Patients with suspected herpes simplex encephalitis: rethinking an initial negative polymerase chain reaction result

Herpes Simplex Encephalitis: an Update

PURPOSE OF REVIEW

The goal of this review is to provide an update on current thinking regarding herpes simplex encephalitis (HSE), emphasizing new information about pathogenesis, diagnosis, and immune responses. Specific questions to be addressed are the following: (1) Is there a genetic predisposition to HSE? (2) What clinical approaches have the greatest impact on improving the long-term outcomes in patients with HSE? And (3) are there immune-mediated mechanisms that may account for relapsing HSE?

RECENT FINDINGS

Toll-like receptor 3 (TLR 3) plays an important role in innate immune responses, including generation of interferons. Multiple single-gene errors in TLR 3 interferon pathways have recently been described in children that result in increased susceptibility to HSE. Conversely, studies in both animal models and humans indicate that both cytolytic viral replication and immune-mediated responses (including cytotoxic T lymphocytes and immune mechanisms mediated by TLR 2) contribute to the pathology of HSV, suggesting possible new therapeutic approaches. In terms of treatment, data clearly indicate that a longer duration between onset of symptoms and initiation of effective antiviral therapy correlates directly with less favorable clinical outcome. Recurrent or relapsing HSE may occasionally occur, but recent observations indicate that many instances of "relapsing HSE", especially in children, are more often anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis triggered by the antecedent HSV infection. Innate immune responses are critical for defense against HSV; genetic defects in this system may predispose patients to HSE. During acute HSE, exuberant immune responses may contribute to the CNS pathology, suggesting that selective immunosuppressive therapy, coupled with potent antiviral drugs, may eventually play a role in the therapeutic management of HSV. While overall clinical outcomes of HSE remain suboptimal, the initiation of high-dose acyclovir therapy as early as possible in the course of the illness provides the best chance for a patient to survive with minimal neurologic damage. Distinguishing relapsing HSE from autoimmune anti-NMDAR antibody encephalitis is critically important because therapeutic approaches will be very different.

Incidence of varicella zoster virus infections of the central nervous system in the elderly: a large tertiary hospital-based series (2007-2014)

The aim of the study was to describe the clinical and epidemiological characteristics of the central nervous system (CNS) infection by varicella zoster virus (VZV) in patients older than 65 years in a tertiary community hospital. We retrospectively analysed the results of cerebrospinal fluid (CSF) testing in patients older than 65 years between 2007 and 2014 with clinically suspected VZV infection with CNS involvement. Patients whose CSF samples were positive for VZV DNA were included, as were those with negative results who simultaneously presented herpes zoster and CSF or magnetic resonance imaging findings suggestive of CNS infection, and in whom other possible aetiologies had been ruled out. The study included 280 patients. The disease was considered to be caused by a VZV infection in 32 patients (11.4%), of which 23 cases were virologically confirmed (detection of VZV DNA in CSF). The most frequent diagnosis of the patients with VZV CNS infection was encephalitis (83.3%), followed by meningitis (13.3%) and cerebellitis (3.3%). The mean annual incidence of VZV CNS infection was 3.0 cases per 100,000 inhabitants. VZV was the most common cause of encephalitis and viral meningitis, ahead of herpes simplex virus (n = 9). At the time of discharge, 12 (40%) patients showed neurological sequelae. Five patients (20%) died during hospitalization, all with encephalitis. Patients with a fatal outcome had significantly higher median age and longer delay before initiating acyclovir. In conclusion, VZV was the first cause of encephalitis in our elderly population. Despite acyclovir treatment, there was a high rate of case fatality and sequelae at discharge.

Survey of the diagnostic and therapeutic approach to new-onset refractory status epilepticus

PURPOSE

We conducted a survey of providers to assess for practice patterns in diagnosing and treating new-onset refractory status epilepticus (NORSE). NORSE is the occurrence of prolonged seizures that are not responsive to initial therapies in otherwise healthy individuals without obvious cause on initial presentation. This entity is thought to have multiple etiologies, including autoimmune.

METHOD

A 29-question electronic survey was sent to providers included in the Neurocritical Care Society emailing list. Questions regarded responders' demographics, existing institutional practice protocols, diagnostic work-up, therapeutic management and expected outcomes in NORSE. Responses were collected from October 23, 2014, to November 25, 2014.

