Non-herpetic acute limbic encephalitis: cerebrospinal fluid cytokines and magnetic resonance imaging findings

An Unusual Case of Limbic Encephalitis Caused by Whipple Disease

Whipple disease (WD), a multisystemic infectious disorder caused by Tropheryma whipplei (T. whipplei), typically presents with gastrointestinal (GI) symptoms such as abdominal pain, diarrhea, GI bleeding, and weight loss. Uncommonly, it can also involve the central nervous system (CNS) and may present with a range of symptoms, including personality changes, dementia, and rhombencephalitis. Prompt antibiotic treatment and careful follow-up are crucial for favorable patient outcomes and a reduction in morbidity and mortality. In this case, we describe a 46-year-old male with primary CNS-WD and discuss the symptomatic manifestations, diagnostic findings, differential diagnosis, and management. This patient initially presented with arthritic complaints and, over a five-year period, developed progressive neurocognitive symptoms, including anxiety, panic attacks, retrograde amnesia, personality changes, aphasia, anhedonia, dysarthria, and rapidly progressive dementia. Magnetic resonance imaging (MRI) revealed symmetric T2 fluid-attenuated inversion recovery (FLAIR) hyperintensities in the bilateral medial temporal lobes, hippocampi, and hypothalamus. A lumbar puncture (LP) showed mild pleocytosis and elevated protein, with no autoimmune or paraneoplastic causes. Temporal lobe biopsy revealed rod-like structures, and T. whipplei DNA was confirmed by polymerase chain reaction (PCR). This case underscores the importance of maintaining a high index of suspicion for WD in patients presenting with atypical symptoms with rapidly progressive dementia, as early detection and management are key to circumventing irreversible neurological damage and death.

The immunobiology of herpes simplex virus encephalitis and post-viral autoimmunity

Herpes simplex virus encephalitis (HSE) is the leading cause of non-epidemic encephalitis in the developed world and, despite antiviral therapy, mortality and morbidity is high. The emergence of post-HSE autoimmune encephalitis reveals a new immunological paradigm in autoantibody-mediated disease. A reductionist evaluation of the immunobiological mechanisms in HSE is crucial to dissect the origins of post-viral autoimmunity and supply rational approaches to the selection of immunotherapeutics. Herein, we review the latest evidence behind the phenotypic progression and underlying immunobiology of HSE including the cytokine/chemokine environment, the role of pathogen-recognition receptors, T- and B-cell immunity and relevant inborn errors of immunity. Second, we provide a contemporary review of published patients with post-HSE autoimmune encephalitis from a combined cohort of 110 patients. Third, we integrate novel mechanisms of autoimmunization in deep cervical lymph nodes to explore hypotheses around post-HSE autoimmune encephalitis and challenge these against mechanisms of molecular mimicry and others. Finally, we explore translational concepts where neuroglial surface autoantibodies have been observed with other neuroinfectious diseases and those that generate brain damage including traumatic brain injury, ischaemic stroke and neurodegenerative disease. Overall, the clinical and immunological landscape of HSE is an important and evolving field, from which precision immunotherapeutics could soon emerge.

MRI of neurosyphilis with mesiotemporal lobe lesions of "knife-cut sign” on MRI: A case report and literature review

Neurosyphilis with mesiotemporal lobe lesions remains a difficult entity to diagnose, especially when it mimics herpes simplex encephalitis (HSE). Here, we report what appeared to be the first case of mesiotemporal imaging of neurosyphilis presenting as a "knife-cut" sign and mimicking HSE pathological hallmarks on imaging. The magnetic resonance imaging (MRI) changes in neurosyphilis and HSE were indistinguishable in the initial diagnosis because of the common involvement of the mesiotemporal lobe. Neurosyphilis was diagnostically confirmed by positive readings in the treponema pallidum hemagglutination assay (TPHA), rapid plasma reagin (RPR) and cerebrospinal fluid-polymerase chain reaction (CSF-PCR) tests for Treponema pallidum infection. Neurosyphilis and HSE had similar clinical features and signs on MRI, except the knife-cut sign which is a common diagnosis in HSE. Therefore, neurosyphilis with mesiotemporal changes and knife-cut signs on MRI should be evaluated in the differential diagnosis in all patients, as similar changes may also occur in HSE patients. The literature review of published articles between 1997 and 2020 was conducted to further validate our clinical observations and discuss diagnostic and treatment options for neurosyphilis with mesiotemporal lobe lesions.

