Neurologic aspects of influenza viruses

Square the Circle: Diversity of Viral Pathogens Causing Neuro-Infectious Diseases

Neuroinfections rank among the top ten leading causes of child mortality globally, even in high-income countries. The crucial determinants for successful treatment lie in the timing and swiftness of diagnosis. Although viruses constitute the majority of infectious neuropathologies, diagnosing and treating viral neuroinfections remains challenging. Despite technological advancements, the etiology of the disease remains undetermined in over half of cases. The identification of the pathogen becomes more difficult when the infection is caused by atypical pathogens or multiple pathogens simultaneously. Furthermore, the modern surge in global passenger traffic has led to an increase in cases of infections caused by pathogens not endemic to local areas. This review aims to systematize and summarize information on neuroinvasive viral pathogens, encompassing their geographic distribution and transmission routes. Emphasis is placed on rare pathogens and cases involving atypical pathogens, aiming to offer a comprehensive and structured catalog of viral agents with neurovirulence potential.

Insights from Avian Influenza: A Review of Its Multifaceted Nature and Future Pandemic Preparedness

Avian influenza viruses (AIVs) have posed a significant pandemic threat since their discovery. This review mainly focuses on the epidemiology, virology, pathogenesis, and treatments of avian influenza viruses. We delve into the global spread, past pandemics, clinical symptoms, severity, and immune response related to AIVs. The review also discusses various control measures, including antiviral drugs, vaccines, and potential future directions in influenza treatment and prevention. Lastly, by summarizing the insights from previous pandemic control, this review aims to direct effective strategies for managing future influenza pandemics.

Virus-induced brain pathology and the neuroinflammation-inflammation continuum: the neurochemists view

Fascinatingly, an abundance of recent studies has subscribed to the importance of cytotoxic immune mechanisms that appear to increase the risk/trigger for many progressive neurodegenerative disorders, including Parkinson's disease (PD), Alzheimer's disease (AD), amyotrophic lateral sclerosis, and multiple sclerosis. Events associated with the neuroinflammatory cascades, such as ageing, immunologic dysfunction, and eventually disruption of the blood-brain barrier and the "cytokine storm", appear to be orchestrated mainly through the activation of microglial cells and communication with the neurons. The inflammatory processes prompt cellular protein dyshomeostasis. Parkinson's and Alzheimer's disease share a common feature marked by characteristic pathological hallmarks of abnormal neuronal protein accumulation. These Lewy bodies contain misfolded α-synuclein aggregates in PD or in the case of AD, they are Aβ deposits and tau-containing neurofibrillary tangles. Subsequently, these abnormal protein aggregates further elicit neurotoxic processes and events which contribute to the onset of neurodegeneration and to its progression including aggravation of neuroinflammation. However, there is a caveat for exclusively linking neuroinflammation with neurodegeneration, since it's highly unlikely that immune dysregulation is the only factor that contributes to the manifestation of many of these neurodegenerative disorders. It is unquestionably a complex interaction with other factors such as genetics, age, and environment. This endorses the "multiple hit hypothesis". Consequently, if the host has a genetic susceptibility coupled to an age-related weakened immune system, this makes them more susceptible to the virus/bacteria-related infection. This may trigger the onset of chronic cytotoxic neuroinflammatory processes leading to protein dyshomeostasis and accumulation, and finally, these events lead to neuronal destruction. Here, we differentiate "neuroinflammation" and "inflammation" with regard to the involvement of the blood-brain barrier, which seems to be intact in the case of neuroinflammation but defect in the case of inflammation. There is a neuroinflammation-inflammation continuum with regard to virus-induced brain affection. Therefore, we propose a staging of this process, which might be further developed by adding blood- and CSF parameters, their stage-dependent composition and stage-dependent severeness grade. If so, this might be suitable to optimise therapeutic strategies to fight brain neuroinflammation in its beginning and avoid inflammation at all.