RESULTS

There were 107 respondents out of 1334 (8%). CT head, continuous EEG, lumbar puncture and microbe serologies were suggested within 24h of presentation as part of a diagnostic work-up. MRI brain, autoimmune work-up (systemic and anti-neuronal antibodies) and cytology/flow cytometry were favored later in the course. About 25% of providers would never perform an autoimmune work-up in this setting. Initial treatment included up to 3 anticonvulsants (including one anesthetic), followed by additional anticonvulsants/anesthetics along with antimicrobials, followed by steroids, plasma exchange, hypothermia and ketogenic diet. Many respondents would never use IV immunoglobulin or steroid-sparing immunosuppressants (29% and 42%, respectively) for NORSE.

CONCLUSIONS

This survey could serve as the foundation for development of a standardized approach for the diagnosis and treatment of NORSE.

Incidence and mortality of herpes simplex encephalitis in Denmark: A nationwide registry-based cohort study

OBJECTIVES

We aimed to investigate the incidence and mortality of herpes simplex encephalitis (HSE) in a nationwide cohort.

METHODS

From the Danish National Patient Registry, we identified all adults hospitalised with a first-time diagnosis of HSE in Denmark during 2004-2014. The HSE diagnoses were verified using medical records and microbiological data. Patients were followed for mortality through the Danish Civil Registry System. We estimated age-standardised incidence rates of HSE and 30-day, 60-day, and 1-year cumulative mortality. Furthermore, we assessed whether calendar year, age, gender, level of comorbidity, virus type, and department type was associated with HSE mortality.

RESULTS

We identified a total of 230 cases of HSE. Median age was 60.7 years (interquartile range: 49.3-71.6). The overall incidence rate was 4.64 cases per million population per year (95% confidence interval: 4.06-5.28). The cumulative mortality within 30 days, 60 days, and 1 year of the HSE admission was 8.3%, 11.3%, and 18.6%, respectively. Advanced age and presence of comorbidity were associated with increased 60-day and 1-year mortality.

CONCLUSIONS

This nationwide study of verified HSE found a higher incidence than reported in previous nationwide studies. Presence of comorbidity was identified as a novel adverse prognostic factor. Mortality rates following HSE remain high.

Sepsis and Other Infectious Disease Emergencies in the Elderly

Waning immunity and declining anatomic and physiologic defenses render the elder vulnerable to a wide range of infectious diseases. Clinical presentations are often atypical and muted, favoring global changes in mental status and function over febrile responses or localizing symptoms. This review encompasses early recognition, evaluation, and appropriate management of these common infections specifically in the context of elders presenting to the emergency department. With enhanced understanding and appreciation of the unique aspects of infections in the elderly, emergency physicians can play an integral part in reducing the morbidity and mortality associated with these often debilitating and life-threatening diseases.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

Herpetic infections have plagued humanity for thousands of years, but only recently have advances in antiviral medications and supportive treatments equipped physicians to combat the most severe manifestations of disease. Prompt recognition and treatment can be life-saving in the care of patients with herpes simplex-1 virus encephalitis, the most commonly identified cause of sporadic encephalitis worldwide. Clinicians should be able to recognize the clinical signs and symptoms of the infection and familiarize themselves with a rational diagnostic approach and therapeutic modalities, as early recognition and treatment are key to improving outcomes. Clinicians should also be vigilant for the development of acute complications, including cerebral edema and status epilepticus, as well as chronic complications, including the development of autoimmune encephalitis associated with antibodies to the N-methyl-D-aspartate receptor and other neuronal cell surface and synaptic epitopes. Herein, we review the pathophysiology, differential diagnosis, and clinical and radiological features of herpes simplex virus-1 encephalitis in adults, including a discussion of the most common complications and their treatment. While great progress has been made in the treatment of this life-threatening infection, a majority of patients will not return to their previous neurologic baseline, indicating the need for further research efforts aimed at improving the long-term sequelae.

Pediatric Emergency Magnetic Resonance Imaging: Current Indications, Techniques, and Clinical Applications

MR imaging plays an important role in the detection and characterization of several pediatric disease entities that can occur in the emergent setting because of its cross-sectional imaging capability, lack of ionizing radiation exposure, and superior soft tissue contrast. In the age of as low as reasonably achievable, these advantages have made MR imaging an increasingly preferred modality for diagnostic evaluations even in time-sensitive settings. In this article, the authors discuss the current indications, techniques, and clinical applications of MR imaging in the evaluation of pediatric emergencies.

