H1N1 encephalitis with malignant edema and review of neurologic complications from influenza

Fluorofurimazine, a novel NanoLuc substrate, enhances real-time tracking of influenza A virus infection without altering pathogenicity in mice

Bioluminescence imaging (BLI) using engineered bioluminescent viruses has emerged as a powerful tool for real-time, noninvasive monitoring of viral replication in living animals. While traditional luciferase-based systems, such as firefly luciferase, have been widely used, the NanoLuc luciferase system offers distinct advantages, including its significantly smaller gene size, increased brightness, and independence from ATP as a cofactor, allowing for extracellular detection. However, the utility of NanoLuc has been limited by its traditional substrate, furimazine, which exhibits poor water solubility and potential cytotoxicity. In this study, we assessed fluorofurimazine (FFz), a novel substrate with improved water solubility and bioavailability, for tracking influenza A virus (IAV) replication in mice. Our findings demonstrate that FFz substantially enhances detection sensitivity in both respiratory organs and brain tissue without increasing toxicity, enabling more precise and sustained monitoring of IAV replication. In vitro, FFz generated higher photon flux at lower concentrations compared to furimazine, translating into superior in vivo sensitivity with reduced toxicity. Crucially, FFz did not alter the pathogenicity of IAV in mice, even at sublethal infectious doses, reinforcing its suitability for use in BLI-based viral pathogenicity studies. These results suggest that combining FFz with NanoLuc provides a more effective and less toxic approach for real-time tracking of viral infections in preclinical models.

IMPORTANCE

Monitoring viral infections in living animals is a valuable approach for understanding how viruses replicate and cause disease. This study focuses on bioluminescent influenza A virus infection in a mouse model and evaluates fluorofurimazine, a new substrate that enhances bioluminescence imaging. Fluorofurimazine allows researchers to monitor viral spread more effectively than the traditional substrate, furimazine, which is often toxic and less reliable. It offers better sensitivity and lower toxicity, enabling longer and more accurate tracking of viral replication in the lungs and even the brain. Importantly, fluorofurimazine does not alter the pathogenicity of the virus, providing an unaltered representation of the infection process. This advancement has the potential to significantly improve how scientists study bioluminescent viral infections and evaluate antiviral drugs and vaccines, making it a valuable tool for research on influenza and other respiratory viruses.

Antibodies against SARS-CoV-2 spike protein in the cerebrospinal fluid of COVID-19 patients and vaccinated controls: a multicentre study

INTRODUCTION

SARS-CoV-2 antibodies in the cerebrospinal fluid (CSF) of COVID-19 patients possibly reflect blood-cerebrospinal fluid barrier (BCB) disruption due to systemic inflammation. However, some studies indicate that CSF antibodies signal a neurotropic infection. Currently, larger studies are needed to clarify this, and it is unknown if CSF antibodies appear solely after infection or also after COVID-19 vaccination. Therefore, we aimed to investigate the CSF dynamics of SARS-CoV-2 antibodies in a multicenter study of COVID-19 patients and vaccinated controls.

METHODS

A cohort study of Danish and Norwegian COVID-19 patients and controls investigated with a lumbar puncture (April 2020-December 2022). Serum and CSF were analysed locally for routine investigations, and centrally at Statens Serum Institut (Danish governmental public health institute) for SARS-CoV-2 IgG antibodies against the spike protein using the Euroimmun (quantitative) and Wantai (qualitative) assays. Primary outcome was the quantity of CSF SARS-CoV-2 antibodies post-COVID versus post-vaccination. Secondary outcomes included regression models examining the relationship between CSF antibodies and serum levels, albumin ratio, CSF pleocytosis, COVID-19 severity, and temporal antibody dynamics.

RESULTS

We included 124 individuals (Mean [SD] age 47.2 [16.6]; 59.7% males surviving COVID-19 and controls. Of these, 86 had paired CSF-serum testing. Antibody-index calculations did not support a SARS-CoV-2 brain infection. Multi-variate regression revealed that CSF SARS-CoV-2 antibodies were most strongly influenced by serum antibody levels and BCB permeability, as measured by increasing albumin ratio. CSF antibody levels displayed a dose-response relationship (p < 0.0001) influenced by preceding vaccinations or infections. CSF antibody levels (median [IQR]) were highest among those both previously infected and vaccinated, 100.0 [25.0-174.0], and those vaccinated without prior infection, 85.0 [12.0-142.0], and lowest among previously infected individuals without preceding vaccination, 5.9 [2.7-55.1], (p = 0.003). SARS-CoV-2 antibodies in CSF were also detected via qualitative assays in the COVID-19 (46.8%) and vaccinated (78.6%) groups, p = 0.03.

CONCLUSION

SARS-CoV-2 antibodies detected in CSF can be derived following both infection and vaccination for COVID-19. CSF antibody levels increase in a dose-response relationship with the number of prior infections and vaccinations and are most strongly influenced by serum antibody levels and BCB permeability. These findings stress the importance of carefully interpreting CSF antibody results when assessing neurological complications following infections not categorized as neurotropic.

Hemorrhagic shock and encephalopathy syndrome: A call for new clinical criteria for early intervention

BACKGROUND

Current epidemiological diagnostic criteria for hemorrhagic shock and encephalopathy syndrome (HSES) may not be optimal for early identification in clinical settings. We analyzed the specific timing at which Bacon's criteria were met after encephalopathy onset.

METHODS

This retrospective observational study was conducted at the National Center for Child Health and Development, a quaternary-care facility that receives critically ill patients from a wide geographic area, between January 2014 and December 2023. Cases of HSES were identified using Bacon's criteria. Data on detailed time courses after seizure onset were extracted from medical records. The primary outcome was the time at which Bacon's criteria were met, measured using median values.

RESULTS

Of the 206 patients with acute encephalopathy, 13 had HSES. Four were excluded due to insufficient data. Only one patient met Bacon's criteria based on initial examinations, while eight met them after presentation. The median time from seizure onset to meeting Bacon's criteria was 4 h. Early diagnostic markers included abnormal blood coagulation, renal dysfunction, and elevated enzyme levels. The median time to initiation of steroid pulse therapy was 11.5 h; it was 9 h for plasma exchange. Irreversible brain damage, indicated by cerebral edema, occurred at a median of 7 h post-seizure.

