Cerebrospinal fluid biomarkers in patients with varicella-zoster virus CNS infections

Biomarkers and genotypes in patients with Central nervous system infection caused by enterovirus

PURPOSE

Enteroviruses (EV) comprises many different types and are the most common cause of aseptic meningitis. How the virus affects the brain including potential differences between types are largely unknown. Measuring biomarkers in CSF is a tool to estimate brain damage caused by CNS infections.

METHODS

A retrospective study was performed in samples from 38 patients with acute neurological manifestations and positive CSF-EV RNA (n = 37) or serum-IgM (n = 1). The EV in 17 samples were typed by sequencing. The biomarkers neurofilament light (NFL), glial fibrillary acidic protein (GFAP), S-100B protein, amyloid-β (Aβ) 40 and Aβ42, total-tau (T-tau) and phosphorylated tau (P-tau) were measured and compared with data derived from a control group (n = 19).

RESULTS

There were no increased levels of GFAP (p ≤ 0.1) nor NFL (p ≤ 0.1) in the CSF of patients with EV meningitis (n = 38) compared with controls. However, we found decreased levels of Aβ42 (p < 0.001), Aβ40 (p < 0.001), T-tau (p ≥ 0.01), P-tau (p ≤ 0.001) and S-100B (p ≤ 0.001). E30 (n = 9) and CVB5 (n = 6) were the most frequent EV-types identified, but no differences in biomarker levels or other clinical parameters were found between the infecting virus type. Seven patients who were followed for longer than one month reported remaining cognitive impairment, although no correlations with biomarker concentrations were observed.

CONCLUSION

There are no indication of neuronal or astrocyte damage in patients with EV meningitis. Yet, decreased concentrations of Aβ40, Aβ42, P-tau and T-tau were shown, a finding of unknown importance. Cognitive impairment after acute disease occurs, but with only a limited number of patients analysed, no conclusion can be drawn concerning any association with biomarker levels or EV types.

Age-adjusted CSF t-tau and NfL do not improve diagnostic accuracy for prodromal Alzheimer's disease

Cerebrospinal fluid total-tau (t-tau) and neurofilament light chain (NfL) are biomarkers of neurodegeneration and are increased in Alzheimer's disease (AD). In order to adjust for age-related increases in t-tau and NfL, cross-sectional age-adjusted norms were developed based on amyloid negative cognitively normal (CN) adults aged 41-78 years (CN, n = 137). The age-adjusted norms for t-tau and NfL did not improve receiver operating curve based diagnostic accuracies in individuals with mild cognitive impairment (MCI) due to AD (AD-MCI, n = 144). Furthermore, while NfL was correlated with higher age in AD-MCI, no significant correlation was found for t-tau. The cox proportional hazard models, applied in 429 participants with baseline t-tau and NfL, showed higher hazard ratio of progression to MCI or dementia without age-adjustments (HR = 3.39 for t-tau and HR = 3.17 for NfL), as compared to using our norms (HR = 2.29 for t-tau and HR = 1.89 for NfL). Our results indicate that utilizing normative reference data could obscure significant age-related increases in these markers associated with neurodegeneration and AD leading to a potential loss of overall diagnostic accuracy.

Cerebrospinal fluid proteomics in meningitis patients with reactivated varicella zoster virus

OBJECTIVE

This study investigated the proteomic characteristics of cerebrospinal fluid (CSF) in patients with varicella zoster virus (VZV) meningitis to understanding the pathogenesis of central nervous system (CNS) infection by reactivated VZV.

METHOD

We used data-independent acquisition model to analyze the CSF proteomic differences of 28 patients with VZV meningitis and 11 herpes zoster (HZ) patients. According to the clinical manifestations at discharge, 28 VZV meningitis patients were divided into favorable outcome group and unfavorable outcome (UO) group and their differences in CSF proteome were also analyzed.

RESULTS

Compared with the HZ group, the proteins (CXCL10, ELANE, IL-1RN, MPO, PRTN3, etc.) related to inflammation and immune cell activation were significantly upregulated in the VZV meningitis group (p < .01). The protein related to the nerve function and energy metabolism (CKMT1B, SLITRK3, Synaptotagmin-3, KIF5B, etc.) were significantly downregulated (p < .05). The levels of a pro-inflammatory factor, IL-18, in CSF were significantly higher in patients in the UO group as compared to patients with favorable prognosis (p < .05).

CONCLUSION

Inflammatory immune response is an important pathophysiological mechanism of CNS infection by VZV, and the CSF IL-18 levels might be a potential prognostic indicator of the outcomes of VZV meningitis.

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.

The brain-specific upregulation of CARD11 in response to avian brain-neurotropic virus infection serves as a potential biomarker

Avian neurotropic viruses are critical problems in poultry industry causing severe central nervous system (CNS) damage with neuroinvasive and neurovirulence properties. Biomarker of neurotropic viral intracranial invasion is of great application value for the diagnosis, but that of avian neurotropic viruses remains elusive. Previously, we found that chicken caspase recruitment domain family, member 11 (CARD11) was only upregulated in virulent Newcastle disease virus-infected chickens and in chicken primary neuronal cells. In this study, CARD11 was systemically expressed in chickens and pigeons detected by absolute qPCR and immunohistochemical (IHC) assay. After virus challenging, only avian neurotropic viruses (avian encephalomyelitis virus [AEV] and pigeon paramyxovirus type 1 [PPMV-1]) except Marek's disease virus (MDV) can invade brain and cause pathological changes. The relative mRNA expression of CARD11 was brain-upregulated in AEV- or PPMV-1-infected animals, rather than MDV and non-neurotropic viruses (fowl adenovirus serotype 4 [FAdV-4] and infectious bronchitis virus [IBV]). Similarly, the protein expression of CARD11 was only upregulated in the cerebra and cerebella infected by avian brain-neurotropic virus using IHC assay. And there were no correlations between the change level of CARD11 and viral load. Our preliminary data suggested that avian CARD11 may be a potential brain biomarker for avian brain-neurotropic virus invasion.

