Viral infections and their relationship to neurological disorders.

The chronic dysfunction of neuronal cells, both central and peripheral, a characteristic of neurological disorders, may be caused by irreversible damage and cell death. In 2016, more than 276 million cases of neurological disorders were reported worldwide. Moreover, neurological disorders are the second leading cause of death. Generally, the etiology of neurological diseases is not fully understood. Recent studies have related the onset of neurological disorders to viral infections, which may cause neurological symptoms or lead to immune responses that trigger these pathological signs. Currently, this relationship is mostly based on epidemiological data on infections and seroprevalence of patients who present with neurological disorders. The number of studies aiming to elucidate the mechanism of action by which viral infections may directly or indirectly contribute to the development of neurological disorders has been increasing over the years but these studies are still scarce. Comprehending the pathogenesis of these diseases and exploring novel theories may favor the development of new strategies for diagnosis and therapy in the future. Therefore, the objective of the present study was to review the main pieces of evidence for the relationship between viral infection and neurological disorders such as Alzheimer's disease, Parkinson's disease, Guillain-Barré syndrome, multiple sclerosis, and epilepsy. Viruses belonging to the families Herpesviridae, Orthomyxoviridae, Flaviviridae, and Retroviridae have been reported to be involved in one or more of these conditions. Also, neurological symptoms and the future impact of infection with SARS-CoV-2, a member of the family Coronaviridae that is responsible for the COVID-19 pandemic that started in late 2019, are reported and discussed.

EEG findings and clinical prognostic factors associated with mortality in a prospective cohort of inpatients with COVID-19.

PURPOSE: Our objective is to describe the most prevalent electroencephalographic findings in COVID-19 hospitalized patients, and to determine possible predictors of mortality including EEG and clinical variables. METHODS: A multicentric prospective observational study in patients with COVID-19 requiring EEG during hospitalization. RESULTS: We found 94 EEG from 62 patients (55 % men, mean age 59.7 ± 17.8 years) were analyzed. Most frequent comorbidity was cardiac (52 %), followed by metabolic (45 %) and CNS disease (39 %). Patients required ICU management by 60 %, with a mortality of 27 % in the whole cohort. The most frequent EEG finding was generalized continuous slow-wave activity (66 %). Epileptic activity was observed in 19 % including non-convulsive status epilepticus, seizures and interictal epileptiform discharges. Periodic patterns were observed in 3 patients (3.2 %). Multivariate analysis found that cancer comorbidity and requiring an EEG during the third week of evolution portended a higher risk of mortality CONCLUSION: We observed that the most prevalent EEG finding in this cohort was generalized continuous slow-wave activity, while epileptic activity was observed in less than 20 % of the cases. Mortality risk factors were comorbidity with cancer and requiring an EEG during the third week of evolution, possibly related to the hyperinflammatory state.

Teleneuropsychology in the time of COVID-19: The experience of The Australian Epilepsy Project.

PURPOSE: Traditional neuropsychological testing carries elevated COVID-19 risk for both examinee and examiner. Here we describe how the pilot study of the Australian Epilepsy Project (AEP) has transitioned to tele-neuropsychology (teleNP), enabling continued safe operations during the pandemic. METHODS: The AEP includes adults (age 18-60) with a first unprovoked seizure, new diagnosis of epilepsy or drug resistant focal epilepsy. Shortly after launching the study, COVID-related restrictions necessitated adaptation to teleNP, including delivery of verbal tasks via videoconference; visual stimulus delivery via document camera; use of web-hosted, computerised assessment; substitution of oral versions for written tests; online delivery of questionnaires; and discontinuation of telehealth incompatible tasks. RESULTS: To date, we have completed 24 teleNP assessments: 18 remotely (participant in own home) and six on-site (participant using equipment at research facility). Five face-to-face assessments were conducted prior to the transition to teleNP. Eight of 408 tests administered via teleNP (1.9 %) have been invalidated, for a variety of reasons (technical, procedural, environmental). Data confirm typical patterns of epilepsy-related deficits (p < .05) affecting processing speed, executive function, language and memory. Questionnaire responses indicate elevated rates of patients at high risk of mood (34 %) and anxiety disorder (38 %). CONCLUSION: Research teleNP assessments reveal a typical pattern of impairments in epilepsy. A range of issues must be considered when introducing teleNP, such as technical and administrative set up, test selection and delivery, and cohort suitability. TeleNP enables large-scale neuropsychological research during periods of social distancing (and beyond), and offers an opportunity to expand the reach and breadth of neuropsychological services.

