Combining coma score and serum biomarker levels to predict unfavorable outcome following childhood brain trauma

Plasma profiles of inflammatory cytokines in children with moderate to severe traumatic brain injury: a prospective cohort study

The role of inflammatory cytokines in children with moderate to severe TBI (m-sTBI) is still incompletely understood. We aimed to investigate the associations between early plasma expression profiles of inflammatory cytokines and clinical outcomes in children with m-sTBI. We prospectively recruited children admitted to the intensive care unit (ICU) of a tertiary pediatric hospital due to m-sTBI from November 2022 to May 2023. Plasma interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-17A, interferon (IFN)-α, IFN-γ and tumor necrosis factor (TNF)-α concentrations were detected by flow cytometry on admission and on days 5 to 7. The primary outcome was in-hospital mortality. The secondary outcome was the 6-month functional outcome assessed by the Glasgow Outcome Scale Extended-Pediatrics (GOS-E Peds) score, dichotomized as favorable (1-4) or unfavorable (5-8). Fifty patients and 20 healthy controls were enrolled. Baseline IL-6, IL-8 and IL-10 levels were significantly higher in TBI patients than in healthy controls. Twelve patients died in the hospital. Compared with survivors, nonsurvivors had significantly increased baseline IL-6 and IL-8 levels. Baseline IL-5, IL-6 and IL-8 levels were also significantly greater in children with unfavorable versus favorable outcomes. The area under the receiver operating characteristic curve (AUC) of the IL-6 and IL-8 levels and motor Glasgow Coma Scale (GCS) score for predicting in-hospital mortality was 0.706, 0.754, and 0.776, respectively. Baseline IL-1β, IL-2, IL-4, IL-10, IL-12p70, IL-17A, IFN-γ, IFN-α and TNF-α levels were not associated with in-hospital mortality or an unfavorable 6-month outcome. On days 5 to 7, the IL-6 and IL-8 levels were significantly decreased in survivors but increased in nonsurvivors compared to their respective baselines.

CONCLUSION

After m-sTBI, the plasma profiles of inflammatory cytokines are markedly altered in children. The trends of IL-6 and IL-8 expression vary among m-sTBI children with different outcomes. Elevated plasma IL-6 and IL-8 levels are related to in-hospital mortality and unfavorable 6-month outcomes.

TRIAL REGISTRATION

This trial was registered in the Chinese Clinical Trial Registry (Registration number: ChiCTR2200065505). Registered November 7, 2022.

WHAT IS KNOWN

• Inflammation is an important secondary physiological response to TBI.

WHAT IS NEW

• The plasma profiles of inflammatory cytokines are markedly altered in children with m-sTBI. Elevated IL-6 and IL-8 levels are related to mortality and unfavorable outcomes.

Blood-Based Biomarkers for Neuroprognostication in Acute Brain Injury

Acute brain injury causes loss of functionality in patients that often is devastating. Predicting the degree of functional loss and overall prognosis requires a multifaceted approach to help patients, and more so their families, make important decisions regarding plans and goals of care. A variety of blood-based markers have been studied as one aspect of this determination. In this review, we discuss CNS-derived and systemic markers that have been studied for neuroprognostication purposes. We discuss the foundation of each protein, the conditions in which it has been studied, and how the literature has used these markers for interpretation. We also discuss challenges to using each marker in each section as well.

Potential Biomarkers in Experimental Animal Models for Traumatic Brain Injury

Traumatic brain injury (TBI) is a complex and multifaceted disorder that has become a significant public health concern worldwide due to its contribution to mortality and morbidity. This condition encompasses a spectrum of injuries, including axonal damage, contusions, edema, and hemorrhage. Unfortunately, specific effective therapeutic interventions to improve patient outcomes following TBI are currently lacking. Various experimental animal models have been developed to mimic TBI and evaluate potential therapeutic agents to address this issue. These models are designed to recapitulate different biomarkers and mechanisms involved in TBI. However, due to the heterogeneous nature of clinical TBI, no single experimental animal model can effectively mimic all aspects of human TBI. Accurate emulation of clinical TBI mechanisms is also tricky due to ethical considerations. Therefore, the continued study of TBI mechanisms and biomarkers, of the duration and severity of brain injury, treatment strategies, and animal model optimization is necessary. This review focuses on the pathophysiology of TBI, available experimental TBI animal models, and the range of biomarkers and detection methods for TBI. Overall, this review highlights the need for further research to improve patient outcomes and reduce the global burden of TBI.

