[Autoimmune Encephalitis Triggered by Herpes Simplex Encephalitis: Main Syndrome, Diagnosis, and Treatment].

Autoimmune disorders, such as choreoathetosis and abnormal behavior secondary to herpes simplex encephalitis (HSE), are discussed in this review. These disorders are known to develop without any evidence of HSE relapse, while they respond to immunotherapies such as intravenous corticosteroids. Recent evidence, including a prospective Spanish cohort study of HSE, revealed that autoimmune encephalitis (AE) can be triggered by HSE, which is closely related to several neuronal surface antibodies (NSAs). Anti-N-methyl-D-aspartate encephalitis (NMDARE) is the most common phenotype of AE post-HSE. Moreover, approximately 30% of cases of AE post-HSE are caused by NSAs against undetermined antigens. Thus, patients suspected of having AE post-HSE should be tested for NSAs using comprehensive techniques combining tissue-based and cultured live neuron assays. The primary syndrome of AE post-HSE is age dependent, as demonstrated in non-post-HSE onset NMDARE. Choreoathetosis is the most common symptom in infants and toddlers, while abnormal behavior and psychiatric symptoms are the most common symptoms in adolescents and adults. Regarding the treatment, current knowledge reveals that intensive immunotherapies can be used to treat AE post-HSE and lead to better outcomes although a minority of cases show recovery without immunotherapy administration.

Diagnosing herpes simplex-1 encephalitis at the time of COVID-19 pandemic.

CASE REPORT: We describe the case of a 73-year-old woman who was diagnosed with herpes simplex virus-1 encephalitis during the COVID-19 pandemic. The diagnosis was somehow delayed because relatives were initially cautious in bringing the patient to the hospital and, here, the work-up focus was on coronavirusrelated aspects as the patient was initially reputed to be infected with COVID-19. CONCLUSIONS: During the current viral outbreak, physicians should not neglect the possibility of other diseases that represent neurological emergencies and require immediate recognition and treatment.

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.

Inconsistent Management of Neonatal Herpes Simplex Virus Infections.

OBJECTIVES: The incidence of neonatal herpes simplex virus (nHSV) infections is monitored periodically in the Netherlands, yet management and outcome is unknown. Comprehensive national guidelines are lacking. We aim to describe management and outcome in the last decade to explore current diagnostic and therapeutic challenges. We aim to identify possible variability in management of patients with a suspected nHSV infection. METHODS: We conducted a retrospective case series of management and outcome of nHSV infections at 2 tertiary care center locations in the Netherlands. RESULTS: An nHSV infection was diagnosed in 1% (12 of 1348) of patients in whom polymerase chain reaction for HSV was performed. Of the patients with nHSV infection, 3 of 12 died, and 4 of 9 (44%) survivors suffered neurologic sequelae. Neurologic symptoms at presentation were seen in only 2 of 8 patients with nHSV encephalitis. A cerebral spinal fluid analysis was performed in 3 of 6 patients presenting with skin lesions. Only 3 of 6 patients with neurologic symptoms received suppressive therapy. nHSV infection was diagnosed in 8 of 189 (4%) patients who were empirically treated. CONCLUSIONS: Management of nHSV infection, particularly when presented with skin lesions, is inconsistent. Many infants without a HSV infection are exposed to antiviral medication. There is substantial interhospital variation in diagnostic and therapeutic management of a suspected infection. Comprehensive guidelines need to be developed to standardize management of suspected nHSV infection.

Cytokine/chemokine elevation during the transition phase from HSV encephalitis to autoimmune anti-NMDA receptor encephalitis.

A 3-year-old girl suffered from anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis after resolution of herpes simplex virus encephalitis (HSE). Methylprednisolone pulse and immunoglobulin therapies showed little effect, but the patient completely recovered after six courses of monthly cyclophosphamide pulse therapy and successive maintenance on mycophenolate mofetil for one year. Anti-NMDA receptor antibody in the cerebrospinal fluid (CSF) was minimally detected during the prodromal febrile period and then was seen to be markedly elevated at the onset of second encephalopathy phase. CSF interleukin (IL)-6, and 10, tumor necrosis factor-α, interferon gamma, C-X-C motif ligands (CXCL)10 and 13, chemokine ligand 2, and migration inhibitory factor showed a second peak during the prodromal period and were reduced at the onset of anti-NMDA receptor encephalitis. These suggest the presence of cytokine/chemokine phase between the initial HSE and the secondary autoimmune encephalitis phases. Treatment strategy during the early stage of this entity should be further explored.

