Mechanisms of epileptogenesis in pediatric epileptic syndromes: Rasmussen encephalitis, infantile spasms, and febrile infection-related epilepsy syndrome (FIRES)

[FIRES Syndrome in a Preschool Child]

Severe epileptic syndromes of childhood are an urgent problem for pediatric neurologists and neuroresuscitators. The article presents a clinical observation of FIRES syndrome in a pediatric patient, which is a form of severe drug-resistant epilepsy in children of preschool and school age, the development of which is caused by hyperthermia, probably associated with herpesvirus (human herpesvirus type 6) infection. The features of the progressive course and the difficulties of diagnostic search are reflected. An empirical approach to etiotropic therapy is described, since the disease manifested itself with respiratory manifestations and fever. The tactic of pathogenetic treatment is described, in which drugs of polyfunctional action, such as Cytoflavin, have a priority, many years of experience in the use of which allows the authors to recommend it as a starting intensive therapy.

Factors not considered in the study of drug-resistant epilepsy: Drug-resistant epilepsy: assessment of neuroinflammation

More than one‐third of people with epilepsy develop drug‐resistant epilepsy (DRE). Different hypotheses have been proposed to explain the origin of DRE. Accumulating evidence suggests the contribution of neuroinflammation, modifications in the integrity of the blood‐brain barrier (BBB), and altered immune responses in the pathophysiology of DRE. The inflammatory response is mainly due to the increase of cytokines and related molecules; these molecules have neuromodulatory effects that contribute to hyperexcitability in neural networks that cause seizure generation. Some patients with DRE display the presence of autoantibodies in the serum and mainly cerebrospinal fluid. These patients are refractory to the different treatments with standard antiseizure medications (ASMs), and they could be responding well to immunomodulatory therapies. This observation emphasizes that the etiopathogenesis of DRE is involved with immunology responses and associated long‐term events and chronic inflammation processes. Furthermore, multiple studies have shown that functional polymorphisms as risk factors are involved in inflammation processes. Several relevant polymorphisms could be considered risk factors involved in inflammation‐related DRE such as receptor for advanced glycation end products (RAGE) and interleukin 1β (IL‐1β). All these evidences sustained the hypothesis that the chronic inflammation process is associated with the DRE. However, the effect of the chronic inflammation process should be investigated in further clinical studies to promote the development of novel therapeutics useful in treatment of DRE.

Brain Magnetic Resonance Imaging Findings in Infantile Spasms

Background: Infantile spasms are an age-specific epileptic disorder. They occur in infancy and early childhood. They can be caused by multiple etiologies. Structural abnormalities represent an important cause of infantile spasms. Brain magnetic resonance imaging (MRI) is one of the integral modalities in the evaluation of this condition. Purpose: The aim of this study is to review and analyze the clinical characteristics and brain MRI findings in a cohort of children diagnosed with infantile spasms. Material and Methods: A cohort of fifty-six children diagnosed with infantile spasms in infancy and early childhood was included. All of them underwent brain MRI for evaluation. The study was conducted in the period from January 2016 to January 2020. Results: Females comprised 57% of the cohort. The mean age for seizure onset was 5.9 months (SD 2.7). Forty-one patients (73%) had active epilepsy, and 51% were diagnosed with global developmental delay. Consanguinity was present in 59% of the cohort. Most of the follow-up MRIs showed structural abnormalities (84%). Hypoxia was reported in 17% of MRIs. Malformations of cortical development were seen in five patients. Brain MRI findings were normal in 16% of patients, and delayed myelination was seen in nineteen patients. Most of the children with active epilepsy (64%) and developmental delay (82%) had an abnormal brain MRI. It was noticed that abnormal second brain MRIs were more likely to be associated with active epilepsy and developmental delay (p = 0.05). Conclusions: Brain MRI is an integral part of infantile spasms’ clinical evaluation. Infantile spasms and abnormal brain MRI can be associated with active epilepsy and global developmental delay.

Genetic Factors in Rasmussen's Encephalitis Characterized by Whole-Exome Sequencing

Rasmussen’s encephalitis (RE) is a rare chronic neurological disorder characterized by unihemispheric brain atrophy and epileptic seizures. The mechanisms of RE are complex. Adaptive immunity, innate immunity and viral infection are all involved in the development of RE. However, there are few studies on the role of genetic factors in the mechanisms of RE. Thus, the objective of this study was to reveal the genetic factors in the mechanisms of RE. Whole-exome sequencing (WES) was performed in 15 RE patients. Ten patients with temporal lobe epilepsy (TLE), which is a common and frequently intractable seizure disorder, were used as the controls. Thirty-one non-silent single nucleotide variants (SNVs) affecting 16 genes were identified in the RE cases. The functions of the genes with SNVs were associated with antigen presentation, antiviral infection, epilepsy, schizophrenia and nerve cell regeneration. Genetic factors of RE were found first in this study. These results suggest that RE patients have congenital abnormalities in adaptive immunity and are susceptible to some harmful factors, which lead to polygenic abnormal disease.

Screening of prototype antiseizure and anti-inflammatory compounds in the Theiler's murine encephalomyelitis virus model of epilepsy

OBJECTIVE

Infection with Theiler's murine encephalomyelitis virus (TMEV) in C57Bl/6J mice results in handling-induced seizures and is useful for evaluating compounds effective against infection-induced seizures. However, to date only a few compounds have been evaluated in this model, and a comprehensive study of antiseizure medications (ASMs) has not yet been performed. Furthermore, as the TMEV infection produces marked neuroinflammation, an evaluation of prototype anti-inflammatory compounds is needed as well.

METHODS

Male C57Bl/6J mice were inoculated with TMEV (day 0) followed by daily administrations of test compounds (day 3-7) and subsequent handling sessions (day 3-7). Doses of ASMs, comprising several mechanistic classes, were selected based on previously published data demonstrating the effect of these compounds in reducing seizures in the 6 Hz model of pharmacoresistant seizures. Doses of anti-inflammatory compounds, comprising several mechanistic classes, were selected based on published evidence of reduction of inflammation or inflammation-related endpoints.

RESULTS

Several prototype ASMs reduced acute seizures following TMEV infection: lacosamide, phenytoin, ezogabine, phenobarbital, tiagabine, gabapentin, levetiracetam, topiramate, and sodium valproate. Of these, phenobarbital and sodium valproate had the greatest effect (>95% seizure burden reduction). Prototype anti-inflammatory drugs celecoxib, dexamethasone, and prednisone also moderately reduced seizure burden.

SIGNIFICANCE

The TMEV model is utilized by the Epilepsy Therapy Screening Program (ETSP) as a tool for evaluation of novel compounds. Compounds reducing seizures in the TMEV comprise distinct mechanistic classes, some with mechanisms of action that extend beyond traditional ASMs.

