S-100beta protein-serum levels in healthy children and its association with outcome in pediatric traumatic brain injury

Pediatric Traumatic Brain Injury: An Update on Preclinical Models, Clinical Biomarkers, and the Implications of Cerebrovascular Dysfunction

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality. Recent studies suggest that children and adolescents have worse post-TBI outcomes and take longer to recover than adults. However, the pathophysiology and progression of TBI in the pediatric population are studied to a far lesser extent compared to the adult population. Common causes of TBI in children are falls, sports/recreation-related injuries, non-accidental trauma, and motor vehicle-related injuries. A fundamental understanding of TBI pathophysiology is crucial in preventing long-term brain injury sequelae. Animal models of TBI have played an essential role in addressing the knowledge gaps relating to pTBI pathophysiology. Moreover, a better understanding of clinical biomarkers is crucial to diagnose pTBI and accurately predict long-term outcomes. This review examines the current preclinical models of pTBI, the implications of pTBI on the brain’s vasculature, and clinical pTBI biomarkers. Finally, we conclude the review by speculating on the emerging role of the gut-brain axis in pTBI pathophysiology.

Serum biomarkers in severe paediatric traumatic brain injury-a narrative review

Severe traumatic brain injury continues to present complex management and prediction challenges for the clinician. While there is some evidence that better systems of care can improve outcome, multiple multi-centre randomised controlled trials of specific therapies have consistently failed to show benefit. In addition, clinicians are challenged in attempting to accurately predict which children will recover well and which children will have severe and persisting neurocognitive deficits. Traumatic brain injury is vastly heterogeneous and so it is not surprising that one therapy or approach, when applied to a mixed cohort of children in a clinical trial setting, has yielded disappointing results. Children with severe traumatic brain injury have vastly different brain injury pathologies of widely varying severity, in any number of anatomical locations at what may be disparate stages of brain development. This heterogeneity may also explain why clinicians are unable to accurately predict outcome. Biomarkers are objective molecular signatures of injury that are released following traumatic brain injury and may represent a way of unifying the heterogeneity of traumatic brain injury into a single biosignature. Biomarkers hold promise to diagnose brain injury severity, guide intervention selection for clinical trials, or provide vital prognostic information so that early intervention and rehabilitation can be planned much earlier in the course of a child's recovery. Serum S100B and serum NSE levels show promise as a diagnostic tool with biomarker levels significantly higher in children with severe TBI including children with inflicted and non-inflicted head injury. Serum S100B and serum NSE also show promise as a predictor of neurodevelopmental outcome. The role of biomarkers in traumatic brain injury is an evolving field with the potential for clinical application within the next few years.

Traumatic brain injury biomarkers in pediatric patients: a systematic review

Traumatic brain injury (TBI) is the main cause of pediatric trauma death and disability worldwide. Recent studies have sought to identify biomarkers of TBI for the purpose of assessing functional outcomes. The aim of this systematic review was to evaluate the utility of TBI biomarkers in the pediatric population by summarizing recent findings in the medical literature. A total of 303 articles were retrieved from our search. An initial screening to remove duplicate studies yielded 162 articles. After excluding all articles that did not meet the inclusion criteria, 56 studies were gathered. Among the 56 studies, 36 analyzed serum biomarkers; 11, neuroimaging biomarkers; and 9, cerebrospinal fluid (CSF) biomarkers. Most studies assessed biomarkers in the serum, reflecting the feasibility of obtaining blood samples compared to obtaining CSF or performing neuroimaging. S100B was the most studied serum biomarker in TBI, followed by SNE and UCH-L1, whereas in CSF analysis, there was no unanimity. Among the different neuroimaging techniques employed, diffusion tensor imaging (DTI) was the most common, seemingly holding diagnostic power in the pediatric TBI clinical setting. The number of cross-sectional studies was similar to the number of longitudinal studies. Our data suggest that S100B measurement has high sensitivity and great promise in diagnosing pediatric TBI, ideally when associated with head CT examination and clinical decision protocols. Further large-scale longitudinal studies addressing TBI biomarkers in children are required to establish more accurate diagnostic protocols and prognostic tools.

Interleukin-8 Predicts Fatigue at 12 Months Post-Injury in Children with Traumatic Brain Injury

Despite many children experiencing fatigue after childhood brain injury, little is known about the predictors of this complaint. To date, traditional indices of traumatic brain injury (TBI) severity have not predicted reliably persisting fatigue (up to three years post-injury). This study aimed to establish whether persisting fatigue is predicted by serum biomarker concentrations in child TBI. We examined whether acute serum biomarker expression would improve prediction models of 12-month fatigue based on injury severity. Blood samples were collected from 87 children (1-17 years at injury) sustaining mild to severe TBI (Glasgow Coma Scale [GCS] range 3-15; mean 12.43; classified as mild TBI [n = 50, 57%] vs. moderate/severe TBI [n = 37, 43%]), and presenting to the emergency departments (ED) and pediatric intensive care units (PICU) at one of three tertiary pediatric hospitals (Royal Children's Hospital (RCH); Hospital for Sick Children (HSC), Toronto; St Justine Children's Hospital (SJH), Montreal). Six serum biomarker concentrations were measured within 24 h of injury (interleukin-6, interleukin-8 [IL-8], soluble vascular cell adhesion molecule [SVCAM], S100 calcium binding protein B [S100B], neuron specific enolase [NSE], and soluble neural cell adhesion molecule [sNCAM]). Fatigue at 12 months post-injury was measured using the Pediatric Quality of Life Inventory Multidimensional Fatigue Scale (parent report), classified as present/absent using previously derived cut-points. At 12 months post-injury, 22% of participants experienced fatigue. A model including IL-8 was the best serum biomarker for estimating the probability of children experiencing fatigue at 12 months post-injury. The IL-8 also significantly improved predictive models of fatigue based on severity.

Neurofilament Heavy Chain and Tau Protein Are Not Elevated in Cerebrospinal Fluid of Adult Patients with Spinal Muscular Atrophy during Loading with Nusinersen

Nusinersen is the first approved drug for the treatment of spinal muscular atrophy (SMA). Treatment of SMA with nusinersen is based on a fixed dosing regimen. For other motoneuron diseases, such as amyotrophic lateral sclerosis (ALS), biomarkers are available for clinical diagnostics; however, no such biomarkers have yet been found for SMA. Serum and cerebrospinal fluid (CSF) samples of 11 patients with adult SMA type 3 were prospectively collected and analyzed during loading with nusinersen. Neurofilament heavy chain, tau protein, S100B protein, and neuron-specific enolase were investigated as potential biomarkers of motor neuron destruction. No significant pathological alterations in levels of neurofilament heavy chain, tau protein, or S100B protein were detected in the CSF or blood samples under baseline conditions or during loading with nusinersen. Neuron-specific enolase was marginally elevated in CSF and blood samples without significant alteration during treatment. In a mixed cohort of adult patients with SMA type 3, neurofilament heavy chain, tau protein, S100B protein, and neuron-specific enolase do not serve as potential biomarkers during the loading phase of nusinersen. The slow progression rate of SMA type 3 may not lead to detectable elevation of levels of these common markers of axonal degradation.