Neurofilament light chain in central nervous system infections: a prospective study of diagnostic accuracy

Diagnosing central nervous system (CNS) infections quickly is often difficult. Neurofilament light chain (NfL) is a component of the axonal cytoskeleton and identified as marker of neuronal damage in several CNS diseases. We evaluated the diagnostic accuracy of NfL for diagnosing CNS infections. We included patients from a prospective cohort of consecutive patients in whom a lumbar puncture was performed for suspected CNS infection in an academic hospital in The Netherlands. The index test was NfL in cerebrospinal fluid (CSF) and reference standard the final clinical diagnosis. Diagnostic accuracy was determined using the area-under-the-curve (AUC) with 95% confidence intervals (CI). The association of CSF NfL with clinical characteristics, diagnosis and outcome was evaluated. Between 2012 and 2015, 273 episodes in adults of which sufficient CSF was available were included. CNS infection was diagnosed in 26%(n = 70), CNS inflammatory disease in 7%(n = 20), systemic infection in 32%(n = 87), and other neurological disorders in 33%(n = 90). Median CSF NfL level was 593 pg/ml (IQR 249–1569) and did not discriminate between diagnostic categories or CNS infection subcategories. AUC for diagnosing any CNS infection compared to patients without CNS infections was 0.50 (95% CI 0.42–0.59). Patients presenting with an altered mental status had higher NfL levels compared to other patients. We concluded that NfL cannot discriminate between causes in patients suspected of CNS infections. High concentrations of NfL are associated with severe neurological disease and the prognostic value of NfL in patients with CNS infections should be investigated in future research.

Serum and cerebrospinal fluid phosphorylated neurofilament heavy subunit as a marker of neuroaxonal damage in tick-borne encephalitis

Extensive axonal and neuronal loss is the main cause of severe manifestations and poor outcomes in tick-borne encephalitis (TBE). Phosphorylated neurofilament heavy subunit (pNF-H) is an essential component of axons, and its detection in cerebrospinal fluid (CSF) or serum can indicate the degree of neuroaxonal damage. We examined the use of pNF-H as a biomarker of neuroaxonal injury in TBE. In 89 patients with acute TBE, we measured CSF levels of pNF-H and 3 other markers of brain injury (glial fibrillary acidic protein, S100B and ubiquitin C-terminal hydrolase L1) and compared the results to those for patients with meningitis of other aetiology and controls. Serum pNF-H levels were measured in 80 patients and compared with findings for 90 healthy blood donors. TBE patients had significantly (P<0.001) higher CSF pNF-H levels than controls as early as hospital admission. Serum pNF-H concentrations were significantly higher in samples from TBE patients collected at hospital discharge (P<0.0001) than in controls. TBE patients with the highest peak values of serum pNF-H, exceeding 10 000 pg ml^-1, had a very severe disease course, with coma or tetraplegia. Patients requiring intensive care had significantly higher serum pNF-H levels than other TBE patients (P<0.01). Elevated serum pNF-H values were also observed in patients with incomplete recovery (P<0.05). Peak serum pNF-H levels correlated positively with the duration of hospitalization (P=0.005). Measurement of pNF-H levels in TBE patients might be useful for assessing disease severity and determining prognosis.

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.

CSF Neurofilament Light Chain Concentrations Predict Outcome in Bacterial Meningitis

Background and Objectives

Neurofilament light chain (NfL) is a biomarker for neuroaxonal damage and has been found to be elevated proportionally to the degree of neuronal damage in neurologic diseases. The objective of this study was to determine the prognostic accuracy of NfL concentrations on unfavorable outcome in adults with community-acquired bacterial meningitis.

Methods

We measured NfL concentration CSF samples from a prospective cohort study of adults with community-acquired bacterial meningitis in The Netherlands and determined associations between NfL CSF concentrations, clinical characteristics, and outcome in multivariate analyses. We identified independent predictors of an unfavorable outcome (Glasgow Outcome Scale scores 1–4) by logistic regression.

Results

CSF NfL concentrations were evaluated in 429 episodes of 425 patients with community-acquired bacterial meningitis. The median age of 429 episodes was 62 years (interquartile range, 50–69 years). Of note, 290 of 422 (68%) episodes presented with an altered mental status (Glasgow Coma Scale score < 14). Most common causative pathogens were Streptococcus pneumoniae (73%), Neisseria meningitidis (7%), and Listeria monocytogenes (5%). The overall case fatality rate was 62 of 429 (15%), and unfavorable outcome occurred in 57 (37%) of 429 episodes. In multivariate analysis, predictors of unfavorable outcome were older age (OR 1.03, 95% CI 1.01–1.05), cranial nerve palsy (OR 4, 95% CI 1.6–10.3), high serum C-reactive protein concentration (OR 1.3, 95% CI 1.01–1.05), and high CSF NfL concentration (OR 1.5, 95% CI 1.07–2.00). CSF NfL concentrations were higher in patients presenting with focal cerebral deficits (717 pg/mL [416–1,401] vs 412 pg/mL [278–731]; p < 0.001). The area under the curve (AUC) for predicting unfavorable outcome in bacterial meningitis of CSF NfL concentration was 0.69 (95% CI, 0.64–0.74).

Discussion

CSF NfL concentration is independently associated with unfavorable outcome in adults with community-acquired bacterial meningitis, suggesting that CSF NfL concentration may be a useful biomarker for prognostic assessment in bacterial meningitis.

Classification of Evidence

Can the level of NfL in CSF (the index test) predict unfavorable outcome in patients with bacterial meningitis, in a cohort of bacterial meningitis patients with a favorable and unfavorable outcome? This study provides Class II evidence that NfL level in CSF is a moderate predictor, with the AUC for predicting unfavorable outcome in bacterial meningitis being 0.69 (95% CI, 0.64–0.74).