CONCLUSIONS

The existing criteria fail in the context of early diagnosis. Routine practice should include early blood tests, including those for coagulation abnormalities, for patients with febrile status epilepticus to identify HSES at an early stage. Future research should validate new diagnostic criteria and explore additional interventions.

Clinical Features and Treatment Outcomes of Influenza-Associated Encephalitis and Encephalopathy: A Study on 16 Children in Vietnam

Objectives. This study aims to report clinical features and treatment outcomes of 16 cases diagnosed with post-influenza encephalopathy/encephalitis. Methods. We recorded clinical characteristics of 16 pediatric patients diagnosed with post-influenza encephalopathy/encephalitis at the Vietnam National Children's Hospital from January 2019 to January 2021. Results. There were 87.5% infected with influenza A, with influenza A/H1pdm09 and influenza A/H3 accounting for 88.9% and 11.1% respectively, and 12.5% of participants infected with influenza B. The time from onset to the appearance of neurological symptoms was 3 days, of which perceptual changes (93.8%), hypertonia (75%), and seizures (43.8%) were prevalent neurological symptoms. The majority of cases had normal cerebrospinal fluid. Cranial CT/MRI imaging revealed abnormalities in 87.5% of patients. 56.3% of patients had sequelae, including epilepsy and cerebral palsy; 25% recovered, and 18.8% died after treatment. Conclusions. Influenza-associated encephalitis/encephalopathy is a complication occurring early in children, with high mortality and sequelae rates.

Identification of neurological complications in childhood influenza: a random forest model

BACKGROUND

Among the neurological complications of influenza in children, the most severe is acute necrotizing encephalopathy (ANE), with a high mortality rate and neurological sequelae. ANE is characterized by rapid progression to death within 1-2 days from onset. However, the knowledge about the early diagnosis of ANE is limited, which is often misdiagnosed as simple seizures/convulsions or mild acute influenza-associated encephalopathy (IAE).

OBJECTIVE

To develop and validate an early prediction model to discriminate the ANE from two common neurological complications, seizures/convulsions and mild IAE in children with influenza.

METHODS

This retrospective case-control study included patients with ANE (median age 3.8 (2.3,5.4) years), seizures/convulsions alone (median age 2.6 (1.7,4.3) years), or mild IAE (median age 2.8 (1.5,6.1) years) at a tertiary pediatric medical center in China between November 2012 to January 2020. The random forest algorithm was used to screen the characteristics and construct a prediction model.

RESULTS

Of the 433 patients, 278 (64.2%) had seizures/convulsions alone, 106 (24.5%) had mild IAE, and 49 (11.3%) had ANE. The discrimination performance of the model was satisfactory, with an accuracy above 0.80 from both model development (84.2%) and internal validation (88.2%). Seizures/convulsions were less likely to be wrongly classified (3.7%, 2/54), but mild IAE (22.7%, 5/22) was prone to be misdiagnosed as seizures/convulsions, and a small proportion (4.5%, 1/22) of them was prone to be misdiagnosed as ANE. Of the children with ANE, 22.2% (2/9) were misdiagnosed as mild IAE, and none were misdiagnosed as seizures/convulsions.

CONCLUSION

This model can distinguish the ANE from seizures/convulsions with high accuracy and from mild IAE close to 80% accuracy, providing valuable information for the early management of children with influenza.

Seizures in Children with Influenza during the 2022-2023 Winter Season, a Case Series

Influenza is a viral infection presenting with general symptoms such as fever, headache, fatigue, and involvement of airways or the gastrointestinal tract. The nervous system may be involved, but less frequently. These neurological complications remain challenging to diagnose; moreover, no guidelines for management and treatment exist. Therefore, when presenting with neurological symptoms, patients undergo invasive diagnostic procedures and empirical treatments before making the correct diagnosis. During the winter of 2022-2023, four children between nine months and nine years of age were admitted to the Lausanne University Hospital, Switzerland, complaining of influenza and neurological complications. This report presents the symptoms of neurological manifestation and the treatment management of the four patients. All the legally authorized representatives gave their written informed consent before study inclusion.

Is decompressive craniectomy necessary in malignant posterior reversible encephalopathy syndrome with brain edema caused uncal herniation? A case report of reversible coma without surgical decompression

BACKGROUND

Posterior reversible encephalopathy syndrome (PRES) is considered a benign entity and is usually reversible with only medical management, but persistent neurologic deficits and disability or death can occur without adequate treatment. Favorable outcomes have been associated with surgical decompression in malignant-type PRES in which hemorrhagic transformation or brain stem compression has developed.

CASE DESCRIPTION

Here we report a case of malignant PRES in a 61-year-old female of Asian descent in which the disease rapidly progressed to coma and a near-fatal condition with uncal herniation caused by severe brain edema; however, this patient achieved a dramatic recovery without surgical decompression.

CONCLUSION

After reviewing previous reports regarding malignant PRES, we propose that hemorrhagic transformation is a crucial indicator for surgical decompression and an important prognostic factor in malignant PRES.

Risk factors for mortality in fulminant acute necrotizing encephalopathy following influenza A in an adolescent boy

Acknowledging the risk factors of mortality and morbidity of each disease is effective for its final outcome. Recognizing these cases can have the value of preventing the occurrence of unfortunate events, such as not recommending the use diclofenac in an influenza epidemic.