SARS-CoV-2, aging, and Post-COVID-19 neurodegeneration

As the world continues to experience the effects of SARS-CoV-2, there is evidence to suggest that the sequelae of viral infection (the post-COVID-19 condition; PCC) at both an individual and population level will be significant and long-lasting. The history of pandemics or epidemics in the last 100 years caused by members of the RNA virus family, of which coronaviruses are a member, provides ample evidence of the acute neurological effects. However, except for the H1N1 influenza pandemic of 1918/1919 (the Spanish flu) with its associated encephalitis lethargica, there is little information on long-term neurological sequelae. COVID-19 is the first pandemic that has occurred in a setting of an aging population, especially in several high-income countries. Its survivors are at the greatest risk for developing neurodegenerative conditions as they age, rendering the current pandemic a unique paradigm not previously witnessed. The SARS-CoV-2 virus, among the largest of the RNA viruses, is a single-stranded RNA that encodes for 29 proteins that include the spike protein that contains the key domains required for ACE2 binding, and a complex array of nonstructural proteins (NSPs) and accessory proteins that ensure the escape of the virus from the innate immune response, allowing for its efficient replication, translation, and exocytosis as a fully functional virion. Increasingly, these proteins are also recognized as potentially contributing to biochemical and molecular processes underlying neurodegeneration. In addition to directly being taken up by brain endothelium, the virus or key protein constituents can be transported to neurons, astrocytes, and microglia by extracellular vesicles and can accelerate pathological fibril formation. The SARS-CoV-2 nucleocapsid protein is intrinsically disordered and can participate in liquid condensate formation, including as pathological heteropolymers with neurodegenerative disease-associated RNA-binding proteins such as TDP-43, FUS, and hnRNP1A. As the SARS-CoV-2 virus continues to mutate under the immune pressure exerted by highly efficacious vaccines, it is evolving into a virus with greater transmissibility but less severity compared with the original strain. The potential of its lingering impact on the nervous system thus has the potential to represent an ongoing legacy of an even greater global health challenge than acute infection.

Exploring the Correlation Between Influenza A Virus (H3N2) Infections and Neurological Manifestations: A Scoping Review

Influenza A virus (IAV), particularly the H3N2 variant, is known to cause respiratory manifestations, but it can also lead to neurological complications ranging from mild symptoms like headache and dizziness to severe conditions such as encephalitis and acute necrotizing encephalopathy (ANE). In this article, the correlation between the H3N2 variant of the IAV and neurological manifestations is discussed. Additionally, prompt recognition and treatment of influenza-associated neurological manifestations are highlighted to prevent infection-related long-term complications. This review briefly discusses various neurological complications linked to IAV infections, such as encephalitis, febrile convulsions, and acute disseminated encephalomyelitis, and the potential mechanisms involved in the development of neurological complications.

Berlin Bowel Bothers: Might Adolf Hitler's Gut Problems Have Been Parkinson-Related?

It has been argued that Adolf Hitler (1889-1945) had Parkinson's disease. He also experienced several gastrointestinal symptoms, for which various explanations have been sought, both contemporaneously and by later authors. In this Historical Note, a possible relationship between Hitler's Parkinson's disease and his gastrointestinal symptoms is explored. Specifically, we posit the hypothesis that Hitler may have suffered from small-intestinal bacterial overgrowth (SIBO), thus providing an early example of SIBO occurring as a prodromal Parkinson's disease symptom.

Investigating neurological symptoms of infectious diseases like COVID-19 leading to a deeper understanding of neurodegenerative disorders such as Parkinson's disease

Apart from common respiratory symptoms, neurological symptoms are prevalent among patients with COVID-19. Research has shown that infection with SARS-CoV-2 accelerated alpha-synuclein aggregation, induced Lewy-body-like pathology, caused dopaminergic neuron senescence, and worsened symptoms in patients with Parkinson's disease (PD). In addition, SARS-CoV-2 infection can induce neuroinflammation and facilitate subsequent neurodegeneration in long COVID, and increase individual vulnerability to PD or parkinsonism. These findings suggest that a post-COVID-19 parkinsonism might follow the COVID-19 pandemic. In order to prevent a possible post-COVID-19 parkinsonism, this paper reviewed neurological symptoms and related findings of COVID-19 and related infectious diseases (influenza and prion disease) and neurodegenerative disorders (Alzheimer's disease, PD and amyotrophic lateral sclerosis), and discussed potential mechanisms underlying the neurological symptoms and the relationship between the infectious diseases and the neurodegenerative disorders, as well as the therapeutic and preventive implications in the neurodegenerative disorders. Infections with a relay of microbes (SARS-CoV-2, influenza A viruses, gut bacteria, etc.) and prion-like alpha-synuclein proteins over time may synergize to induce PD. Therefore, a systematic approach that targets these pathogens and the pathogen-induced neuroinflammation and neurodegeneration may provide cures for neurodegenerative disorders. Further, antiviral/antimicrobial drugs, vaccines, immunotherapies and new therapies (e.g., stem cell therapy) need to work together to treat, manage or prevent these disorders. As medical science and technology advances, it is anticipated that better vaccines for SARS-CoV-2 variants, new antiviral/antimicrobial drugs, effective immunotherapies (alpha-synuclein antibodies, vaccines for PD or parkinsonism, etc.), as well as new therapies will be developed and made available in the near future, which will help prevent a possible post-COVID-19 parkinsonism in the 21st century.