Increased GFAP concentrations in the cerebrospinal fluid of patients with unipolar depression

Inflammatory processes involving altered microglial activity may play a relevant role in the pathophysiology of depressive disorders. Glial fibrillary acidic protein (GFAP) and calcium-binding protein S100B are considered microglial markers. To date, their role has been studied in the serum and tissue material of patients with unipolar depression but not in the cerebrospinal fluid (CSF). Therefore, the aim of the current study was to examine GFAP and S100B levels in the CSF of patients with major depression to better understand their role in affective disorders. In this retrospective study, 102 patients with unipolar depression and 39 mentally healthy controls with idiopathic intracranial hypertension were investigated. GFAP and S100B levels were measured using commercially available ELISA kits. CSF routine parameters were collected during routine clinical care. The mean values of GFAP and S100B were compared using age (and sex) corrected ANOVAs. Matched subgroups were analyzed by using an independent sample t-test. In addition, correlation analyses between GFAP/S100B levels and CSF routine parameters were performed within the patient group. Patients with unipolar depression had significantly higher levels of GFAP than controls (733.22 pg/ml vs. 245.56 pg/ml, p < 0.001). These results remained significant in a sub-analysis in which all controls were compared with patients suffering from depression matched 1:1 by age and sex (632.26 pg/ml vs. 245.56 pg/ml, p < 0.001). Levels of S100B did not differ significantly between patients and controls (1.06 ng/ml vs. 1.17 ng/ml, p = 0.385). GFAP levels correlated positively with albumin quotients (p < 0.050), S100B levels correlated positively with white blood cell counts (p = 0.001), total protein concentrations (p < 0.001), and albumin quotients (p = 0.001) in the CSF. The significance of the study is limited by its retrospective and open design, methodological aspects, and the control group with idiopathic intracranial hypertension. In conclusion, higher GFAP levels in patients with depression may be indicative of altered microglia activity, especially in astrocytes, in patients with unipolar depression. In addition, correlation analyses support the idea that S100B levels could be related to the integrity of the blood-brain/CSF barrier. Further multimodal and longitudinal studies are necessary to validate these findings and clarify the underlying biological processes.

Cognitive impairment without altered levels of cerebrospinal fluid biomarkers in patients with encephalitis caused by varicella-zoster virus: a pilot study

Varicella-zoster virus (VZV) is one of the most common agents causing viral infections of the central nervous system (CNS). VZV encephalitis is associated with severe neurological sequelae, despite antiviral treatment. Cognitive impairment has been reported and VZV has been associated with dementia. Our aim was to investigate the cognitive impairment and cerebrospinal fluid biomarkers in a follow-up study of patients with VZV encephalitis. Thirteen patients with VZV encephalitis, diagnosed by detection of VZV DNA in cerebrospinal fluid (CSF) by PCR and concomitant symptoms of encephalitis, were included. Neuropsychological assessment in parallel with a lumbar puncture to obtain CSF was performed 1.5–7 years after acute disease. The CSF biomarkers neurofilament light chain (NFL), S100B, glial fibrillary acidic protein (GFAP), amyloid-β (Aβ) 40 and Aβ42, total tau (t-tau) and phosphorylated tau (p-tau) were analysed and compared to controls (n = 24). Cognitive impairment was shown in the domains of executive functions and speed/attention and to a minor degree in the domains of learning/memory and language, indicated by a significantly poorer performance on seven neuropsychological test variables. No convincing evidence of alterations in concentrations of biomarkers in the CSF were shown. Our results indicate that patients with VZV encephalitis suffer from cognitive impairment long time after acute disease. Importantly, these impairments do not seem to be accompanied by biomarker evidence of ongoing neuronal or astrocytic injury/activation or induction of dementia-related brain pathologies by the infection.

Serum and cerebrospinal fluid neurofilament light chain in patients with central nervous system infections caused by varicella-zoster virus

Varicella-zoster virus (VZV) is a common cause of viral central nervous system (CNS) infection, and patients may suffer from severe neurological sequelae. The biomarker neurofilament light chain (NFL) is used for assessment of neuronal damage and is normally measured in cerebrospinal fluid (CSF). Novel methods have given the possibility to measure NFL in serum instead, which could be a convenient tool to estimate severity of disease and prognosis in VZV CNS infections. Here, we investigate the correlation of serum and CSF NFL in patients with VZV CNS infection and the association of NFL levels in serum and CSF with different VZV CNS entities. NFL in serum and CSF was measured in 61 patients who were retrospectively identified with neurological symptoms and VZV DNA in CSF detected by PCR. Thirty-three herpes zoster patients and 40 healthy blood donors served as control groups. NFL levels in serum and CSF correlated strongly in the patients with VZV CNS infection. Encephalitis was associated with significantly higher levels of NFL in both serum and CSF compared with meningitis and Ramsay Hunt syndrome. Surprisingly, herpes zoster controls had very high serum NFL levels, comparable with those shown in encephalitis patients. We show that analysis of serum NFL can be used instead of CSF NFL for estimation of neuronal injury in patients with VZV CNS infection. However, high levels of serum NFL also in patients with herpes zoster, without signs of CNS involvement, may complicate the interpretation.

Herpes zoster in HIV-1 infection: The role of CSF pleocytosis in secondary CSF escape and discordance

HIV cerebrospinal fluid (CSF) escape is defined by a concentration of HIV-1 RNA in CSF above the lower limit of quantification of the employed assay and equal to or greater than the plasma HIV-1 RNA level in the presence of treatment-related plasma viral suppression, while CSF discordance is similarly defined by equal or higher CSF than plasma HIV-1 RNA in untreated individuals. During secondary CSF escape or discordance, disproportionate CSF HIV-1 RNA develops in relation to another infection in addition to HIV-1. We performed a retrospective review of people living with HIV receiving clinical care at Sahlgrenska Infectious Diseases Clinic in Gothenburg, Sweden who developed uncomplicated herpes zoster (HZ) and underwent a research lumbar puncture (LP) within the ensuing 150 days. Based on treatment status and the relationship between CSF and plasma HIV-1 RNA concentrations, they were divided into 4 groups: i) antiretroviral treated with CSF escape (N = 4), ii) treated without CSF escape (N = 5), iii) untreated with CSF discordance (N = 8), and iv) untreated without CSF discordance (N = 8). We augmented these with two additional cases of secondary CSF escape related to neuroborreliosis and HSV-2 encephalitis and analyzed these two non-HZ cases for factors contributing to CSF HIV-1 RNA concentrations. HIV-1 CSF escape and discordance were associated with higher CSF white blood cell (WBC) counts than their non-escape (P = 0.0087) and non-discordant (P = 0.0017) counterparts, and the CSF WBC counts correlated with the CSF HIV-1 RNA levels in both the treated (P = 0.0047) and untreated (P = 0.002) group pairs. Moreover, the CSF WBC counts correlated with the CSF:plasma HIV-1 RNA ratios of the entire group of 27 subjects (P = <0.0001) indicating a strong effect of the CSF WBC count on the relation of the CSF to plasma HIV-1 RNA concentrations across the entire sample set. The inflammatory response to HZ and its augmenting effect on CSF HIV-1 RNA was found up to 5 months after the HZ outbreak in the cross-sectional sample and, was present for one year after HZ in one individual followed longitudinally. We suggest that HZ provides a ‘model’ of secondary CSF escape and discordance. Likely, the inflammatory response to HZ pathology provoked local HIV-1 production by enhanced trafficking or activation of HIV-1-infected CD4+ T lymphocytes. Whereas treatment and other systemic factors determined the plasma HIV-1 RNA concentrations, in this setting the CSF WBC counts established the relation of the CSF HIV-1 RNA levels to this plasma set-point.