Neurological features related to influenza virus in the pediatric population: a 3-year monocentric retrospective study

Influenza virus is generally characterized by fever, myalgia, and respiratory symptoms. Neurological entities have already been described, such as acute necrotizing encephalitis (ANE). We aimed to highlight the non-exceptional nature and explore the clinical spectrum and evolution of neurological features related to influenza virus in children. This monocentric observational study included patients under 18 years old, positive for influenza virus, between January 2017 and April 2019 in a pediatric university hospital. Patients were classified into two groups: those with or without a previous significant neurological or metabolic disorder. Two hundred eighty-nine children were identified with influenza infection. Thirty seven had a neurological manifestation: 14 patients who had previous significant neurological or metabolic disorder and 23 patients with no medical history. We identified several clinical patterns: 22 patients had seizures, 7 behavior disorders, 5 disturbances of consciousness, and 3 motor deficits. Four were diagnosed with a known influenza-associated neurological syndrome: 1 ANE, 1 cytotoxic lesion of the corpus callosum, 1 hemiconvulsion-hemiplegia-epilepsia syndrome, and 1 recurrent encephalitis in the context of a RANBP2 mutation. The neurological outcome was favorable in most cases. None of the patients with previous significant disorder retained sequalae or had a recurrence. Two patients had a fatal outcome, and both had a predisposing disorder.

CONCLUSION

Various neurological manifestations can be associated with influenza virus. Certain entities led to a poor prognosis, but in most cases, symptoms improved within a few days. The severity of the neurological manifestations correlated with previous neurological or metabolic disorders.

WHAT IS KNOWN

• Influenza viruses are well known pathogens with a seasonal epidemic evolution, particularly affecting children. These viruses cause acute fever with respiratory symptoms, associated with myalgia and headaches. Neurological presentation in influenza-virus infection is a well-established possibility as influenza virus is considered to be responsible for 27 to 36% of childhood encephalitis. Some specific and severe entity as acute necrotizing encephalitis, cytotoxic lesion of the corpus callosum, or Hemiconvulsion-hemiplegia-epilepsy syndrome are well described.

WHAT IS NEW

• In a French monocentric cohort of 37 children with influenza-related neurologic manifestations, the majority of these manifestations, including seizure, drowsiness, motor deficiency, hallucination… are self limiting and do not lead to after-effects. In rare cases (4/37), they may reveal severe encephalitis requiring rapid and appropriate treatment. Otherwise, comparison of a group of 14 children with underlying neurological or metabolic disorder with a group of 23 children free of any significant disorder show that the severity of the neurological manifestations was largely related to previous neurological or metabolic disorders highlighting the importance of vaccination in this population.

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.

Infectious Meningitis and Encephalitis

Infectious meningitis and encephalitis are associated with significant morbidity and mortality worldwide. Acute bacterial meningitis is rapidly fatal and early recognition and institution of therapy are imperative. Viral meningitis is typically a benign self-limited illness. Chronic meningitis (defined as presenting with >4 weeks of symptoms) is most often caused by tuberculosis and fungal infection. Because the diagnostic testing for tuberculous meningitis is insensitive and cultures often take weeks to grow, therapy is often initiated empirically when the diagnosis is suspected. Human simplex virus encephalitis is the most common cause of encephalitis and requires prompt treatment with intravenous acyclovir.

Fatal case of simply influenza A (H3N2)-associated encephalitis in immunocompetent patient

Influenza virus-associated encephalopathy/encephalitis is a rare entity in adults that can lead to severe neurological sequelae and even death. The clinical presentation can be quite diverse. This absence of a typical presentation along with the difficulty detecting the virus in the cerebrospinal fluid represents a diagnostic challenge. We present the case of a 79-year-old male with sudden onset of decreased consciousness and signs of right hemisphere damage. The presence of influenza A (H3N2) virus in respiratory sample along with compatible findings in cranial magnetic resonance led to the diagnosis. The patient died without responding to treatment with antivirals and immunomodulators and the anatomopathological study did not detect infectious agent. Early diagnostic suspicion is essential to establish adequate treatment and improve the prognosis.

Lower cognitive scores among toddlers in birth cohorts with acute respiratory illnesses, fevers, and laboratory-confirmed influenza

BACKGROUND

We established cohorts to assess associations between viral influenza and cognitive development to inform the value proposition of vaccination.

METHODS

From 2014 through 2017, we called women seeking care at four prenatal clinics in Panama and El Salvador to identify acute respiratory illnesses (ARIs). Within 2 weeks of childbirth, mothers were asked to enroll their neonates in the cognitive development study. Staff obtained nasopharyngeal swabs from children with febrile ARIs for real-time reverse transcription polymerase chain reaction (rtPCR) detection of viral RNA. Toddlers were administered Bayley developmental tests at ages 12 and 18-24 months. We used multilevel linear regression to explore associations between Bayley scores, ARIs, fever, and laboratory-confirmed influenza, controlling for maternal respiratory or Zika illnesses, infant influenza vaccination, birth during influenza epidemics, and the number of children in households.

RESULTS

We enrolled 1567 neonates of which 68% (n = 1062) underwent developmental testing once and 40% (n = 623) twice. Children with previous ARIs scored an average of 3 points lower on their cognitive scores than children without ARIs (p = 0.001). Children with previous fevers scored an average of 2.1 points lower on their cognitive scores than afebrile children (p = 0.02). In the second year, children with previous laboratory-confirmed influenza scored 4 points lower on their cognitive scores than children without influenza (p = 0.04, after controlling for first Bayley cognitive scores).

CONCLUSIONS

ARIs and fever during infancy were associated with lower Bayley scores at 12 months, and laboratory-confirmed influenza was associated with lower cognitive scores at 24 months suggesting the potential value of vaccination to prevent non-respiratory complications of influenza.

Clinical Characteristics of H1N1 Influenza A-Associated Mild Encephalopathy with Reversible Splenial Lesion: 4 Pediatric Cases

OBJECTIVE

Mild encephalopathy with reversible splenial lesion (MERS) is associated with a variety of infections and anti-epileptic drug withdrawal. Here we report the clinical characteristics of H1N1 influenza A-associated MERS based on our experience of four pediatric cases.

METHODS

A detailed retrospective analysis of four patients with H1N1 influenza A-associated MERS was performed at Guangzhou Women and Children's Medical Center.