Management and results of epilepsy surgery associated with acyclovir prophylaxis in four pediatric patients with drug-resistant epilepsy due to herpetic encephalitis and review of the literature.

PURPOSE: Herpes simplex virus encephalitis (HSE) is the most common cause of sporadic viral encephalitis in children and is responsible for epilepsy in approximately half of patients. In addition to medical treatment, epilepsy surgery may be offered to drug-resistant patients but carries a high risk of relapse of herpetic encephalitis. We are reporting our series of patients operated on between 2000 and 2019 with the systematic administration of acyclovir (ACV). RESULTS: Four pediatric patients aged 4.5-12.8 years with drug-resistant epilepsy post-HSE underwent a tailored focal resection following invasive recordings (three patients) and a complete callosotomy (one patient). The total number of the surgical procedures for the four patients was eight, and a systematic administration of ACV as a prophylactic treatment of herpetic encephalitis relapse was done at each step. No patients had a relapse and the ACV was well-tolerated in all the cases. Following surgery two patients are seizure free, the patient who underwent callosotomy is Engel 3 and the fourth patient, in whom a large epileptic zone has contraindicated a second surgery, is Engel 4. CONCLUSIONS: Our series demonstrated the dramatic efficacy of systematic ACV prophylaxis during all cranial surgeries. Moreover, our results on epilepsy, together with those of the literature, encourage more consideration regarding epilepsy surgery in this specific etiology. All types of surgical procedures (curative or palliative) can be offered to the patients, but in the case of focal surgery, due to the poor anatomical limits, invasive recordings are highly recommended.

Surgical outcomes in patients with epilepsy after viral encephalitis: contribution of SEEG study.

BACKGROUND: Nowadays, few surgery analysis has been reported in cases of epilepsy after viral encephalitis(VE). Herein, this study was to evaluate the efficacy of surgery and capability of stereoelectroencephalography (SEEG) in the definition of the epileptogenic zone (EZ) after VE, and also to explore the relationship between the SEEG features and the surgical outcomes. METHODS: We retrospectively analyzed 10 surgically treated patients that identified to suffer from epilepsy secondary to VE using SEEG, and investigated the SEEG features associated with surgical outcomes in these patients. Besides visual analysis, we used the epileptogenicity index (EI), a semi-quantitative and supplementary tool to evaluate the validity of SEEG in the context of VE. RESULTS: Among the 10 operated patients, 3 of them became completely seizure-free. The patients who got totally seizure free or significant improvement, the seizure onset was located either in the antero-mesial temporal structures or focal gyrus; patients who got worthwhile improvement or no improvement, the seizure started from multiple brain lobes. The number of electrodes classified as epileptogenic visually involved were closely correlated with EI positive onses.Anatomic areas defined and shown as EZ on MRI by visual assessment were also defined as epileptogenic by the EI in these cases. CONCLUSION: Apart from exploring the surgical outcome related to epilepsy after VE, we also bring insight into the relationship between the SEEG features and surgical outcome with the application of the supplementary methods.

Elevated expression of EBV and TLRs in the brain is associated with Rasmussen's encephalitis.

