Acyclovir versus vidarabine in herpes simplex encephalitis. Randomised multicentre study in consecutive Swedish patients

Herpes Simplex Virus Encephalitis in Patients With Autoimmune Conditions or Exposure to Immunomodulatory Medications

BACKGROUND AND OBJECTIVES

Among infectious etiologies of encephalitis, herpes simplex virus type 1 (HSV-1) is most common, accounting for ∼15%-40% of adult encephalitis diagnoses. We aim to investigate the association between immune status and HSV encephalitis (HSVE). Using a US Medicaid database of 75.6 million persons, we evaluated the association between HSVE and autoimmune conditions, exposure to immunosuppressive and immunomodulatory medications, and other medical comorbidities.

METHODS

We used the US Medicaid Analytic eXtract data between 2007 and 2010 from the 29 most populated American states. We first examined the crude incidence of HSVE in the population. We then age and sex-matched adult cases of HSVE with a sufficient enrollment period (12 months before HSVE diagnosis) to a larger control population without HSVE. In a case-control analysis, we examined the association between HSVE and exposure to both autoimmune disease and immunosuppressive/immunomodulatory medications. Analyses were conducted with conditional logistic regression progressively adjusting for sociodemographic factors, Charlson Comorbidity Index, and non-autoimmune comorbidities.

RESULTS

Incidence of HSVE was ∼3.01 per 105 person-years among adults. A total of 951 HSVE cases and 95,100 age and sex-matched controls were compared. The HSVE population had higher rates of medical comorbidities than the control population. The association of HSVE and autoimmune conditions was strong (adjusted odds ratio (OR) 2.6; 95% CI 2.2-3.2). The association of HSVE and immunomodulating medications had an OR of 2.2 (CI 1.9-2.6), also after covariate adjustment. When both exposures were included in regression models, the associations remained robust: OR 2.3 (CI 1.9-2.7) for autoimmune disease and 2.0 (CI 1.7-2.3) for immunosuppressive and immunomodulatory medications.

DISCUSSION

In a large, national population, HSVE is strongly associated with preexisting autoimmune disease and exposure to immunosuppressive and immunomodulatory medications. The role of antecedent immune-related dysregulation may have been underestimated to date.

CNS Viral Infections-What to Consider for Improving Drug Treatment: A Plea for Using Mathematical Modeling Approaches

Neurotropic viruses may cause meningitis, myelitis, encephalitis, or meningoencephalitis. These inflammatory conditions of the central nervous system (CNS) may have serious and devastating consequences if not treated adequately. In this review, we first summarize how neurotropic viruses can enter the CNS by (1) crossing the blood-brain barrier or blood-cerebrospinal fluid barrier; (2) invading the nose via the olfactory route; or (3) invading the peripheral nervous system. Neurotropic viruses may then enter the intracellular space of brain cells via endocytosis and/or membrane fusion. Antiviral drugs are currently used for different viral CNS infections, even though their use and dosing regimens within the CNS, with the exception of acyclovir, are minimally supported by clinical evidence. We therefore provide considerations to optimize drug treatment(s) for these neurotropic viruses. Antiviral drugs should cross the blood-brain barrier/blood cerebrospinal fluid barrier and pass the brain cellular membrane to inhibit these viruses inside the brain cells. Some antiviral drugs may also require intracellular conversion into their active metabolite(s). This illustrates the need to better understand these mechanisms because these processes dictate drug exposure within the CNS that ultimately determine the success of antiviral drugs for CNS infections. Finally, we discuss mathematical model-based approaches for optimizing antiviral treatments. Thereby emphasizing the potential of CNS physiologically based pharmacokinetic models because direct measurement of brain intracellular exposure in living humans faces ethical restrictions. Existing physiologically based pharmacokinetic models combined with in vitro pharmacokinetic/pharmacodynamic information can be used to predict drug exposure and evaluate efficacy of antiviral drugs within the CNS, to ultimately optimize the treatments of CNS viral infections.

Herpes simplex encephalitis in France: incidence, 6-month rehospitalizations and mortality

BACKGROUND

Herpes simplex encephalitis (HSE) is a disease with unfavorable vital and functional prognoses. There are no recent epidemiological data on HSE at a national level using real-life databases, especially in France. This study aimed to report the incidence, the clinical characteristics and outcomes of the patients with HSE.

METHODS

We conducted a comprehensive retrospective cohort study on all patients hospitalized for HSE in France between 2015 and 2022 using national hospital discharge databases. Incidence, socio-demographic and clinical characteristics (including comorbidities, seizure, stays' features, intensive care supports) were described. The short- (first stay) and long-term (6-month) outcomes were reported, in terms of mortality and rehospitalizations.

RESULTS

1425 HSE patients were included (median age 67 [54-77] years old, M/F sex ratio 1.07), giving a mean yearly hospital incidence of 2.3 [2.1-2.5] per 1,000,000 inhabitants. 51.2% of the patients were admitted in ICU (n = 730), of whom 59.0% were mechanically ventilated. The overall mortality during the first stay was 14.3% (n = 204), up to 17.9% for ICU patients. Within 6 months, among the survivors, 10.1% had at least one rehospitalization related to HSE. At 6 months, 16.5% of all patients had died (n = 235), 20.8% for ICU patients.

CONCLUSION

In France, the incidence of hospitalizations for HSE was 2.3 per 1,000,000 inhabitants with more than half of the patients admitted in ICU and a 6-month in-hospital mortality about 16.5%. This real-life update on the characteristics and severe outcomes of the disease raises awareness among care practitioners, of the serious nature of the disease, and thus can lead to higher vigilance.

Outcome and Sequelae of Infectious Encephalitis

Acute infectious encephalitis is a widely studied clinical syndrome. Although identified almost 100 years ago, its immediate and delayed consequences are still neglected despite their high frequency and possible severity. We reviewed the available data on sequelae and persisting symptoms following infectious encephalitis with the aim of characterizing the clinical picture of these patients at months to years after hospitalization. We searched PubMed for case series involving sequelae after infectious encephalitis. We carried out a narrative review of the literature on encephalitis caused by members of the Herpesviridae family (herpes simplex virus, varicella zoster virus, and human herpesvirus-6), members of the Flaviviridae family (West Nile virus, tick-borne encephalitis virus, and Japanese encephalitis virus), alphaviruses, and Nipah virus. We retrieved 41 studies that yielded original data involving 3,072 adult patients evaluated after infectious encephalitis. At least one of the five domains of cognitive outcome, psychiatric disorders, neurological deficits, global functioning, and quality of life was investigated in the reviewed studies. Various tests were used in the 41 studies and the investigation took place at different times after hospital discharge. The results showed that most patients are discharged with impairments, with frequent deficits in cognitive function such as memory loss or attention disorders. Sequelae tend to improve within several years following flavivirus or Nipah virus infection, but long-term data are scarce for other pathogens. Further research is needed to better understand the extent of sequelae after infectious encephalitis, and to propose a standardized assessment method and assess the rehabilitation efficacy in these patients.

Clinical Review of Risk of Nephrotoxicity with Acyclovir Use for Treatment of Herpes Simplex Virus Infections in Neonates and Children

OBJECTIVE

This study aims to clarify the risk of nephrotoxicity with intravenous use of acyclovir (ACV) for the treatment of neonates (ages <3 months) and children (ages ≥3 months to <12 years) with herpes simplex virus (HSV) infections and to identify gaps in knowledge that could be further investigated.

METHODS

Multiple databases were searched to identify studies on risk of nephrotoxicity with ACV use for treatment of invasive HSV infections, defined as any neonatal infection or HSV encephalitis (HSE) in children.