A clinical approach to diagnosis of autoimmune encephalitis

Encephalitis is a severe inflammatory disorder of the brain with many possible causes and a complex differential diagnosis. Advances in autoimmune encephalitis research in the past 10 years have led to the identification of new syndromes and biomarkers that have transformed the diagnostic approach to these disorders. However, existing criteria for autoimmune encephalitis are too reliant on antibody testing and response to immunotherapy, which might delay the diagnosis. We reviewed the literature and gathered the experience of a team of experts with the aims of developing a practical, syndrome-based diagnostic approach to autoimmune encephalitis and providing guidelines to navigate through the differential diagnosis. Because autoantibody test results and response to therapy are not available at disease onset, we based the initial diagnostic approach on neurological assessment and conventional tests that are accessible to most clinicians. Through logical differential diagnosis, levels of evidence for autoimmune encephalitis (possible, probable, or definite) are achieved, which can lead to prompt immunotherapy.

Recurrent Herpes Simplex Virus Encephalitis After Neurologic Surgery

BACKGROUND

The herpes simplex virus (HSV) is the most common cause of sporadic encephalitis worldwide. Even with proper treatment, this infection is associated with a mortality rate of 19%-30% and with potential neurologic sequelae. Recurrences of encephalitis are rare and limited to a few cases in the literature. Although the mechanism of reactivation has not yet been clarified, in our patient, the surgery might have acted as a precipitating factor.

CASE DESCRIPTION

The case involved a female 10-year-old patient with a history of type 1 HSV encephalitis since 24 months of age. Secondarily, the patient developed postherpetic epilepsy in the following years. At 10 years old, she was referred to the epilepsy surgery service, and an elective right temporal lobectomy was performed. After surgery, the patient experienced severe clinical deterioration characterized by fever, severe headache, and altered state of consciousness. Encephalitis was diagnosed based on a positive polymerase chain reaction for HSV in the cerebrospinal fluid. The symptoms remitted after 8 weeks of treatment with acyclovir. The histopathologic diagnosis was a chronic encephalitic process with late secondary parenchymal changes without specific viral cytopathic findings. The only limitation that persisted was related to fine movements of the left hand. One year after surgery, the patient rejoined her school activities and is currently free of seizures.

CONCLUSIONS

HSV encephalitis is a rare but serious complication that should be suspected in cases of unexplained postoperative fever with altered consciousness, especially in patients with histories of encephalitic states.

Acute opercular syndrome in 4-year-old boy

Acute opercular syndrome is a rare described syndrome caused by a sudden damage of the cerebral cortex and subcortical white matter, located around the insula. A rare cause of this syndrome can be an infectious agent, particularly herpes simplex virus. Quick diagnosis and immediate initiation of treatment significantly reduce the risk of neurological consequences and mortality. We present a case of encephalitis of unknown etiology and severe course, with the symptoms of acute opercular syndrome in 4-year-old boy.

Virus and Immune-Mediated Encephalitides: Epidemiology, Diagnosis, Treatment, and Prevention

Virus encephalitis remains a major cause of acute neurological dysfunction and permanent disability among children worldwide. Although some disorders, such as measles encephalomyelitis, subacute sclerosing panencephalitis, and varicella-zoster virus-associated neurological conditions, have largely disappeared in resource-rich regions because of widespread immunization programs, other disorders, such as herpes simplex virus encephalitis, West Nile virus-associated neuroinvasive disease, and nonpolio enterovirus-induced disorders of the nervous system, cannot be prevented. Moreover, emerging viral disorders pose new, potential threats to the child's nervous system. This review summarizes current information regarding the epidemiology of virus encephalitis, the diagnostic methods available to detect central nervous system infection and identify viral pathogens, and the available treatments. The review also describes immune-mediated disorders, including acute disseminated encephalomyelitis and N-methyl-D-aspartate receptor antibody encephalitis, conditions that mimic virus encephalitis and account for a substantial proportion of childhood encephalitis.

Use of clinical and neuroimaging characteristics to distinguish temporal lobe herpes simplex encephalitis from its mimics

BACKGROUND

We describe the spectrum of etiologies associated with temporal lobe (TL) encephalitis and identify clinical and radiologic features that distinguish herpes simplex encephalitis (HSE) from its mimics.

METHODS

We reviewed all adult cases of encephalitis with TL abnormalities on magnetic resonance imaging (MRI) from the California Encephalitis Project. We evaluated the association between specific clinical and MRI characteristics and HSE compared with other causes of TL encephalitis and used multivariate logistic modeling to identify radiologic predictors of HSE.