Clinical features of the first critical case of acute encephalitis caused by avian influenza A (H5N6) virus

Highly pathogenic avian influenza viruses (HPAIV), such as H5N1, H5N6, and H7N9, have been reported to frequently infect humans, but acute encephalitis caused by HPAIV in humans has been rarely reported. We report the first critical case of acute encephalitis with mild pneumonia caused by the H5N6 virus. On January 25 of 2022, a 6-year-old girl with severe neurological symptoms was admitted to our hospital and rapidly developed into seizures and coma. Brain imaging showed abnormalities. Electroencephalogram (EEG) presented abnormal slow waves. Cerebrospinal fluid (CSF) contained elevated protein (1.64 g/L) and white cells (546 × 10⁶/L). Laboratory investigations revealed abnormally elevated transaminases, lactate dehydrogenase, and cytokines in serum. A novel reassortant H5N6 virus was identified from the patient’s serum, CSF, and tracheal aspirate specimens. Phylogenic analysis indicated that this virus was a novel reassortant avian-origin influenza A (H5N6) virus that belonged to clade 2.3.4.4b. This patient was diagnosed with acute encephalitis and discharged from the hospital accompanied by a language barrier. An epidemiological investigation confirmed that wild waterfowls were the direct source of infection in this case. Our study highlights the urgent need to pay attention to acute encephalitis caused by HPAIV.

Parkinsonism associated with viral infection

There are several known causes of secondary parkinsonism, the most common being head trauma, stroke, medications, or infections. A growing body of evidence suggests that viral agents may trigger parkinsonian symptoms, but the exact pathological mechanisms are still unknown. In some cases, lesions or inflammatory processes in the basal ganglia or substantia nigra have been found to cause reversible or permanent impairment of the dopaminergic pathway, leading to the occurrence of extrapyramidal symptoms. This chapter reviews current data regarding the viral agents commonly associated with parkinsonism, such as Epstein Barr virus (EBV), hepatitis viruses, human immunodeficiency virus (HIV), herpes viruses, influenza virus, coxsackie virus, and Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). We present possible risk factors, proposed pathophysiology mechanisms, published case reports, common associations, and prognosis in order to offer a concise overview of the viral spectrum involved in parkinsonism.

Risk of Alzheimer's Disease Following Influenza Vaccination: A Claims-Based Cohort Study Using Propensity Score Matching

Background:

Prior studies have found a reduced risk of dementia of any etiology following influenza vaccination in selected populations, including veterans and patients with serious chronic health conditions. However, the effect of influenza vaccination on Alzheimer’s disease (AD) risk in a general cohort of older US adults has not been characterized.

Objective:

To compare the risk of incident AD between patients with and without prior influenza vaccination in a large US claims database.

Methods:

Deidentified claims data spanning September 1, 2009 through August 31, 2019 were used. Eligible patients were free of dementia during the 6-year look-back period and≥65 years old by the start of follow-up. Propensity-score matching (PSM) was used to create flu-vaccinated and flu-unvaccinated cohorts with similar baseline demographics, medication usage, and comorbidities. Relative risk (RR) and absolute risk reduction (ARR) were estimated to assess the effect of influenza vaccination on AD risk during the 4-year follow-up.