Cytokines and chemokines profile in encephalitis patients: A meta-analysis

BACKGROUND

Encephalitis is caused by autoimmune or infectious agents marked by brain inflammation. Investigations have reported altered concentrations of the cytokines in encephalitis. This study was conducted to determine the relationship between encephalitis and alterations of cytokine levels in cerebrospinal fluid (CSF) and serum.

METHODS

We found possibly suitable studies by searching PubMed, Embase, Scopus, and Web of Science, systematically from inception to August 2021. 23 articles were included in the meta-analysis. To investigate sources of heterogeneity, subgroup analysis and sensitivity analysis were conducted. The protocol of the study has been registered in PROSPERO with a registration ID of CRD42021289298.

RESULTS

A total of 23 met our eligibility criteria to be included in the meta-analysis. A total of 12 cytokines were included in the meta-analysis of CSF concentration. Moreover, 5 cytokines were also included in the serum/plasma concentration meta-analysis. According to the analyses, patients with encephalitis had higher CSF amounts of IL-6, IL-8, IL-10, CXCL10, and TNF-α than healthy controls. The alteration in the concentration of IL-2, IL-4, IL-17, CCL2, CXCL9, CXCL13, and IFN-γ was not significant. In addition, the serum/plasma levels of the TNF-α were increased in encephalitis patients, but serum/plasma concentration of the IL-6, IL-10, CXCL10, and CXCL13 remained unchanged.

CONCLUSIONS

This meta-analysis provides evidence for higher CSF concentrations of IL-6, IL-8, IL-10, CXCL10, and TNF-α in encephalitis patients compared to controls. The diagnostic and prognostic value of these cytokines and chemokines should be investigated in future studies.

High neopterin and IP-10 levels in cerebrospinal fluid are associated with neurotoxic tryptophan metabolites in acute central nervous system infections

Background

The host response to intruders in the central nervous system (CNS) may be beneficial but could also be harmful and responsible for neurologic symptoms and sequelae in CNS infections. This immune response induces the activation of the kynurenine pathway (KP) with the production of neuroactive metabolites. Herein, we explored cytokine and KP responses in cerebrospinal fluid (CSF) and serum in patients with encephalitis, aseptic, and bacterial meningitis.

Methods

Cytokines were measured in CSF and serum by multiplex assay in adult patients with encephalitis of infectious, autoimmune or unknown etiology (n = 10), aseptic meningitis (ASM, n = 25), acute bacterial meningitis (ABM, n = 6), and disease control patients with similar symptoms but without pleocytosis in CSF (n = 42). Liquid chromatography-tandem mass spectrometry (LC-MS/ MS) was used to measure KP metabolites in CSF and serum.

Results

A characteristic pattern of increasing cytokine levels and KP metabolites was found in CSF from encephalitis to ASM, with the highest levels in ABM. In ASM and ABM, most inflammatory mediators, including IL-6, IL-8, and IFN-inducible protein-10 (IP-10), showed markedly elevated levels in CSF compared with serum, indicating production within the CNS. In contrast to most mediators, the highest level of IP-10 was found in the ASM group, suggesting a potential role for IP-10 in aseptic/viral meningitis. Neopterin and IP-10 were associated with marked changes in KP metabolites in CSF with increasing kynurenine/tryptophan ratio reflecting indoleamine 2,3-dioxygenase activity. Neopterin, a marker of IFN-γ activity, was associated with an unfavorable balance between neuroprotective and neurotoxic tryptophan metabolites.