Inflammatory Diseases of the Central Nervous System

Pediatric neuroinflammatory conditions are a complex group of disorders with a wide range of clinical presentations. Patients can present with a combination of focal neurologic deficits, encephalopathy, seizures, movement disorders, or psychiatric manifestations. There are several ways that pediatric neuroinflammatory conditions can be classified, including clinical presentation, pathophysiologic mechanism, and imaging and laboratory findings. In this article, we group these conditions into acquired demyelinating diseases, immune-mediated epilepsies/encephalopathies, primary rheumatologic conditions with central nervous system (CNS) manifestations, CNS vasculitis, and neurodegenerative/genetic conditions with immune-mediated pathophysiology and discuss epidemiology, pathophysiology, clinical presentation, treatment, and prognosis of each disorder.

Seizure control after late introduction of anakinra in a patient with adult onset Rasmussen's encephalitis

Neuroinflammation has been considered an important pathophysiological process involved in epileptogenesis and may provide possibilities for new treatment possibilities. We present the case of a 45-year-old female with drug resistant epilepsy and progressive right-sided cerebral hemiatrophy associated with adult onset Rasmussen's encephalitis. Over a period of 26 years, she was treated with 14 different antiseizure medications, intravenous immunoglobulins, glucocorticosteroids, underwent two operations with focal resection and subpial transections, and tried out trigeminal nerve stimulation. Extensive blood tests, including antibodies relevant for autoimmune encephalitis, and brain biopsy did not show any signs of neuroinflammation. Eventually, the patient received the interleukin-1 receptor antagonist, anakinra. Within 1-2 days after injection, seizure frequency decreased significantly, and, after one week, the seizures stopped completely. Anakinra treatment was continued for 2 months. Stopping medication led to a relapse of seizures after 2 weeks, with a frequency of up to 45 seizures per day. Reintroduction of anakinra led to rapid recovery. Treatment with anakinra was continued for 7 months. The treatment was discontinued in April 2020, and the patient has been completely seizure free since then. There have been no other changes in antiseizure medication.

Case Report: Rituximab Improved Epileptic Spasms and EEG Abnormalities in an Infant With West Syndrome and Anti-NMDAR Encephalitis Associated With APECED

Background: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy is a rare autosomal recessive disorder caused by a mutation in the autoimmune regulator gene. Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy typically exhibit hypoparathyroidism, adrenocortical failure, and chronic mucocutaneous candidiasis. There are only a few case reports of autoimmune encephalitis during autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy, but not as an initial manifestation. Furthermore, there are no reports of patients with infantile spasms/West syndrome with autoimmune encephalitis, partly because the median age for paediatric patients with anti-N-methyl-D-aspartate receptor encephalitis, which is the most frequent and best characterised in paediatric autoimmune encephalitides, is 13–14 years. Herein, we present a case of a 3-month-old infant with autoimmune encephalitis as an initial manifestation of autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy who later developed infantile spasms/West syndrome.

Case Presentation: A 3-month-old girl was admitted to our hospital with a fever, involuntary movements in all four limbs, and right-side facial palsy. Acute central nervous system demyelination diseases were suspected from neuroimaging findings and the presence of the cerebrospinal fluid oligoclonal band. She did not respond to multiple methylprednisolone pulse therapies and later developed infantile spasms/West syndrome and diabetes mellitus. Rituximab, a chimeric mouse/human monoclonal antibody directed against human CD20 which depletes B cells, was initially administered as a treatment for autoimmune encephalitis. Unexpectedly, this treatment resulted in complete spasm cessation and resolution of hypsarrhythmia. The patient eventually showed severely delayed developmental milestones, and her electroencephalography findings showed periodic generalised slow spike-and-wave pattern.

Conclusions: Despite the limited ability to extrapolate findings from a single case, rituximab's effects may suggest that B cells play a crucial role in infantile spasms/West syndrome mechanisms; use of rituximab as an aetiology-specific treatment for infantile spasms/West syndrome patients with autoimmune encephalitis or its effectiveness for infantile spasms/West syndrome patients with other underlying mechanisms warrants further investigation.

Spontaneous remission of West syndrome associated with acute infection and fever in five patients

OBJECTIVE

We analyzed the records of 198 patients with West syndrome (WS) seen at a single pediatric neurology center in Argentina between June 2004 and June 2017. Five patients with infection-related spontaneous remission of the electroclinical manifestations were identified.

METHODS

The following parameters were investigated: personal and family history, clinical characteristics of the seizures - mainly spasms - and EEG findings, type of treatment, and outcome. The inclusion criteria for WS were epileptic spasms (ES) in clusters, hypsarrhythmia, and mental deterioration. Infants with ES without hypsarrhythmia and other epileptic encephalopathies with ES were excluded.

RESULTS

Five children, four boys and one girl, met the inclusion criteria of WS with spontaneous remission after a viral infection. The etiology of ES was unknown in four patients and one had a structural etiology. All patients had spontaneous remission of the ES and normalization of the EEG following acute upper respiratory infection in four and exanthema subitum in one; all of them had fever between 38.5 and 40 °C.

CONCLUSION

We report five patients with spontaneous remission of WS following acute viral infection, associated with a respiratory virus in four and exanthema subitum in one.

How Does the Cause of Infantile Hemiparesis Influence Other Conditioning Factors? A Preliminary Study in a Spanish Population

Infantile hemiparesis may be associated with significant morbidity and may have a profound impact on a child’s physical and social development. Infantile hemiparesis is associated with motor dysfunction as well as additional neurologic impairments, including sensory loss, mental retardation, epilepsy, and vision, hearing, or speech impairments. The objective of this study was to analyze the association between the cause of infantile hemiparesis and birth (gestational age), age of diagnosis, and associated disorders present in children with infantile hemiparesis aged 0 to 3 years. An observational and cross-sectional study was performed. A simple and anonymous questionnaire was created ad hoc for parents of children diagnosed with infantile hemiparesis aged between 0 and 3 years about the situation regarding the diagnosis of hemiparesis, birth, cause of hemiparesis, and presence of other associated disorders. Perinatal stroke (60.1%) was the most common cause of hemiparesis, and the most typical associated disorder was epilepsy (34.2%), with the second largest percentage in this dimension corresponding to an absence of associated disorders (20.7%). The most frequent birth was “no premature” (74.1%). The mean age of diagnosis of infantile hemiparesis was registered at 8 months (IQR: 0–36). Knowing the possible association between different conditioning factors and the cause of infantile hemiparesis facilitates the prevention of severe sequelae in children and family, implementing an early comprehensive therapeutic approach in children with infantile hemiparesis.