Results:

From the unmatched sample of eligible patients (n = 2,356,479), PSM produced a sample of 935,887 flu–vaccinated-unvaccinated matched pairs. The matched sample was 73.7 (SD, 8.7) years of age and 56.9% female, with median follow-up of 46 (IQR, 29–48) months; 5.1% (n = 47,889) of the flu-vaccinated patients and 8.5% (n = 79,630) of the flu-unvaccinated patients developed AD during follow-up. The RR was 0.60 (95% CI, 0.59–0.61) and ARR was 0.034 (95% CI, 0.033–0.035), corresponding to a number needed to treat of 29.4.

Conclusion:

This study demonstrates that influenza vaccination is associated with reduced AD risk in a nationwide sample of US adults aged 65 and older.

Neurologic complications of coronavirus and other respiratory viral infections

In humans, several respiratory viruses can have neurologic implications affecting both central and peripheral nervous system. Neurologic manifestations can be linked to viral neurotropism and/or indirect effects of the infection due to endothelitis with vascular damage and ischemia, hypercoagulation state with thrombosis and hemorrhages, systemic inflammatory response, autoimmune reactions, and other damages. Among these respiratory viruses, recent and huge attention has been given to the coronaviruses, especially the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in 2020. Besides the common respiratory symptoms and the lung tropism of SARS-CoV-2 (COVID-19), neurologic manifestations are not rare and often present in the severe forms of the infection. The most common acute and subacute symptoms and signs include headache, fatigue, myalgia, anosmia, ageusia, sleep disturbances, whereas clinical syndromes include mainly encephalopathy, ischemic stroke, seizures, and autoimmune peripheral neuropathies. Although the pathogenetic mechanisms of COVID-19 in the various acute neurologic manifestations are partially understood, little is known about long-term consequences of the infection. These consequences concern both the so-called long-COVID (characterized by the persistence of neurological manifestations after the resolution of the acute viral phase), and the onset of new neurological symptoms that may be linked to the previous infection.

Acute Neurologic Manifestations of Respiratory Viruses

PURPOSE OF REVIEW

Understanding the pathophysiology of COVID-19 and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus that causes the disease has demonstrated the complexity of acute respiratory viruses that can cause neurologic manifestations. This article describes the most common respiratory viruses that have neurologic manifestations, with a focus on SARS-CoV-2 and COVID-19.

RECENT FINDINGS

In vitro and in vivo studies have better elucidated the neurotropism of various respiratory viruses. Understanding host cell receptors that mediate viral binding and entry not only demonstrates how viruses enter host cells but also provides possible mechanisms for therapeutic interventions. Elucidation of SARS-CoV-2 binding and fusion with host cells expressing the angiotensin-converting enzyme 2 (ACE2) receptor may also provide greater insights into its systemic and neurologic sequelae. Respiratory virus neurotropism and collateral injury due to concurrent inflammatory cascades result in various neurologic pathologies, including Guillain-Barré syndrome, encephalopathy, encephalitis, ischemic stroke, intracerebral hemorrhage, and seizures.

SUMMARY

Numerous respiratory viruses can infect the cells of the peripheral and central nervous systems, elicit inflammatory cascades, and directly and indirectly cause various neurologic manifestations. Patients with neurologic manifestations from respiratory viruses are often critically ill and require mechanical ventilation. Neurologists and neurointensivists should be familiar with the common neurologic manifestations of respiratory viruses and the unique and still-evolving sequelae associated with COVID-19.

What can the neurological manifestations of COVID-19 tell us: a meta-analysis

Background

Covid-19 became a global pandemic in 2019. Studies have shown that coronavirus can cause neurological symptoms, but clinical studies on its neurological symptoms are limited. In this meta-analysis, we aimed to summarize the various neurological manifestations that occurred in COVID-19 patients and calculate the incidence of various neurological manifestations. At the same time, we further explored the mechanism of nervous system injury and prognosis in COVID-19 patients in combination with their nervous system manifestations. This study provides a reference for early clinical identification of COVID-19 nervous system injury in the future, so as to achieve early treatment and reduce neurological sequelae.

Methods

We systematically searched all published English literature related to the neurological manifestations of COVID-19 from January 1, 2020, to April 30, 2021, in Pubmed, Embase, and Cochrane Library. The keywords used were COVID-19 and terminology related to the nervous system performance. All included studies were selected by two independent reviewers using EndNote and NoteExpress software, any disagreement was resolved by consensus or by a third reviewer, and the selected data were then collected for meta-analysis using a random-effects model.