RESULTS

There were 5 and 14 studies that evaluated the risk of ACV-associated nephrotoxicity in neonates and children, respectively. The US Food and Drug Administration (FDA) delayed the approval of high (HD; 60 mg/kg/day) ACV in neonates secondary to risk of toxicity. Based on our review, the risk of ACV-associated nephrotoxicity was lower in the neonatal compared with the pediatric population. Acyclovir dose >1500 mg/m2, older age, and concomitant use of nephrotoxic drugs were identified as variables that increased the risk of ACV nephrotoxicity in children. Although the FDA has approved the use of HD ACV for the treatment of HSE in children, the American Academy of Pediatrics recommends a lower dose to minimize the risk of toxicity. The efficacy and safety of high vs lower doses of ACV for the management of HSE in children has yet to be evaluated.

CONCLUSIONS

The risk of ACV-associated nephrotoxicity was lower among neonates compared with older children. Future studies are needed to identify the optimal dosage that minimizes toxicities and maximizes the efficacy of ACV in children with HSE.

TREM2 is down-regulated by HSV1 in microglia and involved in antiviral defense in the brain

Immunological control of viral infections in the brain exerts immediate protection and also long-term maintenance of brain integrity. Microglia are important for antiviral defense in the brain. Here, we report that herpes simplex virus type 1 (HSV1) infection of human induced pluripotent stem cell (hiPSC)-derived microglia down-regulates expression of genes in the TREM2 pathway. TREM2 was found to be important for virus-induced IFNB induction through the DNA-sensing cGAS-STING pathway in microglia and for phagocytosis of HSV1-infected neurons. Consequently, TREM2 depletion increased susceptibility to HSV1 infection in human microglia-neuron cocultures and in the mouse brain. TREM2 augmented STING signaling and activation of downstream targets TBK1 and IRF3. Thus, TREM2 is important for the antiviral immune response in microglia. Since TREM2 loss-of-function mutations and HSV1 serological status are both linked to Alzheimer's disease, this work poses the question whether genetic or virus-induced alterations of TREM2 activity predispose to post-infection neurological pathologies.

A case of severe anterograde amnesia in the era of smartphone technology

A.V. is a young herpes simplex encephalitis (HSE) survivor who suffered extensive bilateral damage to the medial temporal lobe (MTL) leading to a severe and pervasive form of anterograde amnesia. Structural Magnetic Resonance Imaging (MRI) revealed lesions that encompass the hippocampus and amygdala in both hemispheres and that extend more laterally in the right temporal lobe. At the same time, detailed neuropsychological testing showed that the disparity between A.V.'s preserved intellectual functioning (Full Scale IQ: 115) and severe memory deficit (Delayed Memory Index: 42) is one of the largest on record. Despite this deficit, A.V. has regained a higher level of functioning and autonomy compared to previously documented amnesic cases with major bilateral MTL lesions. As a millennial, one advantage which A.V. has over prior amnesic cases is fluency with digital technology - particularly the smartphone. The analysis of his phone and specific app usage showed a pattern that is consistent with the strategy to offload cognitive tasks that would normally be supported by the MTL. A.V.'s behavior is significant in terms of rehabilitation and may have broader implications at the societal level and for public health given the ubiquity of smartphone technology and its potential to become integrated with neural mnemonic functions.

Can we forecast poor outcome in herpes simplex and varicella zoster encephalitis? A narrative review

Herpes simplex virus (HSV) and varicella zoster virus (VZV) are among the most commonly diagnosed infectious causes of sporadic encephalitis worldwide. Despite treatment, mortality and morbidity rates remain high, especially for HSV encephalitis. This review is intended to provide an overview of the existing scientific literature on this topic from the perspective of a clinician who is confronted with serious decisions about continuation or withdrawal of therapeutic interventions. We performed a literature review searching two databases and included 55 studies in the review. These studies documented or investigated specifically outcome and predictive parameters of outcome of HSV and/or VZV encephalitis. Two reviewers independently screened and reviewed full-text articles meeting the inclusion criteria. Key data were extracted and presented as a narrative summary. Both, HSV and VZV encephalitis have mortality rates between 5 and 20% and complete recovery rates range from 14 to 43% for HSV and 33 to 49% for VZV encephalitis. Prognostic factors for both VZV and HSV encephalitis are older age and comorbidity, as well as severity of disease and extent of magnetic resonance imaging (MRI) lesions on admission, and delay in treatment initiation for HSV encephalitis. Although numerous studies are available, the main limiting factors are the inconsistent patient selection and case definitions as well as the non-standardised outcome measures, which hampers the comparability of the studies. Therefore, larger and standardised observational studies applying validated case definitions and outcome measures including quality of life assessment are required to provide solid evidence to answer the research question.

Diagnosing viral encephalitis and emerging concepts

PURPOSE OF REVIEW

This review offers a contemporary clinical approach to the diagnosis of viral encephalitis and discusses recent advances in the field. The neurologic effects of coronaviruses, including COVID-19, as well as management of encephalitis are not covered in this review.

RECENT FINDINGS

The diagnostic tools for evaluating patients with viral encephalitis are evolving quickly. Multiplex PCR panels are now in widespread use and allow for rapid pathogen detection and potentially reduce empiric antimicrobial exposure in certain patients, while metagenomic next-generation sequencing holds great promise in diagnosing challenging and rarer causes of viral encephalitis. We also review topical and emerging infections pertinent to neuroinfectious disease practice, including emerging arboviruses, monkeypox virus (mpox), and measles.

SUMMARY

Although etiological diagnosis remains challenging in viral encephalitis, recent advances may soon provide the clinician with additional tools. Environmental changes, host factors (such as ubiquitous use of immunosuppression), and societal trends (re-emergence of vaccine preventable diseases) are likely to change the landscape of neurologic infections that are considered and treated in clinical practice.

Lifetime quality-adjusted life years lost due to genital herpes acquired in the United States in 2018: a mathematical modeling study

Background

Genital herpes (GH), caused by herpes simplex virus type 1 and type 2 (HSV-1, HSV-2), is a common sexually transmitted disease associated with adverse health outcomes. Symptoms associated with GH outbreaks can be reduced by antiviral medications, but the infection is incurable and lifelong. In this study, we estimate the long-term health impacts of GH in the United States using quality-adjusted life years (QALYs) lost.

Methods

We used probability trees to model the natural history of GH secondary to infection with HSV-1 and HSV-2 among people aged 18-49 years. We modelled the following outcomes to quantify the major causes of health losses following infection: symptomatic herpes outbreaks, psychosocial impacts associated with diagnosis and recurrences, urinary retention caused by sacral radiculitis, aseptic meningitis, Mollaret's meningitis, and neonatal herpes. The model was parameterized based on published literature on the natural history of GH. We summarized losses of health by computing the lifetime number of QALYs lost per genital HSV-1 and HSV-2 infection, and we combined this information with incidence estimates to compute the total lifetime number of QALYs lost due to infections acquired in 2018 in the United States.

Findings

We estimated 0.05 (95% uncertainty interval (UI) 0.02-0.08) lifetime QALYs lost per incident GH infection acquired in 2018, equivalent to losing 0.05 years or about 18 days of life for one person with perfect health. The average number of QALYs lost per GH infection due to genital HSV-1 and HSV-2 was 0.01 (95% UI 0.01-0.02) and 0.05 (95% UI 0.02-0.09), respectively. The burden of genital HSV-1 is higher among women, while the burden of HSV-2 is higher among men. QALYs lost per neonatal herpes infection was estimated to be 7.93 (95% UI 6.63-9.19). At the population level, the total estimated lifetime QALYs lost as a result of GH infections acquired in 2018 was 33,100 (95% UI 12,600-67,900) due to GH in adults and 3,140 (95% UI 2,260-4,140) due to neonatal herpes. Results were most sensitive to assumptions on the magnitude of the disutility associated with post-diagnosis psychosocial distress and symptomatic recurrences.

Interpretation

GH is associated with substantial health losses in the United States. Results from this study can be used to compare the burden of GH to other diseases, and it provides inputs that may be used in studies on the health impact and cost-effectiveness of interventions that aim to reduce the burden of GH.