Conclusion

We show that parenchymal and meningeal inflammations in CNS share a characteristic cytokine profile with a general immune response in the CSF with limited influence from the systemic circulation. IFN-γ activity, assessed by neopterin and IP-10 levels, may play a role in the activation of the KP pathway in these patients, potentially mediating neurotoxic effects.

Electronic supplementary material

The online version of this article (10.1186/s12974-018-1366-3) contains supplementary material, which is available to authorized users.

Limbic encephalitis - a report of four cases

Usually limbic encephalitis (LE) is a paraneoplastic neurologic syndrome. LE symptoms can precede cancer even by a few years. Almost 50% of LE cases are connected with small cell lung carcinoma. Testis and breast cancers, granulomatous disease, thymoma, and teratomas are also often connected with LE. Other cases have infectious and autoimmunological aetiology. In LE limbic system dysfunction is observed, and it is accompanied by cerebellum and brain stem abnormalities as well as polyneuropathy. Paraneoplastic limbic encephalitis is sometimes a part of larger syndrome in which brain stem and spinal cord are involved in an inflammatory process called paraneoplastic encephalomyelitis. The main LE symptoms are: impairment of cognitive functions with subacute beginning, partial and generalised seizures, mental distress, disturbances of consciousness, and limb paresis. In MRI study hyperintensive lesions in the medial part of the temporal lobes in T2 and FLAIR sequences are present. Sharp and slow waves in electroencephalography in the temporal area are also frequent. In cerebrospinal fluid pleocytosis, elevation of protein level, intensification of immunoglobulin synthesis, and oligoclonal bands can be detected. The majority of patients with paraneoplastic LE have onconeural antibodies in the blood. The presented study is a description of the clinical course of the disease in four patients diagnosed with LE.

MR imaging of adult acute infectious encephalitis

BACKGROUND

Imaging is a key tool for the diagnosis of acute encephalitis. Brain CT scan must be urgently performed to rule out a brain lesion with mass effect that would contraindicate lumbar puncture. Brain MRI is less accessible than CT scan, but can provide crucial information with patients presenting with acute encephalitis.

METHOD

We performed a literature review on PubMed on April 1, 2015 with the search terms "MRI" and "encephalitis".

RESULTS

We first described the various brain MRI abnormalities associated with each pathogen of acute encephalitis (HSV, VZV, other viral agents targeting immunocompromised patients or travelers; tuberculosis, listeriosis, other less frequent bacterial agents). Then, we identified specific patterns of brain MRI abnomalies that may suggest a particular pathogen. Limbic encephalitis is highly suggestive of HSV; it also occurs less frequently in encephalitis due to HHV6, syphillis, Whipple's disease and HIV primary infection. Rhombencephalitis is suggestive of tuberculosis and listeriosis. Acute ischemic lesions can occur in patients presenting with severe bacterial encephalitis, tuberculosis, VZV encephalitis, syphilis, and fungal infections.

CONCLUSION

Brain MRI plays a crucial role in the diagnosis of acute encephalitis. It detects brain signal changes that reinforce the clinical suspicion of encephalitis, especially when the causative agent is not identified by lumbar puncture; it can suggest a particular pathogen based on the pattern of brain abnormalities and it rules out important differential diagnosis (vascular, tumoral or inflammatory causes).

Opt-Out HIV Testing of Inmates in North Carolina Prisons: Factors Associated with not Wanting a Test and not Knowing They Were Tested

Opt-out HIV testing is recommended for correctional settings but may occur without inmates' knowledge or against their wishes. Through surveying inmates receiving opt-out testing in a large prison system, we estimated the proportion unaware of being tested or not wanting a test, and associations [prevalence ratios (PRs)] with inmate characteristics. Of 871 tested, 11.8 % were unknowingly tested and 10.8 % had unwanted tests. Not attending an educational HIV course [PR = 2.34, 95 % confidence interval (CI) 1.47-3.74], lower HIV knowledge (PR = 0.95, 95 % CI 0.91-0.98), and thinking testing is not mandatory (PR = 9.84, 95 % CI 4.93-19.67) were associated with unawareness of testing. No prior incarcerations (PR = 1.59, 95 % CI 1.03-2.46) and not using crack/cocaine recently (PR = 2.37, 95 % CI 1.21-4.64) were associated with unwanted testing. Residence at specific facilities was associated with both outcomes. Increased assessment of inmate understanding and enhanced implementation are needed to ensure inmates receive full benefits of opt-out testing: being informed and tested according to their wishes.