Cerebrospinal fluid biomarkers in patients with central nervous system infections: a retrospective study

BACKGROUND

Central nervous system (CNS) may be infected by several agents, resulting in different presentations and outcomes. Analysis of cerebrospinal fluid (CSF) markers could be helpful to differentiate specific conditions and setting an appropriate therapy.

METHODS

Patients presenting with signs and symptoms were enrolled if, before receiving a diagnostic lumbar puncture, signed a written informed consent. We analyzed CSF indexes of blood-brain barrier permeability (CSF to serum albumin ratio or CSAR), inflammation (CSF to serum IgG ratio, neopterin), amyloid deposition (1-42 β-amyloid), neuronal damage (Total tau (T-tau), Phosphorylated tau (P-tau), and 14.3.3 protein) and astrocyte damage (S-100β).

RESULTS

Two hundred and eighty-one patients were included: they were mainly affected by herpesvirus encephalitis, enterovirus meningoencephalitis, bacterial meningitis (Neisseria meningitidis and Streptococcus pneumoniae), and infection by other etiological agents or unknown pathogen. Their CSF features were compared with HIV-negative patients and native HIV-positive individuals without CNS involvement. 14.3.3 protein was found in bacterial and HSV infections while T-tau and neopterin were abnormally high in the herpesvirus group. P-tau, instead, was elevated in enterovirus meningitis. S-100β was found to be high in patients with HSV-1 and HSV-2 infections but not in those with Varicella Zoster Virus (VZV). Thirty-day mortality was unexpectedly low (2.7%): patients who died had higher levels of T-tau and, significantly, lower levels of Aβ1-42.

CONCLUSION

This work demonstrates that CSF biomarkers of neuronal damage or inflammation may vary during CNS infections according to different causative agents. The prognostic value of these biomarkers needs to be assessed in prospective studies.

EEG for children with complex febrile seizures

BACKGROUND

Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours, and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

For the latest update of this review, we searched the following databases on 12 March 2019: Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE (Ovid, 1946 to 11 March 2019); and ClinicalTrials.gov. We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

The review authors selected and retrieved the articles and independently assessed which articles should be included. Any disagreements were resolved by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by Cochrane.

MAIN RESULTS

Of 48 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children under the age of five. An RCT can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size. Since the last version of this review, we have found no new studies.

Chemokines and matrix metalloproteinases in cerebrospinal fluid of patients with central nervous system complications caused by varicella-zoster virus

BACKGROUND

Varicella-zoster virus (VZV) is a common viral agent causing central nervous system (CNS) infections including encephalitis, meningitis, and Ramsay Hunt syndrome. Neurological complications occur frequently despite antiviral treatment. Matrix metalloproteinases (MMPs) and cytokines are involved in the neuroinflammatory response during CNS infection. Their role in VZV CNS infections and how they differ between different CNS entities caused by VZV are poorly investigated.

METHODS

We analyzed the levels of 30 chemokines and 9 MMPs in cerebrospinal fluid (CSF) and serum from 66 patients with VZV CNS infections diagnosed by detection of VZV DNA in CSF and concomitant neurological symptoms and compared with a control group (n = 24).

RESULTS

Levels of CCL19, CXCL8, CXCL9, and CXCL10 were significantly increased and surpassing the levels in serum when analyzing all patients with VZV CNS infections whereas CXCL11 was only increased in CSF of patients with VZV meningitis. MMP-2-levels were highly elevated in CSF of all 66 VZV patients. The patients with encephalitis had the most significantly increased levels of MMPs in CSF, and MMP-3, MMP-8, and MMP-12 were exclusively increased in this group, whereas MMP-9 in CSF was increased in the patients with VZV meningitis.

CONCLUSIONS

We show that both chemokines and MMPs are elevated in the CSF of patients with VZV CNS infections. Encephalitis and meningitis patients differed with respect to other chemokines (CXCL11) and MMPs (MMP-3, MMP-8, MMP-9, and MMP-12), indicating that different location of the virus gives rise to qualitative differences in the ensuing inflammatory response. In addition, the pronounced increase of MMPs in CSF of the patients with encephalitis suggests an association to the severity of this manifestation, compared to VZV meningitis and Ramsay Hunt syndrome. The role of MMPs in association to chemokines should be further investigated to evaluate their significance in the neuropathogenesis of VZV CNS infections and as a potential target for new treatment alternatives.

Varicella zoster virus infections in neurological patients: a clinical study

Background

Varicella zoster virus (VZV) reactivation is a common infectious disease in neurology and VZV the second most frequent virus detected in encephalitis. This study investigated characteristics of clinical and laboratory features in patients with VZV infection.

Methods

Two hundred eighty two patients with VZV reactivation that were hospitalized in the department of neurology in the time from 2005 to 2013 were retrospectively evaluated. Results from cerebrospinal fluid (CSF) analysis were available from 85 patients.

Results

Trigeminal rash was the most common clinical manifestation, followed by segmental rash, CNS infection, facial nerve palsy, postherpetic neuralgia, and radiculitis. MRI of the brain performed in 25/33 patients with encephalitis/meningitis did not show any signs of infection in the brain parenchyma. Only one patient showed contrast enhancement in the hypoglossal nerve. General signs of infection such as fever or elevated CRP values were found in only half of the patients. Furthermore, rash was absent in a quarter of patients with CNS infection and facial nerve palsy, and thus, infection could only be proven by CSF analysis. Although slight inflammatory CSF changes occurred in few patients with isolated rash, the frequency was clearly higher in patients with CNS infection and facial nerve palsy.

Conclusion

Monosegmental herpes zoster is often uncomplicated and a diagnostic lumbar puncture is not essential. In contrast, CSF analysis is an essential diagnostic tool in patients with skin lesions and cranial nerve or CNS affection. In patients with neuro-psychiatric symptoms and inflammatory CSF changes analysis for VZV should be performed even in the absence of skin lesions.