Funding

The Center for Disease Control and Prevention.

Electroencephalography for prognostication of outcome in adults with severe herpes simplex encephalitis

BACKGROUND

Electroencephalography (EEG) is recommended for the practical approach to the diagnosis and prognosis of encephalitis. We aimed to investigate the prognostic value of standard EEG (_stdEEG) in adult patients with severe herpes simplex encephalitis.

METHODS

We performed a retrospective analysis of consecutive ICU patients with severe herpes simplex encephalitis in 38 French centers between 2006 and 2016. Patients with at least one _stdEEG study performed at ICU admission were included. _stdEEG findings were reviewed independently by two investigators. The association between _stdEEG findings (i.e., background activity, lateralized periodic discharges, seizures/status epilepticus, and reactivity to painful/auditory stimuli) and poor functional outcome, defined by a score on the modified Rankin Scale (mRS) of 3 to 6 (moderate to severe disability or death) at 90 days, were investigated.

RESULTS

We included 214 patients with at least one available _stdEEG study. The first _stdEEG was performed after a median time of one (interquartile range (IQR) 0 to 2) day from ICU admission. At the time of recording, 138 (64.5%) patients were under invasive mechanical ventilation. Lateralized periodic discharges were recorded in 91 (42.5%) patients, seizures in 21 (9.8%) and status epilepticus in 16 (7.5%). In the whole population, reactivity to auditory/noxious stimuli was tested in 140/214 (65.4%) patients and was absent in 71/140 (33.2%) cases. In mechanically ventilated patients, _stdEEG reactivity was tested in 91/138 (65.9%) subjects, and was absent in 53/91 (58.2%) cases. Absence of reactivity was the only independent _stdEEG finding associated with poor functional outcome in the whole population (OR 2.80, 95% CI 1.19 to 6.58) and in the subgroup of mechanically ventilated patients (OR 4.99, 95% CI 1.6 to 15.59). Adjusted analyses for common clinical predictors of outcome and sedation at time of _stdEEG revealed similar findings in the whole population (OR 2.03, 95% CI 1.18 to 3.49) and in mechanically ventilated patients (OR 2.62, 95% CI 1.25 to 5.50).

CONCLUSIONS

Absence of EEG reactivity to auditory/noxious stimuli is an independent marker of poor functional outcome in severe herpes simplex encephalitis.

Autoimmune Encephalitis with Autoantibodies to NMDAR1 following Herpes Encephalitis in Children and Adolescents

Herpes simplex virus (HSV) type 1 is a frequent pathogen causing infectious encephalitis (HSVE). Early treatment with intravenous acyclovir has led to a significant decrease in mortality. However, especially in children, deterioration during or after HSVE may occur without any evidence of HSV reactivation or improvement following repeated antiviral therapy. Here, we report 15 patients (age range 3 months to 15 years) who suffered from autoimmune encephalitis with autoantibodies to NMDAR1 following Herpes encephalitis, presenting with movement abnormalities (young children) or neuropsychiatric symptoms (older children) as major complaints, respectively. The diagnosis was based on positive cerebrospinal fluid (CSF) and/or serum anti-NMDAR-antibodies with two children showing only positive CSF antibody findings. The time lag between first symptoms and diagnosis of autoimmune encephalitis was significantly longer than between first symptoms and diagnosis of HSVE (p <0.01). All patients improved during immunosuppressive treatment, during which plasmapheresis or rituximab treatments were applied in 11 patients, irrespective of their age. Despite immunotherapy, no patients relapsed with HSVE. Early diagnosis and treatment of autoimmune encephalitis after HSVE may be associated with a better outcome so that high clinical awareness and routine testing for anti-NMDAR-antibodies after HSVE seems advisable. If autoimmune encephalitis is suspected, antibody testing should also be performed on CSF if negative in serum.

Neurological sequelae after encephalitis associated with herpes simplex virus in children: systematic review and meta-analysis

BACKGROUND

Encephalitis is an inflammation of the cerebral parenchyma manifested by acute symptoms such as fever, headaches, and other neurological disorders. Its etiology is mostly viral, with herpes simplex virus being a frequent etiological agent in children. The development of neurological sequelae is a serious outcome associated with this infection.

OBJECTIVE

To assess the general prevalence and types of neurological sequelae in children after a case of acute viral encephalitis caused by HSV.

METHODS

This systematic review and meta-analysis was developed following the PRISMA guidelines. The literature search was carried out in the MEDLINE, Embase, SciELO, LILACS, Cochrane, CINAHL, PsycINFO, and Web of Science databases. Studies were included of children with confirmed HSV infection and that presented a description of neurological sequelae associated with that infection. For the meta-analysis of general prevalence and of the types of neurological sequelae a random effects model was used.

RESULTS

Of the 2827 articles chosen in the initial search, nine studies were included in the systematic review and meta-analysis. The general prevalence of neurological sequelae was 50.7% (95% CI 39.2-62.2). The most frequent sequelae were related to mental disability, with a 42.1% prevalence (95% CI 30-55.2); on the other hand, the least frequent sequelae were those related with visual impairment, with a 5.9% prevalence (95% CI 2.2-14.6). The included studies presented regular quality and substantial heterogeneity.

CONCLUSION

Even with antiviral therapy, half of patients will develop some type of disability.

When herpes simplex virus encephalitis meets antiviral innate immunity

Herpes simplex virus (HSV) is the most common pathogen of infectious encephalitis, accounting for nearly half of the confirmed cases of encephalitis. Its clinical symptoms are often atypical. HSV PCR in cerebrospinal fluid is helpful for diagnosis, and the prognosis is usually satisfactory after regular antiviral treatment. Interestingly, some patients with recurrent encephalitis have little antiviral effect. HSV PCR in cerebrospinal fluid is negative, but glucocorticoid has a significant effect after treatment. Specific antibodies, such as the NMDA receptor antibody, the GABA receptor antibody, and even some unknown antibodies, can be isolated from cerebrospinal fluid, proving that the immune system contributes to recurrent encephalitis, but the specific mechanism is still unclear. Based on recent studies, we attempt to summarize the relationship between herpes simplex encephalitis and innate immunity, providing more clues for researchers to explore this field further.

Treatment of Herpes Simplex Virus Type 2 Meningitis: A Survey Among Infectious Diseases Specialists in France, Sweden, Australia, and Denmark

Background

We aimed to describe attitudes toward treatment of herpes simplex virus type 2 (HSV-2) meningitis and prioritize future trials.

Methods

This was a self-administered online survey of HSV-2 meningitis treatment among infectious diseases (ID) specialists in France, Sweden, Australia, and Denmark.

Results

A total of 223 ID specialists (45% female) from France (36%), Denmark (24%), Sweden (21%), and Australia (19%) participated in the survey, primarily from university hospitals (64%). The estimated overall response rate was 11% and ranged from 6% (Australia) to 64% (Denmark). Intravenous (IV) acyclovir followed by oral valacyclovir was the favored treatment in 110 of 179 (61%), whereas monotherapy with either IV acyclovir or oral valacyclovir was used by 35 of 179 (20%) and 34 of 179 (19%), respectively. The median total duration was reported to be 7 days (interquartile range, 7-10 days) regardless of antiviral regimen. Immunocompromise influenced decisions on antiviral treatment in 110 of 189 (58%) of respondents, mainly by prolonged total duration of treatment (36/110 [33%]), prolonged IV administration (31/110 [28%]), and mandatory antiviral treatment (25/110 [23%]). Treatment with acyclovir/valacyclovir versus placebo and comparison of acyclovir versus valacyclovir were assigned the highest prioritization scores for future randomized controlled trials on HSV-2 meningitis.

Conclusions

Perceptions of indications for as well as type and duration of antiviral treatment varied substantially among ID specialists.