Toward development of clinically translatable diagnostic and prognostic metrics of traumatic brain injury using animal models: A review and a look forward

Traumatic brain injury is a leading cause of cognitive and behavioral deficits in children in the US each year. There is an increasing interest in both clinical and pre-clinical studies to discover biomarkers to accurately diagnose traumatic brain injury (TBI), predict its outcomes, and monitor its progression especially in the developing brain. In humans, the heterogeneity of TBI in terms of clinical presentation, injury causation, and mechanism has contributed to the many challenges associated with finding unifying diagnosis, treatment, and management practices. In addition, findings from adult human research may have little application to pediatric TBI, as age and maturation levels affect the injury biomechanics and neurophysiological consequences of injury. Animal models of TBI are vital to address the variability and heterogeneity of TBI seen in human by isolating the causation and mechanism of injury in reproducible manner. However, a gap between the pre-clinical findings and clinical applications remains in TBI research today. To take a step toward bridging this gap, we reviewed several potential TBI tools such as biofluid biomarkers, electroencephalography (EEG), actigraphy, eye responses, and balance that have been explored in both clinical and pre-clinical studies and have shown potential diagnostic, prognostic, or monitoring utility for TBI. Each of these tools measures specific deficits following TBI, is easily accessible, non/minimally invasive, and is potentially highly translatable between animals and human outcomes because they involve effort-independent and non-verbal tasks. Especially conspicuous is the fact that these biomarkers and techniques can be tailored for infants and toddlers. However, translation of preclinical outcomes to clinical applications of these tools necessitates addressing several challenges. Among the challenges are the heterogeneity of clinical TBI, age dependency of some of the biomarkers, different brain structure, life span, and possible variation between temporal profiles of biomarkers in human and animals. Conducting parallel clinical and pre-clinical research, in addition to the integration of findings across species from several pre-clinical models to generate a spectrum of TBI mechanisms and severities is a path toward overcoming some of these challenges. This effort is possible through large scale collaborative research and data sharing across multiple centers. In addition, TBI causes dynamic deficits in multiple domains, and thus, a panel of biomarkers combining these measures to consider different deficits is more promising than a single biomarker for TBI. In this review, each of these tools are presented along with the clinical and pre-clinical findings, advantages, challenges and prospects of translating the pre-clinical knowledge into the human clinical setting.

Characterisation of serum total tau following paediatric traumatic brain injury: a case-control study

BACKGROUND

Traumatic brain injury (TBI) is a major health problem in children. Blood-based biomarkers interpreted by use of normative values might improve the accuracy of diagnosis. Ultrasensitive assays can quantify serum concentrations of the neuronal microtubule-associated protein tau, which is increased in adult brains following TBI. We aimed to determine if serum total tau correlates with TBI diagnosis, severity, and radiological findings on CT scans in children younger than 18 years.

METHODS

In this case-control study, we included venous blood samples from healthy control children in the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) biobank. For TBI cases, we recruited children (aged 0-17 years) who presented to the emergency department within 24 h of a TBI in three tertiary-care paediatric hospitals (Toronto, Vancouver, and Melbourne). Children were eligible if they required hospital observation for a minimum of 4 h or admission to the intensive care unit, and were excluded if they had had hospital treatment for a previous TBI, had birth trauma, or their parents could not speak English or French and therefore could not readily give consent. All available control samples were used and a case-control match was therefore not done. Venous and arterial blood samples were collected from patients with TBI within 28 h of injury (day 1). We used an ultrasensitive single-molecule immunoassay to measure serum total tau in blood samples. We first generated reference intervals of serum total tau from the control group, and used these normative data to interpret injury-associated changes in serum total tau in children with TBI. Concentrations of serum tau were measured in all CALIPER participants and patients with TBI, and no participants were excluded before analysis.

FINDINGS

We included samples from 416 control participants from the CALIPER cohort. Median total tau concentrations did not differ between sexes (p=0·12), but three significant reference intervals based on age groups were identified (1-3 years [0·88-19·2 pg/mL], 4-15 years [0·93-5·31 pg/mL], and 16-19 years [0·79-4·20 pg/mL]). Blood samples were obtained from 158 patients with TBI recruited between April 30, 2011, and June 28, 2013. Serum total tau on day 1 of TBI was negatively associated with Glasgow Coma Scale (GCS) score (r_s=-0·42, 95% CI -0·55 to -0·28, p<0·0001). Median total tau was 2·86 pg/mL (IQR 1·52-4·83) in patients with GCS score 13-15 points (n=114), 7·08 pg/mL (3·75-41·1) in those with GCS score 9-12 points (n=13), and 8·48 pg/mL (2·53-70·6) in those with GCS score 3-8 points (n=31). Notably, participants who had GCS scores of 15 points had median total tau concentrations (2·57 pg/mL [1·50-4·61]) indistinguishable from those of control participants (2·46 pg/mL [1·77-3·42]), whereas those with GCS score 13-14 points had elevated total tau (6·41 pg/mL [2·97-42·5]). Serum total tau was not strongly associated with CT findings in patients with mild TBI.

INTERPRETATION

Serum total tau might help to differentiate between patients with mild TBI (GCS 13-14 vs GCS 15), but larger studies are needed to validate these results before this biomarker can be used for diagnosis and prognosis.

FUNDING

Canadian Institutes of Health Research, Ontario Neurotrauma Foundation, and Victoria Neurotrauma Foundation.

The Biomarker S100B and Mild Traumatic Brain Injury: A Meta-analysis

CONTEXT

The usefulness of S100B has been noted as a biomarker in the management of mild traumatic brain injury (mTBI) in adults. However, S100B efficacy as a biomarker in children has previously been relatively unclear.

OBJECTIVE

A meta-analysis is conducted to assess the prognostic value of S100B in predicting intracerebral lesions in children after mTBI.

DATA SOURCES

Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Scopus, and Google Scholar.

STUDY SELECTION

Studies including children suffering mTBI who underwent S100B measurement and computed tomography (CT) scans were included.

DATA EXTRACTION

Of 1030 articles screened, 8 studies met the inclusion criteria.

RESULTS

The overall pooled sensitivity and specificity were 100% (95% confidence interval [CI]: 98%-100%) and 34% (95% CI: 30%-38%), respectively. A second analysis was based on the collection of 373 individual data points from 4 studies. Sensitivity and specificity results, obtained from reference ranges in children with a sampling time <3 hours posttrauma, were 97% (95% CI: 84.2%-99.9%) and 37.5% (95% CI: 28.8%-46.8%), respectively. Only 1 child had a low S100B level and a positive CT scan result without clinically important traumatic brain injury.

LIMITATIONS

Only patients undergoing both a CT scan and S100B testing were selected for evaluation.

CONCLUSIONS

S100B serum analysis as a part of the clinical routine could significantly reduce the number of CT scans performed on children with mTBI. Sampling should take place within 3 hours of trauma. Cutoff levels should be based on pediatric reference ranges.

Brain biomarkers and pre-injury cognition are associated with long-term cognitive outcome in children with traumatic brain injury

Background

Children with traumatic brain injury (TBI) are frequently at risk of long-term impairments of attention and executive functioning but these problems are difficult to predict. Although deficits have been reported to vary with injury severity, age at injury and sex, prognostication of outcome remains imperfect at a patient-specific level. The objective of this proof of principle study was to evaluate a variety of patient variables, along with six brain-specific and inflammatory serum protein biomarkers, as predictors of long-term cognitive outcome following paediatric TBI.

Method

Outcome was assessed in 23 patients via parent-rated questionnaires related to attention deficit hyperactivity disorder (ADHD) and executive functioning, using the Conners 3rd Edition Rating Scales (Conners-3) and Behaviour Rating Inventory of Executive Function (BRIEF) at a mean time since injury of 3.1 years. Partial least squares (PLS) analyses were performed to identify factors measured at the time of injury that were most closely associated with outcome on (1) the Conners-3 and (2) the Behavioural Regulation Index (BRI) and (3) Metacognition Index (MI) of the BRIEF.

Results

Higher levels of neuron specific enolase (NSE) and lower levels of soluble neuron cell adhesion molecule (sNCAM) were associated with higher scores on the inattention, hyperactivity/impulsivity and executive functioning scales of the Conners-3, as well as working memory and initiate scales of the MI from the BRIEF. Higher levels of NSE only were associated with higher scores on the inhibit scale of the BRI.

Conclusions

NSE and sNCAM show promise as reliable, early predictors of long-term attention-related and executive functioning problems following paediatric TBI.