Results

A total of 168 articles (n = 292,693) were included in the study, and the meta-analysis showed that the most common neurological manifestations of COVID-19 were myalgia(33%; 95%CI 0.30–0.37; I² = 99.17%), smell impairment(33%; 95%CI 0.28–0.38; I² = 99.40%), taste dysfunction(33%; 95%CI 0.27–0.39; I² = 99.09%), altered mental status(32%; 95%CI 0.22–0.43; I² = 99.06%), headache(29%; 95%CI 0.25–0.33; I² = 99.42%), encephalopathy(26%; 95%CI 0.16–0.38; I² = 99.31%), alteration of consciousness(13%; 95%CI 0.08–0.19; I² = 98.10%), stroke(12%; 95%CI 0.08–0.16; I² = 98.95%), dizziness(10%; 95%CI 0.08–0.13; I² = 96.45%), vision impairment(6%; 95%CI 0.03–0.09; I² = 86.82%), intracerebral haemorrhage(5%; 95%CI 0.03–0.09; I² = 95.60%), seizure(4%; 95%CI 0.02 -0.05; I² = 98.15%), encephalitis(2%; 95%CI 0.01–0.03; I² = 90.36%), Guillan-Barré Syndrome (GBS) (1%; 95%CI 0.00–0.03; I² = 89.48%).

Conclusions

Neurological symptoms are common and varied in Covid-19 infections, and a growing number of reports suggest that the prevalence of neurological symptoms may be increasing. In the future, the role of COVID-19 neurological symptoms in the progression of COVID-19 should be further studied, and its pathogenesis and assessment methods should be explored, to detect and treat early neurological complications of COVID-19 and reduce mortality.

The neurological sequelae of pandemics and epidemics

Neurological manifestations in pandemics frequently cause short and long-term consequences which are frequently overlooked. Despite advances in the treatment of infectious diseases, nervous system involvement remains a challenge, with limited treatments often available. The under-recognition of neurological manifestations may lead to an increase in the burden of acute disease as well as secondary complications with long-term consequences. Nervous system infection or dysfunction during pandemics is common and its enduring consequences, especially among vulnerable populations, are frequently forgotten. An improved understanding the possible mechanisms of neurological damage during epidemics, and increased recognition of the possible manifestations is fundamental to bring insights when dealing with future outbreaks. To reverse this gap in knowledge, we reviewed all the pandemics, large and important epidemics of human history in which neurological manifestations are evident, and described the possible physiological processes that leads to the adverse sequelae caused or triggered by those pathogens.

New onset status epilepticus in influenza associated encephalopathy: The presenting manifestation of genetic generalized epilepsy

We hereby present a case of a young woman with no history of seizures or epilepsy who experienced a de novo generalized Non Convulsive Status Epilepticus (NCSE) followed by encephalopathy lasting for several days during influenza B infection. Influenza can have a broad spectrum of presentation ranging from an uncomplicated illness to many serious conditions as is the case of influenza associated encephalitis/encephalopathy (IAE). In this context however, it is possible to observe seizures and/or status epilepticus as the presenting manifestation of a genetic generalized epilepsy.

Plasmapheresis for Rescue in Severe Encephalopathy and Multiorgan Failure from Fulminant Influenza (H3N2) Infection

We are presenting a case of 4-years-old previously healthy male with coma, severe acute hepatitis and multiorgan failure in presence of Influenza infection. Literature review highlighted an immune-mediated pathophysiology for such presentations so the child underwent a trial of plasmapheresis which resulted in a rapid clinical improvement and child was discharge in his baseline neurologic status by day 14.

Neurologic Complications in Children Hospitalized With Influenza Infections: Prevalence, Risk Factors and Impact on Disease Severity

BACKGROUND

Influenza infection is a common cause of respiratory disease and hospitalization in children. Neurologic manifestations of the infection have been increasingly reported and may have an impact on the severity of the disease. The aim of this study is to describe neurologic events in pediatric patients hospitalized with influenza and identify associated risk factors.