[Reactivation of latent viruses in Neurology]

After establishing latent infection, some viruses can be reactivated by the alteration of host immunological conditions. First, we reviewed viruses that can cause neuronal damage by reactivation. Then we focused on the herpes simplex virus (HSV). The reactivation leads to neuronal damages through two possible mechanisms; "reactivation of a latent herpes virus" by which viruses can cause direct virus neurotoxicity, and "post-infectious immune inflammatory response" by which a focal reactivation of HSV leads to an inflammatory reaction. The former is radiologically characterized by cortical lesions, the latter is characterized by subcortical white matter lesions. We experienced a female, who underwent the right posterior quadrantectomy and then developed recurrent herpes encephalitis caused by herpes simplex reactivation, which pathologically demonstrated inflammation in the white matter, suggesting a post-infectious immune inflammatory response. The patient was successfully treated with immunosuppressants. The reactivation of the HSV is extremely rare in Japan. Neurologists should recognize this condition because this disorder will increase as epilepsy surgery gains more popularity.

Contribution of diffusion-weighted imaging to distinguish herpetic encephalitis from auto-immune encephalitis at an early stage

OBJECTIVES

To determine whether diffusion-weighted imaging (DWI) can help to distinguish early stage autoimmune (AI) and herpes simplex virus (HSV) encephalitides.

METHODS

This case-control study included patients from a multi-center cohort of AI encephalitides whose initial MRI including DWI was performed within ten days after symptoms onset. They were compared with patients with HSV encephalitis enrolled prospectively in a single-center from June, 2020 to December, 2020. The final diagnosis of AI encephalitis required a positive autoantibody assay, and that of HSV encephalitis required a positive HSV polymerase chain reaction based on cerebrospinal fluid. Brain MRI were evaluated for restricted diffusion, fluid-inversion recovery (FLAIR) abnormalities, lesion topography, hemorrhagic changes, and contrast enhancement.

RESULTS

Forty-nine patients were included of which, 19 (38.8%) had AI encephalitis. Twenty-seven patients (55.1%) were males and the median age was 46.0 years (interquartile range (IQR):[22.0; 65.0]). Brain MRI were performed after a median of 4 days (IQR:[2.0; 7.0]) of symptom onset and time between symptom onset and MRI was not significantly different (p=0.60). Twenty-six patients had restricted diffusion lesions in the medial temporal lobe, including 25/30 in the HSV encephalitis group (p<0.001). FLAIR abnormalities were observed in 36 patients, including 29/30 in the HSV encephalitis group (p<0.001). Lesion topography, hemorrhagic changes, and contrast enhancement did not differ significantly between the two groups.

CONCLUSION

Our results suggest that restricted diffusion lesions in the medial temporal lobe are a hallmark of HSV encephalitis and may help distinguish it from early-stage AI encephalitis.

A Review of the Treatment of Herpes Simplex Virus-1 Encephalitis in Six Immunocompetent Patients

Introduction

The optimal treatment regimen for herpes simplex-1 (HSV-1) encephalitis is ill-defined. Current guidelines recommend the initiation of acyclovir in all suspected cases of encephalitis; however, there is limited research regarding the details of acyclovir treatment or the adjuvant use of corticosteroids. Specifically, there is a paucity of evidence-based guidelines detailing the optimal management of HSV-1 encephalitis in immunocompetent patients. In this study, we conducted a review of cases of immunocompetent patients with HSV-1 encephalitis to compare patterns in treatment and outcomes. 

Methods

A review of the literature was performed using PubMed using the terms herpes encephalitis, HSV, herpes zoster, and immunocompetent to identify cases of HSV-1 encephalitis in immunocompetent patients. The results were screened for cases describing the treatment regimen of HSV-1 encephalitis-positive, immunocompetent patients. 

Results

Six cases were identified. All six patients were treated with acyclovir with one patient receiving adjuvant corticosteroid therapy. Additionally, three patients were found to have acyclovir resistance and were transitioned to foscarnet. Eventually, one patient expired, two patients recovered with chronic morbidities of varying severity, and three patients made a full recovery. 

Discussion

Inconsistencies in the patient's disease course, therapeutic regimen, and comorbidities could all play a role in the varying case outcomes. While the optimal timing and composition of therapies in HSV-1 encephalitis in immunocompetent patients are still unclear, it seems the timely administration of antiviral treatment remains essential. Further research is needed to optimize HSV-1 encephalitis therapeutic regimens and improve patient outcomes. 

Challenges for nurses in caring for patients with acute encephalitis: lack of knowledge, time and rehabilitation

AIM

To explore the experiences of registered nurses providing care to adult patients affected by encephalitis, from admission into hospital through to discharge.

STUDY DESIGN

A qualitative phenomenological methodology was used. Sample and setting: Eight registered nurses in a city centre teaching hospital.

METHODS

Data collection took place using in-depth, semi-structured interviews. Data were analysed and themes identified using framework analysis.

FINDINGS

Three key findings were identified: nurses felt that they lacked knowledge of encephalitis, lacked time to give these patients the care they needed, and they lacked access to rehabilitation for patients with encephalitis.

CONCLUSION

This study provides the first evidence on nurses' experiences of providing care to patients affected by encephalitis. It has shown that they often lack the knowledge and time to give adequate support to patients. They also lack access to rehabilitation for these patients.

Cognitive decline following acute viral infections: literature review and projections for post-COVID-19

Recently, much attention has been drawn to the importance of the impact of infectious disease on human cognition. Several theories have been proposed, to explain the cognitive decline following an infection as well as to understand better the pathogenesis of human dementia, especially Alzheimer's disease. This article aims to review the state of the art regarding the knowledge about the impact of acute viral infections on human cognition, laying a foundation to explore the possible cognitive decline followed coronavirus disease 2019 (COVID-19). To reach this goal, we conducted a narrative review systematizing six acute viral infections as well as the current knowledge about COVID-19 and its impact on human cognition. Recent findings suggest probable short- and long-term COVID-19 impacts in cognition, even in asymptomatic individuals, which could be accounted for by direct and indirect pathways to brain dysfunction. Understanding this scenario might help clinicians and health leaders to deal better with a wave of neuropsychiatric issues that may arise following COVID-19 pandemic as well as with other acute viral infections, to alleviate the cognitive sequelae of these infections around the world.

Existing Data Sources for Clinical Epidemiology: The Danish Study Group of Infections of the Brain Database (DASGIB)

Central nervous system (CNS) infections are rare diseases that are associated with considerable morbidity and mortality. Increased knowledge based on contemporary data is a prerequisite for improved management and prevention of these serious conditions. Yet, population-based databases of patients hospitalized with CNS infections remain scarce. The Danish Study Group of Infections of the Brain (DASGIB) has prospectively registered information on all adults ≥18 years of age admitted with CNS infections at departments of infectious diseases in Denmark since 2015. The main variables collected are baseline demographics, blood and cerebrospinal fluid tests, imaging results, and outcome using the Glasgow Outcome Scale score. To investigate important aspects for each type of CNS infections, additional variables are included specifically for bacterial meningitis, viral meningitis, encephalitis, brain abscess, neurosyphilis, and Lyme neuroborreliosis. From 2015 to 2020, a total of 3579 cases of CNS infections have been recorded in the DASGIB database. Using the unique civil registration number assigned to all Danish residents, the database can be unambiguously linked with nationwide healthcare registries at the individual level. This enables researchers to conduct detailed population-based and longitudinal observational studies of risk and prognosis of CNS infections and to compare them with matched population cohorts. The database is well-suited for epidemiological research and the DASGIB network forms a solid infrastructure for future national and international collaborations.