RESULTS

All patients exhibited mild influenza-like illness and seizures. Three patients presented with a new-onset seizure with fever after 5 years of age. 75% patients had altered mental status. For all four patients, influenza A (H1N1) viral RNA was detected in throat swab specimens at least twice. Brain magnetic resonance images revealed similar ovoid lesions in the corpus callosum, mainly in the splenium and for one patient in the splenium and genu of the corpus callosum. Only one patient had an abnormal electroencephalogram tracing. Cells and protein in the cerebrospinal fluid were normal in all patients. All patients received oseltamivir and one patient received intravenous immunoglobulin. As a result, all patients fully recovered after 2 months and showed no neurologic sequelae at discharge.

CONCLUSION

This case series provides insight towards clinical features of H1N1 influenza A-associated MERS.

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.

Continuous Blood purification on Influenza-Associated Neurological Disease in children: a retrospective cohort study

Background

Due to lack of proven therapies, we evaluated the effect of CBP on Influenza-Associated Neurological Disease in children.

Methods

A single-center, retrospective, cohort study was conducted in Luoyang, Henan province, China from January 2018 to January 2020. Children (<18 years) with influenza-associated neurological disease were enrolled in the study. Children with indications for CBP and parental consent received CBP (Continuous Blood purification), while others received maximal intensive care treatment because of the absence of parental consent. The outcomes of the CBP and non-CBP groups were compared. Categorical variables were presented as percentage and compared by Chi-square test. Continuous variables were expressed as median (interquartile ranges) and compared with non-parametric independent sample test. Statistical analyses were carried out by SPSS (version 26.0) and p < 0.05 (2 tailed) was considered to be statistically significant.

Results

30 children with influenza-associated neurological disease were recruited to the study. 18 received CBP and the other 12 received maximal intensive care. There were no differences between CBP and non-CBP children in age, sex, body weight, type of influenza virus, neurological complications, Glasgow score, PIM-2 score and PCIS at admission (p > 0.05). The inflammatory factors (CRP, PCT and IL-6) of 30 cases were tested at admission and after 3 days of admission. In the CBP group, there was a significant decrease in IL-6 levels at 3 days of admission (p = 0.003) and a decrease in CRP and PCT levels, but no significant difference (p > 0.05). In the non-CBP group, there were no significant difference on levels of CRP, PCT and IL-6 at admission and 3-day of admission (p > 0.05). The 28-day mortality was significantly lower in the CBP group compared with the non-CBP group (11.11% vs. 50%, p = 0.034).

Conclusions

CBP definitely reduces IL-6 levels significantly. We did find that the survival rate of patients in the CBP group was improved. But we don’t know if there is a relationship between the reduction of IL-6 levels and the survival rate. Trial registration: http://www.chictr.org.cn/index.aspx(ChiCTR2000031754).

Infectious disease-associated encephalopathies

Infectious diseases may affect brain function and cause encephalopathy even when the pathogen does not directly infect the central nervous system, known as infectious disease-associated encephalopathy. The systemic inflammatory process may result in neuroinflammation, with glial cell activation and increased levels of cytokines, reduced neurotrophic factors, blood-brain barrier dysfunction, neurotransmitter metabolism imbalances, and neurotoxicity, and behavioral and cognitive impairments often occur in the late course. Even though infectious disease-associated encephalopathies may cause devastating neurologic and cognitive deficits, the concept of infectious disease-associated encephalopathies is still under-investigated; knowledge of the underlying mechanisms, which may be distinct from those of encephalopathies of non-infectious cause, is still limited. In this review, we focus on the pathophysiology of encephalopathies associated with peripheral (sepsis, malaria, influenza, and COVID-19), emerging therapeutic strategies, and the role of neuroinflammation.

Is the Frontal Lobe the Primary Target of SARS-CoV-2?

Acute delirium and other neuropsychiatric symptoms have frequently been reported in COVID-19 patients and are variably referred to as acute encephalopathy, COVID-19 encephalopathy, SARS-CoV-2 encephalitis, or steroid-responsive encephalitis. COVID-19 specific biomarkers of cognitive impairment are currently lacking, but there is some evidence that SARS-CoV-2 could preferentially and directly target the frontal lobes, as suggested by behavioral and dysexecutive symptoms, fronto-temporal hypoperfusion on MRI, EEG slowing in frontal regions, and frontal hypometabolism on 18F-FDG-PET imaging. We suggest that an inflammatory parainfectious process targeting preferentially the frontal lobes (and/or frontal networks) could be the underlying cause of these shared clinical, neurophysiological, and imaging findings in COVID-19 patients. We explore the biological mechanisms and the clinical biomarkers that might underlie such disruption of frontal circuits and highlight the need of standardized diagnostic procedures to be applied when investigating patients with these clinical findings. We also suggest the use of a unique label, to increase comparability across studies.

Myelopathy associated with SARS-COV-2 infection. A systematic review

Background׃COVID-19 (CoranaVirus disease 2019) is an ongoing infectious disease caused by the RNA SARS-CoV-2 virus (Severe Acute Respiratory Syndrome CoronaVirus-2). More than one-third of COVID-19 patients report neurological symptoms and cases of neurological diseases are increasingly accumulating. The aim of this systematic review was to characterize all - to date - reported cases with COVID-19 related myelopathy. Methods׃Eighteen papers were included in this review. Patients of all ages could be affected, although there is a predilection for middle-aged people. Results׃There were no significant co-morbidities or immunodeficiencies in the affected patients. COVID-19 related myelopathy started roughly within the first month after COVID-19 onset, either concomitantly with COVID-19 symptoms or within 10 days after their remission. The vast majority of cases fulfilled our criteria for postinfectious transverse myelitis. However, some cases were considered to have had parainfectious or infectious myelitis or, in one case, vascular myelopathy. Motor, sensory and bowel and/or bladder symptoms predominated the clinical presentation of myelopathies, explained mainly by centrally localized and longitudinally extensive lesions within the cervical and/or thoracic segments of the spinal cord. Occasionally lesions were complicated by necrosis and hemorrhages. Treatment with corticosteroids, intravenous immunoglobulin or plasma exchange was offered mostly a mild to marked improvement within a period of some weeks. Conclusions׃ Considering the imminent arrival of new vaccines against COVID-19 pandemic, and their potential risk for postvaccination transverse myelitis, this characterization of COVID-19 related myelopathy is of utmost importance.