White matter damage after traumatic brain injury: A role for damage associated molecular patterns

Traumatic brain injury (TBI) is a leading cause of mortality and long-term morbidity worldwide. Despite decades of pre-clinical investigation, therapeutic strategies focused on acute neuroprotection failed to improve TBI outcomes. This lack of translational success has necessitated a reassessment of the optimal targets for intervention, including a heightened focus on secondary injury mechanisms. Chronic immune activation correlates with progressive neurodegeneration for decades after TBI; however, significant challenges remain in functionally and mechanistically defining immune activation after TBI. In this review, we explore the burgeoning evidence implicating the acute release of damage associated molecular patterns (DAMPs), such as adenosine 5'-triphosphate (ATP), high mobility group box protein 1 (HMGB1), S100 proteins, and hyaluronic acid in the initiation of progressive neurological injury, including white matter loss after TBI. The role that pattern recognition receptors, including toll-like receptor and purinergic receptors, play in progressive neurological injury after TBI is detailed. Finally, we provide support for the notion that resident and infiltrating macrophages are critical cellular targets linking acute DAMP release with adaptive immune responses and chronic injury after TBI. The therapeutic potential of targeting DAMPs and barriers to clinical translational, in the context of TBI patient management, are discussed.

Chapter 6 state of the science of pediatric traumatic brain injury: biomarkers and gene association studies

OBJECTIVES

Our objective is to review the most widely used biomarkers and gene studies reported in pediatric traumatic brain injury (TBI) literature, to describe their findings, and to discuss the discoveries and gaps that advance the understanding of brain injury and its associated outcomes. Ultimately, we aim to inform the science for future research priorities.

DATA SOURCES

We searched PubMed, MEDLINE, CINAHL, and the Cochrane Database of Systematic Reviews for published English language studies conducted in the last 10 years to identify reviews and completed studies of biomarkers and gene associations in pediatric TBI. Of the 131 biomarker articles, only 16 were specific to pediatric TBI patients, whereas of the gene association studies in children with TBI, only four were included in this review.

CONCLUSION

Biomarker and gene attributes are grossly understudied in pediatric TBI in comparison to adults. Although recent advances recognize the importance of biomarkers in the study of brain injury, the limited number of studies and genomic associations in the injured brain has shown the need for common data elements, larger sample sizes, heterogeneity, and common collection methods that allow for greater understanding of the injured pediatric brain. By building on to the consortium of interprofessional scientists, continued research priorities would lead to improved outcome prediction and treatment strategies for children who experience a TBI.

IMPLICATIONS FOR NURSING RESEARCH

Understanding recent advances in biomarker and genomic studies in pediatric TBI is important because these advances may guide future research, collaborations, and interventions. It is also important to ensure that nursing is a part of this evolving science to promote improved outcomes in children with TBIs.

Serum Biomarkers Help Predict Attention Problems in Critically Ill Children With Traumatic Brain Injury

OBJECTIVE

To evaluate the association between acute serum biomarkers, and the changes in attention at 1 year following traumatic brain injury.

DESIGN AND SETTING

A prospective observational and laboratory study conducted in PICUs at five Canadian children's hospitals.

STUDY POPULATION AND MEASUREMENTS

Fifty-eight patients aged 5 to 17 years with traumatic brain injury were enrolled in the study. Nine brain-specific and inflammatory serum protein biomarkers were measured multiple times over the first week following injury. Attention was measured at "baseline" to represent pre-injury function and at 1 year following injury using the Conners Third Parent Rating Scale.

RESULTS

Compared with baseline, there were significantly more clinical symptoms of inattention at 1 year post injury. The Glasgow Coma Scale score, age at injury, baseline levels of inattention, and highest levels of serum biomarkers were used to estimate the probability of developing inattention. These independent variables were first evaluated individually followed by combinations of the best predictors using area under the receiver operating characteristic curve analyses. A combination of high baseline levels of inattention and high serum levels of the biomarker neuron-specific enolase was the best predictor for inattention. Glasgow Coma Scale and age at injury were not associated with inattention at 1 year post injury.

CONCLUSIONS

Combining baseline assessment of attention with measurement of serum biomarkers shows promise as reliable, early predictors of long-term attention after childhood traumatic brain injury.

Role of Systems Biology in Brain Injury Biomarker Discovery: Neuroproteomics Application

Years of research in the field of neurotrauma have led to the concept of applying systems biology as a tool for biomarker discovery in traumatic brain injury (TBI). Biomarkers may lead to understanding mechanisms of injury and recovery in TBI and can be potential targets for wound healing, recovery, and increased survival with enhanced quality of life. The literature available on neurotrauma studies from both animal and clinical studies has provided rich insight on the molecular pathways and complex networks of TBI, elucidating the proteomics of this disease for the discovery of biomarkers. With such a plethora of information available, the data from the studies require databases with tools to analyze and infer new patterns and associations. The role of different systems biology tools and their use in biomarker discovery in TBI are discussed in this chapter.

Reducing head computed tomography after mild traumatic brain injury: Screening value of clinical findings and S100B protein levels

PRIMARY OBJECTIVE

The present prospective study was performed to investigate whether primary clinical findings and serum S100B concentrations at 3 and 6 hours post-trauma can contribute to the selection of patients for an initial computed tomography (CT) scanning.

RESEARCH DESIGN AND METHODS

S100B was measured in serum samples obtained at 3 and 6 hours after the injury. Adjusted odds ratios (OR) and 95% confidence interval (CI) associated with demographics and clinical predictors of positive CT scan were calculated. Sensitivity, specificity, negative and positive predictive values were also calculated for S100B levels.

MAIN OUTCOMES AND RESULTS

It was found that the presence of loss of consciousness (OR = 2.3; 95% CI = 1.00-4.01; p = 0.008) and post-traumatic vomiting ≥ 2 episodes (OR = 1.8; 95% CI = 1.08-3.29; p = 0.019) are factors associated with positive CT scan. In this study the best cut-off point of 0.115 µg L(-1) for 3-hour S100B has sensitivity of 94.9% (95% CI = 86.8-98.3) with specificity of 35.4% (95% CI = 25.2-47.0) to predict intracranial injury on CT scanning. The corresponding results for 6-hour S100B > 0.210 µg L(-1) were 98.7% (95% CI = 92.1-99.9) for sensitivity and 39.2% (95% CI = 28.6-50.8) for specificity.

CONCLUSIONS

Serum S100B measurement along with clinical evaluation of patients with mild traumatic brain injury has promising screening value to support selection of patients for CT scanning.

[Biomarkers in pediatric polytrauma]

BACKGROUND

Trauma represents one of the leading causes of death in children. Beside an injury pattern that differs from adult trauma patients, children seem to develop multiple organ dysfunction syndrome (MODS) less frequently. Compared to adult MODS, pediatric MODS has also been described to occur earlier in the posttraumatic course.

METHOD

Biomarkers for early identification of patients at high-risk for posttraumatic complications are of high clinical relevance. However, little is known from clinical studies about the relevance of biomarkers during the posttraumatic course.

AIM

Therefore, the purpose of this review is to summarize current knowledge on this topic in order to investigate the prognostic significance of different parameters.

Brain injury biomarkers as outcome predictors in pediatric severe traumatic brain injury

BACKGROUND

To systematically review the literature on brain injury biomarkers, defined as any injury biomarker detected in cerebrospinal fluid (CSF) or blood injury biomarkers primarily expressed in the brain parenchyma, to determine outcome prediction in pediatric severe traumatic brain injury (sTBI).

METHODS

A search of MEDLINE(®), EMBASE(®), PsycINFO(®), Pubmed(®), and the Cochrane Database, as well as grey literature sources, personal contacts, hand searches, and reference lists. The search terms used were traumatic brain injury, biomarkers, prognosis, and children. No language, publication type, or publication date restrictions were imposed. All articles were critically reviewed by two clinicians independently.