Review: Tau in biofluids - relation to pathology, imaging and clinical features

Tau is a microtubule-binding protein that is important for the stability of neuronal axons. It is normally expressed within neurons and is also secreted into the brain interstitial fluid that communicates freely with cerebrospinal fluid (CSF) and, in a more restricted manner, blood via the glymphatic clearance system of the brain. In Alzheimer's disease (AD), neuroaxonal degeneration results in increased release of tau from neurons. Furthermore, tau is truncated and phosphorylated, which leads to aggregation of tau in neurofibrillary tangles of the proximal axoplasm. Neuroaxonal degeneration and tangle formation are reflected by increased concentrations of total tau (T-tau, measured using assays that detect most forms of tau) and phospho-tau (P-tau, measured using assays with antibodies specific to phosphorylated forms of tau). In AD CSF, both T-tau and P-tau concentrations are increased. In stroke and other CNS disorders with neuroaxonal injury but without tangles, T-tau is selectively increased, whereas P-tau concentration often stays normal. In tauopathies (diseases with both neurodegeneration and neurofibrillary tangles) other than AD, CSF T-tau and P-tau concentrations are typically unaltered, which is a puzzling result that warrants further investigation. In the current review, I discuss the association of T-tau and P-tau concentrations in body fluids with neuropathological changes, imaging findings and clinical features in AD and other CNS diseases.

Mass-spectrometric profiling of cerebrospinal fluid reveals metabolite biomarkers for CNS involvement in varicella zoster virus reactivation

Background

Varicella zoster virus (VZV) reactivation spans the spectrum from uncomplicated segmental herpes zoster to life-threatening disseminated CNS infection. Moreover, in the absence of a small animal model for this human pathogen, studies of pathogenesis at the organismal level depend on analysis of human biosamples. Changes in cerebrospinal fluid (CSF) metabolites may reflect critical aspects of host responses and end-organ damage in neuroinfection and neuroinflammation. We therefore applied a targeted metabolomics screen of CSF to three clinically distinct forms of VZV reactivation and infectious and non-infectious disease controls in order to identify biomarkers for CNS involvement in VZV reactivation.

Methods

Metabolite profiles were determined by targeted liquid chromatography-mass spectrometry in CSF from patients with segmental zoster (shingles, n = 14), facial nerve zoster (n = 16), VZV meningitis/encephalitis (n = 15), enteroviral meningitis (n = 10), idiopathic Bell’s palsy (n = 11), and normal pressure hydrocephalus (n = 15).

Results

Concentrations of 88 metabolites passing quality assessment clearly separated the three VZV reactivation forms from each other and from the non-infected samples. Internal cross-validation identified four metabolites (SM C16:1, glycine, lysoPC a C26:1, PC ae C34:0) that were particularly associated with VZV meningoencephalitis. SM(OH) C14:1 accurately distinguished facial nerve zoster from Bell’s palsy. Random forest construction revealed even more accurate classifiers (signatures comprising 2–4 metabolites) for most comparisons. Some of the most accurate biomarkers correlated only weakly with CSF leukocyte count, indicating that they do not merely reflect recruitment of inflammatory cells but, rather, specific pathophysiological mechanisms. Across all samples, only the sum of hexoses and the amino acids arginine, serine, and tryptophan correlated negatively with leukocyte count. Increased expression of the metabolites associated with VZV meningoencephalitis could be linked to processes relating to neuroinflammation/immune activation, neuronal signaling, and cell stress, turnover, and death (e.g., autophagy and apoptosis), suggesting that these metabolites might sense processes relating to end-organ damage.

Conclusions

The results provide proof-of-concept for the value of CSF metabolites as (1) disease-associated signatures suggesting pathophysiological mechanisms, (2) degree and nature of neuroinflammation, and (3) biomarkers for diagnosis and risk stratification of VZV reactivation and, likely, neuroinfections due to other pathogens.

Trial registration

Not applicable (non-interventional study).

Electronic supplementary material

The online version of this article (10.1186/s12974-017-1041-0) contains supplementary material, which is available to authorized users.

EEG for children with complex febrile seizures

BACKGROUND

Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours, and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

For the latest update of this review, we searched the Cochrane Epilepsy Group Specialized Register (23 January 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online (CRSO, 23 January 2017), MEDLINE (Ovid, 23 January 2017), and ClinicalTrials.gov (23 January 2017). We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

The review authors selected and retrieved the articles and independently assessed which articles should be included. Any disagreements were resolved by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by Cochrane.

MAIN RESULTS

Of 41 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children. An RCT can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size. Since the last version of this review, we have found no new studies.

Applying fluid biomarkers to Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disease that starts with a clinically silent phase of a decade or more during which brain pathologies accumulate predominantly in the medial temporal lobe but also elsewhere in the brain. Network dysfunction and clinical symptoms typically appear when senile plaque (amyloid-β) and neurofibrillary tangle (tau) pathologies meet in the brain parenchyma, producing synapse and neuronal loss. For plaque and tangle pathologies, reliable fluid biomarkers have been developed. These require sampling of cerebrospinal fluid. Reliable blood tests for plaque and tangle pathologies are currently lacking, but blood tests for general neurodegeneration have recently been developed. In AD, plaques and tangles often coexist with other pathologies, including Lewy bodies, and to what extent these contribute to symptoms is currently unknown. There are also important differential diagnoses that may be possible to distinguish from AD with the aid of biomarkers. The scope of this review is fluid biomarkers for AD and related pathologies. The purpose is to provide the reader with an updated account of currently available fluid biomarkers for AD and clinically relevant differential diagnoses.

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.