METHODS

Retrospective cohort study which included all hospitalized patients with microbiologic confirmation of influenza disease over 4 epidemic seasons, focusing on neurologic complications. Demographic, laboratory and clinical data, as well as past history, were recorded. Descriptive and analytic statistical study was performed using SPSS and R statistical software.

RESULTS

Two hundred forty-five patients were included. Median age was 21 months (interquartile range, 6-57) and 47.8% had a previous underlying condition. Oseltamivir was administered to 86% of patients, median hospitalization was 4 days (interquartile range, 3-6), and pediatric intensive care unit admission rate 8.9%. Twenty-nine patients (11.8%) developed neurologic events, febrile seizures being the most frequent, followed by nonfebrile seizures and encephalopathy. Status epilepticus occurred in 4 children, and 69.6% of seizures recurred. Patients with a previous underlying condition were at greater risk of developing a neurologic complication [odds ratio (OR), 4.55; confidence interval (CI), 95% 1.23-16.81). Male sex (OR, 3.21; CI 95%, 1.22-8.33), influenza B virus (OR, 2.82; CI 95%, 1.14-7.14) and neurologic events (OR, 3.34; CI 95%, 1.10-10.19) were found to be risk factors for pediatric intensive care unit admission.

CONCLUSIONS

A significant proportion of influenza-related hospitalized patients develop neurologic complications, especially seizures which may be prolonged or recurrent. Previous underlying conditions pose the greatest risk to neurologic events, which increase disease severity.

Acute amnestic syndrome with hippocampal lesion due to influenza B-associated encephalopathy

Acute encephalopathy is a rare complication of influenza, particularly in adults. We report the case of a 77-year-old woman presenting with complete anterograde and significant retrograde amnesia developing during an influenza B infection. Cranial magnetic resonance imaging (MRI) showed hippocampal lesions including restricted diffusion during the acute phase. Symptoms partially improved following treatment with intravenous methylprednisolone and immunoglobulins but an amnesic syndrome persisted. We discuss possible causes of neurological complications in influenza infections.

The Neurologic Manifestations of Coronavirus Disease 2019

The coronavirus disease 2019 (COVID-19) is an ongoing global pandemic that has so far affected 216 countries and more than 5 million individuals worldwide. The infection is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). While pulmonary manifestations are the most common, neurological features are increasingly being recognized as common manifestations of the COVID-19, especially in the cases of severe infection. These include acute cerebrovascular disease, encephalitis, and Guillain-Barre syndrome (GBS). Here, we review the neuropathogenesis of SARS-CoV-2 and the central and peripheral nervous system manifestations of COVID-19.

[Two adult patients with acute necrotizing encephalopathy following influenza virus infection]

Influenza encephalopathy is characterized by high fever, disturbance of consciousness following influenza virus infection. We encountered 2 adult patients with influenza-associated acute necrotizing encephalopathy (Case 1, a 70-year-old woman with diabetes; Case 2, a 49-year-old woman with multiple myeloma), showing hemorrhagic lesions in the bilateral thalamus. Case 1 presented with fever and disturbance of consciousness followed by status epilepticus, and Case 2 developed fever and drowsiness as initial manifestation. Influenza type A was positive in Case 1 and influenza type B was positive in Case 2. In the acute phase, 2 patients required respiratory ventilation and were treated with anti-influenza drug, steroid and immunoglobulin. Cognitive impairment remained in the both patients in the chronic phase. When acute necrotizing encephalopathy is suspected, intensive treatment should be started as early as possible to improve clinical outcome of patients.

New-Onset Refractory Status Epilepticus in Children: Etiologies, Treatments, and Outcomes

OBJECTIVES

To elucidate etiologies, treatment, functional and neurocognitive outcomes of children with new-onset refractory status epilepticus.

DESIGN

A single-center retrospective study.

SETTING

A tertiary care children's hospital.

PATIENTS

All patients between 1 month and 21 years old admitted with new-onset refractory status epilepticus between January 2004 and July 2017.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical presentation, laboratory data, imaging studies, and treatments were collected during hospitalization. Outcomes were assessed at hospital discharge and follow-up in the outpatient neurology clinic based on functional and neurocognitive outcomes as well as development of epilepsy. A total of 674 unique patients presented with status epilepticus of which 40 had new-onset refractory status epilepticus. Patients were classified into either refractory status epilepticus or super-refractory status epilepticus. The etiology of most children with new-onset refractory status epilepticus remained cryptogenic. The most common identified etiology was viral (20%). None of the patients had a contributory positive neuronal antibody test. Several treatments were tried including immunotherapy which was used in half of the patients. Five patients died (12.5%) during the acute phase of their disease, with four lost to follow-up. Twenty out of the remaining 31 patients (65%) developed epilepsy and 18 (58%) had persistent neurocognitive impairment. There was no statistical significant difference in various outcome measures and various etiologies, patients' characteristics, and treatments.