The role of inflammatory mediators in epilepsy: Focus on developmental and epileptic encephalopathies and therapeutic implications

In recent years, there has been an increasing interest in the potential involvement of neuroinflammation in the pathogenesis of epilepsy. Specifically, the role of innate immunity (that includes cytokines and chemokines) has been extensively investigated either in animal models of epilepsy and in clinical settings. Developmental and epileptic encephalopathies (DEE) are a heterogeneous group of epileptic disorders, in which uncontrolled epileptic activity results in cognitive, motor and behavioral impairment. By definition, epilepsy in DEE is poorly controlled by common antiepileptic drugs but may respond to alternative treatments, including steroids and immunomodulatory drugs. In this review, we will focus on how cytokines and chemokines play a role in the pathogenesis of DEE and why expanding our knowledge about the role of neuroinflammation in DEE may be crucial to develop new and effective targeted therapeutic strategies to prevent seizure recurrence and developmental regression.

Rasmussen's encephalitis: mechanisms update and potential therapy target

Rasmussen’s encephalitis (RE) is rare neurological diseases characterized as epilepsia partialis continua, invariably hemiparesis, and cognitive impairment. This disease is encountered frequently in childhood and presents with progressive atrophy of the unilateral hemisphere, and there are also sustained neurological complications. Owing to uncertain pathogenesis, the most effective way to limit the influence of seizures currently is cerebral hemispherectomy. In this review, we focus on four main lines of pathogenesis: virus infection, antibody-mediated, cell-mediated immunity, and microglia activation. Although one or more antigenic epitopes may give rise to infiltrating T cell responses in RE brain tissue, no exact antigen was confirmed as the definite cause of the disease. On the other hand, the appearance of antibodies related with RE seem to be a secondary pathological process. Synthetic studies have suggested an adaptive immune mechanism mediated by CD8⁺ T cells and an innate immune mechanism mediated by activated microglia and neuroglia. Accordingly, opinions have been raised that immunomodulatory treatments aimed at initial damage to the brain that are induced by cytotoxic CD8⁺ T cell lymphocytes and microglia in the early stage of RE slow down disease progression. However, systematic exploration of the theory behind these therapeutic effects based on multicenter and large sample studies are needed. In addition, dysfunction of the adenosine system, including the main adenosine removing enzyme adenosine kinase and adenosine receptors, has been demonstrated in RE, which might provide a novel therapeutic target for treatment of RE in future.

Diminished toll-like receptor response in febrile infection-related epilepsy syndrome (FIRES)

Background

Defective human TLR3 signaling causes recurrent and refractory herpes simplex encephalitis/encephalopathy. Children with febrile infection-related epilepsy syndrome with refractory seizures may have defective TLR responses.

Methods

Children with febrile infection-related epilepsy syndrome were enrolled in this study to evaluate TLR1-9 responses (IL-6, IL-8, IL-12p40, INF-α, INF-γ, and TNF-α) in their peripheral blood mononuclear cells (PBMCs) and monocyte-derived dendritic cells (MDDCs), compared to those with febrile seizures and non-refractory epilepsy with/without underlying encephalitis/encephalopathy.

Results

Adenovirus and enterovirus were found in throat cultures of enrolled patients (2–13 years) as well as serologic IgM elevation of mycoplasma pneumonia and herpes simplex virus, although neither detectable pathogens nor anti-neural autoantibodies in the CSF could be noted. Their PBMCs and MDDCs trended to have impaired TLR responses and significantly lower in cytokine profiles of TLR3, TLR4, TLR7/8, and TLR9 responses but not other TLRs despite normal TLR expressions and normal candidate genes for defective TLR3 signaling. They also had decreased naïve T and T regulatory cells, and weakened phagocytosis.

Conclusion

Children with febrile infection-related epilepsy syndrome (FIRES) could have impaired TLR3, TLR4, TLR7/8, and TLR9 responses possibly relating to their weakened phagocytosis and decreased T regulatory cells.

Arx expansion mutation perturbs cortical development by augmenting apoptosis without activating innate immunity in a mouse model of X-linked infantile spasms syndrome

X-linked infantile spasms syndrome (ISSX) is a clinically devastating developmental epileptic encephalopathy with life-long impact. Arx(GCG)10+7 , a mouse model of the most common triplet-repeat expansion mutation of ARX, exhibits neonatal spasms, electrographic phenotypes and abnormal migration of GABAergic interneuron subtypes. Neonatal presymptomatic treatment with 17β-estradiol (E2) in Arx(GCG)10+7 reduces spasms and modifies progression of epilepsy. Cortical pathology during this period, a crucial point for clinical intervention in ISSX, has largely been unexplored, and the pathogenic cellular defects that are targeted by early interventions are unknown. In the first postnatal week, we identified a transient wave of elevated apoptosis in Arx(GCG)10+7 mouse cortex that is non-Arx cell autonomous, since mutant Arx-immunoreactive (Arx+) cells are not preferentially impacted by cell death. NeuN+ (also known as Rbfox3) survival was also not impacted, suggesting a vulnerable subpopulation in the immature Arx(GCG)10+7 cortex. Inflammatory processes during this period might explain this transient elevation in apoptosis; however, transcriptomic and immunohistochemical profiling of several markers of inflammation revealed no innate immune activation in Arx(GCG)10+7 cortex. Neither neonatal E2 hormone therapy, nor ACTH(1-24), the frontline clinical therapy for ISSX, diminished the augmented apoptosis in Arx(GCG)10+7 , but both rescued neocortical Arx+ cell density. Since early E2 treatment effectively prevents seizures in this model, enhanced apoptosis does not solely account for the seizure phenotype, but may contribute to other aberrant brain function in ISSX. However, since both hormone therapies, E2 and ACTH(1-24), elevate the density of cortical Arx+-interneurons, their early therapeutic role in other neurological disorders hallmarked by interneuronopathy should be explored.This article has an associated First Person interview with the first author of the paper.

Emerging roles for the intestinal microbiome in epilepsy

The gut microbiome is emerging as a key regulator of brain function and behavior and is associated with symptoms of several neurological disorders. There is emerging evidence that alterations in the gut microbiota are seen in epilepsy and in response to seizure interventions. In this review, we highlight recent studies reporting that individuals with refractory epilepsy exhibit altered composition of the gut microbiota. We further discuss antibiotic treatment and infection as microbiome-related factors that influence seizure susceptibility in humans and animal models. In addition, we evaluate how the microbiome may mediate effects of the ketogenic diet, probiotic treatment, and anti-epileptic drugs on reducing both seizure frequency and severity. Finally, we assess the open questions in interrogating roles for the microbiome in epilepsy and address the prospect that continued research may uncover fundamental insights for understanding risk factors for epilepsy, as well as novel approaches for treating refractory epilepsy.