Acute Fulminant Cerebral Edema: A Newly Recognized Phenotype in Children With Suspected Encephalitis

BACKGROUND

Encephalitis is a severe neurological syndrome associated with significant morbidity and mortality. The California Encephalitis Project (CEP) enrolled patients for more than a decade. A subset of patients with acute and fulminant cerebral edema was noted.

METHODS

All pediatric encephalitis patients with cerebral edema referred to the CEP between 1998 and 2012 were reviewed. A case definition was developed for acute fulminant cerebral edema (AFCE) that included the CEP case definition for encephalitis and progression to diffuse cerebral edema on neuroimaging and/or autopsy, and no other recognized etiology for cerebral edema (eg, organic, metabolic, toxin). Prodromic features, demographic and laboratory data, neuroimaging, and outcomes were compared with non-AFCE encephalitis cases.

RESULTS

Of 1955 pediatric cases referred to the CEP, 30 (1.5%) patients met the AFCE case definition. The median age for AFCE and non-AFCE cases was similar: 8.2 years (1-18 years) and 8.0 years (0.5-18 years), respectively. Asian-Pacific Islanders comprised a larger proportion of AFCE cases (44%) compared with non-AFCE cases (14%, P < .01). AFCE cases often had a prodrome of high fever, vomiting, and profound headache. Mortality among AFCE patients was significantly higher than among non-AFCE patients (80% vs 13%, P < .01). A confirmed etiology was identified in only 2 cases (enterovirus, human herpes virus type 6), while 10 others had evidence of a respiratory pathogen.Thirty pediatric patients referred to the California Encephalitis Project with a unique, and often fatal, form of encephalitis are reported. Demographic and clinical characteristics, possible etiologies and a proposed case definition for acute fulminant cerebral edema (AFCE) are described.

CONCLUSIONS

AFCE is a recently recognized phenotype of encephalitis with a high mortality. AFCE may be triggered by common pediatric infections. Here, we propose a case definition.

The use of therapeutic plasma exchange as adjunctive therapy in the treatment of coronavirus disease 2019: A critical appraisal of the current evidence

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a major pandemic. While vaccine development moves forward, optimal treatment continues to be explored. Efforts include an ever-expanding number of clinical trials along with newly proposed experimental and off-label investigational therapies; one of which is therapeutic plasma exchange (TPE). There have been a number of publications on TPE use as adjunctive therapy for coronavirus disease 2019 (COVID-19), but no prospective randomized controlled trials (RCTs) have been completed. This article critically appraises the current available evidence on TPE as a treatment modality for SARS-CoV-2 infection.

Influenza-Associated Encephalopathy and Acute Necrotizing Encephalopathy in Children: A Retrospective Single-Center Study

Background

Although influenza primarily affects the respiratory system, it can cause severe neurological complications, especially in younger children, but knowledge about the early indicators of acute necrotizing encephalopathy (ANE) is limited. The main purpose of this article is to summarize the clinical characteristics, diagnosis, and treatment of neurological complications of influenza in children, and to identify factors associated with ANE.

Material/Methods

This was a retrospective study of children with confirmed influenza with neurological complications treated between 01/2014 and 12/2019 at Guangzhou Women and Children’s Medical Center. A receiver operating characteristics curve analysis was performed to determine the prognostic value of selected variables.

Results

Sixty-three children with IAE (n=33) and ANE (n=30) were included. Compared with the IAE group, the ANE group showed higher proportions of fever and acute disturbance of consciousness, higher alanine aminotransferase, higher aspartate aminotransferase, higher creatinine kinase, higher procalcitonin, higher cerebrospinal fluid (CSF) protein, and lower CSF white blood cells (all P<0.05). The areas under the curve (AUCs) for procalcitonin and CSF proteins, used to differentiate IAE and ANE, were 0.790 and 0.736, respectively. The sensitivity and specificity of PCT >4.25 ng/ml to predict ANE were 73.3% and 100.0%, respectively. The sensitivity and specificity of CSF protein >0.48 g/L to predict ANE were 76.7% and 69.7%, respectively. Thirteen (43.3%) children with ANE and none with IAE died (P<0.0001).

Conclusions

High levels of CSF protein and serum procalcitonin might be used as early indicators for ANE. All children admitted with neurological findings, especially during the influenza season, should be evaluated for influenza-related neurological complications.

Respiratory virus-related meningoencephalitis in adults

Purpose

Respiratory viruses (RVs) are pathogens that can cause central nervous system (CNS) infection, but previous research has been limited to a pediatric population. In recent years, several cases of adult RV meningoencephalitis have begun to be reported. We decided to research the CNS infection of RV in the entire neuroinfection registry.

Methods

We retrospectively reviewed the neurologic infection registry of Seoul National University (Seoul, Korea). Among a total of 661 patients in the registry, 10 adult patients were diagnosed with RV-related meningoencephalitis on RV multiplex polymerase chain reaction (PCR) screening test. We analyzed the clinical presentation, laboratory findings, and clinical course of the 10 patients.

Results

Three patients were definite RV meningoencephalitis who had positive PCR results from cerebrospinal fluid. The other seven patients were diagnosed with probable RV meningoencephalitis if they had positive PCR results in the sputum and negative results in other extensive workup.

Conclusion

RV-related meningoencephalitis should be considered a possible etiology in adult meningoencephalitis patients. To diagnose these viruses, screening test of RV PCR is recommended even in patients without upper respiratory infection symptoms.

Rapidly progressive acute necrotizing encephalopathy associated with influenza A in an elderly adult

Background

Among the influenza‐associated encephalopathies, acute necrotizing encephalopathy (ANE) has a particularly poor prognosis. While it usually progresses within 48 h, we encountered a rapidly evolving case with the patient falling into coma from lucidity within 10 min.