Rasmussen's encephalitis (RE) is a rare pediatric neurological disorder, the etiology of which remains unclear. It has been speculated that the immunopathogenesis of RE involves damage to neurons, which eventually leads to the occurrence of RE. Viral infection may be a critical factor in triggering RE immunopathogenesis. In this study, we analyzed the expression of Epstein-Barr virus (EBV) antigens as well as of Toll-like receptor 3 (TLR3), TLR9, and downstream adapter TIRdomain-containing adapter-inducing interferon-ß (TRIF) in the brain tissues of 26 patients with RE and 16 control individuals using immunohistochemistry (IHC). In the RE group, EBV antigens were detected in 53% of individuals at various expression levels. In contrast, there was no detectable EBV antigen expression in control brain tissues. Moreover, we found marked increases in the expression of TLR3, TLR9, and TRIF in the brain tissues of RE patients compared with levels in the control group. Furthermore, among RE cases, EBV expression and high TLR3 expression were associated with more severe brain atrophy. Our results suggest that the elevated expression of EBV and TLRs may be involved in RE occurrence through the activation of downstream molecules.

Theiler's murine encephalomyelitis virus infection of SJL/J and C57BL/6J mice: Models for multiple sclerosis and epilepsy.

Mouse models are great tools to study the mechanisms of disease development. Theiler's murine encephalomyelitis virus is used in two distinct viral infection mouse models to study the human diseases multiple sclerosis (MS) and epilepsy. Intracerebral (i.c.) infection of the SJL/J mouse strain results in persistent viral infection of the central nervous system and a MS-like disease, while i.c. infection of the C57BL/6J mouse strain results in acute seizures and epilepsy. Our understanding of how the immune system contributes to the development of two disparate diseases caused by the same virus is presented.

Somatic mutations rather than viral infection classify focal cortical dysplasia type II as mTORopathy.

PURPOSE OF REVIEW: Genetic studies in focal cortical dysplasia type II (FCD II) provided ample evidence for somatic mutations in genes associated with the mammalian target of rapamycin (mTOR) pathway. Interestingly, the mTOR pathway can also be activated by the E6 oncogene of human papilloma viruses, and available data in FCD II remain controversial. We review and discuss the contradicting etiologies. RECENT FINDINGS: The neuroembryologic basis of cortical development and timing of a somatic mutation occurring in proliferating neuroblasts can mechanistically link mTORopathies. When a somatic mutation occurs in proliferating neuroblasts at an early stage of their anticipated total number of 33 mitotic cell cycles, large hemispheric lesions will develop from their affected progeny. Somatic mutations occurring at later periods of neuroblast expansion will result in circumscribed and small FCD II. Recently published data did not support evidence for viral infection in FCD II. SUMMARY: Genetic and histopathological data rather than viral infection classify FCD II into the spectrum of mTORopathies. Size and extent of the resulting cerebral lesion can be well explained by timing of somatic mutations during cortical development.

[Epileptic encephalopathy associated with human herpes virus 6 (HHV-6) encephalitis after the second cord blood transplantation in a patient with pediatric acute lymphoblastic leukemia].

The incidence of HHV-6 encephalitis during hematopoietic stem cell transplantation (HSCT) in children is thought to be less than that in adults and risk factors, prognosis and complications are virtually unknown. Herein, we report a pediatric case developing epileptic encephalopathy following HHV-6 encephalitis after a second cord blood transplantation (CBT). A 7-year-old boy with relapsed B-precursor acute lymphoblastic leukemia in second remission underwent CBT. However, he received a second CBT due to graft failure. On day 25 after the second CBT, he developed short-term memory defects and seizures. He was diagnosed with HHV-6 encephalitis because HHV-6 DNA was detected in his blood and cerebrospinal fluid and abnormal hippocampal signals were seen on cranial magnetic resonance imaging (MRI). After treatment with foscarnet, HHV-6 DNA levels and MRI findings improved; however, he developed epileptic encephalopathy five months after the onset of encephalitis. There are very few reports on pediatric epileptic encephalopathy associated with HHV-6 encephalitis after HSCT. Detailed studies are needed to analyze risk factors, prognosis, and complications.

The role of parvovirus in the etiology of somatic pathology.