Epilepsy Benchmarks Area III: Improved Treatment Options for Controlling Seizures and Epilepsy-Related Conditions Without Side Effects

The goals of Epilepsy Benchmark Area III involve identifying areas that are ripe for progress in terms of controlling seizures and patient symptoms in light of the most recent advances in both basic and clinical research. These goals were developed with an emphasis on potential new therapeutic strategies that will reduce seizure burden and improve quality of life for patients with epilepsy. In particular, we continue to support the proposition that a better understanding of how seizures are initiated, propagated, and terminated in different forms of epilepsy is central to enabling new approaches to treatment, including pharmacological as well as surgical and device-oriented approaches. The stubbornly high rate of treatment-resistant epilepsy—one-third of patients—emphasizes the urgent need for new therapeutic strategies, including pharmacological, procedural, device linked, and genetic. The development of new approaches can be advanced by better animal models of seizure initiation that represent salient features of human epilepsy, as well as humanized models such as induced pluripotent stem cells and organoids. The rapid advances in genetic understanding of a subset of epilepsies provide a path to new and direct patient-relevant cellular and animal models, which could catalyze conceptualization of new treatments that may be broadly applicable across multiple forms of epilepsies beyond those arising from variation in a single gene. Remarkable advances in machine learning algorithms and miniaturization of devices and increases in computational power together provide an enhanced opportunity to detect and mitigate seizures in real time via devices that interrupt electrical activity directly or administer effective pharmaceuticals. Each of these potential areas for advance will be discussed in turn.

Efficacy and tolerability of mycophenolate mofetil in a pediatric Rasmussen syndrome

Rasmussen syndrome (RS) is a chronic encephalopathy with uncertain etiology and immune-mediated pathogenesis. The only definitive treatment is represented by functional hemispherectomy. We describe the case of a 6.5-year-old female patient who developed several episodes of focal, unilateral clonic seizures. Following laboratory and instrumental investigations, the patient was diagnosed as having RS. A treatment with corticosteroids, intravenous immunoglobulin, and the antiseizure medication (carbamazepine and levetiracetam) did not completely control the seizures. Therefore, the patient was treated with mycophenolate mofetil (MMF), showing a good clinical response, with reduction of the seizures, and stability of the radiological findings. This case suggests the potential utility of MMF in the immune approach to RS.

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Rasmussen encephalitis (RE) is an immune-mediated disease of unknown etiology.

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Current definitive treatment for RE is represented by hemispherectomy.

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The immune approach of RE has been performed with several agents.

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In this case, mycophenolate mofetil was successfully used in a patient with RE.

De Novo Germline Mutations in SEMA5A Associated With Infantile Spasms

Infantile spasm (IS) is an early-onset epileptic encephalopathy that usually presents with hypsarrhythmia on an electroencephalogram with developmental impairment or regression. In this study, whole-exome sequencing was performed to detect potential pathogenic de novo mutations, and finally we identified a novel damaging de novo mutation in SEMA5A and a compound heterozygous mutation in CLTCL1 in three sporadic trios with IS. The expression profiling of SEMA5A in the human brain showed that it was mainly highly expressed in the cerebral cortex, during the early brain development stage (8 to 9 post-conception weeks and 0 to 5 months after birth). In addition, we identified a close protein-protein interaction network between SEMA5A and candidate genes associated with epilepsy, autism spectrum disorder (ASD) or intellectual disability. Gene enrichment and function analysis demonstrated that genes interacting with SEMA5A were significantly enriched in several brain regions across early fetal development, including the cortex, cerebellum, striatum and thalamus (q < 0.05), and were involved in axonal, neuronal and synapse-associated processes. Furthermore, SEMA5A and its interacting genes were associated with ASD, epilepsy syndrome and developmental disorders of mental health. Our results provide insightful information indicating that SEMA5A may contribute to the development of the brain and is associated with IS. However, further genetic studies are still needed to evaluate the role of SEMA5A in IS to definitively establish the role of SEMA5A in this disorder.

The short-term and long-term outcome of febrile infection-related epilepsy syndrome in children

BACKGROUND

The febrile infection-related epilepsy syndrome (FIRES) is a catastrophic epileptic encephalopathy which developed the refractory status epilepticus following or during a nonspecific febrile illness. To analyze the short-term and long-term outcome of FIRES in the children, we retrospectively analyzed the related data.

METHODS

The motor outcome was evaluated by modified Rankin scale (mRS). Poor motor outcome was defined as a mRS score of 4 or higher at discharge. Significant motor decline was defined as the mRS difference more than 2 before hospital admission and at discharge.

RESULTS

We totally enrolled 25 patients for analysis. Four patients were expired during hospitalization, and one patient was lost to follow-up after discharge. Therefore, a total 20 patients were finally analyzed. The age of disease onset ranged from 1.6 to 17.2 years (mean: 9.6 ± 4.4 years). Newly acquired epilepsy and cognitive deficit occurred in 100% and 61%, respectively. The duration of the anesthetic agents ranged from 7 to 149 days (mean: 34.2 ± 36.1 days). The duration of anesthetic agent usage (p = 0.011), refractory epilepsy (p = 0.003), and the use of ketogenic diet (p = 0.004) were significantly associated with the poor long-term motor outcome, and the number of anesthetic agents tended to be associated with the poor long-term motor outcome (p = 0.050). In-hospital mortality was 16%. Significant functional decline at discharge occurred in 100%. However, there was improvement in long-term follow-up.

CONCLUSION

The outcome of FIRES is poor with significant mortality and morbidities. Refractory epilepsy with cognitive deficit in survived cases is common, but improvement is possible.

Central nervous system lymphatic unit, immunity, and epilepsy: Is there a link?

The recent definition of a network of lymphatic vessels in the meninges surrounding the brain and the spinal cord has advanced our knowledge on the functional anatomy of fluid movement within the central nervous system (CNS). Meningeal lymphatic vessels along dural sinuses and main nerves contribute to cerebrospinal fluid (CSF) drainage, integrating the cerebrovascular and periventricular routes, and forming a circuit that we here define as the CNS-lymphatic unit. The latter unit is important for parenchymal waste clearance, brain homeostasis, and the regulation of immune or inflammatory processes within the brain. Disruption of fluid drain mechanisms may promote or sustain CNS disease, conceivably applicable to epilepsy where extracellular accumulation of macromolecules and metabolic by-products occur in the interstitial and perivascular spaces. Herein we address an emerging concept and propose a theoretical framework on: (a) how a defect of brain clearance of macromolecules could favor neuronal hyperexcitability and seizures, and (b) whether meningeal lymphatic vessel dysfunction contributes to the neuroimmune cross-talk in epileptic pathophysiology. We propose possible molecular interventions targeting meningeal lymphatic dysfunctions, a potential target for immune-mediated epilepsy.