RESULTS

Of 251 cases of TL encephalitis, 43% had an infectious etiology compared with 16% with a noninfectious etiology. Of infectious etiologies, herpes simplex virus was the most commonly identified agent (n = 60), followed by tuberculosis (n = 8) and varicella zoster virus (n = 7). Of noninfectious etiologies, more than half (n = 21) were due to autoimmune disease. Patients with HSE were older (56.8 vs 50.2 years; P = .012), more likely to be white (53% vs 35%; P = .013), more likely to present acutely (88% vs 64%; P = .001) and with a fever (80% vs 49%; P < .001), and less likely to present with a rash (2% vs 15%; P = .010). In a multivariate model, bilateral TL involvement (odds ratio [OR], 0.38; 95% confidence interval [CI], .18-.79; P = .010) and lesions outside the TL, insula, or cingulate (OR, 0.37; 95% CI, .18-.74; P = .005) were associated with lower odds of HSE.

CONCLUSIONS

In addition to HSE, other infectious and noninfectious etiologies should be considered in the differential diagnosis for TL encephalitis, depending on the presentation. Specific clinical and imaging features may aid in distinguishing HSE from non-HSE causes of TL encephalitis.

Herpes simplex encephalitis in Iceland 1987-2011

Herpes simplex encephalitis (HSE) is a serious disease with 10-20% mortality and high rate of neuropsychiatric sequelae. This study is a long-term, nationwide study in a single country, Iceland. Clinical data were obtained from patient records and from DNA PCR and antibody assays of CSF. Diagnosis of HSE was classified as definite, possible or rejected based on symptoms, as well as virological, laboratory and brain imaging criteria. A total of 30 definite cases of HSE were identified during the 25 year period 1987-2011 corresponding to incidence of 4.3 cases/106 inhabitants/year. Males were 57% of all patients, median age 50 years (range, 0-85). Fever (97%), cognitive deficits (79%), impaired consciousness (79% with GCS < 13), headache (55%) and seizures (55%) were the most common symptoms. Brain lesions were found in 24 patients (80%) by MRI or CT. All patients received intravenous acyclovir for a mean duration of 20 days. Three patients (10%) died within one year and 21/28 pts (75%) had a Karnofsky performance score of <70% with memory loss (59%), dysphasia (44%), frontal symptoms (44%) and seizures (30%) as the most frequent sequelae. Mean delay from onset of symptoms to treatment was 6 days; this was associated with adverse outcome. In conclusion, the incidence of `HSE is higher than recently reported in a national registry study from Sweden. Despite advances in rapid diagnosis and availability of treatment of HSE, approximately three of every four patients die or are left with serious neurological impairment.

Comparison of clinical manifestations, outcomes and cerebrospinal fluid findings between herpes simplex type 1 and type 2 central nervous system infections in adults

In previous reports on the viral causes of central nervous system (CNS) infections, it has been generally recognized that HSV-1 is a major cause of encephalitis, while HSV-2 is the predominant cause of aseptic meningitis in adults. To examine this matter, the clinical characteristics in the two types of HSV CNS infections were investigated. In a retrospective cohort study which included all adult patients (≥16 years) between January 1999 and December 2013 in a 2,700-bed tertiary care hospital, all the patients in whom PCR of the CSF for HSV was positive were identified. Ninety-five patients with positive CSF PCR results for HSV were included, 21 with HSV-1 and 74 with HSV-2. Many patients with HSV-1 had encephalitis (13/21, 61.9%), whereas most patients with HSV-2 had meningitis (62/74, 83.8%). However, HSV-1 and HSV-2 accounted for similar proportion of patients with HSV encephalitis (13/25, 52.0% vs. 12/25, 48.0%). Neurological sequelae were more frequent among patients with HSV-1 (9/21, 42.9% vs. 6/74, 8.1%; P = 0.001). The present study suggests that HSV-2 is not only a major cause of aseptic meningitis, but also it may cause serious manifestation as HSV-1 encephalitis in adults.

Diagnosis and management of acute encephalitis: A practical approach

Encephalitis results in considerable morbidity and mortality in the United States and worldwide. Neurologists are often consulted or directly care for patients with encephalitis admitted to the hospital and must be able to discriminate between encephalitis and the many conditions that mimic it. Moreover, neurologists must be familiar with the myriad causes of encephalitis in order to develop a practical approach to diagnostic testing and treatment. An understanding of recent advances in management, particularly with respect to autoimmune etiologies and critical care approaches, is equally important. Here, we summarize a general approach to the care of adult patients with encephalitis.