RESULTS

A total of 7,150 articles were identified initially with 16 studies identified for review. Eighteen different biomarkers were examined; 11 in CSF and 7 in blood. Outcomes assessed included either in-hospital mortality or functional state (hospital discharge, 3-months or 6-months; Glasgow Outcome Scale or Pediatric Cerebral Performance Category). Significant correlations were established between sTBI outcomes and various biomarkers in CSF (IL-6, IL-8, IL-1β, S100β, NGF, NSE, DCX, ET-1, HMGB-1, cytochrome C) and blood (GFAP, NF-H, UCH-L1, SBDP-145, leptin). Mixed results were obtained for blood S100β. Outcome did not correlate with several biomarkers in either CSF (BDNF, GDNF, α-Syn) or blood (NSE, MBP). The Class of Evidence was considered II in 1 study and III in the remaining 15 studies.

CONCLUSIONS

Based on the status of current sTBI biomarker research, we recommend that future research should be directed at both novel biomarker discovery and validation of biomarker panels in large, well-designed longitudinal studies.

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.

Traumatic injury elicits JNK-mediated human astrocyte retraction in vitro

Brain injury causes dysfunction of the blood-brain barrier (BBB). The BBB is comprised of perivascular astrocytes whose end-feet ensheath brain microvascular endothelial cells. We investigated trauma-induced morphological changes of human astrocytes (HA) and human cerebral microvascular endothelial cells (hCMEC/D3) in vitro, including the potential role of mitogen-activated protein kinase (MAPK) signal-transduction pathways. HA or hCMEC/D3 were grown on flexible culture membranes and subjected to single traumatic injury normalized to 20%, 30% or 55% membrane deformation. Cells were assayed for morphological changes (i.e. retraction) and MAPK phosphorylation and/or expression (c-Jun NH2-terminal kinase (JNK)1/2, extracellular signal-regulated kinase (ERK)1/2, and p38). HA retraction was rapidly elicited with a single traumatic injury (55% membrane deformation; p<0.01). Morphological recovery of HA was observed within 2h (p<0.05). Traumatic injuries increased phospho-JNK1/2 (p<0.05) in HA, indicating MAPK activation. Pre-treatment of HA with structurally distinct JNK inhibitors (25μM), either SP600125 or SU3327, reduced JNK phosphorylation (p<0.05) and trauma-induced HA retraction (P<0.05). In contrast to HA, traumatic injury failed to induce either morphological changes or MAPK activation in hCMEC/D3. In summary, traumatic injury induces JNK-mediated HA retraction in vitro, while sparing morphological changes in cerebral microvascular endothelial cells. Astrocyte retraction from microvascular endothelial cells in vivo may occur after brain trauma, resulting in cellular uncoupling and BBB dysfunction. JNK may represent a potential therapeutic target for traumatic brain injuries.

Changes in cerebral oxygen saturation correlate with S100B in infants undergoing cardiac surgery with cardiopulmonary bypass

OBJECTIVES

The relationship of cerebral saturation measured by near-infrared spectroscopy with serum biomarker of brain injury S100B was investigated in infants undergoing cardiac surgery with cardiopulmonary bypass.

DESIGN

Prospective cohort study.

SETTING

Single-center children's hospital.

PATIENTS

Forty infants between 1 and 12 months old weighing greater than or equal to 4 kg with congenital heart disease undergoing cardiac surgery with cardiopulmonary bypass were enrolled.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Serum S100B was measured at eight time points over 72 hours using enzyme-linked immunosorbent assay. Physiologic data including arterial, cerebral, and somatic regional oxygen saturations measured by near-infrared spectroscopy were synchronously recorded at 1-minute intervals from anesthesia induction through 72 postoperative hours. The arterial-cerebral oxygen saturation difference was calculated as the difference between arterial saturation and cerebral regional saturation. Thirty-eight patients, 5.4 ± 2.5 months old, were included in the analysis; two were excluded due to the use of postoperative extracorporeal membrane oxygenation. Seventeen patients (44.7%) had preoperative cyanosis. S100B increased during cardiopulmonary bypass in all patients, from a median preoperative baseline of mean ± SE: 0.055 ± 0.038 to a peak of 0.610 ± 0.038 ng/mL, p less than 0.0001. Patients without preoperative cyanosis had a higher S100B peak at the end of cardiopulmonary bypass. Although the absolute cerebral regional saturation on cardiopulmonary bypass was not associated with S100B elevation, patients who had arterial-cerebral oxygen saturation difference greater than 50 at any time during cardiopulmonary bypass had a higher S100B peak (mean ± SE: 1.053 ± 0.080 vs 0.504 ± 0.039 ng/mL; p < 0.0001).

CONCLUSIONS

A wide cerebral arteriovenous difference measured by near-infrared spectroscopy during cardiopulmonary bypass is associated with increased serum S100B in the perioperative period and may be a modifiable risk factor for neurological injury.

The challenge of mild traumatic brain injury: role of biochemical markers in diagnosis of brain damage

During the past decade there has been an increasing recognition of the incidence of mild traumatic brain injury (mTBI) and a better understanding of the subtle neurological and cognitive deficits that may result from it. A substantial, albeit suboptimal, effort has been made to define diagnostic criteria for mTBI and improve diagnostic accuracy. Thus, biomarkers that can accurately and objectively detect brain injury after mTBI and, ideally, aid in clinical management are needed. In this review, we discuss the current research on serum biomarkers for mTBI including their rationale and diagnostic performances. Sensitive and specific biomarkers reflecting brain injury can provide important information regarding TBI pathophysiology and serve as candidate markers for predicting abnormal computed tomography findings and/or the development of residual deficits in patients who sustain an mTBI. We also outline the roles of biomarkers in settings of specific interest including pediatric TBI, sports concussions and military injuries, and provide perspectives on the validation of such markers for use in the clinic. Finally, emerging proteomics-based strategies for identifying novel markers will be discussed.

Association between cerebrospinal fluid S100B protein and neuronal damage in patients with central nervous system infections

PURPOSE

S100B protein is widely used as a measure of glial activity or damage in several brain conditions. Central nervous system (CNS) infections can cause neurological sequelae because of parenchyma invasion. It is difficult to predict further neuronal damage in the CNS infection. The present study is aimed to evaluate the role of the cerebrospinal fluid (CSF) S100B protein as an indicator of neuronal damage in CNS infection.

MATERIALS AND METHODS

We measured the concentration of CSF S100B protein in 62 patients with a CNS infection using an Enzyme-Linked Immunosorbent Assay. The patients with CNS infections were classified as having no neuronal damage (CNS-N) or as having neuronal damage (CNS+N) according to the presence of neurological change or structural lesions on brain MRI.

RESULTS

The CSF S100B protein level of the CNS+N group (n=22, 0.235 μg/L, 0.10-2.18) was significantly higher than that of the CNS-N group (n=40, 0.087 μg/L, 0.06-0.12) and control group (n=40, 0.109 μg/L, 0.07-0.14, p<0.01). Using an arbitrary cut off value, S100B-positive CSF was detected in 2.5% of the CNS-N group and in 50% of the CNS+N group (p<0.05).

CONCLUSION

These findings suggest that increased S100B protein levels in the CSF may be associated with the neuronal damage following CNS infections.

Inability of S100B to predict postconcussion syndrome in children who present to the emergency department with mild traumatic brain injury: a brief report

OBJECTIVE

This study aimed to explore the ability of the serum marker S100B to predict the development and severity of postconcussion syndrome (PCS) at 3 months in children after mild traumatic brain injury (mTBI).

METHODS

This is a retrospective analysis of a prospective observational study conducted in a pediatric emergency department (ED). Children were eligible for the study if they were between the ages 5 and 18 years, presented within 6 hours of injury, met the case definition of mTBI from American Congress of Rehabilitation Medicine, had a Glasgow Coma Scale score of greater than 13, consented to have blood drawn for S100B levels, and completed the 3-month telephone follow-up. At the follow-up, the Rivermead Postconcussion Questionnaire was conducted to determine the development and severity of PCS.

