addressing the diagnosis and the overall management of children with anti-N-methyl-d-aspartate receptor encephalitis; in particular, knowing that peculiar and recurrent paroxysmal nonepileptic rhythmic theta-delta patterns can occur in these patients could help distinguish paroxysmal epileptic and nonepileptic electroencephalographic activity., (© The Author(s) 2014.)

Anti-N-methyl D-aspartate receptor (NMDAR) encephalitis is a severe neuropsychiatric disorder that associates with prominent memory and behavioural deficits. Patients' antibodies react with the N-terminal domain of the GluN1 (previously known as NR1) subunit of NMDAR causing in cultured neurons a selective and reversible internalization of cell-surface receptors. These effects and the frequent response to immunotherapy have suggested an antibody-mediated pathogenesis, but to date there is no animal model showing that patients' antibodies cause memory and behavioural deficits. To develop such a model, C57BL6/J mice underwent placement of ventricular catheters connected to osmotic pumps that delivered a continuous infusion of patients' or control cerebrospinal fluid (flow rate 0.25 µl/h, 14 days). During and after the infusion period standardized tests were applied, including tasks to assess memory (novel object recognition in open field and V-maze paradigms), anhedonic behaviours (sucrose preference test), depressive-like behaviours (tail suspension, forced swimming tests), anxiety (black and white, elevated plus maze tests), aggressiveness (resident-intruder test), and locomotor activity (horizontal and vertical). Animals sacrificed at Days 5, 13, 18, 26 and 46 were examined for brain-bound antibodies and the antibody effects on total and synaptic NMDAR clusters and protein concentration using confocal microscopy and immunoblot analysis. These experiments showed that animals infused with patients' cerebrospinal fluid, but not control cerebrospinal fluid, developed progressive memory deficits, and anhedonic and depressive-like behaviours, without affecting other behavioural or locomotor tasks. Memory deficits gradually worsened until Day 18 (4 days after the infusion stopped) and all symptoms resolved over the next week. Accompanying brain tissue studies showed progressive increase of brain-bound human antibodies, predominantly in the hippocampus (maximal on Days 13-18), that after acid extraction and characterization with GluN1-expressing human embryonic kidney cells were confirmed to be against the NMDAR. Confocal microscopy and immunoblot analysis of the hippocampus showed progressive decrease of the density of total and synaptic NMDAR clusters and total NMDAR protein concentration (maximal on Day 18), without affecting the post-synaptic density protein 95 (PSD95) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. These effects occurred in parallel with memory and other behavioural deficits and gradually improved after Day 18, with reversibility of symptoms accompanied by a decrease of brain-bound antibodies and restoration of NMDAR levels. Overall, these findings establish a link between memory and behavioural deficits and antibody-mediated reduction of NMDAR, provide the biological basis by which removal of antibodies and antibody-producing cells improve neurological function, and offer a model for testing experimental therapies in this and similar disorders., (© The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Variations in clinical presentation can lead to delays in the diagnosis and initiation of treatment of anti-N-methyl-D-aspartate receptor encephalitis. Most patients have an EEG study performed early in the course of their illness. Although not specific, there may be clues in the electroclinical features that should alert clinicians and electroencephalographers to the possibility of this diagnosis. This case is a reminder that anti- anti-N-methyl-D-aspartate receptor encephalitis may present initially with a movement disorder as the sole symptom, without features of an encephalopathy. In addition, it adds to the growing body of evidence that recognition of certain electroclinical clues may shorten the time to diagnosis. [Published with video sequence].

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., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Introduction: Paraneoplastic neurological syndromes (PNS) are neurologic deficits triggered by an underlying remote tumor. PNS can antedate clinical manifestation of ovarian malignancy and enable its diagnosis at an early stage. Interestingly, neoplasms associated with PNS are less advanced and metastasize less commonly than those without PNS. This suggests that PNS may be associated with a naturally occurring antitumor response. Methods: We review the literature on the diagnosis, pathogenesis and management of PNS associated with ovarian tumors: paraneoplastic cerebellar degeneration (PCD) and anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis. An approach to the diagnostic workup of underlying tumors is discussed. Results: PCD can precede the manifestation of ovarian carcinoma. Anti-NMDAR encephalitis in young women appears often as a result of ovarian teratoma. Since ovarian tumors and nervous tissue share common antigens (e.g., cdr2, NMDAR), autoimmune etiology is a probable mechanism of these neurologic disorders. The concept of cross-presentation, however, seems insufficient to explain entirely the emergence of PNS. Early resection of ovarian tumors is a significant part of PNS management and improves the outcome. Conclusions: The diagnosis of PNS potentially associated with ovarian tumor indicates a need for a thorough diagnostic procedure in search of the neoplasm. In some patients, explorative laparoscopy/laparotomy can be considered.