The scope of the present research was to study parvovirus circulation in Tbilisi population and its role in etiology of somatic pathologies. Parvovirus circulation in persons with autism and disorder of the nervous system was examined. Blood of 110 patients was examined. Among them 35 were children (up to 15 years old) and 75 adults, mainly with different somatic pathologies such as mineral metabolism disorder, allergic reactions, cystic fibrosis, cerebral palsy and autism. Almost all the children came from the so called frequently ill category and suffered from disbacteriosis. Among adults, 16 were parents of the ill children, while the rest came with hepatitis, mineral metabolism disorder of different type and psoriasis. Blood serum of 30 adults was taken as an adult control group. Their age varied from 18 to 25 years. 10 children aged 2-15 constituted a children control group. Preventive examination was made and there were practically, absolutely healthy persons. A total of 150 persons were involved in the research. Frequency of parvoviral antibody detection in the ill children and adults is much higher than in healthy individuals. Consequently, positive results for the presence of M and G immunoglobulins in children equals to 54% and 85% respectively. In adults these indicator stand at 24% and 60% respectively. At the same time in 25% and 70% of parents of positive children were found to be positive for M immunoglobulin and G immunoglobulin respectively. Thus our investigation made it clear that parvoviral infection actively circulates in Georgia. The present research did not study manifested parvoviral infection, i.e. 5th disease. If it had than the number of positive results probably would have been much higher. In autistic children presence of parvoviral infection is consistent with the literature data.

Epileptic encephalopathy after HHV6 post-transplant acute limbic encephalitis in children: confirmation of a new epilepsy syndrome.

Generalised epilepsy and cognitive deterioration were recently described in three children following human herpesvirus 6 (HHV6)-associated post-transplant acute limbic encephalitis (PALE). Magnetic resonance imaging (MRI) showed bilateral signal change and/or atrophy in the medial temporal structures and there was no evidence of an ongoing viral or immune-mediated process. We report another child who developed this condition after cord blood transplantation for congenital neutropenia at the age of three. He presented with epileptic spasms four months after HHV6-associated PALE. Cognitive regression, prominent electroencephalographic abnormalities and different types of generalised seizures ensued during the following months and proved refractory to antiepileptic and immunomodulating treatment, which included steroids, immunoglobulin and rituximab. MRI was normal at onset of epilepsy but subsequently showed the development of right hippocampal sclerosis. Results from serial blood and cerebrospinal fluid (CSF) analyses were inconclusive, including lack of patient's CSF and serum reactivity with cultures of dissociated rat hippocampal neurons. This report confirms the existence of a new epilepsy syndrome featuring generalised seizures and epileptic encephalopathy after HHV6-associated PALE in children. Presentation with epileptic spasms, lack of CSF and serum reactivity with cultured rat hippocampal neurons, and rituximab inefficacy are novel features that contribute to delineate the syndrome and argue against an immune-mediated basis of this condition.

TNF-overexpression in Borna disease virus-infected mouse brains triggers inflammatory reaction and epileptic seizures.

Proinflammatory state of the brain increases the risk for seizure development. Neonatal Borna disease virus (BDV)-infection of mice with neuronal overexpression of tumor necrosis factor-α (TNF) was used to investigate the complex relationship between enhanced cytokine levels, neurotropic virus infection and reaction pattern of brain cells focusing on its role for seizure induction. Viral antigen and glial markers were visualized by immunohistochemistry. Different levels of TNF in the CNS were provided by the use of heterozygous and homozygous TNF overexpressing mice. Transgenic TNF, total TNF (native and transgenic), TNF-receptor (TNFR1, TNFR2), IL-1 and N-methyl-D-aspartate (NMDA)-receptor subunit 2B (NR2B) mRNA values were measured by real time RT-PCR. BDV-infection of TNF-transgenic mice resulted in non-purulent meningoencephalitis accompanied by epileptic seizures with a higher frequency in homozygous animals. This correlated with lower weight gain, stronger degree and progression of encephalitis and early, strong microglia activation in the TNF-transgenic mice, most obviously in homozygous animals. Activation of astroglia could be more intense and associated with an unusual hypertrophy in the transgenic mice. BDV-antigen distribution and infectivity in the CNS was comparable in TNF-transgenic and wild-type animals. Transgenic TNF mRNA-expression was restricted to forebrain regions as the transgene construct comprised the promoter of NMDA-receptor subunit2B and induced up-regulation of native TNF mRNA. Total TNF mRNA levels did not increase significantly after BDV-infection in the brain of transgenic mice but TNFR1, TNFR2 and IL-1 mRNA values, mainly in the TNF overexpressing brain areas. NR2B mRNA levels were not influenced by transgene expression or BDV-infection. Neuronal TNF-overexpression combined with BDV-infection leads to cytokine up-regulation, CNS inflammation and glial cell activation and confirmed the presensitizing effect of elevated cytokine levels for the development of spontaneous epileptic seizures when exposed to additional infectious noxi.