Herpes Simplex Virus 1 and 2 Infections during Differentiation of Human Cortical Neurons

Herpes simplex virus 1 (HSV-1) and 2 (HSV-2) can infect the central nervous system (CNS) with dire consequences; in children and adults, HSV-1 may cause focal encephalitis, while HSV-2 causes meningitis. In neonates, both viruses can cause severe, disseminated CNS infections with high mortality rates. Here, we differentiated human induced pluripotent stem cells (iPSCs) towards cortical neurons for infection with clinical CNS strains of HSV-1 or HSV-2. Progenies from both viruses were produced at equal quantities in iPSCs, neuroprogenitors and cortical neurons. HSV-1 and HSV-2 decreased viability of neuroprogenitors by 36.0% and 57.6% (p < 0.0001), respectively, 48 h post-infection, while cortical neurons were resilient to infection by both viruses. However, in these functional neurons, both HSV-1 and HSV-2 decreased gene expression of two markers of synaptic activity, CAMK2B and ARC, and affected synaptic activity negatively in multielectrode array experiments. However, unaltered secretion levels of the neurodegeneration markers tau and NfL suggested intact axonal integrity. Viral replication of both viruses was found after six days, coinciding with 6-fold and 22-fold increase in gene expression of cellular RNA polymerase II by HSV-1 and HSV-2, respectively. Our results suggest a resilience of human cortical neurons relative to the replication of HSV-1 and HSV-2.

Long-term sequelae of herpes simplex virus encephalitis-related white matter injury: correlation of neuropsychological outcome and diffusion tensor imaging

The pathophysiology of the memory impairment following Herpes Simplex virus encephalitis is not yet established and understood. This study attempts to elucidate the role of white matter injury and its impact on neuropsychological outcome in patients with history of Herpes Simplex virus encephalitis. This is a single-institution prospective study assessing 9 patients and 15 matched controls utilizing a combination of MRI with diffusion tensor imaging and neuropsychological testing. Tract-based spatial statistics analysis was performed and correlated with neuropsychological outcomes. Significantly decreased fractional anisotropy (FA) values were noted in corpus callosum, corona radiata, left posterior thalamic radiation, cingulum, superior longitudinal fasciculus, fornix, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and uncinated fasciculus. Impaired facial recognition significantly correlated with reduction in FA of right uncinate fasciculus, right inferior longitudinal fasciculus, and splenium genu of corpus callosum. FA value of left cingulum significantly correlated with logical memory, auditory verbal learning. FA value of fornix correlated with visual recognition; FA value of left uncinate fasciculus with auditory verbal learning and delayed recall. In conclusion, this study demonstrates microstructural abnormalities involving several white matter tracts corresponding to neuropsychological deficits.

Protocol for DexEnceph: a randomised controlled trial of dexamethasone therapy in adults with herpes simplex virus encephalitis

INTRODUCTION

Herpes simplex virus (HSV) encephalitis is a rare severe form of brain inflammation that commonly leaves survivors and their families with devastating long-term consequences. The virus particularly targets the temporal lobe of the brain causing debilitating problems in memory, especially verbal memory. It is postulated that immunomodulation with the corticosteroid, dexamethasone, could improve outcomes by reducing brain swelling. However, there are concerns (so far not observed) that such immunosuppression might facilitate increased viral replication with resultant worsening of disease. A previous trail closed early because of slow recruitment.

METHOD

DexEnceph is a pragmatic multicentre, randomised, controlled, open-label, observer-blind trial to determine whether adults with HSV encephalitis who receive dexamethasone alongside standard antiviral treatment with aciclovir for have improved clinical outcomes compared with those who receive standard treatment alone. Overall, 90 patients with HSV encephalitis are being recruited from a target of 45 recruiting sites; patients are randomised 1:1 to the dexamethasone or control arms of the study. The primary outcome measured is verbal memory as assessed by the Weschler Memory Scale fourth edition Auditory Memory Index at 26 weeks after randomisation. Secondary outcomes are measured up to 72 weeks include additional neuropsychological, clinical and functional outcomes as well as comparison of neuroimaging findings. Patient safety monitoring occurs throughout and includes the detection of HSV DNA in cerebrospinal fluid 2 weeks after randomisation, which is indicative of ongoing viral replication. Innovative methods are being used to ensure recrutiment targets are met for this rare disease.

DISCUSSION

DexEnceph aims to be the first completed randomised controlled trial of corticosteroid therapy in HSV encephalitis. The results will provide evidence for future practice in managing adults with the condition and has the potential to improve outcomes .

ETHICS AND DISSEMINATION

The trial has ethical approval from the UK National Research Ethics Committee (Liverpool Central, REF: 15/NW/0545, 10 August 2015). Protocol V.2.1, July 2019. The results will be published and presented as soon as possible on completion.

TRIAL REGISTRATION NUMBERS

ISRCTN11774734, EUDRACT 2015-001609-16.

Viral and Prion Infections Associated with Central Nervous System Syndromes in Brazil

Virus-induced infections of the central nervous system (CNS) are among the most serious problems in public health and can be associated with high rates of morbidity and mortality, mainly in low- and middle-income countries, where these manifestations have been neglected. Typically, herpes simplex virus 1 and 2, varicella-zoster, and enterovirus are responsible for a high number of cases in immunocompetent hosts, whereas other herpesviruses (for example, cytomegalovirus) are the most common in immunocompromised individuals. Arboviruses have also been associated with outbreaks with a high burden of neurological disorders, such as the Zika virus epidemic in Brazil. There is a current lack of understanding in Brazil about the most common viruses involved in CNS infections. In this review, we briefly summarize the most recent studies and findings associated with the CNS, in addition to epidemiological data that provide extensive information on the circulation and diversity of the most common neuro-invasive viruses in Brazil. We also highlight important aspects of the prion-associated diseases. This review provides readers with better knowledge of virus-associated CNS infections. A deeper understanding of these infections will support the improvement of the current surveillance strategies to allow the timely monitoring of the emergence/re-emergence of neurotropic viruses.

Prevalence and clinical manifestations of herpes simplex virus infection among suspected patients of herpes simplex encephalitis in Shiraz, Iran

Encephalitis has infectious and noninfectious etiology. Among infectious agents, viruses are the main causes of encephalitis; Herpes simplex virus (HSV) is known as the most common causative agent of viral encephalitis. In this current cross-sectional investigation, we aimed to assess the prevalence of HSV in the cerebrospinal fluid (CSF) specimens of Herpes Simplex Encephalitis (HSE) suspected patients and also determining the clinical symptoms and laboratory findings of this viral complication. Two hundred consecutive HSE suspected patients with clinical diagnosis of encephalitis were included in the study and then the presence of HSV DNA in their CSF was applied by Polymerase Chain Reaction (PCR) assay. Molecular detection of two hundred (117 males with mean age: 43 years, 83 females with mean age: 39 years) CSF samples showed that 22 (11.11%) cases were positive for HSV infection. 15(68.18%) of the positive samples were more than 50 years old, however, there was no significant correlation between age distribution, gender and HSE clinical manifestations. Fever (91%), headache (72.7%), seizer (59%), and weakness (59%) were the most common symptoms in positive patients and also mortality rate was (18.18%). CSF laboratory abnormalities of HSE cases were as follows; lymphocytic pleocytosis 19 (86.3%), leukocytosis 19 (86.3%), elevated protein level 16 (72.7%), and hypoglycorrhachia 3(13.6%). Screening of HSE suspected patients is crucial in the treatment of patients and reduce the mobility and morbidity of patients. Qualitative PCR as an available method in most developing countries could be a reliable method to monitor consecutive HSE suspected patients.

Herpesvirus encephalitis diagnosed by polymerase chain reaction at the National Institute of Neurology of Mexico

The frequency of central nervous system infections due to herpesvirus have been studied in various populations; however, studies in Mexican mestizo patients are scant. This paper documents the frequency of herpesvirus encephalitis in Mexican mestizo patients from the National Institute of Neurology and Neurosurgery (NINN) of Mexico. To study the frequency of herpetic viral encephalitis at the NINN in the period from 2004 to 2009. We reviewed clinical records from patients with clinically suspected encephalitis; polymerase chain reaction assays were done for detection of herpesviruses in cerebrospinal fluid (CSF) samples. The total number of patients studied was 502; in 59 (12%), the diagnosis of herpetic encephalitis was confirmed by PCR-based testing of CSF. Of them, 21 (36%) were positive for herpes simplex virus type 1, 15 (25%) for Epstein-Barr virus, 10 (17%) for varicella zoster virus, 8 (14%) for cytomegalovirus, 3 (5%) for human herpesvirus 6, and 2 (3%) for herpes simplex virus 2. Our results show a varied frequency of viral encephalitis in mestizo patients due to herpesviruses in a tertiary neurological center and point out the importance of modern molecular technology to reach the etiological diagnosis in cases of encephalitis.