RESULTS

A total of 76 children were included in this cohort. The children had a mean (SD) age of 14.0 (3.1) years, 60.5% were male, and 89.5% had a Glasgow Coma Scale of 15. Twenty-eight (36.8%) developed PCS. For the children who developed PCS, the mean (SD) S100B level was 0.092 (0.376) µg/L. For children who did not develop PCS (n = 48), the mean (SD) S100B level was 0.022 (0.031) µg/L. The analyses did not support an association between initial S100B levels measured in the ED and development of PCS or severity of PCS symptoms.

CONCLUSIONS

In this small sample, S100B, measured immediately after injury in the ED, did not seem to predict those children with mTBI who will go on to develop PCS.

Systematic review of clinical research on biomarkers for pediatric traumatic brain injury

Abstract The objective was to systematically review the medical literature and comprehensively summarize clinical research performed on biomarkers for pediatric traumatic brain injury (TBI) and to summarize the studies that have assessed serum biomarkers acutely in determining intracranial lesions on CT in children with TBI. The search strategy included a literature search of PubMed,(®) MEDLINE,(®) and the Cochrane Database from 1966 to August 2011, as well as a review of reference lists of identified studies. Search terms used included pediatrics, children, traumatic brain injury, and biomarkers. Any article with biomarkers of traumatic brain injury as a primary focus and containing a pediatric population was included. The search initially identified 167 articles. Of these, 49 met inclusion and exclusion criteria and were critically reviewed. The median sample size was 58 (interquartile range 31-101). The majority of the articles exclusively studied children (36, 74%), and 13 (26%) were studies that included both children and adults in different proportions. There were 99 different biomarkers measured in these 49 studies, and the five most frequently examined biomarkers were S100B (27 studies), neuron-specific enolase (NSE) (15 studies), interleukin (IL)-6 (7 studies), myelin basic protein (MBP) (6 studies), and IL-8 (6 studies). There were six studies that assessed the relationship between serum markers and CT lesions. Two studies found that NSE levels ≥15 ng/mL within 24 h of TBI was associated with intracranial lesions. Four studies using serum S100B were conflicting: two studies found no association with intracranial lesions and two studies found a weak association. The flurry of research in the area over the last decade is encouraging but is limited by small sample sizes, variable practices in sample collection, inconsistent biomarker-related data elements, and disparate outcome measures. Future studies of biomarkers for pediatric TBI will require rigorous and more uniform research methodology, common data elements, and consistent performance measures.

Ability of S100B to predict severity and cranial CT results in children with TBI

OBJECTIVES

To evaluate the ability of S100B to predict severity of TBI and abnormal cranial CT results for children with TBI.

METHODS

This is a secondary analysis of a previously established cohort of consecutive patients presenting to the emergency department with TBI limited to children <19 years of age, who arrived within 6 hours of injury, received a cranial CT scan and consented to blood drawn for S100B.

RESULTS

A total of 109 children were included in this cohort. The mean S100B levels were higher in children with moderate/severe TBI as compared to children with mild TBI based GCS score (0.281 µg L(-1), 95%CI = 0.101, 0.461 vs 0.053, 95%CI = 0.010, 0.095). S100B levels were significantly elevated in children following TBI with abnormal cranial CT as compared to children with a normal cranial CT (0.210 µg L(-1), SD = 0.313 vs 0.036 µg L(-1), SD = 0.046, p = 0.03). Area under the curve for S100B was also significant (0.72, 95%CI = 0.58, 0.86) for prediction of abnormal cranial CT for children with TBI. S100B did not predict abnormal cranial CT for children following TBI with a GCS of 15 (AUC = 0.53, 95%CI = 0.36, 0.71).

CONCLUSIONS

For children following TBI, S100B appears to predict severity of TBI; however, it may not be clinically useful as an independent screening test to select children with mild TBI who need a cranial CT.

Advanced neuromonitoring and imaging in pediatric traumatic brain injury

While the cornerstone of monitoring following severe pediatric traumatic brain injury is serial neurologic examinations, vital signs, and intracranial pressure monitoring, additional techniques may provide useful insight into early detection of evolving brain injury. This paper provides an overview of recent advances in neuromonitoring, neuroimaging, and biomarker analysis of pediatric patients following traumatic brain injury.

Perioperative inflammatory response and protein S-100β concentrations - relationship with post-operative cognitive dysfunction in elderly patients

BACKGROUND

One major concern in about one third of elder patients after total hip-replacement surgery is post-operative cognitive dysfunction (POCD). Previous studies have suggested that cognitive impairment is accompanied with changes in serum S-100β protein (S-100β) and inflammatory markers. Thus, the aim of the current study was to investigate the value of serum S-100β and interleukin(IL)-1β, IL-6, tumour necrosis factor-α (TNF-α), and C-reactive protein (CRP) in reflecting POCD after total hip-replacement surgery.

METHODS

Forty-two elderly patients were enrolled, and 37 patients completed the follow-up. Serum S-100β protein and IL-1β, IL-6, TNF-α, and CRP were determined pre-operatively, as well as 1 h and 6 h post-operatively. Neuropsychological tests were performed pre-operatively, as well as on day 1, 3, and 7 post-operatively.

RESULTS

Seventeen (45.9%, 17/37) patients developed POCD 1 day after surgery, and three (8.1%, 3/37) developed POCD 7 days after surgery. [Correction added after publication 7 February 2012: in the preceding sentence (54.1%, 17/37) was corrected to (45.9%, 17/37)]. Patients with POCD 1 day after surgery had significantly higher serum levels of IL-6 at 6 h (135 ± 32 pg/ml vs. 91 ± 29 pg/ml, P < 0.05) and S-100β at 1 h (1872 ± 385 pg/ml vs. 1289 ± 143 pg/ml, P < 0.05. No significant post-operative change was detected in levels of TNF-α, IL-1, or CRP.

CONCLUSION

The serum levels of pro-inflammatory marker IL-6 and S-100β protein increased after total hip-replacement in elderly patients, and such increase may serve as predicting parameters for the occurrence of POCD.

Use of serum biomarkers to predict cerebral hypoxia after severe traumatic brain injury

The management of severe traumatic brain injury (TBI) focuses on prevention and treatment of secondary insults such as cerebral hypoxia (CH). There are a number of biomarkers that are thought to play a part in secondary injury following severe TBI. This study evaluates the association between S100β, neuron-specific enolase (NSE), and glial fibrillary acidic protein (GFAP), detected in the serum of severe TBI patients and CH as measured by brain tissue oxygen partial pressure (Pbo(2)). Patients with severe TBI were prospectively enrolled. Pressure times time (PTD; mm Hg*h), measuring the depth and duration of CH, was calculated for 12-h periods for episodes of moderate (Pbo(2) < 20 mm Hg) and severe (Pbo(2) < 15 mm Hg) CH, and compared to serum levels of S100β, NSE, and GFAP drawn prior to periods of monitoring. An adjusted mixed model analysis was applied as was receiver operating characteristic (ROC) curve analysis. Of 76 patients enrolled, 24 had Pbo(2) monitoring. One hundred and thirty serum samples were matched with 12-h periods of monitoring. Significant associations were found in adjusted analyses between increasing serum levels of S100β (coefficient=0.57, 0.56; p<0.001), NSE (coefficient=0.48, 0.52; p<0.001), and GFAP (coefficient=0.29, 0.30; p=0.003 and 0.002), and increasing PTD of moderate (Pbo(2)<20 mm Hg) and severe (Pbo(2)<15 mm Hg) CH. AUCs for the prediction of moderate and severe CH were 0.62 and 0.66 for S100β, 0.55 and 0.71 for NSE, and 0.50 and 0.62 for GFAP, respectively. Specificities were between 76% and 90% for S100β and NSE. S100β, NSE, and GFAP demonstrate promise as candidate serum markers of impending CH. The fact that these biomarker elevations occur prior to the onset of clinical manifestations suggests that we may be able to predict imminent events following TBI. Given the morbidity of CH, early intervention and prevention may have a significant impact on outcomes and help guide decisions about the timing of interventions.