CONCLUSIONS

In this single-center cohort, more than half of the children with new-onset refractory status epilepticus did not have an identifiable etiology. Unlike adult patients, the presence of positive neuronal antibody syndrome was rare. There was no difference in outcome between those with or without an identifiable etiology. As expected, patients with super-refractory status epilepticus had worse functional and neurocognitive outcomes. More standardized diagnostic and treatment algorithms are needed along with prospective multicenter studies.

Acute necrotizing encephalopathy in an adult as a complication of H1N1 infection

Acute necrotizing encephalitis is one of the recognized influenza-associated encephalopathies which has a characteristic multifocal symmetric involvement of the thalami bilaterally with only very few cases were reported in adults. We present a case of a young adult female who was presented with post-H1N1 Acute Necrotizing Encephalopathy with full neurological recovery after proper clinicoradiological diagnosis and rapid treatment with steroids and intravenous immunoglobulins.

A rare case of influenza A in a hospitalized adult presenting with encephalitis and a seizure

Influenza A in hospitalized adults uncommonly may present with neurologic manifestations, e.g., encephalitis. Encephalitis is the most common influenza related neurologic complication in adults, However, seizures in hospitalized adults due to influenza are extremely rare. This is a case of a 58 year old female hospitalized for influenza A. On admission, she was confused and obtunded. Her EEG showed diffuse global slowing indicative of encephalitis. On hospital day (HD) #2, she had a seizure. She had no history of a seizure disorder, and was not febrile at the time of the seizure. While seizures are not uncommon in children (febrile seizures) with influenza B, but in adults with influenza A, only a few cases of seizures have been reported. This case was most interesting in having both encephalitis and seizure complicating influenza A. If present, neuropsychiatric manifestations may be due to ostelamivir, but encephalitis and seizures are not among the neurologic adverse effects of ostelamivir. In adults hospitalized with influenza A, clinicians should be alert to the possibility of neurologic complications.

Neurologic Complications of Influenza B Virus Infection in Adults, Romania

Infection with this virus should be considered as an etiologic factor for encephalitis.

We characterized influenza B virus–related neurologic manifestations in an unusually high number of hospitalized adults at a tertiary care facility in Romania during the 2014–15 influenza epidemic season. Of 32 patients with a confirmed laboratory diagnosis of influenza B virus infection, neurologic complications developed in 7 adults (median age 31 years). These complications were clinically diagnosed as confirmed encephalitis (4 patients), possible encephalitis (2 patients), and cerebellar ataxia (1 patient). Two of the patients died. Virus sequencing identified influenza virus B (Yam)-lineage clade 3, which is representative of the B/Phuket/3073/2013 strain, in 4 patients. None of the patients had been vaccinated against influenza. These results suggest that influenza B virus can cause a severe clinical course and should be considered as an etiologic factor for encephalitis.

Successful Treatment of Influenza-Associated Acute Necrotizing Encephalitis in an Adult Using High-Dose Oseltamivir and Methylprednisolone: Case Report and Literature Review

A case of influenza-associated acute necrotizing encephalitis (ANE) is described in an otherwise healthy adult. The patient was treated successfully with a combination of high-dose methylprednisolone and high-dose oseltamivir. The patient relapsed after discontinuing 150 mg twice daily oseltamivir but quickly improved and eventually recovered after reinitiation of high-dose oseltamivir for an additional 2 weeks. The clinical presentation, pathogenesis, and treatment of influenza-associated ANE is reviewed. The use of high-dose oseltamivir in combination with methylprednisolone may offer additional therapeutic benefit for this rare and poorly understood complication of influenza infection.