Neuroinfectious Disease Emergencies

Neuroinfectious diseases can affect immunocompetent and immunosuppressed individuals and cause a variety of emergencies including meningitis, encephalitis, and abscess. Neurologic infections are frequently complicated by secondary injuries that also present emergently such as cerebrovascular disease, acute obstructive hydrocephalus, and seizure. In most cases, timely recognition and early treatment of infection can improve the morbidity and mortality of infectious neurologic emergencies.

Novel Insights to Enhance Therapeutics With Acyclovir in the Management of Herpes Simplex Encephalitis

Acyclovir is an antiviral drug poorly absorbed in the gastrointestinal tract due to its hydrophilicity, with low oral bioavailability (~20%). Although acyclovir is prescribed in the management of herpes simplex encephalitis (HSE), the disease has a poor prognosis, particularly if the treatment is delayed, reaching mortality rates of 70% if left untreated. Thus, high acyclovir doses are administered by intravenous (IV) infusion, usually at a dosage of 10 mg kg^-1 8-hourly in adults with normal renal function. However, the mortality related to HSE treated with acyclovir remains high (~20%) and permanent sequelae are commonly reported after 1 year (~50%). This review analyzed clinical trials following IV acyclovir administration. Novel insights aiming to improve drug bioavailability were reviewed, including acyclovir or its prodrugs, leading to the systemic distribution of the drug or drug targeting. Much research effort has been made to improve antiviral therapy, searching for delivery systems increasing acyclovir bioavailability by non-invasive pathways, such as oral and nasal pathways, or parenterally administered nanotechnology-based systems leading to drug targeting. Nanocarriers administered by non-invasive pathways represent feasible alternatives to treat HSE, even though not be industrially manufactured yet.

Treatment of Viral Encephalitis

Viral encephalitis is difficult to treat. Herpes simplex encephalitis has been successfully treated with acyclovir, but is still a cause for significant morbidity even with that treatment. A rare form of autoimmune encephalitis related to NMDA receptor antibody after infection by herpes simplex can be treated with corticosteroid therapy. Arthropod-borne encephalitides, such as West Nile virus encephalitis and Eastern equine encephalitis, are primarily treated with supportive measures. Attempts have been made to use immunoglobulin therapy with limited effects. Progressive multifocal leukoencephalopathy has been treated with an emerging immune activation therapy in a limited number of patients with incomplete success.

An unexpectedly high occurrence of aciclovir-induced neuropsychiatric symptoms in patients treated for herpesvirus CNS infection: a prospective observational study

Background

Aciclovir is effective in herpesvirus infections of the CNS. Aciclovir-induced neuropsychiatric symptoms (AINS) have been reported and are associated with high CSF concentrations of aciclovir metabolite 9-carboxymethoxymethylguanine (CMMG). Risk factors except for renal failure have not been explored, and disruption of the blood–brain barrier (BBB) in acute CNS infection may be of interest.

Objectives

To investigate the impact of risk factors on aciclovir and CMMG concentrations, and to relate the results to AINS.

Methods

We investigated 21 consecutively included, consenting patients treated with aciclovir or valaciclovir for herpesvirus CNS infection. Regression models were constructed to study the impact of risk factors including BBB disruption, as measured with CSF:serum albumin ratio, on CSF aciclovir and CMMG concentrations. Medical records were assessed retrospectively to identify patients with AINS.

Results

Increased CSF:serum albumin ratio, as well as decreased renal function and high aciclovir doses, was associated with increased aciclovir and CMMG concentrations in the CSF. We identified five patients with new neuropsychiatric symptoms; four of those were considered to have AINS and had increased CSF CMMG concentrations. Only one patient without suspicion of AINS had an increased CSF CMMG concentration.

Conclusions

In patients with herpesvirus CNS infections, BBB disruption is associated with increasing aciclovir and CMMG CSF concentrations. We also found an unexpectedly high number of patients with AINS. Evaluation of CSF:serum albumin ratios, renal function and CSF concentrations of aciclovir and CMMG may all contribute to the optimization of aciclovir dosing and avoidance of AINS.

Cerebrospinal fluid biomarkers of brain injury, inflammation and synaptic autoimmunity predict long-term neurocognitive outcome in herpes simplex encephalitis

OBJECTIVES

The aim was to investigate the correlation between biomarkers of brain injury and long-term neurocognitive outcome, and the interplay with intrathecal inflammation and neuronal autoimmunity, in patients with herpes simplex encephalitis (HSE).

METHODS

A total of 53 adult/adolescent HSE patients were included from a prospective cohort in a randomized placebo-controlled trial investigating the effect of a 3-month follow-up treatment with valaciclovir. Study subjects underwent repeated serum/cerebrospinal fluid (CSF) sampling and brain magnetic resonance imaging in the first 3 months along with cognitive assessment using the Mattis Dementia Rating Scale (MDRS) at 24 months. CSF samples were analysed for biomarkers of brain injury, inflammation and synaptic autoimmunity. The predefined primary analysis was the correlation between peak CSF neurofilament protein (NFL), a biomarker of neuronal damage, and MDRS at 24 months.

RESULTS

Impaired cognitive performance significantly correlated with NFL levels (rho = -0.36, p = 0.020). Development of IgG anti-N-methyl-D-aspartate receptor (NDMAR) antibodies was associated with a broad and prolonged proinflammatory CSF response. In a linear regression model, lower MDRS at 24 months was associated with previous development of IgG anti-N-methyl-D-aspartate receptor (NMDAR) (beta = -0.6249, p = 0.024) and age (z-score beta = -0.2784, p = 0.024), but not CSF NFL, which however significantly correlated with subsequent NMDAR autoimmunization (p = 0.006).

DISCUSSION

Our findings show that NFL levels are predictive of long-term neurocognitive outcome in HSE, and suggest a causative chain of events where brain tissue damage increases the risk of NMDAR autoimmunisation and subsequent prolongation of CSF inflammation. The data provides guidance for a future intervention study of immunosuppressive therapy administered in the recovery phase of HSE.

Valaciclovir therapy for herpes encephalitis: caution advised

Recently some authors have suggested that oral valaciclovir 1 g q8h is a valid alternative to intravenous aciclovir for herpes encephalitis. We are concerned about numerous caveats that we think have not been sufficiently addressed to allow such use outside of a controlled research setting.

Diagnosis and Management of Neonatal Herpes Simplex Infection in the Emergency Department

Neonatal herpes simplex virus infection (HSV) is rare in neonates, with an estimated global incidence of 10 per 100,000 live births. Neonatal HSV is challenging to diagnose due to often vague signs and symptoms. Untreated, the mortality of some HSV subtypes exceeds 80%. Overtesting and overtreatment can result in prolonged hospitalizations and expose neonates to medication toxicity. In contrast, prompt evaluation and use of empiric antiviral therapy before the results of definitive testing can improve outcomes for infants with HSV. A wide degree of practice variation exists with respect to testing and treatment for neonatal HSV, and more research is required to safely risk-stratify this population. This review presents the epidemiology, risk factors, presenting features, and emergency department management of neonatal HSV infection.