Is serum S100B protein a biomarker for amitriptyline-induced cardiovascular toxic effects?

The aim of this study was to assess the role of serum S100B protein as a biomarker for cardiovascular effects in an anesthetized rat model of amitriptyline toxicity. Adult male Wistar rats (n = 28) were randomized into four groups. While the control group received normal saline, the experimental groups received different doses of amitriptyline (0.625 or 0.94 or 1.25 mg/kg/min) infusion. Mean arterial pressure (MAP), heart rate (HR), electrocardiogram parameters, and serum S100B protein levels were recorded during the experiment. Linear Pearson's correlation coefficient was used to examine the association between cardiovascular parameters and serum levels of S100B protein. In the experimental groups, amitriptyline caused a significant decrease in MAP and HR (P < 0.001), a prolongation in QRS duration and QT intervals (P < 0.01), but it did not change PR intervals significantly. At the end of the experiment of the second group, a significant correlation was found between HR and serum S100B protein levels (r = -0.963, P = 0.037). At the end of the experiment of the third and fourth groups, a significant correlation between MAP, HR, all ECG parameters, and serum S100B protein levels was found. Serum S100B protein levels correlate well with amitriptyline-induced cardiovascular toxicity and can be used as a biomarker for predicting cardiovascular toxic effects of amitriptyline.

Association of CSF biomarkers and secondary insults following severe traumatic brain injury

BACKGROUND

Management of severe traumatic brain injury (TBI) focuses on mitigating secondary insults. There are a number of biomarkers that are thought to play a part in secondary injury following severe TBI. Two of these, S100β and neuron-specific enolase (NSE), have been extensively studied in the setting of neurological injury. This pilot study was undertaken to investigate the relationship of S100β and NSE to clinical markers of severity and poor outcome: intracranial hypertension (ICH), and cerebral hypoperfusion (CH).

METHODS

Patients at the R Adams Cowley Shock Trauma Center were prospectively enrolled over an 18-month period. Inclusion criteria were: age > 18, admission within the first 6 h after injury, Glasgow Coma Scale (GCS) < 9 on admission, isolated TBI, and placement of an intraventricular catheter (IVC). Patients were managed according to an institutional protocol based on the Brain Trauma Foundation Guidelines. CSF was collected from the IVC on admission and twice daily for 7 days. S100β and NSE levels were analyzed by ELISA. CSF levels drawn before (PRE) and after (POST) 12-h time periods were compared to percentage time intracranial pressure (ICP) > 20 mmHg (% ICP(20)) and cerebral perfusion pressure (CPP) < 60 mmHg (% CPP(60)), and cumulative "Pressure times Time Dose" (PTD) for episodes of ICP > 20 mmHg (PTD ICP(20)) and CPP < 60 mmHg (PTD CPP(60)). Statistical analysis was performed using the Student's t test to compare means and non-parametric Wilcoxon statistic to compare ranked data. Linear regression methods were applied to compare levels of S100β and NSE with ICP and CPP(.)

RESULTS

Twenty-three patients were enrolled. The cohort of patients was severely injured and neurologically compromised on admission (admission GCS = 5.6 ± 3.1, Injury Severity Score (ISS) = 31.9 ± 10.6, head Abbreviated Injury Scale (AIS) = 4.4 ± 0.7, Marshall score = 2.6 ± 0.9). Elevated levels of S100β and NSE were found in all 223 CSF samples analyzed. ICH was found to be associated with PRE and POST S100β levels when measured as % ICP(20) (r = 0.20 and r = 0.23, P < 0.01) and PTD ICP(20) (r = 0.35 and r = 0.26, P < 0.001). POST increasing NSE levels were weakly correlated with increasing PTD ICP(20) (r = 0.17, P = 0.01). PRE S100β levels were associated with episodes of CH as measured by % CPP(60) (r = 0.20, P = 0.002) and both PRE and POST S100β levels were associated with PTD CPP(60) (r = 0.24 and r = 0.23, P < 0.001). PRE and POST NSE levels were also associated with episodes of CH as measured by % CPP(60) (r = 0.22 and r = 0.18, P < 0.01) and PTD CPP(60) (r = 0.20 and r = 0.21, P < 0.01).

CONCLUSIONS

In this preliminary analysis, S100β levels were associated with ICH and CH over a full week of ICP monitoring. We also found associations between CH and NSE levels in CSF of patients with severe TBI. Our results suggest that there is an association between levels of ICH and CH and these biomarkers when measured before episodes of clinically significant secondary insults. These markers of neuronal cell death demonstrate promise as both indicators of impending clinical deterioration and targets of future therapeutic interventions.

Mild traumatic brain injury in children

Head injury occurs frequently in childhood and results in approximately 500,000 emergency department visits and over $1 billion in costs annually. Nearly 75% of these children are ultimately diagnosed with mild traumatic brain injury (MTBI), a misnomer because many will have radiographically identified intracranial injuries and long-term consequences. Identification of the brain at risk and prevention of secondary injury is associated with the largest reduction in head trauma morbidity and mortality. This article reviews the current literature to discuss the initial evaluation, management, and long-term outcomes in children sustaining MTBI.

Can low serum levels of S100B predict normal CT findings after minor head injury in adults?: an evidence-based review and meta-analysis

OBJECTIVE

To determine whether low levels of S100B in serum can predict normal computed tomography (CT) findings after minor head injury (MHI) in adults.

PARTICIPANTS

Not applicable.

DESIGN

Systematic evidence-based review of the peer-reviewed literature with meta-analytical interpretation.

PRIMARY MEASURES

Not applicable.

RESULTS

We identified 12 eligible articles that specifically studied adult MHI patients with S100B and cranial CT scans in the acute phase after injury, comprising a total of 2466 separate patients. Individual negative predictive values of 90% to 100% were found for the ability of a negative (under cutoff) S100B level to predict a normal CT scan. A total of 6 patients included in the studies had low S100B levels and positive CT scans (0.26%) and only 1 of these patients (0.04%) had a clinically relevant CT finding. The pooled negative predictive value for all studies was more than 99% (95% CI 98%-100%), with an average prevalence for any CT finding at 8%. The studies are consistently classed as level 2 and level 3 grades of evidence, suggesting a grade B recommendation.

CONCLUSION

Low serum S100B levels accurately predict normal CT findings after MHI in adults. S100B sampling should be considered in MHI patients with no focal neurological deficit, an absence of significant extracerebral injury, should be taken within 3 hours of injury, and the cutoff for omitting CT set at less than 0.10 microg/L. Care givers should also be aware of other clinical factors predictive of intracranial complications after MHI.

Glucose dysregulation and neurological injury biomarkers in critically ill children

CONTEXT

Targeting normoglycemia with intensive insulin therapy (IIT) improved short-term outcome of pediatric intensive care unit (PICU) patients but increased the incidence of hypoglycemia. Both hyperglycemia and hypoglycemia may adversely affect the developing brain.

OBJECTIVE

We studied the impact of targeting normoglycemia with IIT on brain injury markers.

DESIGN

This is a preplanned analysis of PICU patients included in a randomized controlled study.

SETTING

The study was conducted at a university hospital PICU.

PATIENTS

Seven hundred PICU patients participated.

INTERVENTIONS

Patients were assigned to IIT targeting normal-for-age fasting blood glucose levels or insulin infusion only to prevent excessive hyperglycemia.

MAIN OUTCOME MEASURES

Serum S100B and neuron-specific enolase (NSE), biomarkers of astrocytic and neuronal damage, respectively, were measured on fixed days (n = 700) and in a nested case-control design before and after hypoglycemia (n = 126).