Successful Treatment of Influenza-Associated Acute Necrotizing Encephalitis in an Adult Using High-Dose Oseltamivir and Methylprednisolone: Case Report and Literature Review

A case of influenza-associated acute necrotizing encephalitis (ANE) is described in an otherwise healthy adult. The patient was treated successfully with a combination of high-dose methylprednisolone and high-dose oseltamivir. The patient relapsed after discontinuing 150 mg twice daily oseltamivir but quickly improved and eventually recovered after reinitiation of high-dose oseltamivir for an additional 2 weeks. The clinical presentation, pathogenesis, and treatment of influenza-associated ANE is reviewed. The use of high-dose oseltamivir in combination with methylprednisolone may offer additional therapeutic benefit for this rare and poorly understood complication of influenza infection.

Aliphatic and alicyclic camphor imines as effective inhibitors of influenza virus H1N1

A series of camphor derived imines was synthesised and evaluated in vitro for antiviral activity. Theoretical evaluations of ADME properties were also carried out. Most of these compounds exhibited significant activity against the drug-resistant strains of influenza A virus. Especially, compounds 2 (SI = 632) and 3 (SI = 417) presented high inhibition against influenza subtypes A/Puerto Rico/8/34 and A/California/07/09 of H1N1pdm09. Analysis of the structure-activity relationship showed that the activity was strongly dependent on the length of the aliphatic chain: derivatives with a shorter chain possessed higher activity, while the suppressing action of compounds with long aliphatic chains was lower.

Acute necrotising encephalopathy in a child with H1N1 influenza infection: a clinicoradiological diagnosis and follow-up

Acute necrotising encephalopathy of childhood (ANEC) is a fulminant disorder with rapid progressive encephalopathy, seizures and poor outcome. It has been reported in association with various viral infections. We describe the clinicoradiological findings and short-term follow-up in a child with H1N1 influenza-associated ANEC. Laminar, target or tricolour pattern of involvement of the thalami was seen on apparent diffusion coefficient images. Our patient had significant morbidity at discharge despite early diagnosis and management with oseltamivir and immunoglobulin. Repeat imaging after 3 months had shown significant resolution of thalamic swelling, but there was persistence of cytotoxic oedema involving bilateral thalami. She was pulsed with intravenous steroids and maintained on a tapering schedule of oral steroids. This report emphasises the need for a high index of suspicion to establish early diagnosis, promotion of widespread immunisation strategies to prevent influenza outbreak, and more research to establish standard treatment protocols for this under-recognised entity.

Compounds with anti-influenza activity: present and future of strategies for the optimal treatment and management of influenza. Part I: Influenza life-cycle and currently available drugs

Influenza is a contagious respiratory acute viral disease characterized by a short incubation period, high fever and respiratory and systemic symptoms. The burden of influenza is very heavy. Indeed, the World Health Organization (WHO) estimates that annual epidemics affect 5-15% of the world's population, causing up to 4-5 million severe cases and from 250,000 to 500,000 deaths. In order to design anti-influenza molecules and compounds, it is important to understand the complex replication cycle of the influenza virus. Replication is achieved through various stages. First, the virus must engage the sialic acid receptors present on the free surface of the cells of the respiratory tract. The virus can then enter the cells by different routes (clathrin-mediated endocytosis or CME, caveolae-dependent endocytosis or CDE, clathrin-caveolae-independent endocytosis, or macropinocytosis). CME is the most usual pathway; the virus is internalized into an endosomal compartment, from which it must emerge in order to release its nucleic acid into the cytosol. The ribonucleoprotein must then reach the nucleus in order to begin the process of translation of its genes and to transcribe and replicate its nucleic acid. Subsequently, the RNA segments, surrounded by the nucleoproteins, must migrate to the cell membrane in order to enable viral assembly. Finally, the virus must be freed to invade other cells of the respiratory tract. All this is achieved through a synchronized action of molecules that perform multiple enzymatic and catalytic reactions, currently known only in part, and for which many inhibitory or competitive molecules have been studied. Some of these studies have led to the development of drugs that have been approved, such as Amantadine, Rimantadine, Oseltamivir, Zanamivir, Peramivir, Laninamivir, Ribavirin and Arbidol. This review focuses on the influenza life-cycle and on the currently available drugs, while potential antiviral compounds for the prevention and treatment of influenza are considered in the subsequent review.