Early-onset neonatal sepsis

Early-onset sepsis remains a common and serious problem for neonates, especially preterm infants. Group B streptococcus (GBS) is the most common etiologic agent, while Escherichia coli is the most common cause of mortality. Current efforts toward maternal intrapartum antimicrobial prophylaxis have significantly reduced the rates of GBS disease but have been associated with increased rates of Gram-negative infections, especially among very-low-birth-weight infants. The diagnosis of neonatal sepsis is based on a combination of clinical presentation; the use of nonspecific markers, including C-reactive protein and procalcitonin (where available); blood cultures; and the use of molecular methods, including PCR. Cytokines, including interleukin 6 (IL-6), interleukin 8 (IL-8), gamma interferon (IFN-γ), and tumor necrosis factor alpha (TNF-α), and cell surface antigens, including soluble intercellular adhesion molecule (sICAM) and CD64, are also being increasingly examined for use as nonspecific screening measures for neonatal sepsis. Viruses, in particular enteroviruses, parechoviruses, and herpes simplex virus (HSV), should be considered in the differential diagnosis. Empirical treatment should be based on local patterns of antimicrobial resistance but typically consists of the use of ampicillin and gentamicin, or ampicillin and cefotaxime if meningitis is suspected, until the etiologic agent has been identified. Current research is focused primarily on development of vaccines against GBS.

Nucleic acid amplification technology for the diagnosis of genital herpes infection

Nucleic acid amplification technologies are well-characterized methods for the rapid and sensitive diagnosis of a wide variety of infectious diseases. Herpes simplex virus amplification is no exception, demonstrating as much as a ninefold enhancement in sensitivity over viral culture in some settings. Currently, there are no US Food and Drug Administration-approved systems for herpes simplex virus amplification; hence, most laboratories utilize in-house-developed PCR-based systems. Unfortunately, the utilization of herpes simplex virus amplification has been confined to the investigations of suspected herpes simplex virus encephalitis, largely due to cost and the need for appropriately trained technical staff. Recent methodological advances will help to render herpes simplex virus nucleic acid amplification technologies more applicable to routine practice. However, the use of nucleic acid amplification technologies for the diagnosis of genital herpes infection remains highly controversial.

Nervous System Complications of Systemic Viral Infections

Invasion of the central nervous system (CNS) by viral agents typically produces a meningoencephalitis in which either meningitis or encephalitis may predominate. Viruses may also infect cranial or spinal blood vessels to produce ischemic injury. Viral and other infections may also elicit a host immune response which is cross-reactive with components of the neural tissue, resulting in encephalomyelitis, transverse myelitis, injury to peripheral nerves, or optic neuritis. This chapter discusses the pathogenesis of CNS viral infections and reviews clinical features of these disorders, major agents responsible in immunocompromised and immunocompetent individuals, and treatment. Prion diseases and postinfectious viral CNS syndromes including postinfectious encephalomyelitis, acute hemorrhagic leukoencephalitis, cerebellar ataxia, and transverse myelitis are also discussed.

Case definitions, diagnostic algorithms, and priorities in encephalitis: consensus statement of the international encephalitis consortium

BACKGROUND

Encephalitis continues to result in substantial morbidity and mortality worldwide. Advances in diagnosis and management have been limited, in part, by a lack of consensus on case definitions, standardized diagnostic approaches, and priorities for research.

METHODS

In March 2012, the International Encephalitis Consortium, a committee begun in 2010 with members worldwide, held a meeting in Atlanta to discuss recent advances in encephalitis and to set priorities for future study.

RESULTS

We present a consensus document that proposes a standardized case definition and diagnostic guidelines for evaluation of adults and children with suspected encephalitis. In addition, areas of research priority, including host genetics and selected emerging infections, are discussed.

CONCLUSIONS

We anticipate that this document, representing a synthesis of our discussions and supported by literature, will serve as a practical aid to clinicians evaluating patients with suspected encephalitis and will identify key areas and approaches to advance our knowledge of encephalitis.