Characteristic Cytokine and Chemokine Profiles in Encephalitis of Infectious, Immune-Mediated, and Unknown Aetiology

Background

Encephalitis is parenchymal brain inflammation due to infectious or immune-mediated processes. However, in 15–60% the cause remains unknown. This study aimed to determine if the cytokine/chemokine-mediated host response can distinguish infectious from immune-mediated cases, and whether this may give a clue to aetiology in those of unknown cause.

Methods

We measured 38 mediators in serum and cerebrospinal fluid (CSF) of patients from the Health Protection Agency Encephalitis Study. Of serum from 78 patients, 38 had infectious, 20 immune-mediated, and 20 unknown aetiology. Of CSF from 37 patients, 20 had infectious, nine immune-mediated and eight unknown aetiology.

Results

Heat-map analysis of CSF mediator interactions was different for infectious and immune-mediated cases, and that of the unknown aetiology group was similar to the infectious pattern. Higher myeloperoxidase (MPO) concentrations were found in infectious than immune-mediated cases, in serum and CSF (p = 0.01 and p = 0.006). Serum MPO was also higher in unknown than immune-mediated cases (p = 0.03). Multivariate analysis selected serum MPO; classifying 31 (91%) as infectious (p = 0.008) and 17 (85%) as unknown (p = 0.009) as opposed to immune-mediated. CSF data also selected MPO classifying 11 (85%) as infectious as opposed to immune-mediated (p = 0.036). CSF neutrophils were detected in eight (62%) infective and one (14%) immune-mediated cases (p = 0.004); CSF MPO correlated with neutrophils (p<0.0001).

Conclusions

Mediator profiles of infectious aetiology differed from immune-mediated encephalitis; and those of unknown cause were similar to infectious cases, raising the hypothesis of a possible undiagnosed infectious cause. Particularly, neutrophils and MPO merit further investigation.

Cerebrospinal fluid markers of neuroinflammation in delirium: a role for interleukin-1β in delirium after hip fracture

OBJECTIVE

Exaggerated central nervous system (CNS) inflammatory responses to peripheral stressors may be implicated in delirium. This study hypothesised that the IL-1β family is involved in delirium, predicting increased levels of interleukin-1β (IL-1β) and decreased IL-1 receptor antagonist (IL-1ra) in the cerebrospinal fluid (CSF) of elderly patients with acute hip fracture. We also hypothesised that Glial Fibrillary Acidic Protein (GFAP) and interferon-γ (IFN-γ) would be increased, and insulin-like growth factor 1 (IGF-1) would be decreased.

METHODS

Participants with acute hip fracture aged >60 (N=43) were assessed for delirium before and 3-4 days after surgery. CSF samples were taken at induction of spinal anaesthesia. Enzyme-linked immunosorbent assays (ELISA) were used for protein concentrations.

RESULTS

Prevalent delirium was diagnosed in eight patients and incident delirium in 17 patients. CSF IL-1β was higher in patients with incident delirium compared to never delirium (incident delirium 1.74 pg/ml (1.02-1.74) vs. prevalent 0.84 pg/ml (0.49-1.57) vs. never 0.66 pg/ml (0-1.02), Kruskal-Wallis p=0.03). CSF:serum IL-1β ratios were higher in delirious than non-delirious patients. CSF IL-1ra was higher in prevalent delirium compared to incident delirium (prevalent delirium 70.75 pg/ml (65.63-73.01) vs. incident 31.06 pg/ml (28.12-35.15) vs. never 33.98 pg/ml (28.71-43.28), Kruskal-Wallis p=0.04). GFAP was not increased in delirium. IFN-γ and IGF-1 were below the detection limit in CSF.