Infections and risk of epilepsy in children and young adults: A nationwide study

OBJECTIVE

The development of epilepsy has been linked to infections of the central nervous system, but recently also to infections and inflammation outside of the central nervous system. Thus we investigated the association between infections and the risk of subsequent epilepsy.

METHODS

This was a Danish nationwide population-based cohort study comprising a total of 1 938 555 individuals born between 1982 and 2012. Individuals were followed from birth until December 31, 2012, death, disappearance, emigration, or epilepsy diagnosis, whichever came first (28 512 666 person-years of follow-up). The exposure was hospital contacts for infection and the outcome was a diagnosis of epilepsy as recorded in the Danish National Hospital Register. Hazard ratios were calculated using Cox proportional hazards models adjusted for age, sex, calendar period, Apgar score, gestational age, birth weight, and parental history of epilepsy.

RESULTS

A total of 25 825 individuals received an epilepsy diagnosis during the study period, among whom 8235 (32%) had a previous hospital contact for infection. A hospital contact for infection was associated with a 78% increase in the risk of subsequently receiving an epilepsy diagnosis (hazard ratio 1.78, 95% confidence interval [CI] 1.73-1.83) compared with those without infection. The highest risk was observed after central nervous system infections (hazard ratio 4.97, 95% CI 4.42-5.59), but increased risks were identified across all infected organ systems and types of pathogens. The risk of receiving an epilepsy diagnosis was correlated with the temporal proximity of the infection (P < 0.001) and increased with the number of hospital contacts for infection (P < 0.001) and with the severity of infection (P < 0.001).

SIGNIFICANCE

The risk of receiving an epilepsy diagnosis was increased after a wide range of infections, suggesting that systemic inflammatory processes may be involved in the development of epilepsy.

Metabolic etiologies in West syndrome

West syndrome (WS) is an early life epileptic encephalopathy associated with infantile spasms, interictal electroencephalography (EEG) abnormalities including high amplitude, disorganized background with multifocal epileptic spikes (hypsarrhythmia), and often neurodevelopmental impairments. Approximately 64% of the patients have structural, metabolic, genetic, or infectious etiologies and, in the rest, the etiology is unknown. Here we review the contribution of etiologies due to various metabolic disorders in the pathology of WS. These may include metabolic errors in organic molecules involved in amino acid and glucose metabolism, fatty acid oxidation, metal metabolism, pyridoxine deficiency or dependency, or acidurias in organelles such as mitochondria and lysosomes. We discuss the biochemical, clinical, and EEG features of these disorders as well as the evidence of how they may be implicated in the pathogenesis and treatment of WS. The early recognition of these etiologies in some cases may permit early interventions that may improve the course of the disease.

Febrile Infection-Related Epilepsy Syndrome (FIRES), a possible cause of super-refractory status epilepticus. Case report

Introducción: El estado epiléptico superrefractario (EES) es una patología con importante morbimortalidad que afecta el ambiente neuronal según el tipo y duración de las crisis.Presentación del caso: Se presenta el caso de un escolar con estado epiléptico superrefractario y crisis multifocales. Se descartaron causas metabólicas, estructurales, infecciosas, toxicológicas y autoinmunes y se utilizaron diferentes manejos anticonvulsivantes sin respuesta, lográndose control de las crisis 6 semanas después del ingreso a UCI. Se realizó un seguimiento de 12 años, periodo en el que el paciente presentó múltiples recaídas del estado epiléptico asociadas a la presencia de epilepsia refractaria con múltiples tipos de crisis, en su mayoría vegetativas; además se dio involución cognitiva.Discusión: Esta forma de estado epiléptico corresponde al síndrome de estado epiléptico facilitado por fiebre (FIRES), entidad de posible origen inmunológico conocida por ser refractaria al tratamiento agudo y al manejo cró- nico de la epilepsia y que se presenta como secuela. Su evolución no se ha descrito a largo plazo y por tanto no hay consenso sobre el manejo en la fase crónica.Conclusión: Es importante considerar esta etiología en estado epiléptico superrefractario para utilizar de forma temprana diferentes estrategias terapéuticas, como la dieta cetogénica, que permitan, por un lado, controlar su condición crítica y las crisis epilépticas a largo plazo y, por el otro, mejorar el pronóstico cognitivo, logrando así un impacto en la calidad de vida.

[Immunological mechanism of prednisone in the treatment of infantile spasm]

OBJECTIVE

To investigate the immunological mechanism of prednisone in the treatment of infantile spasm (IS) by evaluating the immune function of IS children before and after treatment.

METHODS

Thirty children with IS were enrolled as IS group. Thirty healthy infants who underwent physical examination were enrolled as healthy control group. Fasting venous blood was collected for both groups before and after prednisone treatment. Chemiluminescence was used to measure serum levels of interleukin-1B (IL-1B), interleukin-2R (IL-2R), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α). Immunoturbidimetric assay was used to measure serum levels of immunoglobulin A (IgA), immunoglobulin M (IgM), and immunoglobulin G (IgG). Flow cytometry was used to measure the percentages of T lymphocyte subsets (CD3⁺, CD4⁺, and CD8⁺). The clinical outcome and electroencephalographic findings were evaluated for all IS children after prednisone treatment.

RESULTS

The IS group had significantly higher serum levels of IL-2R, IL-8, and TNF-α than the healthy control group before treatment (P<0.05). The mean number of daily ictal clusters was positively correlated with the levels of IL-2R, IL-8, and TNF-α in IS children, the mean number of total daily seizures was positively correlated with IL-8 level, and any two indices out of IL-2R, IL-8, and TNF-α were positively correlated with each other (P<0.05). Among the 30 IS children treated with prednisone, 19 achieved seizure control; electroencephalography showed that 18 children achieved complete remission of hyperarrhythmia. After treatment, the IS group had significant reductions in the numbers of daily ictal clusters and total daily seizures, significant improvement in developmental quotient (P<0.05), and significant reductions in serum levels of IL-2R, L-8, and TNF-α, the percentage of CD4⁺ T lymphocytes, and CD4⁺/CD8⁺ ratio (P<0.05), as well as a significant increase in the percentage of CD8⁺ T lymphocytes (P<0.05).

CONCLUSIONS

IS children have immune dysfunction. Prednisone can control seizures in IS children, possibly by regulating and improving immune dysfunction.