Seizures and epilepsy in herpes simplex virus encephalitis: current concepts and future directions of pathogenesis and management.

Mortality related to herpes simplex virus encephalitis (HSE) dropped dramatically with the systematic initiation of antiviral treatment in encephalitic syndromes. Further efforts need to be taken to reduce long-term morbidity in the survivors. In this regard, the high rate of postencephalitic epilepsy, which is frequently refractory to medical treatment, contributes significantly to the unfavorable clinical outcome of the disease. Seizures during the acute phase of HSE are the main risk for the development of postencephalitic epilepsy. Yet, there are no randomized controlled trials for the management of acute seizures, preventive measures or the ideal duration of antiepileptic treatment. Hence, concepts for the medical treatment of seizures during the acute phase of HSE and postencephalitic epilepsy are eagerly awaited. Epilepsy surgery is a potential treatment option for the latter, but only promising in a subgroup of patients suffering from unilateral mesio-temporal lobe epilepsy and congruent neuropsychological impairment. Relapsing HSE and post-infectious autoimmune conditions can lead to seizures in the aftermath of acute HSE. These conditions need to be kept in mind in order to promptly assure the initiation of accurate diagnostic steps and respective treatment. The purpose of this review is to summarize the current pathogenetical understanding, clinical and diagnostic considerations, and treatment options of seizures in acute HSE and postencephalitic epilepsy.

Lymphocyte adhesion to CCR5 ligands is reduced by anti-CCR5 gene delivery.

Immune-mediated damage to the central nervous system (CNS) is an important contributor to many CNS diseases, including epilepsy. Chemokines play a role in leukocyte recruitment to, and migration across, the blood-brain barrier (BBB) during many such processes. We previously investigated the role of the chemokine receptor CCR5 in a rat model of epilepsy based on intraperitoneal kainic acid (KA) administration. Before KA injection, rats were given intramarrow inoculations of SV(RNAiR5-RevM10.AU1), which carries an interfering RNA (RNAi) that targets CCR5. Decreased CCR5 expression in blood cells after vector administration reduced expression of CCR5 ligands MIP-1α and RANTES in the microvasculature, and strongly protected from BBB leakage, CNS loss and inflammation and facilitated CNS repair. We show here that rSV40-mediated downregulation of CCR5 in lymphocytes decreased cellular adhesion to surfaces carrying CCR5 ligands. These data suggest that reducing CCR5 in peripheral blood mononuclear cells (PBMCs) might alter their adhesion to the microvasculature and their participation in inflammatory processes.

Periodic lateralized epileptiform discharges of pediatric patients in Taiwan.