RESULTS

Admission levels of S100B and NSE differed according to diagnosis and illness severity (P < 0.0001). IIT did not affect the time course of these markers. Patients experiencing hypoglycemia in PICU had higher S100B and NSE from admission onward than those without hypoglycemia. In the nested case-control study, both markers decreased after hypoglycemia (P = 0.001 and P = 0.009), unlike in the controls on matched days.

CONCLUSIONS

IIT in PICU did not evoke neurological damage detectable by circulating S100B and NSE, despite increased incidence of hypoglycemia. Elevated markers in patients with hypoglycemia were not caused by hypoglycemia itself but rather reflect an increased incidence of hypoglycemia in the most severely ill. This hypoglycemia risk appears difficult to capture by classical illness severity scores.

S-100B in serum and urine after traumatic head injury in children

BACKGROUND

Children with head trauma are frequently seen in many emergency units. The clinical evaluation of these patients is difficult for a number of reasons and improved diagnostic tools are needed. S-100B, a protein found in glial cells, has previously been shown to be a sensible marker for brain damage after head injury in adults, but few studies have focused on its use in children.

METHODS

In this study, 111 children with head trauma were included and venous blood and urine samples were taken at arrival (S1 and U1) and 6 hours later (S2 and U2). S-100B levels were analyzed. Clinical and radiologic evaluations were performed according to hospital routine. Two groups were identified- group 1: no computed tomography (CT) scan performed ora CT scan without any sign of trauma-related intracranial pathology (n = 105). Group 2: A CT scan with signs of trauma-related intracranial pathology (n = 6).

RESULTS

In group 1, the median (inter quartile range) serum S-100B value in S1-samples was 0.111 microg/L (0.086-0.153), and in group 2, it was 0.282 microg/L (0.195-1.44) (p < 0.01). Also, S2 values significantly differed between the two groups. Urine values were, however, not significantly differing between the groups.

CONCLUSIONS

Serum S-100B values within 6 hours after head trauma in children were significantly higher in patients with intracranial pathology compared with those without intracranial complications. Identification of these high-risk patients already in the emergency department is of major importance, and we suggest that S-100B could be a valuable diagnostic tool in addition to those used in clinical practice today.

Trajectory analysis of serum biomarker concentrations facilitates outcome prediction after pediatric traumatic and hypoxemic brain injury

Traumatic brain injury (TBI) and hypoxic ischemic encephalopathy (HIE) are leading causes of morbidity and mortality in children. Several studies over the past several years have evaluated the use of serum biomarkers to predict outcome after pediatric brain injury. These studies have all used simple point estimates such as initial and peak biomarker concentrations to predict outcome. However, this approach does not recognize patterns of change over time. Trajectory analysis is a type of analysis which can capture variance in biomarker concentrations over time and has been used with success in the social sciences. We used trajectory analysis to evaluate the ability of the serum concentrations of 3 brain-specific biomarkers - S100B, neuron-specific enolase (NSE) and myelin basic protein (MBP) - to predict poor outcome (Glasgow Outcome Scale scores 3-5) after pediatric TBI and HIE. Clinical and biomarker data from 100 children with TBI or HIE were evaluated. For each biomarker, we validated 2-, 3- and 4-group models for outcome prediction, using sensitivity and specificity. For S100B, the 3-group model predicted poor outcome with a sensitivity of 59% and specificity of 100%. For NSE, the 3-group model predicted poor outcome with a sensitivity of 48% and specificity of 98%. For MBP, the 3-group model predicted poor outcome with a sensitivity of 73% and specificity of 61%. Thus, when the models predicted a poor outcome, there was a very high probability of a poor outcome. In contrast, 17% of subjects with a poor outcome were predicted to have a good outcome by all 3 biomarker trajectories. These data suggest that trajectory analysis of biomarker data may provide a useful approach for predicting outcome after pediatric brain injury.

Role of Neuroprotein S-100B in the Diagnostic of Pediatric Mild Brain Injury

Traumatic brain injury is one of the leading causes of death and disability in children and adolescents. Patients with moderate or severe lesions can be readily recognized clinically, require immediate radiologic diagnostics by computed tomography (CT) or magnetic resonance imaging (MRI), admission to intensive care units, and, in some cases, will go on to require neurosurgical intervention. Patients with mild traumatic brain injuries (MTBIs) are diagnostically challenging. Often, the event is unobserved and head injury can only be suspected. Clinical symptoms are unreliable and clinical findings from neurological examination have to be interpreted with care. As a small percentage of MTBI patients progress to have a life-threatening intracranial hemorrhage, the recognition of this group of patients and their judicious and timely management is, therefore, an important goal. Subjecting every MTBI patient to a cranial CT scanning results in high costs and unnecessary exposure to ionizing radiation. Admitting all MTBI patients for observation and performing CTs only in case of clinical deterioration is costly and a substantial drain on resources, not to mention the radiation exposure and a source of stress for the majority of patients. Current European guidelines for diagnostics and therapy in MTBI patients are only partially applicable to the pediatric population. This article reviews the clinical problem, treatment options and guidelines, as well as diagnostic tools, with special focus on neuroprotein S-100B in pediatric and adolescent patients with MTBIs.

Clinical applications of biomarkers in pediatric traumatic brain injury

INTRODUCTION

The diagnosis, treatment, and prediction of outcome in pediatric traumatic brain injury (TBI) present significant challenges to the treating clinician. Clinical and radiological tools for assessing injury severity and predicting outcome, in particular, lack sensitivity and specificity. In patients with mild TBI, often there is uncertainty about which patients should undergo radiological imaging and who is at risk for long term neurological sequelae. In severe TBI, often there is uncertainty about which patients will experience secondary insults and what the outcome for individual patients will be. In several other clinical specialties, biomarkers are used to diagnose disease, direct treatment, and prognosticate. However, an ideal biomarker for brain injury has not been found.

METHODS

In this review, we examine the various factors that must be taken into account in the search for a reliable biomarker in brain injury. We review the important studies that have investigated common biomarkers of structural brain injury, in particular S100B, neuron-specific enolase, myelin basic protein, and glial fibrillary acid protein.

DISCUSSION

The potential uses and limitations of these biomarkers in the context of TBI are discussed.

Update on protein biomarkers in traumatic brain injury with emphasis on clinical use in adults and pediatrics

PURPOSE

This review summarizes protein biomarkers in mild and severe traumatic brain injury in adults and children and presents a strategy for conducting rationally designed clinical studies on biomarkers in head trauma.

METHODS

We performed an electronic search of the National Library of Medicine's MEDLINE and Biomedical Library of University of Pennsylvania database in March 2008 using a search heading of traumatic head injury and protein biomarkers. The search was focused especially on protein degradation products (spectrin breakdown product, c-tau, amyloid-beta(1-42)) in the last 10 years, but recent data on "classical" markers (S-100B, neuron-specific enolase, etc.) were also examined.

RESULTS

We identified 85 articles focusing on clinical use of biomarkers; 58 articles were prospective cohort studies with injury and/or outcome assessment.

CONCLUSIONS

We conclude that only S-100B in severe traumatic brain injury has consistently demonstrated the ability to predict injury and outcome in adults. The number of studies with protein degradation products is insufficient especially in the pediatric care. Cohort studies with well-defined end points and further neuroproteomic search for biomarkers in mild injury should be triggered. After critically reviewing the study designs, we found that large homogenous patient populations, consistent injury, and outcome measures prospectively determined cutoff values, and a combined use of different predictors should be considered in future studies.