Neuroinflammation in epileptogenesis: Insights and translational perspectives from new models of epilepsy

Animal models have provided a wealth of information on mechanisms of epileptogenesis and comorbidogenesis, and have significantly advanced our ability to investigate the potential of new therapies. Processes implicating brain inflammation have been increasingly observed in epilepsy research. Herein we discuss the progress on animal models of epilepsy and comorbidities that inform us on the potential role of inflammation in epileptogenesis and comorbidity pathogenesis in rodent models of West syndrome and the Theiler's murine encephalomyelitis virus (TMEV) mouse model of viral encephalitis-induced epilepsy. Rat models of infantile spasms were generated in rat pups after right intracerebral injections of proinflammatory compounds (lipopolysaccharides with or without doxorubicin, or cytokines) and were longitudinally monitored for epileptic spasms and neurodevelopmental and cognitive deficits. Anti-inflammatory treatments were tested after the onset of spasms. The TMEV mouse model was induced with intracerebral administration of TMEV and prospective monitoring for handling-induced seizures or seizure susceptibility, as well as long-term evaluations of behavioral comorbidities of epilepsy. Inflammatory processes are evident in both models and are implicated in the pathogenesis of the observed seizures and comorbidities. A common feature of these models, based on the data so far available, is their pharmacoresistant profile. The presented data support the role of inflammatory pathways in epileptogenesis and comorbidities in two distinct epilepsy models. Pharmacoresistance is a common feature of both inflammation-based models. Utilization of these models may facilitate the identification of age-specific, syndrome- or etiology-specific therapies for the epilepsies and attendant comorbidities, including the drug-resistant forms.

Preclinical Screening for Treatments for Infantile Spasms in the Multiple Hit Rat Model of Infantile Spasms: An Update

Infantile spasms are the typical seizures of West syndrome, an infantile epileptic encephalopathy with poor outcomes. There is an increasing need to identify more effective and better tolerated treatments for infantile spasms. We have optimized the rat model of infantile spasms due to structural etiology, the multiple-hit rat model, for therapy discovery. Here, we test three compounds administered after spasms induction in the multiple hit model for efficacy and tolerability. Specifically, postnatal day 3 (PN3) male Sprague-Dawley rats were induced by right intracerebral injections of doxorubicin and lipopolysaccharide. On PN5 p-chlorophenylalanine was given intraperitoneally (i.p.). Daily monitoring of weights and developmental milestones was done and rats were intermittently video monitored. A blinded, randomized, vehicle-controlled study design was followed. The caspase 1 inhibitor VX-765 (50-200 mg/kg i.p.) and the GABA_B receptor inhibitor CGP35348 (12.5-100 mg/kg i.p.) each was administered in different cohorts as single intraperitoneal injections on PN4, using a dose- and time-response design with intermittent monitoring till PN5. 17β-estradiol (40 ng/g/day subcutaneously) was given daily between PN3-10 and intermittent monitoring was done till PN12. None of the treatments demonstrated acute or delayed effects on spasms, yet all were well tolerated. We discuss the implications for therapy discovery and challenges of replication trials.

Inflammation in Epileptic Encephalopathies

West syndrome (WS) is an infantile epileptic encephalopathy that manifests with infantile spasms (IS), hypsarrhythmia (in ~60% of infants), and poor neurodevelopmental outcomes. The etiologies of WS can be structural-metabolic pathologies (~60%), genetic (12%-15%), or of unknown origin. The current treatment options include hormonal treatment (adrenocorticotropic hormone and high-dose steroids) and the GABA aminotransferase inhibitor vigabatrin, while ketogenic diet can be given as add-on treatment in refractory IS. There is a need to identify new therapeutic targets and more effective treatments for WS. Theories about the role of inflammatory pathways in the pathogenesis and treatment of WS have emerged, being supported by both clinical and preclinical data from animal models of WS. Ongoing advances in genetics have revealed numerous genes involved in the pathogenesis of WS, including genes directly or indirectly involved in inflammation. Inflammatory pathways also interact with other signaling pathways implicated in WS, such as the neuroendocrine pathway. Furthermore, seizures may also activate proinflammatory pathways raising the possibility that inflammation can be a consequence of seizures and epileptogenic processes. With this targeted review, we plan to discuss the evidence pro and against the following key questions. Does activation of inflammatory pathways in the brain cause epilepsy in WS and does it contribute to the associated comorbidities and progression? Can activation of certain inflammatory pathways be a compensatory or protective event? Are there interactions between inflammation and the neuroendocrine system that contribute to the pathogenesis of WS? Does activation of brain inflammatory signaling pathways contribute to the transition of WS to Lennox-Gastaut syndrome? Are there any lead candidates or unexplored targets for future therapy development for WS targeting inflammation?

Moyamoya in a Patient with FIRES: A First Case Report

Febrile infection-related epilepsy syndrome (FIRES) is a form of epileptic encephalopathy with severe refractory epilepsy that presents in previously healthy, school-aged children after significant febrile illness with concomitant rise in body temperature. Suspected causes include genetic or acquired channelopathies, as well as mitochondrial disturbances. In FIRES, the EEG shows diffuse slowing, generalized, and/or multifocal discharges. Seizures are present and resistant to treatment. Moyamoya angiopathy (MMA) is characterized by progressive stenosis of cerebral arteries and subsequent development of a network of collateral circulation that is prone to rupture. We present here a case of a 6-year-old patient with a postfebrile illness, acute and explosive bilateral independent seizure onset that was most consistent with FIRES, but also with imaging evidence of right-sided-only MMA. Our patient demonstrated two diseases not described together previously in the literature. It is unknown whether this patient's MMA is related to FIRES. In spite of successful corrective surgery (encephaloduroarteriosynangiosis), the patient continues to suffer from intractable seizures (mostly on the right) and apparent mild encephalopathy. The impact of our interventions (surgery, antiepileptic medication) is unclear. In this article, we describe a case of MMA and FIRES, and the history, physical, laboratory, imaging, and developmental elements of the 6-year-old patient with previously normal development.

Shared HLA Class I and II Alleles and Clonally Restricted Public and Private Brain-Infiltrating αβ T Cells in a Cohort of Rasmussen Encephalitis Surgery Patients

Rasmussen encephalitis (RE) is a rare pediatric neuroinflammatory disease characterized by intractable seizures and unilateral brain atrophy. T cell infiltrates in affected brain tissue and the presence of circulating autoantibodies in some RE patients have indicated that RE may be an autoimmune disease. The strongest genetic links to autoimmunity reside in the MHC locus, therefore, we determined the human leukocyte antigen (HLA) class I and class II alleles carried by a cohort of 24 RE surgery cases by targeted in-depth genomic sequencing. Compared with a reference population the allelic frequency of three alleles, DQA1*04:01:01, DQB1*04:02:01, and HLA-C*07:02:01:01 indicated that they might confer susceptibility to the disease. It has been reported that HLA-C*07:02 is a risk factor for Graves disease. Further, eight patients in the study cohort carried HLA-A*03:01:01:01, which has been linked to susceptibility to multiple sclerosis. Four patients carried a combination of three HLA class II alleles that has been linked to type 1 diabetes (DQA1*05:01:01:01~DQB1*02:01:01~DRB1*03:01:01:01), and five patients carried a combination of HLA class II alleles that has been linked to the risk of contracting multiple sclerosis (DQA1*01:02:01:01, DQB1*06:02:01, DRB1*15:01:01:01). We also analyzed the diversity of αβ T cells in brain and blood specimens from 14 of these RE surgery cases by sequencing the third complementarity regions (CDR3s) of rearranged T cell receptor β genes. A total of 31 unique CDR3 sequences accounted for the top 5% of all CDR3 sequences in the 14 brain specimens. Thirteen of these sequences were found in sequencing data from healthy blood donors; the remaining 18 sequences were patient specific. These observations provide evidence for the clonal expansion of public and private T cells in the brain, which might be influenced by the RE patient’s HLA haplotype.