Case Presentation

A 71‐year‐old man was found unconscious after taking a 10‐min bath and brought to the emergency room. The head computed tomography (HCT) was normal, and he was diagnosed with heatstroke as a complication of influenza A. Despite effective therapy to correct his temperature, his consciousness did not improve, and within 24 h he progressed to multiple organ injury. Repeat HCT and subsequent magnetic resonance imaging revealed irreparably progressed ANE.

Conclusion

To effectively treat ANE, early recognition and diagnosis are critical. Our case suggests that ANE should be considered and added to the differential diagnosis for adult patients with rapid cognitive deterioration.

Novel pathogenic characteristics of highly pathogenic avian influenza virus H7N9: viraemia and extrapulmonary infection

The H7N9 virus mutated in 2017, resulting in new cases of highly pathogenic avian influenza (HPAI) H7N9 virus infection. H7N9 was found in a viraemic patient in Guangdong province, China. The present study aimed to clarify the pathogenic characteristics of HPAI H7N9. Virus was isolated from the plasma and sputum of the patient with HPAI H7N9. Liquid phase chip technology was used to detect the plasma cytokines from the infected patient and healthy controls. Mice were infected with strains A/Guangdong/GZ8H002/2017(H7N9) and A/Zhejiang/DTID-ZJU01/2013(H7N9) to observe the virus's pathogenic characteristics. Serum and brain tissue were collected at 2, 4, and 6 days after infection. The viruses in serum and brain tissue were detected and isolated. The two strains were infected into A549 cells, exosomes were extracted, and virus genes in the exosomes were assessed. Live virus was isolated from the patient's plasma. An acute cytokine storm was detected during the whole course of the disease. In animal experiments, A/Guangdong/GZ8H002/2017(H7N9) was more pathogenic than A/Zhejiang /DTID-ZJU01/2013(H7N9) and resulted in the death of mice. Live virus was isolated from infected mouse serum. Virus infection was also detected in the brain of mice. Under viral stress, A549 cells secreted exosomes containing the entire viral genome. The viraemic patient was confirmed to have an HPAI H7N9 infection. A/Guangdong/GZ8H002/2017(H7N9) showed significantly enhanced toxicity. Patient deaths might result from cytokine storms and brain infections. Extrapulmonary tissue infection might occur via the exosome pathway. The determined pathogenic characteristics of HPAI H7N9 will contribute to its future treatment.

Aphasia and confusion - influenza encephalopathy: atypical presentation of influenza

Influenza encephalopathy, a rare manifestation of influenza infection in the adult population which is not widely recognised, can present with confusion and focal neurological symptoms, including aphasia. The aim of this report is to illustrate the unique presentation of influenza encephalopathy and discuss the need for close attention to and monitoring of this rare but highly fatal disease.A 28-year-old woman was admitted with acute-onset confusion and incoherent speech. CT of the head was unremarkable. Cerebrospinal fluid analysis showed elevation of protein, but was otherwise unremarkable. A detailed history revealed recent upper respiratory symptoms which prompted a rapid influenza test which was positive and oseltamivir was started. The patient's confusion and aphasia gradually improved and her speech was back to her baseline by the next day.

Neurological Manifestations of Influenza A (H1N1): Clinical Features, Intensive Care Needs, and Outcome

OBJECTIVES

To describe neurological manifestations in children with Influenza A (H1N1).

METHODS

This retrospective study was conducted in the Pediatric intensive care unit (PICU) and Pediatric Neurology unit of a tertiary care teaching hospital in North India involving children with PCR confirmed Influenza A (H1N1) with neurological manifestations during 2019 outbreak.

RESULTS

Six children (5 females, 1 male) were enrolled. All presented with neurological symptoms (seizures and altered sensorium) accompanied with fever and respiratory symptoms with duration of illness of 2-7 d. The admission Glasgow Coma Scale ranged from 4 to 12. Only 2 cases showed cerebrospinal fluid pleocytosis. Neuroimaging was suggestive of diffuse cerebral edema, acute necrotizing encephalopathy of childhood, and acute disseminated encephalomyelitis. All were treated with Oseltamivir. Four cases had clinical features of raised intracranial pressure (ICP) and were managed in PICU, 3 of them needed mechanical ventilation, 3 needed vasoactive drugs, 3 received 3% saline infusion, 1 underwent invasive ICP monitoring, and 3 (cases 4, 5 and 6) received intravenous methylprednisolone (30 mg/kg) for 5 d. Total duration of hospital stay was 10-30 d. Case 2 expired due to refractory raised ICP. Among survivors, 3 children had residual neurological deficits and the remaining 2 had achieved premorbid condition.

CONCLUSIONS

Influenza A (H1N1) can present with isolated or predominant neurological manifestations which can contribute to poor outcome. The authors suggest to rule out H1N1 in any child who presents with unexplained neurological manifestations during seasonal outbreaks of H1N1.

Successful Outcome in an Adult Patient with Influenza-associated Hemorrhagic Shock and Encephalopathy Syndrome

A 50-year-old woman presented with coma and hemorrhagic shock. A rapid influenza antigen test revealed influenza A infection; other laboratory examinations ruled out any other suspected infections. She was diagnosed with hemorrhagic shock and encephalopathy syndrome (HSES) induced by influenza A. She was administered methylprednisolone pulse therapy and peramivir. Subsequently, she was discharged without any sequelae. Only a few cases of influenza-induced HSES have been reported, and the clinical outcomes were very poor. We herein report a successfully treated adult case of influenza-induced HSES and review this rare syndrome.

Neurological complications associated with influenza in season 2017/18 in Austria- a retrospective single center study

BACKGROUND

Neurological complications associated with influenza (NCI) are rare events in adults with seasonal influenza. Information about the characteristics of neurological complications and the burden of disease has been limited to case reports, mainly during the pandemic 2009. Influenza-associated encephalopathy/encephalitis (IAE) is one of the most severe and frequently reported NCI, mostly caused by influenza A. Isolated case reports exist about NCI caused by influenza B.

OBJECTIVES

The aim of this single center retrospective study is the better understanding of the frequency and the characteristics of NCI in adults in season 2017-2018, depending on the influenza subtype A or B.