Cerebrospinal fluid viral load and biomarkers of neuronal and glial cells in Ramsay Hunt syndrome

Reactivation of varicella zoster virus (VZV) can manifest with facial palsy diagnosed as Ramsay Hunt Syndrome (RHS) or Ramsay Hunt Syndrome zoster sine herpete (RHS-ZSH). These syndromes are associated with poor prognosis despite treatment with antivirals and corticosteroids. Concentrations of biomarkers such as neurofilament protein (NFL), S-100β protein and glial fibrillary acidic protein (GFAp) have previously been measured in cerebrospinal fluid (CSF) to assess neuronal damage and glial pathology. We employed immunochemical methods to measure concentrations of NFL, S-100β protein and GFAp in CSF from patients with RHS (n = 15) and RHS-ZSH (n = 13) diagnosed by detection of VZV DNA in the CSF by quantitative PCR, and compared with a control group (n = 52). The biomarker concentrations were correlated with CSF viral load and outcome measured by House-Brackmann score. NFL and GFAp concentrations were increased compared with controls (P = 0.008 and P = 0.04), while S-100β levels were decreased. This pattern was more pronounced in patients with RHS compared to the patients with RHS-ZSH (NS and P = 0.028). The amount of viral DNA in CSF correlated with increased GFAp (P = 0.003) and NFL (P = 0.006). No correlations were found between biomarker concentrations and patient outcome. Patients with facial palsy caused by VZV had biochemical signs of neuronal damage and astrogliosis. High amounts of viral DNA may be associated with the degree of damage on neuronal and astroglial cells. Prospective studies are warranted to elucidate the association of elevated biomarkers in the CSF and outcome assessed by more sensitive tests.

Varicella-zoster virus (VZV) DNA in serum of patients with VZV central nervous system infections

OBJECTIVES

Varicella-zoster virus (VZV) is a common viral agent causing central nervous system (CNS) infections, normally diagnosed by detection of VZV DNA in cerebrospinal fluid (CSF). Our aim was to investigate trends in VZV DNAemia in VZV CNS infections, which could potentially contribute to diagnosis and secondly, correlate the amount of VZV DNA in serum to severity of disease.

METHODS

Seventy-two patients with VZV CNS infections diagnosed by detection of VZV DNA in CSF and concomitant neurological symptoms were included. The amount of VZV DNA was measured by real-time PCR in paired serum and CSF samples and compared to a control group of herpes zoster (n = 36).

RESULTS

An increased amount of VZV DNA was detected in serum in patients with encephalitis compared to patients with meningitis or Ramsay-Hunt syndrome, respectively (p = 0.003 and p = 0.024). A greater proportion of patients with VZV CNS infections and detectable VZV DNA in serum had ongoing rash compared to those without detectable VZV DNA in serum (p ≤ 0.001). The viral load in serum of patients with neurological symptoms was lower compared to in patients with herpes zoster without neurological symptoms (p ≤ 0.001) and only 32/72 of the patients with VZV CNS disease had VZV DNA detected in serum.

CONCLUSION

Increased amount of VZV DNA in serum of patients with VZV CNS infections seems associated with encephalitis and ongoing rash. Additionally, viral DNA analysis by PCR in serum may be a helpful diagnostic tool although viral DNA analysis by PCR in CSF is the method of choice for diagnosis.

Elevated levels of cerebrospinal fluid S100B are associated with brain injury and unfavorable outcomes in children with central nervous system infections

PURPOSE

This work aimed to assess whether elevated levels of cerebrospinal fluid (CSF) S100B are associated with brain injury and unfavorable outcomes at discharge in children with central nervous system (CNS) infections.

METHODS

CSF S100B and associated clinical parameters were retrospectively analyzed in 83 children with CNS infections and 88 children without neurological pathology served as controls. Children with CNS infections were divided into an infectious encephalitis group and an infectious meningitis group based on whether cerebral parenchyma was involved, and CSF S100B levels in different age subgroups between the two groups were compared. The predictive value of CSF S100B in children with infectious encephalitis was evaluated by multivariate logistic regression analysis, and the discriminative power was investigated by receiver operating characteristic (ROC) analysis.

RESULTS

CSF S100B levels in the infectious encephalitis group were significantly higher than the infectious meningitis and the control group at each age range. CSF S100B ≥ 0.96 μg/L had 62.9% sensitivity and 76.2% specificity for diagnosing cerebral parenchyma injury in children with CNS infections. Increased CSF S100B levels were proven to be an independent predictor of unfavorable outcomes in children with infectious encephalitis and the optimal cut-off value (1.77 μg/L of CSF S100B) for predicting unfavorable outcomes in children with infectious encephalitis showed 61.1% sensitivity and 96.2% specificity.

CONCLUSIONS

This study has demonstrated that elevated levels of CSF S100B are associated with brain injury and could be used as an independent predictor of clinically unfavorable outcomes at discharge in children with CNS infections.

EEG for children with complex febrile seizures

BACKGROUND

This is an updated version of original Cochrane review published in Issue 1, 2014.Febrile seizures can be classified as simple or complex. Complex febrile seizures are associated with fever that lasts longer than 15 minutes, occur more than once within 24 hours and are confined to one side of the child's body. It is common in some countries for doctors to recommend an electroencephalograph (EEG) for children with complex febrile seizures. A limited evidence base is available to support the use of EEG and its timing after complex febrile seizures among children.

OBJECTIVES

To assess the use of EEG and its timing after complex febrile seizures in children younger than five years of age.

SEARCH METHODS

For the latest update of this review, we searched the Cochrane Epilepsy Group Specialized Register (6 July 2015), the Cochrane Central Register of Controlled Trials (CENTRAL, 2005, Issue 6), MEDLINE (6 July 2015) and ClinicalTrials.gov (6 July 2015). We applied no language restrictions.

SELECTION CRITERIA

All randomised controlled trials (RCTs) that examined the utility of an EEG and its timing after complex febrile seizures in children.

DATA COLLECTION AND ANALYSIS

Review authors selected and retrieved the articles and independently assessed which articles should be included. We resolved disagreements by discussion and by consultation with the Cochrane Epilepsy Group. We applied standard methodological procedures expected by Cochrane.

MAIN RESULTS

Of 37 potentially eligible studies, no RCTs met the inclusion criteria.

AUTHORS' CONCLUSIONS

We found no RCTs as evidence to support or refute the use of EEG and its timing after complex febrile seizures among children. An RCT can be planned in such a way that participants are randomly assigned to the EEG group and to the non-EEG group with sufficient sample size. Since the last version of this review, we found no new studies.

Plasma Concentration of the Neurofilament Light Protein (NFL) is a Biomarker of CNS Injury in HIV Infection: A Cross-Sectional Study

Background

Cerebrospinal fluid (CSF) neurofilament light chain protein (NFL) is a sensitive marker of neuronal injury in a variety of neurodegenerative conditions, including the CNS dysfunction injury that is common in untreated HIV infection. However, an important limitation is the requirement for lumbar puncture. For this reason, a sensitive and reliable blood biomarker of CNS injury would represent a welcome advance in both clinical and research settings.