Immunomodulatory Strategies in Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 (HSV-1) can be responsible for life-threatening HSV encephalitis (HSE). The mortality rate of patients with HSE who do not receive antiviral treatment is 70%, with most survivors suffering from permanent neurological sequelae. The use of intravenous acyclovir together with improved diagnostic technologies such as PCR and magnetic resonance imaging has resulted in a reduction in the mortality rate to close to 20%. However, 70% of surviving patients still do not recover complete neurological functions. Thus, there is an urgent need to develop more effective treatments for a better clinical outcome. It is well recognized that cerebral damage resulting from HSE is caused by viral replication together with an overzealous inflammatory response. Both of these processes constitute potential targets for the development of innovative therapies against HSE. In this review, we discuss recent progress in therapy that may be used to ameliorate the outcome of patients with HSE, with a particular emphasis on immunomodulatory agents. Ideally, the administration of adjunctive immunomodulatory drugs should be initiated during the rise of the inflammatory response, and its duration should be limited in time to reduce undesired effects. This critical time frame should be optimized by the identification of reliable biomarkers of inflammation.

Clinical Performance Measures for Neurocritical Care: A Statement for Healthcare Professionals from the Neurocritical Care Society

BACKGROUND

Performance measures are tools to measure the quality of clinical care. To date, there is no organized set of performance measures for neurocritical care.

METHODS

The Neurocritical Care Society convened a multidisciplinary writing committee to develop performance measures relevant to neurocritical care delivery in the inpatient setting. A formal methodology was used that included systematic review of the medical literature for 13 major neurocritical care conditions, extraction of high-level recommendations from clinical practice guidelines, and development of a measurement specification form.

RESULTS

A total of 50,257 citations were reviewed of which 150 contained strong recommendations deemed suitable for consideration as neurocritical care performance measures. Twenty-one measures were developed across nine different conditions and two neurocritical care processes of care.

CONCLUSIONS

This is the first organized Neurocritical Care Performance Measure Set. Next steps should focus on field testing to refine measure criteria and assess implementation.

The prevalence, characteristics and outcome of seizure in tuberculous meningitis

Seizures are a common finding in patients with tuberculous meningitis (TBM), and associate with four times increased risk of death and neurological disability, especially in children. It has been reported that brain inflammation, diffuse neuronal injury, and reactive gliosis may all contribute to the pathogenesis of seizures in TBM. Early seizure onset may be associated with meningeal irritation and cerebral oedema; while, the late seizures are usually due to infarction, hydrocephalus, tuberculoma and paradoxical response. Moreover, recurrent uncontrolled seizures can evolve to status epileptics resulting in an increased risk of chronic epilepsy and poor prognosis. Therefore, this review aimed to assess the frequency of seizures in patients with TBM, and discuss the etiologies, mechanisms, and characteristics of seizures in TBM. Besides, we have searched the literature to identify the prognostic factors for chronic epilepsy after TBM.

Hyponatremia Is Predictive of HSV-1 Encephalitis among Patients with Viral Encephalitis

Encephalitis is an inflammatory process involving the brain parenchyma associated with neurologic dysfunction. The main causes of infectious encephalitis are viruses, including Herpes simplex virus type 1 (HSV-1). As the mortality rate of HSV-1 encephalitis could be reduced with early acyclovir treatment, it is imperative to distinguish HSV-1 encephalitis from other type of viral encephalitis as early as possible. However, sophisticated methods for definitive diagnosis of HSV-1 encephalitis are not readily available. We aimed to explore distinctive clinical and laboratory features of HSV-1 encephalitis. All of the adult patients with viral encephalitis hospitalized between 2011-2017 were enrolled, including 16 patients with HSV-1 encephalitis and 51 patients non-HSV-1 viral encephalitis. Determination of viruses in cerebrospinal fluid was performed by PCR tests. Female sex, hyponatremia, and abnormalities in MRI were independently associated with HSV-1 encephalitis (p < 0.05 for each). In particular, hyponatremia (< 135 mEq/L) was found in nine patients with HSV-1 encephalitis (56.3%) and 10 patients with non-HSV-1 viral encephalitis (19.6%) (p = 0.005). As serum sodium is determined easily and quickly in clinical practice, the presence of hyponatremia among patients with viral encephalitis could be helpful for the early diagnosis of HSV-1 encephalitis before cerebrospinal fluid PCR results were available. Moreover, the presence of positive finding in MRI could further support the diagnosis. This is the first study that compared the serum sodium levels among patients between HSV-1 and non-HSV-1 viral encephalitis. We thus propose the diagnostic value of hyponatremia for HSV-1 encephalitis.

AT-533, a Hsp90 inhibitor, attenuates HSV-1-induced inflammation

Inflammatory events are tightly associated with the death caused by Herpes simplex virus 1 (HSV-1) infection of the brain. Heat shock protein 90 (Hsp90) is a molecular chaperone that is stimulated in response to many stressful conditions (e.g., inflammation and hypoxia) and Hsp90 inhibitors are suggested to be potent inhibitors of the inflammatory response. The aim of this study was to investigate the effect of Hsp90 inhibitor AT-533 on HSV-1-induced inflammation. AT-533 at a non-antiviral concentration was found to show a prominent inhibitory effect on the production of cytokines induced by HSV-1 infection, such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and interleukin 1β (IL-1β). Mechanically, HSV-1 early infection induced inflammation through NF-κB signaling and NLRP3 inflammasome activation, as illustrated by the nuclear translocation of NF-κB and the enhanced cleavage of caspase-1. Besides, HSV-1 enhanced the interaction between NLRP3 and Hsp90. Moreover, AT-533 reduced the nuclear translocation of NF-κB and inflammasome activation via inhibiting the chaperone function of Hsp90. Furthermore, AT-533 inhibited the cleavage of pro-IL-1β to mature IL-1β in a NLRP3-independent manner. In summary, AT-533 may be a promising therapeutic strategy in HSV-1-infected inflammation management.

Efficacy of acyclovir for herpes simplex encephalitis: A protocol for a systematic review of randomized controlled trial

BACKGROUND

Clinical researches indicate that acyclovir can be used to herpes simplex encephalitis (HSE). However, no systematic review has explored its efficacy for the treatment of HSE. Therefore, this study systematically will investigate the efficacy and safety of acyclovir for patients with HSE.

METHODS

We will search the following databases from inceptions to March 1, 2019 without any language restrictions: Cochrane Library, Embase, MEDICINE, PsycINFO, Web of Science, Allied and Complementary Medicine Database, Chinese Biomedical Literature Database, and China National Knowledge Infrastructure. This study will include randomized controlled trials that assess the efficacy and safety of acyclovir for patients with HSE. Two authors will independently carry out the study selection, data extraction, and risk of bias assessment. Cochrane risk of bias tool will be used to assess the risk of bias assessment.

RESULTS

This study will systematically assess the efficacy and safety of acyclovir for HSE. The primary outcome is mortality rate, which is measured by Glasgow coma score, or other instruments. The secondary outcomes include quality of life, as assessed by 36-Item Short Form Health Survey or relevant scales; overall survival, the number of patient who died; the number of patient who had severe sequelae, and adverse events.

CONCLUSIONS

The findings of this study may provide the existing evidence on the efficacy and safety of acyclovir for HSE.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42019125999.

To what extent can clinical characteristics be used to distinguish encephalitis from encephalopathy of other causes? Results from a prospective observational study

Background

Recognizing patients with encephalitis may be challenging. The cardinal symptom, encephalopathy, has a wide array of differential diagnoses. In this prospective study we aimed to explore the etiology of encephalitis and to assess the diagnostic accuracy of symptoms and clinical findings in patients with encephalitis in an encephalopathic population.

Methods

Patients with acute onset of encephalopathy (n = 136) were prospectively enrolled from January 2014–December 2015 at Oslo University Hospital, Ullevaal. Clinical and biochemical characteristics of patients who met the case definition of encephalitis were compared to patients with encephalopathy of other causes.