STUDY DESIGN

We reviewed 874 adult patients with laboratory confirmed influenza admitted to the Christian Doppler University Hospital Salzburg, Austria from December 2017 until March 2018 looking for NCI.

RESULTS

37 (4 %) of the 874 patients with confirmed influenza had NCI. 4 (11 %) had influenza A and 33 (89 %) had influenza B. IAE was the most frequent complication diagnosed in 24 (65 %) patients, of whom all but one had influenza B and 3 (13 %) had neurological residuals. Moreover 6 (16 %) had isolated epileptic seizures, 2 (5 %) had acute inflammatory demyelinating polyneuropathy (AIDP), and 5 (14 %) were classified as having infection-associated stroke.

CONCLUSIONS

We report an incidence of 4 % for NCI and a high frequency of IAE caused by subtype B. Therefore, we recommend considering both influenza A and B as an etiologic factor of encephalopathy and other neurological disease in adults.

Neurologic Manifestations of Severe Respiratory Viral Contagions

Endemic and pandemic viral respiratory infections have recently emerged as a critical topic of investigation given the recent severe acute respiratory syndrome coronavirus-2 outbreak. Data from such outbreaks indicate that severe systemic comorbidities including acute neurologic illness are associated with illness and lead to significant outcome differences. Herein, we will discuss the neurologic manifestations of severe viral respiratory infections including coronavirus, influenza, respiratory syncytial virus, metapneumovirus, and enterovirus.

Data Sources

PubMed and EMBASE were searched by two independent investigators up to March 2020.

Study Selection

Data selection included preclinical and clinical studies detailing neurologic manifestations of viral respiratory infections.

Data Extraction and Synthesis

Two independent investigators reviewed and extracted the data.

Conclusions

Neurologic manifestations including seizures, status epilepticus, encephalitis, critical illness neuromyopathy, acute disseminated encephalomyelitis, acute necrotizing encephalitis, Guillan-Barré syndrome, transverse myelitis, and acute flaccid myelitis have all been associated with severe viral respiratory infections. Having an understanding of the direct neurotropism of such viruses is imperative to understanding pathogenesis, clinical presentation, and potential treatment paradigms aimed at improving morbidity and mortality.

Acute Necrotizing Encephalopathy of Childhood with H1N1 Infection

Acute necrotizing encephalopathy of childhood (ANEC) is an uncommon and fulminant complication of seasonal influenza infection associated with high mortality and poor neurological outcome. We report a 4.5-year-old female who had pneumonia, ANEC, and raised intracranial pressure (ICP) with polymerase chain reaction proven H1N1 infection. Management included mechanical ventilation, invasive monitoring and control of ICP, oseltamivir, methylprednisolone, and supportive care in pediatric intensive care unit. She survived with poor neurological status at discharge.

Characteristics and outcome of influenza-associated encephalopathy/encephalitis among children in a tertiary pediatric hospital in Italy, 2017-2019

Background

Influenza is the most frequent cause of acute upper respiratory tract infections during winter season. Although rare, neurological manifestations are known to occur during influenza infection and approximatively three-quarters of cases are in children. In this study, we aimed to characterize the burden and clinical spectrum of influenza-associated encephalopathy and encephalitis in children admitted at a tertiary pediatric hospital in Italy over two influenza seasons (2017–2019).

Methods

We retrospectively analyzed clinical, laboratory, instrumental data and outcome of patients discharged with ICD9-CM 487.0 code.

Results

Fifteen children (13.1% of those discharged with a diagnosis of influenza infection in the study period), had influenza-associated central nervous system (CNS) manifestations. Eight patients (53.3%) were diagnosed as influenza encephalitis, 7 (46.7%) as influenza encephalopathy. Median age was 27 months. In children under 2 years of age (40% of all cases) altered consciousness was the most frequent neurological manifestation while respiratory symptoms were present at admission in all cases. Younger children also required intensive care support more frequently. Five subjects (33.3%) presented comorbidity. None of the patients had received seasonal influenza vaccination. The median time from onset of respiratory signs to onset of neurological manifestations was 24 h. Cerebrospinal fluid (CSF) analysis was normal in most patients and polymerase chain reaction for influenza virus RNA on CSF, when performed, was negative in all samples. Neuroradiological investigations, performed in 5 children, reported cortical and subcortical white matter signal alterations. Oseltamivir was administered only in 2 cases. Fourteen patients recovered without sequelae, and only a 2-year-old girl had minimal impairment in fine motor skills at discharge.

Conclusions

All children presenting acute neurological features during influenza season should be evaluated for influenza-associated CNS complications even if the respiratory involvement is mild. Absence of underlying diseases or other risk factors are not protective factors against CNS influenza-associated complications. The lack of CSF pleocytosis does not exclude CNS involvement. Children under 2 years of age are at higher risk of requiring intensive care support.

Use of MRI in the diagnosis and prognosis of acute necrotizing encephalopathy in a Chinese teenager: A case report

RATIONALE

Acute necrotizing encephalopathy (ANE) is a rapidly progressing disease associated with frequent neurologic sequelae and has poor prognosis. Currently, the diagnosis and treatment of ANE rely on neuroradiologic findings and offering supportive care. Here, we report the successful treatment of a teenager diagnosed with ANE using combination of high-dose methylprednisolone and oseltamivir.

PATIENT CONCERNS

The patient, a 15-year-old female, presented with impaired consciousness and seizures secondary to acute upper respiratory tract infection. A series of brain magnetic resonance images (MRIs) were obtained toward establishing a possible diagnosis.

DIAGNOSIS

Based on the history of presenting illness and subsequent brain MRI scans, the patient was diagnosed to be suffering from ANE.

INTERVENTIONS

Following the diagnosis, the patient was placed on therapy comprising of high-dose methylprednisolone and oseltamivir.

OUTCOMES

After treatment with methylprednisolone and oseltamivir for 15 days, the patient recovered nearly completely from ANE as confirmed by subsequent brain MRI scans. No complications or other emerging clinical symptoms were noted for the duration of follow-up that lasted 6 months.