Next-generation sequencing in neuropathologic diagnosis of infections of the nervous system

Objective:

To determine the feasibility of next-generation sequencing (NGS) microbiome approaches in the diagnosis of infectious disorders in brain or spinal cord biopsies in patients with suspected CNS infections.

Methods:

In a prospective pilot study, we applied NGS in combination with a new computational analysis pipeline to detect the presence of pathogenic microbes in brain or spinal cord biopsies from 10 patients with neurologic problems indicating possible infection but for whom conventional clinical and microbiology studies yielded negative or inconclusive results.

Results:

Direct DNA and RNA sequencing of brain tissue biopsies generated 8.3 million to 29.1 million sequence reads per sample, which successfully identified with high confidence the infectious agent in 3 patients for whom validation techniques confirmed the pathogens identified by NGS. Although NGS was unable to identify with precision infectious agents in the remaining cases, it contributed to the understanding of neuropathologic processes in 5 others, demonstrating the power of large-scale unbiased sequencing as a novel diagnostic tool. Clinical outcomes were consistent with the findings yielded by NGS on the presence or absence of an infectious pathogenic process in 8 of 10 cases, and were noncontributory in the remaining 2.

Conclusions:

NGS-guided metagenomic studies of brain, spinal cord, or meningeal biopsies offer the possibility for dramatic improvements in our ability to detect (or rule out) a wide range of CNS pathogens, with potential benefits in speed, sensitivity, and cost. NGS-based microbiome approaches present a major new opportunity to investigate the potential role of infectious pathogens in the pathogenesis of neuroinflammatory disorders.

Descriptive study of symptomatic epilepsy by age of onset in patients with a 3-year follow-up at the Neuropaediatric Department of a reference centre

OBJECTIVE

We conducted a descriptive study of symptomatic epilepsy by age at onset in a cohort of patients who were followed up at a neuropaediatric department of a reference hospital over a 3-year period PATIENTS AND METHODS: We included all children with epilepsy who were followed up from January 1, 2008 to December 31, 2010 RESULTS: Of the 4595 children seen during the study period, 605 (13.17%) were diagnosed with epilepsy; 277 (45.79%) of these had symptomatic epilepsy. Symptomatic epilepsy accounted for 67.72% and 61.39% of all epilepsies starting before one year of age, or between the ages of one and 3, respectively. The aetiologies of symptomatic epilepsy in our sample were: prenatal encephalopathies (24.46% of all epileptic patients), perinatal encephalopathies (9.26%), post-natal encephalopathies (3.14%), metabolic and degenerative encephalopathies (1.98%), mesial temporal sclerosis (1.32%), neurocutaneous syndromes (2.64%), vascular malformations (0.17%), cavernomas (0.17%), and intracranial tumours (2.48%). In some aetiologies, seizures begin before the age of one; these include Down syndrome, genetic lissencephaly, congenital cytomegalovirus infection, hypoxic-ischaemic encephalopathy, metabolic encephalopathies, and tuberous sclerosis.

CONCLUSIONS

The lack of a universally accepted classification of epileptic syndromes makes it difficult to compare series from different studies. We suggest that all epilepsies are symptomatic because they have a cause, whether genetic or acquired. The age of onset may point to specific aetiologies. Classifying epilepsy by aetiology might be a useful approach. We could establish 2 groups: a large group including epileptic syndromes with known aetiologies or associated with genetic syndromes which are very likely to cause epilepsy, and another group including epileptic syndromes with no known cause. Thanks to the advances in neuroimaging and genetics, the latter group is expected to become increasingly smaller.

Evidence for Resident Memory T Cells in Rasmussen Encephalitis

Rasmussen encephalitis (RE) is a rare pediatric neuroinflammatory disease of unknown etiology characterized by intractable seizures, and progressive atrophy usually confined to one cerebral hemisphere. Surgical removal or disconnection of the affected cerebral hemisphere is currently the only intervention that effectively stops the seizures. Histopathological evaluation of resected brain tissue has shown that activated brain resident macrophages (microglia) and infiltrating T cells are involved in the inflammatory reaction. Here, we report that T cells isolated from seven RE brain surgery specimens express the resident memory T cell (T_RM) marker CD103. CD103 was expressed by >50% of CD8⁺ αβ T cells and γδ T cells irrespective of the length of time from seizure onset to surgery, which ranged from 0.3 to 8.4 years. Only ~10% of CD4⁺ αβ were CD103⁺, which was consistent with the observation that few CD4⁺ T cells are found in RE brain parenchyma. Clusters of T cells in brain parenchyma, which are a characteristic of RE histopathology, stained for CD103. Less than 10% of T cells isolated from brain specimens from eight surgical cases of focal cortical dysplasia (FCD), a condition that is also characterized by intractable seizures, were CD103⁺. In contrast to the RE cases, the percent of CD103⁺ T cells increased with the length of time from seizure onset to surgery. In sections of brain tissue from the FCD cases, T cells were predominantly found around blood vessels, and did not stain for CD103. The presence of significant numbers of T_RM cells in RE brain irrespective of the length of time between clinical presentation and surgical intervention supports the conclusion that a cellular immune response to an as yet unidentified antigen(s) occurs at an early stage of the disease. Reactivated T_RM cells may contribute to disease progression.