Periodic lateralized epileptiform discharges are special electroencephalographic abnormalities present in adults with stroke, brain tumor, intracranial hemorrhage, or other rare etiologies. Few reports focused on the etiologies in pediatric patients. We retrospectively reviewed 8002 of our pediatric electroencephalographic records for the past 12 years and listed all associated illness and their outcomes. Forty-four children with periodic lateralized epileptiform discharges were collected. We found that there was an obvious difference in etiologies of our pediatric patients from those reported in the literature. Nearly two thirds of our patients (28 children) were associated with central nervous system infections. The other etiologies included head injury, encephalopathy, epilepsy, and others. Herpes simplex virus was responsible for two thirds (12) of the 18 children with identified pathogens causing a central nervous system infection. Ten patients failed to have a defined pathogen. Periodic lateralized epileptiform discharges have a different clinical significance in pediatric patients than in adults. In Taiwan, central nervous system infection is the most common etiology of periodic lateralized epileptiform discharges in pediatric patients. Herpes simplex virus, although the most common pathogen, should not be considered to be the only cause of encephalitis in children with periodic lateralized epileptiform discharges.

The value of CSF analysis for the differential diagnosis of HTLV-I associated myelopathy and multiple sclerosis.

Cerebrospinal fluid (CSF) and serum of 17 patients with HAM/TSP (HTLV-I associated myelopathy/tropical spastic paraparesis), six with multiple sclerosis and six with idiopathic epilepsy (non inflammatory control) from Brazil were analysed for the presence of intrathecal synthesis of virus-specific antibodies against measles, rubella, varicella zoster virus and herpes simplex virus by enzyme-linked immunosorbent assay (ELISA). All HAM/TSP and multiple sclerosis cases had an intrathecal immune response (oligoclonal IgG). In HAM/TSP, only 1/17 case showed a polyspecific intrathecal immune response against measles and rubella virus. In multiple sclerosis, specific antibodies against measles and rubella (MRZ response) were observed in all patients but not in the control with idiopathic epilepsy. The diagnostic and theoretical relevance of mono- and polyspecific immune responses is discussed for these chronic neurological diseases.

The value of csf analysis for the differential diagnosis of HTLV-I associated myelopathy and multiple sclerosis

Amostras do líquido cefalorraquidiano (LCR) e soro de 17 pacientes brasileiros com HAM/TSP, seis com esclerose múltipla e seis com epilepsia idiopática (controle nao-inflamatório) foram analisadas para a presença de anticorpos para o vírus de sarampo, rubéola, varicela zoster e herpes simples pelo método de ELISA. Todos os casos de HAM/TSP e esclerose múltipla tinham resposta imune poliespecífica intratecal para sarampo e rubéola. Anticorpos específicos para sarampo e rubéola (resposta MRZ) foram observados em todos os pacientes com esclerose múltipla, mas nao nos controles com epilepsia idiopática. A relevância das respostas poliespecífica e monoespecífica é discutida para essas doenças neurológicas crônicas.

AIDS-associated progressive multifocal leukoencephalopathy revealed by new-onset seizures.

PURPOSE: To describe the clinical features of new-onset seizures in HIV-1-infected persons with progressive multifocal leukoencephalopathy (PML), and to discuss potential mechanisms. PATIENTS AND METHODS: Forty-nine consecutive HIV-1-infected patients with PML attended our institutions between January 1988 and September 1993. We retrospectively analyzed cases with seizures as the presenting symptom of PML. RESULTS: Twenty percent of the HIV-1-infected patients with PML presented with new-onset seizures of various types, generalized or partial. None of them met the criteria of the AIDS dementia complex or had a concomitant opportunistic infection. Their mean CD4 cell count was < 60/mm3. Brain magnetic resonance imaging showed areas of increased signal intensity on T2-weighted images in 9 cases, and atrophy in only 1 case. Lesions most often involved subcortical white matter in parieto-occipital or frontal lobes, but 2 patients had posterior fossa lesions. Image-guided stereotactic brain biopsies in 8 cases and postmortem examination in 2 confirmed the diagnosis of PML. Typical histological lesions were observed in all cases, and positive immunolabelling of oligodendroglial nuclei was obtained in all cases with the polyclonal antibody directed against late SV40 antigens. Putative causative factors for the seizures include demyelinated lesions adjacent to the cerebral cortex acting as irritative foci, axonal conduction abnormalities, or disturbances of the neuron-glia balance. CONCLUSION: These cases illustrate that PML should be considered as a possible cause of new-onset seizures in patients with HIV-1 infection.