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.

Mild-to-severe traumatic brain injury in children: altered cytokines reflect severity

Background

Paediatric traumatic brain injury (TBI) is recognised to have significant longer-term neurocognitive effects. Childhood is a time of high risk for head injury. Functional recovery is variable with a combination of any or all of physical, cognitive and emotional impairment. Immune activation and alteration in cytokine levels are present following TBI which may differ from adults.

Methods

Pro- and anti-inflammatory cytokines including Interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, IL-17A, Tumor Necrosis Factor (TNF)-α and Interferon (IFN)-γ were examined at baseline and following in vitro treatment with endotoxin of whole blood, in the following children: severe TBI (sTBI: initial Glasgow coma scale(GCS) ≤ 8), mild TBI (mTBI; GCS 14/15) at 0-4d and at 10-14d post-TBI and compared to healthy age-matched controls.

Results

The study enrolled 208 children, including 110 with TBI cohort (n = 104 mild; 6 severe) and controls (n = 98). At baseline all children with TBI had increased IL-6. The mTBI group had significantly increased IFN-γ versus controls. In sTBI at baseline, IFN-γ was decreased compared to controls. At baseline IL-8, IL-10, IL-17A, and TNF-α were decreased in mTBI compared to controls. This persisted at 2 week post-mTBI. The AUC for detecting mTBI was 0.801 CI (0.73–086) using IL6/IL10 ratio. mTBI showed a greater fold change in IL-8 and TNF-α in response to endotoxin stimulation, a response that persisted at 2 weeks. Children with sTBI did not have a significant IL-6 response to endotoxin, but did show an increase in IL-17A.

Conclusion

Children with all TBI including mTBI show altered cytokine profiles and altered endotoxin responses. Although cytokines increased in sTBI especially in response to endotoxin, suppressed responses were found in mTBI coupled with persistent immune dysfunction post-injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02390-5.

[GCS score combined with CT score and serum S100B protein level Can evaluate severity and early prognosis of acute traumatic brain injury]

OBJECTIVE

To explore the value of Glasgow Coma Scale (GCS) score and CT score combined with serum S100B protein level for evaluation of injury severity and predicting early prognosis of acute traumatic brain injury (TBI).

OBJECTIVE

A total of 108 patients with TBI admitted within 24 h after injury in the Emergency Department of West China Hospital from May, 2019 to May, 2020 were enrolled in this study. The clinical data, laboratory test results, CT examination, GCS score, Full Outline of Unresponsiveness score, Fisher CT classification, Rotterdam CT score, and serum S100B protein level of the patients were collected upon admission. The patients were followed up for 28 days and divided based on their Glasgow Outcome Scale (GOS) scores into poor prognosis group (GOS 1-3) and good prognosis group (GOS 4-5). The indexes related to poor prognosis were analyzed for their efficacy for predicting the patinets' prognosis. According to the results of head CT, the patients were divided into CT^- positive (CT⁺) group and CT^- negative (CT^-) group, and the efficacy of serum S100B protein level for predicting CT positivity was evaluated.

OBJECTIVE

Compared with those with favorable prognosis, the patients with poor prognosis had significantly lower GCS scores (P < 0.01) and higher Rotterdam CT score and serum S100B protein levels (P < 0.01). Among the 3 index, serum S100B protein level had the highest AUC value (0.79); among the combined indexes, GCS score combined with serum S100B protein had the highest AUC value (0.80). Serum S100B protein level was significantly higher in CT⁺ group than in CT - group (P < 0.05) with a significant correlation with Rotterdam CT score (r=0.26, P < 0.01).

OBJECTIVE

Serum S100B protein level, GCS score, and Rotterdam CT score can be used as indicators for evaluating the severity of acute TBI, and they are all closely related with early prognosis of the patients. The combination of serum S100B protein, GCS score and Rotterdam CT score has better performance than any of the 3 indexes alone for predicting early prognosis of the patients. Serum S100B protein level is correlated with head imaging findings of patients with acute TBI, but its value in selection of appropriate imaging modalities awaits further investigation.