Adenosinergic signaling in epilepsy

Despite the introduction of at least 20 new antiepileptic drugs (AEDs) into clinical practice over the past decades, about one third of all epilepsies remain refractory to conventional forms of treatment. In addition, currently used AEDs have been developed to suppress neuronal hyperexcitability, but not necessarily to address pathogenic mechanisms involved in epilepsy development or progression (epileptogenesis). For those reasons endogenous seizure control mechanisms of the brain may provide alternative therapeutic opportunities. Adenosine is a well characterized endogenous anticonvulsant and seizure terminator of the brain. Several lines of evidence suggest that endogenous adenosine-mediated seizure control mechanisms fail in chronic epilepsy, whereas therapeutic adenosine augmentation effectively prevents epileptic seizures, even those that are refractory to conventional AEDs. New findings demonstrate that dysregulation of adenosinergic mechanisms are intricately involved in the development of epilepsy and its comorbidities, whereas adenosine-associated epigenetic mechanisms may play a role in epileptogenesis. The first goal of this review is to discuss how maladaptive changes of adenosinergic mechanisms contribute to the expression of seizures (ictogenesis) and the development of epilepsy (epileptogenesis) by focusing on pharmacological (adenosine receptor dependent) and biochemical (adenosine receptor independent) mechanisms as well as on enzymatic and transport based mechanisms that control the availability (homeostasis) of adenosine. The second goal of this review is to highlight innovative adenosine-based opportunities for therapeutic intervention aimed at reconstructing normal adenosine function and signaling for improved seizure control in chronic epilepsy. New findings suggest that transient adenosine augmentation can have lasting epigenetic effects with disease modifying and antiepileptogenic outcome. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.

Pathophysiology of mitochondrial disease causing epilepsy and status epilepticus

Epilepsy is part of the clinical phenotype in nearly 40% of children with mitochondrial disease, yet the underlying molecular mechanisms remain poorly understood. Energy depletion has been postulated as the cause of mitochondrial epilepsy, but if this were the case, then 100% of patients with mitochondrial disease would be expected to present with seizures. This review explores other potential disease mechanisms underlying mitochondrial epilepsy, including oxidative stress, impaired calcium homeostasis, immune dysfunction, and deficiency of vitamins, cofactors, reducing equivalents, and other metabolites. Different mechanisms are likely to predominate in different mitochondrial disorders, since mitochondrial function varies between neurons and astrocytes, between different types of neurons, and in different brain regions. Systematic studies in cell and animal models of mitochondrial disease are needed in order to develop effective therapies for mitochondrial epilepsy. This article is part of a Special Issue entitled "Status Epilepticus".

Evidence for the involvement of gamma delta T cells in the immune response in Rasmussen encephalitis

Background

Rasmussen encephalitis (RE) is a rare neuroinflammatory disease characterized by intractable seizures and progressive atrophy on one side of the cerebrum. Perivascular cuffing and clusters of T cells in the affected cortical hemisphere are indicative of an active cellular immune response.

Methods

Peripheral blood mononuclear cells (PBMCs) and brain-infiltrating lymphocytes (BILs) were isolated from 20 RE surgery specimens by standard methods, and CD3⁺ T cell populations were analyzed by flow cytometry. Gamma delta T cell receptor spectratyping was carried out by nested PCR of reversed transcribed RNA extracted from RE brain tissue, followed by high resolution capillary electrophoresis. A MiSeq DNA sequencing platform was used to sequence the third complementarity determining region (CDR3) of δ1 chains.

Results

CD3⁺ BILs from all of the RE brain specimens comprised both αβ and γδ T cells. The median αβ:γδ ratio was 1.9 (range 0.58–5.2) compared with a median ratio of 7.7 (range 2.7–40.8) in peripheral blood from the same patients. The αβ T cells isolated from brain tissue were predominantly CD8⁺, and the majority of γδ T cells were CD4⁻ CD8⁻. Staining for the early activation marker CD69 showed that a fraction of the αβ and γδ T cells in the BILs were activated (median 42 %; range 13–91 %, and median 47 %; range 14–99 %, respectively). Spectratyping T cell receptor (TCR) Vδ1-3 chains from 14 of the RE brain tissue specimens indicated that the γδ T cell repertoire was relatively restricted. Sequencing δ1 chain PCR fragments revealed that the same prevalent CDR3 sequences were found in all of the brain specimens. These CDR3 sequences were also detected in brain tissue from 15 focal cortical dysplasia (FCD) cases.

Conclusion

Neuroinflammation in RE involves both activated αβ and γδ T cells. The presence of γδ T cells with identical TCR δ1 chain CDR3 sequences in all of the brain specimens examined suggests that a non-major histocompatibility complex (MHC)-restricted immune response to the same antigen(s) is involved in the etiology of RE. The presence of the same δ1 clones in CD brain implies the involvement of a common inflammatory pathway in both diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0352-2) contains supplementary material, which is available to authorized users.

Evaluation and treatment of autoimmune neurologic disorders in the pediatric intensive care unit

Autoimmunity is being increasingly recognized as a cause of neurologic presentations both inside and outside the intensive care unit (ICU) setting. Pediatric autoimmune neurologic diseases likely to be seen in the ICU include autoimmune encephalitidies such as N-Methyl-D-aspartate (NMDA) receptor encephalitis, central nervous system vasculitis, demyelinating disorders, and neurologic involvement of systemic autoimmune disorders. In addition, there are conditions of suspected autoimmune etiology such as febrile infection-related epilepsy syndrome (FIRES) and rapid-onset obesity, hypoventilation, hypothalamic dysfunction, and autonomic dysregulation (ROHHAD) syndrome that are rare, but when they do present, it is often to the ICU. Refractory seizures, altered mental status, and disordered breathing are the most common indications for intensive care for these patients.

Intracerebroventricular injection of propionic acid, an enteric metabolite implicated in autism, induces social abnormalities that do not differ between seizure-prone (FAST) and seizure-resistant (SLOW) rats

Autism is a complex neurodevelopmental disorder that is characterized by social abnormalities. Genetic, dietary and gut-related factors are implicated in autism, however the causal properties of these factors and how they may interact are unclear. Propionic acid (PPA) is a product of gut microbiota and a food preservative. PPA has been linked to autism, and PPA administration to rats is an animal model of the condition. Seizure-prone (FAST) and seizure-resistant (SLOW) rats were initially developed to investigate differential vulnerability to developing epilepsy. However, FAST rats also display autistic-like features, and have been proposed as a genetic model of autism. Here we examined the effects of PPA on social behavior in FAST and SLOW rats. A single intracerebroventricular injection of PPA, or phosphate-buffered saline (PBS), was administered to young-adult male FAST and SLOW rats. Immediately after treatment, rats were placed in same-treatment and same-strain pairs, and underwent social behavior testing. PPA induced social abnormalities in both FAST and SLOW rat strains. While there was no evidence of social impairment in FAST rats that were not treated with PPA, these rats were hyperactive relative to SLOW rats. Post-mortem immunofluorescence analysis of brain tissue indicated that PPA treatment resulted in increased astrogliosis in the corpus callosum and cortex compared to PBS treatment. FAST rats had increased astrogliosis in the cortex compared to SLOW rats. Together these findings support the use of PPA as a rat model of autism, but indicate there are no interactive effects between the PPA and FAST models.