A guide to utilization of the microbiology laboratory for diagnosis of infectious diseases: 2013 recommendations by the Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM)(a)

The critical role of the microbiology laboratory in infectious disease diagnosis calls for a close, positive working relationship between the physician and the microbiologists who provide enormous value to the health care team. This document, developed by both laboratory and clinical experts, provides information on which tests are valuable and in which contexts, and on tests that add little or no value for diagnostic decisions. Sections are divided into anatomic systems, including Bloodstream Infections and Infections of the Cardiovascular System, Central Nervous System Infections, Ocular Infections, Soft Tissue Infections of the Head and Neck, Upper Respiratory Infections, Lower Respiratory Tract infections, Infections of the Gastrointestinal Tract, Intraabdominal Infections, Bone and Joint Infections, Urinary Tract Infections, Genital Infections, and Skin and Soft Tissue Infections; or into etiologic agent groups, including Tickborne Infections, Viral Syndromes, and Blood and Tissue Parasite Infections. Each section contains introductory concepts, a summary of key points, and detailed tables that list suspected agents; the most reliable tests to order; the samples (and volumes) to collect in order of preference; specimen transport devices, procedures, times, and temperatures; and detailed notes on specific issues regarding the test methods, such as when tests are likely to require a specialized laboratory or have prolonged turnaround times. There is redundancy among the tables and sections, as many agents and assay choices overlap. The document is intended to serve as a reference to guide physicians in choosing tests that will aid them to diagnose infectious diseases in their patients.

Encephalitis and postinfectious encephalitis

PURPOSE OF REVIEW

Encephalitis and postinfectious encephalitis represent two important conditions for the neurologist, both in terms of their presentations as neurologic emergencies and their potential to cause death or serious neurologic impairment. This article reviews the major infectious and noninfectious causes of encephalitis and discusses postinfectious encephalitis as an indirect effect of systemic illness.

RECENT FINDINGS

Encephalitis caused by herpes simplex virus type 1 and West Nile virus are of major importance. In addition, within the past few years we have gained improved understanding of the neurologic syndromes caused by varicella-zoster virus, the recognition of enterovirus 71 as a significant human pathogen, and the realization that encephalitis may also occur by autoimmune mechanisms requiring immunosuppressive therapy. We have also learned that postinfectious encephalitis may be recurrent rather than monophasic, and that children and adults initially diagnosed with postinfectious encephalitis may later develop classic multiple sclerosis.

SUMMARY

Encephalitis and postinfectious encephalitis present as neurologic emergencies requiring prompt diagnosis and initiation of treatment. Important concerns are to identify infectious conditions requiring antibiotic or antiviral therapy and postinfectious or other autoimmune encephalitides requiring immunosuppression.

Should a hospitalized child receive empiric treatment with acyclovir?

Background

Herpes simplex encephalitis is associated with substantial morbidity and mortality and may be related to timely diagnosis and treatment. While awaiting the results of testing, hospitalization and empiric treatment with acyclovir is recommended, though the direct and indirect costs associated with this management are substantial. We sought to examine children hospitalized for possible herpes simplex encephalitis, following clinical and laboratory assessment in the emergency department, and empiric treatment with acyclovir, in order to describe the proportion receiving a complete course of treatment; and to identify the clinical variables which are associated with receiving a complete course, as compared with an incomplete course of acyclovir.

Methods

Hospitalized children prescribed acyclovir were included in this case control study. Clinical, laboratory and diagnostic variables were abstracted for children prescribed a complete (≥ 14 days) or an incomplete course (<14 days) of acyclovir. Odds ratios and 95% confidence intervals were calculated.

Results

289 children met eligibility criteria, 30 (10%) received a complete course and 259 (90%) received an incomplete course. A history of mucocutaneous herpes simplex virus infection (p < 0.01), Glasgow Coma Scale ≤ 13 (p = 0.02), focal neurologic findings (p = 0.001) and elevated cerebrospinal fluid white blood cell count (p = 0.05) were associated with a complete course of acyclovir.

Conclusions

Many children did not complete a full course of therapy. Unnecessary testing and treatment is burdensome to families and the health care system. Possible predictive variables include abnormal Glascow Coma Scale, focal neurologic findings and cerebrospinal fluid pleocytosis.

Infectious encephalitis: a description of a Norwegian cohort

BACKGROUND

Prompt recognition and rapid initiation of adequate treatment are important for the outcome of encephalitis. Despite extensive diagnostic testing, the causative agent often remains unknown. The aim of this study was to investigate in how many patients the causative agent was found.