Methods

To explore whether plasma concentrations of NFL might be used to detect CNS injury in HIV infection, an ultrasensitive Single molecule array (Simoa) immunoassay was developed. Using a cross-sectional design, we measured NFL in paired CSF and plasma samples from 121 HIV-infected subjects divided into groups according to stage of their systemic disease, presence of overt HIV-associated dementia (HAD), and after antiretroviral treatment (ART)-induced viral suppression. HIV-negative controls were also examined.

Findings

Plasma and CSF NFL concentrations were very highly correlated (r = 0.89, P < 0.0001). While NFL was more than 50-fold lower plasma than CSF it was within the quantifiable range of the new plasma assay in all subjects, including the HIV negatives and the HIV positives with normal CSF NFL concentrations. The pattern of NFL changes were almost identical in plasma and CSF, both exhibiting similar age-related increases in concentrations along with highest values in HAD and substantial elevations in ART-naïve neuroasymptomatic subjects with low blood CD4⁺ T cells.

Interpretation

These results show that plasma NFL may prove a valuable tool to evaluate ongoing CNS injury in HIV infection that may be applied in the clinic and in research settings to assess the presence if active CNS injury. Because CSF NFL is also elevated in a variety of other CNS disorders, sensitive measures of plasma NFL may similarly prove useful in other settings.

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Plasma NFL is a sensitive marker of neuronal injury

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Plasma and CSF NFL concentrations were highly correlated

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Plasma NFL is useful to detect active axonal injury in treated and untreated HIV

A sensitive blood biomarker of neuronal injury has long been sought for. Here we describe an ultrasensitive quantification measurement of the axonal neurofilament light chain protein (NFL) in blood. We test this in the setting of HIV brain injury in which cerebrospinal fluid (CSF) NFL has been well characterized and noted to be a reliable biomarker of neuronal injury.

Blood and CSF NFL were highly correlated and measurement of plasma NFL was able to detect both severe and subclinical neuronal injury in HIV.

CSF NFL is elevated in a wide range of additional neurodegenerative settings, so the reported findings likely have broader implications, though this requires additional direct study.

Long-term neuropsychiatric consequences of aseptic meningitis in adult patients

Aseptic meningitis is considered a benign and self-limiting clinical condition. In contrast to viral encephalitis and bacterial meningitis, the prognosis is usually good. The existing literature is scarce on the potential long-term neuropsychiatric consequences of aseptic meningitis. Previous studies have primarily been retrospective and differences in methodologies make it difficult to draw conclusions regarding the prevalence and nature of neuropsychiatric manifestations. However, studies have reported decreased psychomotor speed and impaired executive and visuo-constructive functions following aseptic meningitis. Larger controlled prospective studies are urgently needed to elucidate the neuropsychiatric complications of aseptic meningitis.

Cerebrospinal fluid (CSF) neuronal biomarkers across the spectrum of HIV infection: hierarchy of injury and detection

The character of central nervous system (CNS) HIV infection and its effects on neuronal integrity vary with evolving systemic infection. Using a cross-sectional design and archived samples, we compared concentrations of cerebrospinal fluid (CSF) neuronal biomarkers in 143 samples from 8 HIV-infected subject groups representing a spectrum of untreated systemic HIV progression and viral suppression: primary infection; four groups of chronic HIV infection neuroasymptomatic (NA) subjects defined by blood CD4+ T cells of >350, 200–349, 50–199, and <50 cells/µL; HAD; treatment-induced viral suppression; and ‘elite’ controllers. Samples from 20 HIV-uninfected controls were also examined. The neuronal biomarkers included neurofilament light chain protein (NFL), total and phosphorylated tau (t-tau, p-tau), soluble amyloid precursor proteins alpha and beta (sAPPα, sAPPβ) and amyloid beta (Aβ) fragments 1–42, 1–40 and 1–38. Comparison of the biomarker changes showed a hierarchy of sensitivity in detection and suggested evolving mechanisms with progressive injury. NFL was the most sensitive neuronal biomarker. Its CSF concentration exceeded age-adjusted norms in all HAD patients, 75% of NA CD4<50, 40% of NA CD4 50–199, and 42% of primary infection, indicating common neuronal injury with untreated systemic HIV disease progression as well as transiently during early infection. By contrast, only 75% of HAD subjects had abnormal CSF t-tau levels, and there were no significant differences in t-tau levels among the remaining groups. sAPPα and β were also abnormal (decreased) in HAD, showed less marked change than NFL with CD4 decline in the absence of HAD, and were not decreased in PHI. The CSF Aβ peptides and p-tau concentrations did not differ among the groups, distinguishing the HIV CNS injury profile from Alzheimer's disease. These CSF biomarkers can serve as useful tools in selected research and clinical settings for patient classification, pathogenetic analysis, diagnosis and management.

Role of DNA repair in host immune response and inflammation

In recent years, the understanding of how DNA repair contributes to the development of innate and acquired immunity has emerged. The DNA damage incurred during the inflammatory response triggers the activation of DNA repair pathways, which are required for host-cell survival. Here, we reviewed current understanding of the mechanism by which DNA repair contributes to protection against the oxidized DNA damage generated during infectious and inflammatory diseases and its involvement in innate and adaptive immunity. We discussed the functional role of DNA repair enzymes in the immune activation and the relevance of these processes to: transcriptional regulation of cytokines and other genes involved in the inflammatory response; V(D)J recombination; class-switch recombination (CSR); and somatic hypermutation (SHM). These three last processes of DNA damage repair are required for effective humoral adaptive immunity, creating genetic diversity in developing T and B cells. Furthermore, viral replication is also dependent on host DNA repair mechanisms. Therefore, the elucidation of the pathways of DNA damage and its repair that activate innate and adaptive immunity will be important for a better understanding of the immune and inflammatory disorders and developing new therapeutic interventions for treatment of these diseases and for improving their outcome.