CONCLUSION

This study provides novel evidence of CNS inflammation involving the IL-1β family in delirium and suggests a rise in CSF IL-1β early in delirium pathogenesis. Future larger CSF studies should examine the role of CNS inflammation in delirium and its sequelae.

Role of IL-6 and neopterin in the pathogenesis of herpetic encephalitis

Herpetic encephalitis (HSE) is one of the most severe infection of the central nervous system (CNS), connected with high mortality rate, even when appropriate therapy has been introduced. Better understanding of pathomechanisms responsible for neuronal injury during the course of the disease can be useful in the assessment of the risk of the occurrence of severe complications, as well as in potential introduction of additional therapeutic methods. The purpose of this study is to assess the correlation between concentration of neopterin and IL-6 in the CSF and serum, and the course of HSE. In this study, 36 patients with HSE were investigated, and the control group consisted of 32 patients in whom the infection of the CNS was excluded. We observed significantly higher concentration of neopterin and IL-6 in the CSF of patients with HSV as compared with the control group. Neopterin and IL-6 levels in the CSF correlated with the course of HSE. Higher values were connected with the risk of respiratory failure, development of permanent neurologic complications and patient death. Negative correlations between concentration of IL-6 and neopterin and patient condition assessed by Glasgow Coma Scale (GCS) were observed. Neopterin with high sensitivity and specificity allowed to predict the risk of death or severe neurological complications. Increased concentration of neopterin and IL-6 in the CSF and serum revealed reciprocal positive correlation. Assessment of the concentration of IL-6 and neopterin in the serum was not useful to predict the course of HSE.

Autoimmune-mediated encephalitis

Autoimmune-mediated encephalitis may occur as a paraneoplastic or as a non-paraneoplastic condition. The role of neuroimaging in autoimmune-mediated encephalitis has changed in the last decade partly due to improvements in sequence optimisation and higher field strength and partly due to the discovery of an increasing number of antibodies to neuronal cell and cell membrane antigens. Imaging is important since it can support the clinical diagnosis particularly in the absence of antibodies. Structural imaging findings can be subtle and are usually best seen on FLAIR images. A progressive as well as a relapsing-remitting course can be observed. Autoimmune-mediated encephalitis is classically linked to involvement of the hippocampus and amygdala, but extensive changes in the temporal cortex, basal ganglia, hypothalamus, brain stem, frontal and parietal cortex are not unusual. This report is based on a review of the literature (except the literature in Japanese) and own findings in patients with autoimmune-mediated encephalitis.

A Boy with Non-Herpes Simplex Acute Limbic Encephalitis and Antiglutamate Receptor Antibodies

This report concerns a 12-year-old male with intractable seizures over a long period. The case fulfilled the diagnostic criteria for nonherpetic acute limbic encephalitis. He had frequent convulsions starting with a partial seizure at the left angle of the mouth and progressing to secondary generalized seizures. He was treated with several anticonvulsants, combined with methylprednisolone and γ-globulin under mechanical ventilation. However, his convulsions reappeared after tapering of the barbiturate. His magnetic resonance imaging showed a high intensity area in the hippocampus by FLAIR and diffusion. After five months he recovered without serious sequelae. Virological studies, including for herpes simplex virus, were all negative. He was transiently positive for antiglutamate receptor antibodies in cerebrospinal fluid and serum.

Serum and cerebrospinal fluid levels of cytokines in acute encephalopathy associated with human herpesvirus-6 infection