Anti-N-methyl-D-aspartate receptor encephalitis after Herpes simplex virus-associated encephalitis: an emerging disease with diagnosis and therapeutic challenges.

INTRODUCTION: Morbidity and mortality of Herpes simplex virus encephalitis (HSE) remain high. Relapses of neurological signs may occur after initial clinical improvement under acyclovir treatment. METHODS: We report here a case of post-HSE anti-N-methyl-d-aspartate receptor-mediated encephalitis in an adult and perform a systematic search on PubMed to identify other cases in adults. RESULTS: We identified 11 previously published cases, to discuss diagnostic and therapeutic management. Symptoms in adults are often inappropriate behaviors, confusion and agitation. Diagnosis of anti-NMDA-R encephalitis after HSE is often delayed. Treatment consists in steroids, plasma exchange, and rituximab. Prognosis is often favorable. CONCLUSION: Anti-NMDA-R antibodies should be searched in cerebrospinal fluid of patients with unexpected evolution of HSE. This emerging entity reopens the hot debate about steroids in HSE.

Can we differentiate between herpes simplex encephalitis and Japanese encephalitis?

BACKGROUND: Herpes simplex encephalitis (HSE) occurs without regional and seasonal predilections. HSE is important to differentiate from arboviral encephalitis in endemic areas because of therapeutic potential of HSE. This study evaluates clinical features, MRI and laboratory findings which may help in differentiating HSE from Japanese encephalitis (JE). METHODS: Confirmed patients with JE and HSE in last 10years were included. The presenting clinical symptoms including demographic information, seizure, behavioral abnormality, focal weakness and movement disorders were noted. Cranial MRI was done and location and nature of signal alteration were noted. Electroencephalography (EEG), cerebrospinal fluid (CSF), blood counts and serum chemistry were done. Outcome was measured by modified Rankin Scale (mRS). Death, functional outcome and neurological sequelae were noted at 3, 6 and 12months follow up, and compared between HSE and JE. Outcome was categorized as poor (mRS;>2) and good (mRS≤2). RESULTS: 97 patients with JE and 40 HSE were included. JE patients were younger than HSE and occurred in post monsoon period whereas HSE occurred throughout the year. Seizure (86% vs 40%) and behavioral abnormality (48% vs 10%) were commoner in HSE; whereas movement disorders (76% vs 0%) and focal reflex loss (42% vs 10%) were commoner in JE. CSF findings and laboratory parameters were similar in both the groups. Thalamic involvement in JE and temporal involvement in HSE were specific markers of respective encephalitis. Delta slowing on EEG was more frequent in JE than HSE. 20% JE and 30% HSE died in the hospital, and at 1year follow up JE patients showed better outcome compared to HSE (48% vs 24%). Memory loss (72% vs 22%) was the predominant sequelae in HSE. CONCLUSION: Seizure and behavioral abnormality are common features in HSE whereas focal reflex loss is commoner in JE. In a patient with acute encephalitis, thalamic lesion suggests JE and temporal lobe involvement HSE. Long term outcome in JE is better compared to HSE.

Gene Editing for Treatment of Neurological Infections.

The study of neurological infections by viruses defines the field of neurovirology, which has emerged in the last 30 years and was founded upon the discovery of a number of viruses capable of infecting the human nervous system. Studies have focused on the molecular and biological basis of viral neurological diseases with the aim of revealing new therapeutic options. The first studies of neurovirological infections can be traced back to the discovery that some viruses have an affinity for the nervous system with research into rabies by Louis Pasteur and others in the 1880s. Today, the immense public health impact of neurovirological infections is illustrated by diseases such as neuroAIDS, progressive multifocal leukoencephalopathy, and viral encephalitis. Recent research has seen the development of powerful new techniques for gene editing that promise revolutionary opportunities for the development of novel therapeutic options. In particular, clustered regulatory interspaced short palindromic repeat-associated 9 system provides an effective, highly specific and versatile tool for targeting DNA viruses that are beginning to allow the development of such new approaches. In this short review, we discuss these recent developments, how they pertain to neurological infections, and future prospects.