LESSONS

Contrary to common reports, ANE can occur beyond pediatric populations and its treatment should not be restricted to supportive care. Our case suggests that the use of high-dose corticosteroids and oseltamivir leads to promising prognosis.

Diminished immune responses with aging predispose older adults to common and uncommon influenza complications

Influenza (flu) is a serious disease for older adults, with increased severity of infection and greater risk for hospitalization and death. Flu infection is limited to pulmonary epithelial cells, yet there are many systemic symptoms and older adults are more susceptible to flu-related complications. In older adults, flu rarely comes without additional complications and there is a perfect storm for enhanced disease due to multiple factors including existing co-morbidities, plus impaired lung function and dysregulated immune responses that occur with even healthy aging. Commonly, opportunistic secondary bacterial infections prosper in damaged lungs. Intensified systemic inflammation with aging can cause dysfunction in extra-pulmonary organs and tissues such as cardiovascular, musculoskeletal, neuropathologic, hepatic, and renal complications. Often overlooked is the underappreciated connections between many of these conditions, which exacerbate one another when in parallel. This review focuses on flu infection and the numerous complications in older adults associated with diminished immune responses.

Active neuroborreliosis or inflammation: are the diagnostic guidelines at stake?

Neuroborreliosis can induce a variety of neurological syndromes: e.g., cranial neuritis, plexitis, radiculitis, meningitis, cerebellitis, … We report on five cases of patients with a diagnosis of neuroborreliosis based on clinical symptoms, serologic tests and MR imaging results. However, neither of them fulfils the diagnostic criteria for definite neuroborreliosis. Are the diagnostic criteria still valid or is there a need to revise them? Is our diagnosis correct? Are these cases post-Lyme auto-immune neuronal inflammation, and not due to still active spirochetal infection? Do we need to consider immunosuppressive therapy instead of third-generation cephalosporins?

Acute encephalopathy associated with influenza infection: Case report and review of the literature

Influenza has been associated with neurological complications. We describe the case of a toddler who presented with symptoms and signs of acute encephalopathy and hydrocephalus. Neuroimaging demonstrated cerebral edema and multifocal diffusion restriction in the thalamus and splenium of the corpus callosum. Influenza A was detected from the nasopharyngeal aspirate. The final diagnosis was acute influenza-associated encephalopathy. Despite treatment with a neuraminidase inhibitor and intravenous immune globulin, the toddler developed neurological sequelae. This case highlights a rare but severe complication of influenza in young children and the importance of influenza vaccination.

CSF neopterin, a useful biomarker in children presenting with influenza associated encephalopathy?

PURPOSE

Neurological complications of influenza cause significant disease in children. Central nervous system inflammation, the presumed mechanism of influenza-associated encephalopathy, is difficult to detect. Characteristics of children presenting with severe neurological complications of influenza, and potential biomarkers of influenza-associated encephalopathy are described.

METHODS

A multi-center, retrospective case-series of children with influenza and neurological complications during 2017 was performed. Enrolled cases met criteria for influenza-associated encephalopathy or had status epilepticus. Functional outcome at discharge was compared between groups using the Modified Rankin Scale (mRS).

RESULTS

There were 22 children with influenza studied of whom 11/22 had encephalopathy and 11/22 had status epilepticus. Only one child had a documented influenza immunization. The biomarker CSF neopterin was tested in 10/11 children with encephalopathy and was elevated in 8/10. MRI was performed in all children with encephalopathy and was abnormal in 8 (73%). Treatment of children with encephalopathy was with corticosteroids or intravenous immunoglobulin in 9/11 (82%). In all cases oseltamivir use was low (59%) while admission to the intensive care unit was frequent (14/22, 66%). Clinical outcome at discharge was moderate to severe disability (mRS score > 2) in the majority of children with encephalopathy (7/11, 64%), including one child who died. Children with status epilepticus recovered to near-baseline function in all cases.

CONCLUSION

Raised CSF neopterin was present in most cases of encephalopathy, and along with diffusion restriction on MRI, is a useful diagnostic biomarker. Lack of seasonal influenza vaccination represents a missed opportunity to prevent illness in children, including severe neurological disease.

Neurologic Alterations Due to Respiratory Virus Infections

Central Nervous System (CNS) infections are one of the most critical problems in public health, as frequently patients exhibit neurologic sequelae. Usually, CNS pathologies are caused by known neurotropic viruses such as measles virus (MV), herpes virus and human immunodeficiency virus (HIV), among others. However, nowadays respiratory viruses have placed themselves as relevant agents responsible for CNS pathologies. Among these neuropathological viruses are the human respiratory syncytial virus (hRSV), the influenza virus (IV), the coronavirus (CoV) and the human metapneumovirus (hMPV). These viral agents are leading causes of acute respiratory infections every year affecting mainly children under 5 years old and also the elderly. Up to date, several reports have described the association between respiratory viral infections with neurological symptoms. The most frequent clinical manifestations described in these patients are febrile or afebrile seizures, status epilepticus, encephalopathies and encephalitis. All these viruses have been found in cerebrospinal fluid (CSF), which suggests that all these pathogens, once in the lungs, can spread throughout the body and eventually reach the CNS. The current knowledge about the mechanisms and routes used by these neuro-invasive viruses remains scarce. In this review article, we describe the most recent findings associated to neurologic complications, along with data about the possible invasion routes of these viruses in humans and their various effects on the CNS, as studied in animal models.

Transient Generalized Chorea in Influenza A Encephalopathy

Background

Influenza A infections are a rare cause of movement disorders. Previously described patients have suffered from acute-onset myoclonus and/or dystonia or post-viral parkinsonism.

Case Report

We present the case of a 74-year-old female patient with transient generalized chorea due to influenza A-mediated encephalopathy.

Discussion

We discuss whether the clinical presentation and the magnetic resonance imaging changes may be attributable to cytokine-mediated encephalopathy or to direct cytotoxic effects of the virus. Additionally, we would like to make clinicians aware of this clinical sign in the context of viral encephalopathy.