METHODS

Adults (≥ 18 y) diagnosed with ICD codes indicating encephalitis between 2000 and 2009 at Oslo University Hospital, Ullevål were retrospectively studied. Causative agents, clinical presentation, and demographic characteristics were registered. Those with an identified causative agent were compared to those for whom no agent could be found.

RESULTS

Of 136 registered patients, 70 were included in the study. Sixty-six did not fulfil our inclusion criteria or were diagnosed with other, more probable conditions. The causative agent was found in 30/70 (43%) patients; herpes simplex type 1 (10/70, 14%) and varicella zoster virus (6/70, 9%) were the most frequently identified agents. A bacterial cause was found in 6/70 (9%). Patients with an identified agent were more often men and had been ill longer than those for whom no agent could be found. Computed tomography and magnetic resonance imaging were more likely to be abnormal in those patients where a causative agent was found. Five of the 70 (7%) patients died of the infection. The identification rate did not increase during the study period.

CONCLUSIONS

The diagnosis of encephalitis remains a challenge, and in many patients no causative agent is found. Clinically, immune-mediated encephalitis cannot be differentiated from infectious encephalitis and represents an important differential diagnosis. More knowledge is needed to improve our diagnostic skills.

Rapidly progressive dementia: prion diseases and other rapid dementias

Dementias that occur over weeks to months require a different differential than the slowly progressive dementias that occur over years. Because of the rapidity of decline in cognition, the evaluation of the patient is usually urgent and requires an extensive workup with multiple tests running in parallel. Creutzfeldt-Jakob disease, perhaps the prototypic rapidly progressive dementia (RPD), is often the first diagnosis many neurologists consider when faced with a patient with rapid cognitive decline. Many conditions other than prion disease, however, can present with RPD. Other etiologies include autoimmune conditions, cancers, uncommon presentations of other more common neurodegenerative dementias, and others. This chapter discusses some of the major etiologies for RPDs and offers an algorithm for diagnosis. Some topics, such as other neurodegenerative dementias and autoimmune dementias, are covered in other chapters in this issue, and will be mentioned here only briefly.

Epidemiology of central nervous system infection

In cases of central nervous system infection, it is crucial for the neuroradiologist to provide an accurate differential diagnosis of the possible pathogens involved so that treating physicians can be aided in the choice of empiric therapy. This approach requires the radiologist to be aware of local epidemiology and have knowledge of infectious agents that are endemic to their area of practice. This article reviews and discusses the changing epidemiology of pathogens most often observed in meningitis, brain abscess, epidural abscess, postoperative infections, and human immunodeficiency virus infection.

Management of suspected viral encephalitis in adults--Association of British Neurologists and British Infection Association National Guidelines

In the 1980s the outcome of patients with herpes simplex encephalitis was shown to be dramatically improved with aciclovir treatment. Delays in starting treatment, particularly beyond 48 h after hospital admission, are associated with a worse prognosis. Several comprehensive reviews of the investigation and management of encephalitis have been published. However, their impact on day-to day clinical practice appears to be limited. The emergency management of meningitis in children and adults was revolutionised by the introduction of a simple algorithm as part of management guidelines. In February 2008 a group of clinicians met in Liverpool to begin the development process for clinical care guidelines based around a similar simple algorithm, supported by an evidence base, whose implementation is hoped would improve the management of patients with suspected encephalitis.

Neuro-intensive care of patients with acute CNS infections

Infections in the central nervous system (CNS) are caused by a wide range of microorganisms resulting in distinct clinical syndromes including meningitis, encephalitis, and pyogenic infections, such as empyema and brain abscess. Bacterial and viral infections in the CNS can be rapidly fatal and can result in severe disability in survivors. Appropriate identification and acute management of these infections often occurs in a critical care setting and is vital to improving outcomes in this group of patients. This review of diagnosis and management of acute bacterial and viral infections in the CNS provides a general approach to patients with a suspected CNS infection and also provides a more detailed review of the diagnosis and management of patients with suspected bacterial meningitis, viral encephalitis, brain abscess, and subdural empyema.

Management of suspected viral encephalitis in children - Association of British Neurologists and British Paediatric Allergy, Immunology and Infection Group national guidelines

In the 1980s the outcome of patients with herpes simplex encephalitis was shown to be dramatically improved with aciclovir treatment. Delays in starting treatment, particularly beyond 48 h after hospital admission, are associated with a worse prognosis. Several comprehensive reviews of the investigation and management of encephalitis have been published. However, their impact on day-to-day clinical practice appears to be limited. The emergency management of meningitis in children and adults was revolutionised by the introduction of a simple algorithm as part of management guidelines. In February 2008 a group of clinicians met in Liverpool to begin the development process for clinical care guidelines based around a similar simple algorithm, supported by an evidence base, whose implementation is hoped would improve the management of patients with suspected encephalitis.