Pediatric brain trauma outcome prediction using paired serum levels of inflammatory mediators and brain-specific proteins

Many potential brain trauma biomarkers have been reported, but no previous study has described outcome prediction using combinations of biomarker levels. We aimed to investigate the outcome predictive values of multiple biomarkers from different mediator families and to determine whether combinations of two serum biomarkers may achieve higher outcome predictive values than individual biomarker levels. A prospective observational study was conducted involving 28 children requiring intensive care management following brain trauma. Day 1 post-injury serum concentrations of eight different biomarkers--S100b protein (S100b), neuron-specific enolase (NSE), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), soluble intracellular adhesion molecule (SICAM), L-selectin, and endothelin--were quantified using enzyme-linked immunosorbent assay (ELISA). Global outcome was assessed at 6 months post-injury using the Glasgow Outcome Score (GOS). Receiver operator characteristic curve (ROC) analysis and its multivariate extension, Multivariate ROC (MultiROC), were used to assess the outcome predictive values of the individual and the paired biomarkers. None of the eight biomarkers assessed individually achieved an area under the ROC curve (AUC) of more than 0.95 for predicting unfavorable outcome, but five of the 20 biomarker pairs assessed had this high degree of outcome predictability. Two combinations using S100b as the "screening marker" and either L-selectin or IL-6 as the "varying marker" achieved an AUC of 0.98, and their specificity and sensitivity for unfavorable outcome prediction were 96% and 100%, respectively. Prognostic pairs combining serum levels of two biomarkers (inflammatory mediators and brain-specific proteins) offer better outcome predictive values for unfavorable outcome after childhood brain trauma than may be achieved using individual marker levels.

Comparison of S100B and NSE between cardiac surgery and interventional therapy for children

This study aimed to compare the release of S100B and NSE between cardiac surgery and interventional therapy for children and to investigate whether S100B serum concentration correlates with cardiopulmonary bypass in children. For this study, 40 children with congenital heart disease were selected and assigned to two groups: group A (20 children undergoing surgical therapy) and group B (20 children undergoing interventional therapy). In group A, blood samples were drawn 10 min after the induction of anesthesia, immediately after aortic cross-clamping, immediately at the end of cardiopulmonary bypass (CPB), immediately at the end of the operation, then 6 and 24 h after the operation. In group B, blood samples were drawn 10 min after the induction of anesthesia, immediately at the end of the procedure, then 6 and 24 h after the procedure. In group A, S100B plasma levels during the perioperative period and 6 h after the operation were higher than the preoperative level (p < 0.05). The NSE plasma concentrations at the termination of CPB and postoperatively were higher than the preoperative level (p < 0.05). Significant correlation was found between the peak value of S100B at the termination of CPB and the durations of both CPB and aortic cross-clamping. In group B, the differences in S100B and NSE between the post- and preoperative levels were not statistically significant (p > 0.05). The perioperative cerebral impairment indirectly evaluated by the release of NSE and S100B protein is greater in children undergoing CPB than in children undergoing interventional therapy. The release of S100B had a strong correlation with the durations of CPB and aortic cross-clamping in children.

Diagnostic value of S100B and neuron-specific enolase in mild pediatric traumatic brain injury

OBJECT

During recent years, several biomarkers have been introduced for use in the diagnosis of traumatic brain injury (TBI). The primary objective of this investigation was to determine if S100B (or S100 calcium-binding protein B) and neuron-specific enolase (NSE) serum concentrations can effectively be used to discriminate between symptomatic and asymptomatic children with minor head trauma.

METHODS

The authors conducted a prospective clinical study that involved patients age 6 months to 15 years who had sustained minor head trauma. Children with concomitant extracranial injuries were excluded. Blood samples were obtained within 6 hours of injury to measure S100B and NSE levels in serum. The authors defined 2 diagnostic groups: a mild TBI group (patients with Glasgow Coma Scale [GCS] scores of 13-15) in whom there were clinical signs of concussion (short loss of consciousness, amnesia, nausea, vomiting, somnolence, headache, dizziness, or impaired vision) and a head contusion group (patients with a GCS score of 15) in whom symptoms were absent. Both S100B and NSE concentrations were compared between the 2 groups. Secondary end points were defined as follows: correlation of S100B/NSE and a) the presence of scalp lacerations, b) GCS score, c) age, and d) correlation between S100B and NSE.

RESULTS

One hundred forty-eight patients were enrolled (53 in the contusion group, 95 in the mild TBI group). After adjusting for differences in age and time of injury to blood sample withdrawal, there was no significant difference in S100B or NSE between patients in the 2 groups. Scalp lacerations and GCS score had no affect on posttraumatic S100B or NSE concentrations. The correlation between S100B and NSE was significant. Both markers showed a significant negative correlation with age.

CONCLUSIONS

The authors demonstrated that S100B and NSE do not discriminate between symptomatic and asymptomatic children with minor head injury. There seem to be limitations in marker sensitivity when investigating pediatric patients with mild TBI.

Relationship of serum S100B levels and intracranial injury in children with closed head trauma

OBJECTIVE

To determine if serum levels of S100B are higher in children with CHT and ICI as detected by cranial CT and if long bone fractures affect the level of S100B in children with CHT and skeletal injury.

METHODS

Children <18 years of age who presented to an urban pediatric emergency department or were transferred from a referral hospital within 6 hours after accidental closed head trauma and who underwent cranial computed tomography were enrolled prospectively. Mean serum S100B levels for children with or without intracranial injury (ICI) and long-bone fractures were evaluated through analysis of covariance.

RESULTS

One hundred fifty-two children, 24 with ICI and 128 without ICI, were enrolled prospectively. Twenty-five children had long-bone fractures. Children with ICI were significantly younger than those without ICI (6.9 vs 9.8 years; P = .01). The time of venipuncture after injury was significantly later in children with ICI (P = .03). Mean S100B levels were significantly greater for children with ICI (212.9 vs 84.4 ng/L; P = .001), children with long-bone fractures (P = .008), and nonwhite children (P = .03). After controlling for time of venipuncture, long-bone fractures, and race, mean S100B levels were still greater for children with ICI (409 vs 118 ng/L; P = .001). The ability of serum S100B measurements to detect ICI, determined as the area under the curve, was 0.67.

CONCLUSIONS

After controlling for time of venipuncture, long-bone fractures, and race, S100B levels were still higher in children with ICI than in those without ICI. However, the ability of serum S100B measurements to detect ICI was poor.

Neuron-specific enolase and S-100B are associated with neurologic outcome after pediatric cardiac arrest

OBJECTIVE

To characterize the pattern of serum biochemical markers of central nervous system injury (neuron-specific enolase [NSE], S-100B, plasminogen activator inhibitor-1 [PAI-1]) after pediatric cardiac arrest and determine whether there is an association between biomarker concentrations and neurologic outcome.

DESIGN

Prospective, observational study.

SETTING

Urban, tertiary care children's hospital.

PATIENTS

Cardiac arrest survivors, n = 35.

INTERVENTIONS

Serial blood sampling, pediatric cerebral performance category, and standardized neurologic examination.

MEASUREMENTS AND MAIN RESULTS

Serial serum NSE and S-100B concentrations over 96 hrs and PAI-1 at 24 hrs were measured in children (age <18 yrs) who had return of spontaneous circulation following cardiac arrest. Neurologic outcome was prospectively categorized as poor if the change in pre- to postarrest pediatric cerebral performance category was > or =2. Biomarker concentrations were compared between outcome groups and between survival groups using longitudinal analysis correcting for multiple comparisons. Median levels (25th, 75th percentiles) are reported. Receiver operating characteristic analyses were performed at all time points. Biomarker concentrations showed statistically significant differences. Of the 35 patients, neurologic outcomes were poor in 19, with 15 deaths. Median NSE concentrations differed by outcome when measured at > or =48 hrs, and by survival at > or =24 hrs. S-100B concentrations were not significantly associated with neurologic outcome. S-100B levels were associated with survival outcome at > or =48 hrs. PAI-1 levels were not significantly associated with either neurologic or survival outcomes.

CONCLUSIONS

The timing, intensity, and duration of serum NSE and S-100B biomarker concentration patterns are associated with neurologic and survival outcomes following pediatric cardiac arrest. Serum NSE concentrations at > or =48 hrs are associated with neurologic outcome, whereas serum S-100B levels at > or =48 hrs are associated with survival. Prospective analysis of these markers may help to predict outcomes and guide postresuscitative therapies.