[Cognitive Impairment in Patients with Bacterial Meningitis and Encephalitides].

Cognitive impairments, including dementia, can present as first symptoms at the acute stage, and/or as sequelae in the chronic stages, in some patients with bacterial meningitis (BM) or encephalitides. BM and encephalitides are lifethreatening neurological emergencies, and early recognition, efficient decision-making, and rapid commencement of therapy can be lifesaving. Empirical therapy should be initiated promptly whenever BM or encephalitides are a probable diagnosis. In this article cognitive impairments, including dementia, presenting in patients with BM, Herpes simplex virus encephalitis (HSVE), Human herpesvirus-6 (HHV-6) encephalitis, and Anti N-methyl-d-aspartate (NMDA) receptor encephalitis are reviewed. In the above mentioned diseases, cognitive impairment without fever might be observed at the time of disease onset. cognitive impairment has been also noted in some aged or immunocompromised patients at the onset of BM. Immediate memory disturbance as one of the first symptoms of HHV-6 encephalitis presented in 74% of patients with this disease. Cognitive impairment, including dementia as sequela, was also found in 10-27% of patients with BM, 54-69% of patients with HSVE, 33% of HHV-6 encephalitis patients, and 39% of patients with anti-NMDA receptor encephalitis. Suitable therapeutic management of these diseases at the acute stage is thus required in order to avoid these sequelae.

Managing atypical and typical herpetic central nervous system infections: results of a multinational study.

There have been many studies pertaining to the management of herpetic meningoencephalitis (HME), but the majority of them have focussed on virologically unconfirmed cases or included only small sample sizes. We have conducted a multicentre study aimed at providing management strategies for HME. Overall, 501 adult patients with PCR-proven HME were included retrospectively from 35 referral centres in 10 countries; 496 patients were found to be eligible for the analysis. Cerebrospinal fluid (CSF) analysis using a PCR assay yielded herpes simplex virus (HSV)-1 DNA in 351 patients (70.8%), HSV-2 DNA in 83 patients (16.7%) and undefined HSV DNA type in 62 patients (12.5%). A total of 379 patients (76.4%) had at least one of the specified characteristics of encephalitis, and we placed these patients into the encephalitis presentation group. The remaining 117 patients (23.6%) had none of these findings, and these patients were placed in the nonencephalitis presentation group. Abnormalities suggestive of encephalitis were detected in magnetic resonance imaging (MRI) in 83.9% of the patients and in electroencephalography (EEG) in 91.0% of patients in the encephalitis presentation group. In the nonencephalitis presentation group, MRI and EEG data were suggestive of encephalitis in 33.3 and 61.9% of patients, respectively. However, the concomitant use of MRI and EEG indicated encephalitis in 96.3 and 87.5% of the cases with and without encephalitic clinical presentation, respectively. Considering the subtle nature of HME, CSF HSV PCR, EEG and MRI data should be collected for all patients with a central nervous system infection.

Effects of RNA interference therapy against herpes simplex virus type 1 encephalitis.

BACKGROUND: Herpetic encephalitis (HSE) is caused mainly by herpes simplex virus type 1 (HSV-1) with an annual incidence of 1-4 cases/million inhabitants. Currently, HSE treatment faces difficulties such as the use of antivirals with elevated toxicity, metabolic side effects and HSV-1 resistance. An alternative to antivirals is the use of small interfering RNA (siRNA) as a viral replication inhibitor. In this work, siRNA targeting the UL-39 region was evaluated for HSE treatment in vivo. METHODS: BALB/c mice were inoculated with HSV-1 and treated with siRNA. The treatment was evaluated through kinetics of HSV-1 replication inhibition, number of siRNA doses administered and treatment with siRNA plus acyclovir. All groups were evaluated for signs of HSE, mortality and HSV-1 replication inhibition. RESULTS: The treated group of the kinetic experiment demonstrated a reduction of HSE signs and an HSV-1 replication inhibition of 43.6-99.9% in the brain and 53-98% in trigeminal ganglia (TG). Animals treated with one or two doses of siRNA had a prolonged survival time, reduced clinical signs of HSE and HSV-1 replication inhibition of 67.7% in brains and 85.7% in TG of animals treated with two doses of siRNA. Also, animals treated with siRNA plus acyclovir demonstrated reduced signs of HSE and mortality, as well as HSV-1 replication inhibition in the brain (83.2%) and TG (74.5%). CONCLUSIONS: These findings demonstrated that siRNA was capable of reducing HSE clinical signs, prolonging survival time and inhibiting HSV-1 replication in mice. Thus, siRNA can be a potential alternative to the standard HSE treatment especially to reduce clinical signs and extend survival time in vivo.