Human herpesvirus-6 (HHV-6) is a causative agent of exanthema subitum. The immunological pathogenesis of acute encephalopathy associated with HHV-6 infection is still unclear. We measured the concentrations of interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-2 (IL-2), IL-4, IL-6, IL-10, and soluble TNF receptor 1 (sTNFR1) in serum and cerebrospinal fluid (CSF) during the acute stage in 15 infants with acute encephalopathy and 12 with febrile seizures associated with HHV-6 infection. The serum IL-6, IL-10, sTNFR1, CSF IL-6, and sTNFR1 levels of infants with encephalopathy who had neurological sequelae (n=9) were significantly higher than those with febrile seizures (p=0.011, 0.043, 0.002, 0.029, and 0.005, respectively). In acute encephalopathy, serum IL-6, sTNFR1, and CSF IL-6 levels in infants with neurological sequelae were significantly higher than those without (n=6) neurological sequelae (p=0.043, 0.026, and 0.029, respectively), and serum IFN-gamma, IL-6, IL-10, and sTNFR1 levels were significantly higher than those in the CSF (p=0.037, 0.037, 0.001, and 0.021, respectively). There were no significant differences in serum or CSF cytokine levels between infants who were positive for HHV-6 DNA in the CSF (n=6) compared to those who were negative (n=9). We suggest that cytokines mediate the pathogenesis of acute encephalopathy associated with HHV-6 infection, and that the elevated levels of serum IL-6, sTNFR1, and CSF IL-6 are important for predicting neurological sequelae.

[A case of glioblastoma misdiagnosed initially due to positive finding of anti-glutamate receptor antibody]

A 53-year-old man was admitted to our hospital after suffering four attacks with loss of consciousness and/or topographic agnosia. Three months after the first attack, the cerebrospinal fluid analysis showed no abnormal findings. IgG-autoantibodies and IgM-autoantibodies against glutamate receptor epsilon2 (GluRepsilon2) were detected in cerebrospinal fluid and serum respectively. At that time, we diagnosed him as having limbic encephalopathy. Brain MRI revealed a high intensity lesion on T2-weighted and FLAIR images in the medial regions of the bilateral temporal lobes and splenium. A diffusion-weighted image revealed high intensity lesions which were also weakly enhanced by Gd-DTPA in the deep white matter beside the posterior horns. The patient then developed numbness in the right hand. The cerebralspinal fluid analysis, four months after the onset of the disease, exhibited slight pleocytosis and elevated protein. IgG-autoantibodies against GluRepsilon2 were detected in the serum. The lesions beside the posterior horns were ring-like enhanced more strongly. Brain biopsy led to a diagnosis of glioblastoma. We suggest that patients with autoantibodies against GluRepsilon2 should be carefully diagnosed with limbic encephalopathy associated with autoimmune mechanisms even if radiological findings are typical of the disease.

Neuropathological studies of patients with possible non-herpetic acute limbic encephalitis and so-called acute juvenile female non-herpetic encephalitis

OBJECTIVE

This study was to clarify the neuropathological findings of non-herpetic acute limbic encephalitis (NHALE) and so-called acute juvenile female non-herpetic encephalitis (AJFNHE).

METHODS

We examined three rare autopsied cases consisting of probable one NHALE and two AJFNHLE. For comparison, we also studied 10 autopsied cases of hippocampal sclerosis mainly caused by anoxia.

RESULTS

In NHALE, neuronal loss with gliosis and microglia/macrophage infiltrations were mainly seen in the CA1 areas in the hippocampus. However, there were no apparent anoxic neuronal changes in the remaining neurons in the CA1, and astrocyte proliferations and microglia/macrophage infiltrations were also observed in the claustrum, while these were mildly present in the basal ganglia. In AJFNHE, pathological findings differed from those of NHALE with regard of the absence of limited pathology in the limbic system, microglia/macrophages widely infiltrated the brain including the hippocampal areas and mild lymphocytic infiltrations were observed in the subarachnoid spaces as well as in the parenchyma.

CONCLUSIONS

The pathomechanism of NHALE and AJFNHE is obscure and autoimmune theory is proposed, however we must collect and examine many autopsied cases in order to clarify the pathomechanism.