Results

Among 136 patients with encephalopathy, 19 (14%) met the case-definition of encephalitis. For 117 patients other causes of encephalopathy were found, infection outside the CNS was the most common differential diagnosis. Etiology of encephalitis was confirmed in 53% (4 bacterial, 4 viral, 1 parasitic, and 1 autoimmune). Personality change, nausea, fever, focal neurology, recent travel history, and low inflammation markers were significantly more abundant in patients with encephalitis, but the diagnostic accuracy for individual parameters were low (area under the curve (AUC) < 0.7). The combination of fever (OR = 6.6, 95% CI, 1.6–28), nausea (OR = 8.9, 95% CI, 1.7–46) and a normal level of ESR (erythrocyte sedimentation rate < 17 mm/hr, OR = 6.9, 95% CI, 1.5–33) was significant in multivariate analysis with an AUC (area under the curve) of 0.85 (95% CI, 0.76–0.94). Moderately increased pleocytosis in CSF (5-100 × 10⁶/L) further increased the diagnostic accuracy of this combination, AUC 0.90 (95% CI, 0.81–0.98).

Conclusions

There is a wide diversity in differential diagnoses in patients with encephalopathy, and no single symptom or finding can be used to predict encephalitis with high accuracy in this group. The combination of fever, nausea and a low ESR in an encephalopathic population, increased the diagnostic accuracy of encephalitis compared to solitary parameters. The triad could be a useful clinical tool for early diagnosis of encephalitis, and these patients should be considered for further diagnostics such as lumbar puncture (LP).

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3570-2) contains supplementary material, which is available to authorized users.

The clinical approach to managing herpes simplex virus encephalitis

This article explains the approach to managing a patient with herpes simplex virus encephalitis. Acute encephalopathy is a common and often intimidating presentation in an acute general medical setting. Application of key principles will enable the generalist to take life-saving action before obtaining any specialist input. Viral infection is the most common cause (48.2%) of encephalitis; another large group is cases of autoimmune aetiology. Early diagnosis of encephalitis is crucial to ensure that the right treatment is given on time. Guidelines on the management of viral encephalitis were published by the British Association of Neurologists and British Infection Association ( Solomon et al, 2012 ), but adherence to these standards by clinicians has been found to be suboptimal ( Han and Coebergh, 2017 ). This puts lives in danger, in the context of a treatable, serious, acute presentation. Although viral infection is the most common cause of encephalitis, an awareness of rarer forms of autoimmune encephalitis is necessary. The differential diagnosis of autoimmune encephalitis is important because the disease is potentially treatable with immunosuppressive agents. Paraneoplastic limbic encephalitis may present months or years before the detection of a tumour.

Viral Encephalitis

Viruses are a frequent cause of encephalitis. Common or important viruses causing encephalitis include herpesviruses, arboviruses, enteroviruses, parechoviruses, mumps, measles, rabies, Ebola, lymphocytic choriomeningitis virus, and henipaviruses. Other viruses may cause an encephalopathy. Host factors and clinical features of infection are important to consider in identifying the cause for encephalitis. Cerebrospinal fluid evaluation, serologic/polymerase chain reaction studies, and neuroimaging are cornerstones of diagnostic evaluation in encephalitis. Treatable forms of encephalitis are important to consider in all cases. Central nervous system inflammation may also occur because of postinfectious autoimmunity, such as acute disseminated encephalomyelitis or antibody-mediated encephalitis after herpes simplex virus encephalitis.

Increased level of compleasomes in cerebrospinal fluid of patients with herpes simplex encephalitis

Herpes simplex encephalitis (HSE) is a common cause of viral encephalitis (HSV-1) characterised by pronounced inflammation and elevated intracranial pressure. We have shown in a rat model that HSV-1 infection causes an interaction between complement factors and proteasomes, leading to formation of proteasome/complement complexes (compleasomes). Exposure of the proteasome regulatory subunit antisecretory factor 1 (AF1) leads to a decrease in intracranial pressure. The aim of this study was to evaluate the acute and prolonged formation of compleasomes in cerebrospinal fluid (CSF) from patients with HSE. Cerebrospinal fluid samples (n = 55) from 24 HSE patients were analysed for compleasome complexes. Samples from healthy controls (n = 23) and patient controls (n = 27) served as baseline information. Sandwich enzyme-linked immunosorbent assay (ELISA) for proteasomes and their complex formation with complement factor 3 or 4, and Western blot for C3 activation were performed on CSF samples. Increased compleasome formation, both presenting as an initial formation and showing exposure of subunit AF1 in the compleasomes, was found in CSF samples drawn from patients with HSE compared with samples from the control groups (p < 0.0005). The total protein CSF concentration was equal in all groups. The levels were higher in the acute phase compared with late in the disease course (p < 0.0005). Complement 3 breakdown product iC3b was detected in CSF samples of the HSE patients. The early increased formation of compleasomes in CSF suggests that this complex may be involved in host defence against HSE.

A Different Perspective on the Phenomenon of Hemiplegic Encephalitis: A Case Report

Encephalitis is an acute inflammation of the central nervous system that is characterized by fever, headache, and sleep disorders. Among the causes of meningoencephalitis are bacterial and viral infections, autoimmune diseases, and drug reactions. This case report describes a male patient who experienced hemiplegia following encephalitis. A 35-year-old patient consulted a physician with complaints of fever and headache. The clinical evaluation was encephalitis and the patient was treated accordingly. A severe neurological deficit developed, and the patient became bedridden, After treatment, the patient was included in an inpatient physical therapy program and was subsequently discharged with the ability to walk using parallel bars. The aim of this case report was to draw attention to the rehabilitation process applied after the diagnosis and treatment of a patient with hemiplegia that developed as a complication of encephalitis.

Acute encephalitis - diagnosis and management

Encephalitis, inflammation of the brain, is most commonly caused by a viral infection (especially herpes simplex virus [HSV] type 1 in the UK) although autoimmune causes, such as N-methyl D-aspartate receptor (NMDAR) antibody encephalitis, are increasingly recognised. Most patients present with a change in consciousness level and may have fever, seizures, movement disorder or focal neurological deficits. Diagnosis hinges crucially on lumbar puncture and cerebrospinal fluid (CSF) examination, but imaging and electroencephalography (EEG) may also be helpful. Treatment of HSV encephalitis with aciclovir dramatically improves outcome, but the optimal management of autoimmune encephalitis is still uncertain. Many patients with encephalitis are left with residual physical or neuropsychological deficits which require long-term multidisciplinary management. Here we review assessment of patients with suspected encephalitis, general aspects of management and areas of ongoing research.

Neurological Disorders Associated with Human Alphaherpesviruses

Herpes simplex virus (HSV) encephalitis is the most common cause of sporadic fatal encephalitis worldwide, and central nervous system (CNS) involvement is observed in approximately one-third of neonatal HSV infections . In recent years, single-gene inborn errors of innate immunity have been shown to be associated with susceptibility to HSV encephalitis . Temporal lobe abnormalities revealed by magnetic resonance imaging-the most sensitive imaging method for HSV encephalitis-are considered strong evidence for the disease. Detection of HSV DNA in the cerebrospinal fluid by polymerase chain reaction (PCR) is the gold standard for the diagnosis of HSV encephalitis and neonatal meningoencephalitis. Intravenous acyclovir for 14-21 days is the standard treatment in HSV encephalitis. Neurological outcomes in neonates are improved by intravenous high-dose acyclovir for 21 days followed by oral acyclovir suppressive therapy for 6 months. Varicella-zoster virus (VZV) causes a wide range of CNS manifestations. VZV encephalitis typically occurs after primary infection, and reactivation of VZV may cause encephalitis. On the other hand, VZV infection of cerebral arteries produces vasculopathy, which can manifest as ischemic stroke. Vasculopathy can occur after primary infection or reactivation of VZV. PCR detection of VZV DNA in the cerebrospinal fluid can be used for the diagnosis of encephalitis or vasculopathy. Although there are no controlled treatment trials to assess VZV treatments of encephalitis or vasculopathy, intravenous acyclovir is a common treatment.