Diagnosis and quantitative detection of HSV DNA in samples from patients with suspected herpes simplex encephalitis

Diagnosis of herpes simplex encephalitis (HSE) is based on the detection of herpes simplex virus (HSV) DNA in patients' CSF samples. HSV DNA quantitation has the potential for estimating the effects of antiviral therapy. The aim of this study was to diagnose HSV DNA in HSE suspected patients and the quantitative analysis of its genome using real-time PCR to assess the value of the viral load in the course of antiviral treatment. The CSF samples were collected from 236 consecutive HSE suspected patients from November 2004 to May 2008. Upon DNA extraction, the samples were analyzed by Real-Time PCR assay. A set of primers amplified a common sequence of HSV glycoprotein B gene. The copy numbers of unknown samples were expressed via a standard curve drawn with a known amount of amplified cloned plasmid. Of the 236 samples, 137 (58%) came from males and 99 (42%) from females. The HSV genome was detected in 22 (9.3%) patients by PCR, 13 males/ 9 females. Serial CSF samples were available from 10 of the 22 patients. The range of the HSV DNA copy numbers in the clinical samples ranged from 2.5 × 10² to 1.7 × 10⁶ copies/mL of CSF. Quantitative PCR results can be helpful in evaluating the efficacy of antiviral therapy in the above-mentioned patients. There is an association between the initial viral load and the duration of treatment course.

Herpes encephalitis masquerading as tumor

A 54 year old lady presented with lethargy and 15 kg weight loss over the past year. CT scan of the head revealed left temporal lobe hypodensity with a discrete area of hemorrhage within the left mesial temporal lobe. Due to concerns about impending central herniation, lumbar puncture was not performed. MRI of the brain showed a large lesion of the left temporal lobe, extending to the left frontal lobe, and very patchy meningeal enhancement. There was a noncontiguous lesion of the right insula. A differential diagnosis of herpes simplex encephalitis (HSE) and multifocal infiltrative glioma was entertained. MR spectroscopy demonstrated an increased choline peak at the level of the medial left temporal lobe and MR perfusion demonstrated patchy areas of hyperperfusion within the left anterior temporal lobe, both suggestive of neoplastic disease. Following open brain biopsy, pathology revealed herpes simplex virus (HSV) positive nuclei in the cortex and subcortical white matter. As both herpes simplex encephalitis and low-grade glioma demontrate MRI findings of hypointensity on T1 images and hyperintensity on T2 images, the diagnosis of herpes encephalitis can be clouded by confounding factors, especially when cerebrospinal fluid (CSF) cannot be obtained.

Herpes simplex encephalitis and management of acyclovir in encephalitis patients in France

This study reports on the clinical profiles of herpes simplex encephalitis (HSE) case-patients and the management of acyclovir prescriptions. We designed a study on the causes of encephalitis in France in 2007. Case-patients fulfilling the inclusion criteria were enrolled in all the hospitals that volunteered to participate. Fifty-five of 253 enrolled case-patients were diagnosed with HSE. Three (5%) HSE patients died and 48 (89%) were discharged with persistent neurological symptoms. All HSE patients were prescribed acyclovir, 10 of whom had a 2-week course; 42 a 3-week course; two received incomplete courses; and one received two courses of 21 days each due to relapse. The acyclovir dosage was reported for 45 adult HSE patients, 25 (53%) of whom received 10 mg/kg t.i.d. and 22 (47%) received 15 mg/kg t.i.d. The mortality rate was low despite 49% of patients being admitted to intensive-care units. A high dose of acyclovir was not associated with a better outcome in HSE patients. Most patients had persisting symptoms on discharge suggesting neuropsychological rehabilitation is an important issue for survivors.

[Postoperative herpetic meningoencephalitis after lumbar surgery: a case report]

We report a case of a patient with an herpetic meningoencephalitis complicating lumbar surgery. A combination of factors like a postoperative sepsis, an abnormal MRI, and a positive viral PCR and culture made the diagnosis. A prolonged acyclovir treatment was employed with satisfactory results. This case remembers us the possibility of herpes reactivation in a stressful situation (including surgical stress).