Autoantibodies against Glutamate Receptor ε2-Subunit Detected in a Subgroup of Patients with Reversible Autoimmune Limbic Encephalitis

We investigated the presence of autoantibodies against glutamate receptor (GluR) epsilon2 in serum and cerebrospinal fluid (CSF) samples from 12 consecutive patients with acute encephalitis/encephalopathy by immunoblotting using recombinant GluR epsilon2 as antigen. In 4 patients, IgM autoantibodies against GluR epsilon2 were detected in CSF in the early phase of the disease but were not detectable after several months. Seizures and psychiatric symptoms were noted during the acute phase of the disease in these 4 patients, who showed various degrees of residual amnesia. Immunotherapy was performed on 3 patients (patients 1, 3 and 4), and they showed marked improvements. Immunohistochemistry using these patients' sera showed that immunoreactivity is specifically detected in the cytoplasm of rat hippocampal and cortical neurons. The clinical features and neuroimaging findings of patients with IgM autoantibodies against GluR epsilon2 in CSF resemble those of patients with reversible autoimmune limbic encephalitis.

Limbic encephalitis: a cause of temporal lobe epilepsy with onset in adult life

Limbic encephalitis (LE) was described in the 1960s as a clinical-pathological syndrome in adults. Initially, the paraneoplastic form was the center of interest. An increasing number of diagnostically valuable autoantibodies in patients' sera (and cerebrospinal fluid) have been identified. Lately, the impact of non-paraneoplastic LE cases has been acknowledged. In the serum of some of these patients, antibodies against voltage-dependent potassium channels (VGKC antibodies) have been detected. The characteristic MRI course of LE patients has recently been described in detail: hippocampal swelling and T2/FLAIR signal increase are early findings. After a few months, the swelling regresses, followed by hippocampal atrophy with continuous signal increase. A general consensus on formal diagnostic criteria for all LE subsyndromes has not yet been reached. This article proposes such diagnostic criteria and formulates suggestions for treatment.

Paraneoplastic limbic encephalitis caused by ovarian teratoma with autoantibodies to glutamate receptor

We report a rare case of paraneoplastic limbic encephalitis with autoantibodies to glutamate receptor (GluR) in the cerebrospinal fluid (CSF). The 35-year-old woman with consciousness disturbance was diagnosed initially as non-herpetic encephalitis. Her signs and symptoms improved with acyclovir and steroid pulse therapy. However, after the treatment, an ovarian tumor was discovered, and we detected autoantibodies to GluR in the CSF. A possible association between the ovarian teratoma and GluR is suggested.

Acute limbic encephalitis: a new entity?

Clinical cases similar to herpes simplex virus (HSV) encephalitis have accumulated in Japan. Detailed examinations have failed to demonstrate HSV infection. Recently, these cases have been named "non-herpetic acute limbic encephalitis". Only a single autopsy case was so far reported in an abstract form, because many cases showed a good prognosis. The case presented here was that following fever, a 59-year-old woman developed disturbance of consciousness and uncontrollable generalized seizures. Brain MRI revealed abnormal signals in the bilateral medial temporal lobe and along the lateral part of the putamen. Autoantibody against the NMDA glutamate receptor (GluR) IgM-epsilon2 was detected in the serum, and the GluR IgG-delta2 antibody was positive in cerebrospinal fluid. She died 12 days after onset. An autopsy examination revealed scattered foci consisting of neuronal loss, neuronophagia and some perivascular lymphocytic infiltration in the hippocampus and amygdala, but no haemorrhagic necrosis in the brain. HSV-1, -2 and human herpes virus-6 were negative immunohistochemically. We believe that our autopsy case may contribute to understanding the neuropathological background of non-herpetic acute limbic encephalitis.

Herpes simplex encephalitis presenting with bilateral hippocampal lesions on magnetic resonance imaging, simultaneously complicated by small cell lung carcinoma

We report a 75-year-old man who developed herpes simplex encephalitis (HSE), presenting with bilateral hippocampal lesions on magnetic resonance imaging, and this case was simultaneously complicated by small cell lung carcinoma. We identified a new anti-neuronal antibody in the cerebrospinal fluid of this patient. Our findings suggest that HSE and paraneoplastic limbic encephalitis (PLE) can overlap, and we discuss the relationships of HSE, PLE, and related disorders.