Herpes Simplex Virus Infections of the Central Nervous System.

PURPOSE OF THE REVIEW: This article summarizes knowledge of herpes simplex virus (HSV) infections of the central nervous system (CNS). Disease pathogenesis, detection of DNA polymerase chain reaction (PCR) for diagnosis and prognosis, and approaches to therapy warrant consideration. RECENT FINDINGS: HSV infection of the CNS is one of few treatable viral diseases. Clinical trials indicate that outcome following neonatal herpes simplex virus type 2 (HSV-2) infections of the CNS is significantly improved when 6 months of suppressive oral acyclovir therapy follows IV antiviral therapy. In contrast, herpes simplex virus type 1 (HSV-1) infections of the brain do not benefit from extended oral antiviral therapy. This implies a difference in disease pathogenesis between HSV-2 and HSV-1 infections of the brain. PCR detection of viral DNA in the CSF is the gold standard for diagnosis. Use of PCR is now being adopted as a basis for determining the duration of therapy in the newborn. SUMMARY: HSV infections are among the most common encountered by humans; seropositivity occurs in 50% to 90% of adult populations. Herpes simplex encephalitis, however, is an uncommon result of this infection. Since no new antiviral drugs have been introduced in nearly 3 decades, much effort has focused on learning how to better use acyclovir and how to use existing databases to establish earlier diagnosis.

Long-term outcome of severe herpes simplex encephalitis: a population-based observational study.

INTRODUCTION: Herpes simplex encephalitis (HSE) is a rare disease with a poor prognosis. No recent evaluation of hospital incidence, acute mortality and morbidity is available. In particular, decompressive craniectomy has rarely been proposed in cases of life-threatening HSE with temporal herniation, in the absence of evidence. This study aimed to assess the hospital incidence and mortality of HSE, and to evaluate the characteristics, management, the potential value of decompressive craniectomy and the outcome of patients with HSE admitted to intensive care units (ICUs). METHODS: Epidemiological study: we used the hospital medical and administrative discharge database to identify hospital stays, deaths and ICU admissions relating to HSE in 39 hospitals, from 2010 to 2013. Retrospective monocentric cohort: all patients with HSE admitted to the ICU of the university hospital during the study were included. The use of decompressive craniectomy and long-term outcome were analyzed. The initial brain images were analyzed blind to outcome. RESULTS: The hospital incidence of HSE was 1.2/100,000 inhabitants per year, 32 % of the patients were admitted to ICUs and 17 % were mechanically ventilated. Hospital mortality was 5.5 % overall, but was as high as 11.9 % in ICUs. In the monocentric cohort, 87 % of the patients were still alive after one year but half of them had moderate to severe disability. Three patients had a high intracranial pressure (ICP) with brain herniation and eventually underwent decompressive hemicraniectomy. The one-year outcome of these patients did not seem to be different from that of the other patients. It was not possible to predict brain herniation reliably from the initial brain images. CONCLUSIONS: HSE appears to be more frequent than historically reported. The high incidence we observed probably reflects improvements in diagnostic performance (routine use of PCR). Mortality during the acute phase and long-term disability appear to be stable. High ICP and brain herniation are rare, but must be monitored carefully, as initial brain imaging is not useful for identifying high-risk patients. Decompressive craniectomy may be a useful salvage procedure in cases of intractable high ICP.

Pediatric Herpes Simplex Virus Encephalitis Complicated by N-Methyl-D-aspartate Receptor Antibody Encephalitis.

N-methyl-D-aspartate receptor antibodies (NMDAR-Abs) can contribute to neurological relapse after herpes simplex virus encephalitis (HSE). We describe a child with NMDAR-Ab encephalitis after HSE, which was recognized and treated early. We discuss the case in the context of existing reports, and we propose a modified immunotherapy strategy to minimize risk of viral reactivation.