CSF in Alzheimer's disease

Alzheimer's disease (AD) is a progressive brain amyloidosis that injures brain regions involved in memory consolidation and other cognitive functions. Neuropathologically, the disease is characterized by accumulation of a 42-amino acid protein called amyloid beta, and N-terminally truncated fragments thereof, in extracellular senile plaques together with intraneuronal inclusions of hyperphosphorylated tau protein in neurofibrillary tangles, and neuronal and axonal degeneration and loss. Clinical chemistry tests for these pathologies have been developed for use on cerebrospinal fluid samples. Here, we review what these markers have taught us on the disease process in AD and how they can be implemented in routine clinical chemistry. We also provide an update on new marker development and ongoing analytical standardization effort.

Biomarkers of Brain Injury in Cerebral Infections

BACKGROUND

Central nervous system (CNS) infections present a major burden of disease worldwide and are associated with high rates of mortality and morbidity. Swift diagnosis and initiation of appropriate treatment are vital to minimize the risk of poor outcome; however, tools are lacking to accurately diagnose infection, assess injury severity, and predict outcome. Biomarkers of structural neurological injury could provide valuable information in addressing some of these challenges.

CONTENT

In this review, we summarize experimental and clinical research on biomarkers of neurological injury in a range of CNS infectious diseases. Data suggest that in both adults and children, the biomarkers S100B and neuron-specific enlose (NSE), among others, can provide insight into the pathophysiology of CNS infection and injury severity, evolution, and response to treatment. Research into the added utility of combining a panel of biomarkers and in assessing biomarker association with clinical and radiological outcomes warrants further work. Various factors, including age, the establishment of normative values, and comparison of biomarker concentrations across different testing platforms still present challenges in biomarker application.

SUMMARY

Research regarding the value of biomarkers in CNS infections is still in its infancy. However, early evidence supports their utility in diagnosis and prognosis, and potentially as effective surrogate end points in the assessment of novel interventions.

Neurofilament heavy chain as a marker of neuroaxonal pathology and prognosis in acute encephalitis

BACKGROUND AND PURPOSE

The neurological outcome of acute encephalitis can be devastating and early prognosis remains difficult. Biomarkers that quantify the extent of early brain injury are needed to improve the prognostic accuracy and aid patient management. Our objective was to assess whether cerebrospinal fluid (CSF) protein biomarkers of neuroaxonal and glial cell injury are elevated in distinct forms of acute encephalitis and predictive of poor outcome.

METHODS

This was a prospective study of patients presenting with acute encephalitis to three teaching hospitals in London, UK. Levels of neurofilament heavy chain (NfH, SMI35) and S100B were quantified in CSF using enzyme-linked immunosorbent assay. The outcome was assessed by the Glasgow Outcome Scale (GOS).

RESULTS

Fifty-six patients with acute encephalitis were recruited and classified into the following diagnostic categories: infectious (n = 20), inflammatory (n = 14) and unknown etiology (n = 22). Pathological levels of NfH and S100B were observed in 24/56 (43%) and 54/56 (96%), respectively. Patients with infectious encephalitis had significantly higher NfH levels compared with the other two groups (P < 0.05). A poor outcome (GOS < 5) was associated with significantly higher CSF NfH levels within samples taken 2 weeks after symptom onset.

CONCLUSIONS

This study suggests that longitudinal CSF NfH levels are of superior prognostic value compared with CSF S100B levels. Prolonged release of NfH, a marker of neuroaxonal damage, was associated with poor outcome. Potentially there is a window of opportunity for future neuroprotective treatment strategies in encephalitis.

Cerebrospinal fluid biomarkers for Alzheimer disease and subcortical axonal damage in 5,542 clinical samples

Introduction

The neuronal loss in Alzheimer disease (AD) has been described to affect grey matter in the cerebral cortex. However, in the elderly, AD pathology is likely to occur together with subcortical axonal degeneration on the basis of cerebrovascular disease. Therefore, we hypothesized that biomarkers for AD and subcortical axonal degeneration would correlate in patients undergoing testing for dementia biomarkers, particularly in older age groups.

Methods

We performed correlation and cluster analyses of cerebrospinal fluid (CSF) biomarker data from 5,542 CSF samples analyzed in our routine clinical neurochemistry laboratory in 2010 through 2012 for the established CSF AD biomarkers total tau (T-tau), phosphorylated-tau (P-tau), amyloid β1-42 (Aβ42), and for neurofilament light (NFL), which is a protein expressed in large-caliber myelinated axons, the CSF levels of which correlate with subcortical axonal injury.

Results

Aβ42, T-tau, and P-tau correlated with NFL. By cluster analysis, we found a bimodal data distribution in which a group with a low Aβ42/P-tau ratio (suggesting AD pathology) had high levels of NFL. High levels of NFL also correlated with the presence of an AD biomarker pattern defined by Aβ42/P-tau and T-tau. Only 29% of those with an AD biomarker signature had normal NFL levels. Age was a possible confounding factor for the associations between NFL and established AD biomarkers, but in a logistic regression analysis, both age and NFL independently predicted the AD biomarker pattern.

Conclusions

The association between an AD-like signature using the established biomarkers Aβ42, T-tau, and P-tau with increased levels of NFL provides in vivo evidence of an association between AD and subcortical axonal degeneration in this uniquely large dataset of CSF samples tested for dementia biomarkers.

Cognitive impairment 3 years after neurological Varicella-zoster virus infection: a long-term case control study

Varicella-zoster virus (VZV) is one of the most common viruses causing central nervous system (CNS) infection, sometimes with severe neurological complications and sequelae despite appropriate antiviral treatment. Whether the neurological sequelae of VZV CNS infections include long-term cognitive impairment and how this impairment might affect the patients is still largely unknown. In this study, 14 patients with predominant CNS manifestations caused by VZV infection underwent cognitive testing 3 years (median 39.5 months, range 31-52 months) after acute disease. The results were compared with those for 28 controls, matched for age and gender. The tests covered the cognitive domains of speed and attention, memory and learning, visuospatial function, language and executive function. To further assess the cognitive dysfunction caused by neurological VZV infection, patients were classified into the concept of mild cognitive impairment (MCI), which is associated with development of dementia in other pathologies. The VZV patients performed significantly worse than controls on four tests covering the domains of speed and attention, memory and learning and executive function. The cut-off was set at 1.5 SD below mean age. In addition, a greater proportion of VZV patients were classified with MCI as compared with controls. In conclusion, patients with previous VZV infection affecting the brain had signs of long-term cognitive impairment in the domains of speed and attention, memory and learning and executive function. However, larger study populations are needed to confirm these results.