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.

Biomarkers in traumatic brain injury: new concepts

Traumatic brain injury is a multifaceted condition that encompasses a spectrum of injuries: contusions, axonal injuries in specific brain regions, edema, and hemorrhage. Brain injury determines a broad clinical and disability spectrum due to the implication of various cellular pathways, genetic phenotypes, and environmental factors. It is challenging to predict patient outcomes, to appropriately evaluate the patients, to determine a suitable treatment strategy and rehabilitation program, and to communicate with patient relatives. Biomarkers detected from body fluids are potential evaluation tools for traumatic brain injury patients. These may serve as internal indicators of cerebral damage, delivering valuable information about the dynamic cellular, biochemical, and molecular environments. The diagnostic and prognostic value of biomarkers tested both in animal models of traumatic brain injury is still under question, despite a considerable scientific literature. Recent publications emphasize that a more realistic approach involves combining multiple types of biomarkers with other investigative tools (imaging, outcome scales, and genetic polymorphisms). Additionally, there is increasing interest in the use of biomarkers as tools for treatment monitoring and as surrogate outcome variables to facilitate the design of distinct randomized controlled trials. This review highlights the latest available evidence regarding biomarkers in adults after traumatic brain injury and discusses new approaches in the evaluation of this patient group.

Plasma Levels, Temporal Trends and Clinical Associations between Biomarkers of Inflammation and Vascular Homeostasis after Pediatric Traumatic Brain Injury

Expression of inflammatory (interleukin-6 [IL-6]) and vascular homeostatic (angiopoietin-2 [AP-2], endothelin-1 [ET-1], endocan-2 [EC-2]) biomarkers in pediatric traumatic brain injury (TBI) was examined in this prospective, observational cohort study of 28 children hospitalized with mild, moderate, and severe TBI by clinical measures (age, sex, Glasgow Coma Scale score [GCS], Injury Severity Score [ISS], and cerebral autoregulation status). Biomarker patterns suggest an inverse relationship between GCS and AP-2, GCS and IL-6, ISS and ET-1, but a direct relationship between GCS and ET-1 and ISS and AP-2. Biomarker patterns suggest an inverse relationship between AP-2 and ET-1, AP-2 and EC-2, but a direct relationship between AP-2 and IL-6, IL-6 and EC-2, and IL-6 and ET-1. Plasma concentrations of inflammatory and vascular homeostatic biomarkers suggest a role for inflammation and disruption of vascular homeostasis during the first 10 days across the severity spectrum of pediatric TBI. Although not statistically significant, without impact on cerebral autoregulation, biomarker patterns suggest a relationship between inflammation and alterations in vascular homeostasis. The large variation in biomarker levels within TBI severity and age groups, and by sex suggests other contributory factors to biomarker expression.

Blood purification by nonselective hemoadsorption prevents death after traumatic brain injury and hemorrhagic shock in rats

BACKGROUND

Patients who sustain traumatic brain injury (TBI) and concomitant hemorrhagic shock (HS) are at high risk of high-magnitude inflammation which can lead to poor outcomes and death. Blood purification by hemoadsorption (HA) offers an alternative intervention to reduce inflammation after injury. We tested the hypothesis that HA would reduce mortality in a rat model of TBI and HS.

METHODS

Male Sprague Dawley rats were subjected to a combined injury of a controlled cortical impact to their brain and pressure-controlled HS. Animals were subsequently instrumented with an extracorporeal blood circuit that passed through a cartridge for sham or experimental treatment. In experimental animals, the treatment cartridge was filled with proprietary beads (Cytosorbents, Monmouth Junction, NJ) that removed circulating molecules between 5 kDa and 60 kDa. Sham rats had equivalent circulation but no blood purification. Serial blood samples were analyzed with multiplex technology to quantify changes in a trauma-relevant panel of immunologic mediators. The primary outcome was survival to 96 hours postinjury.

RESULTS

Hemoadsorption improved survival from 47% in sham-treated rats to 86% in HA-treated rats. There were no treatment-related changes in histologic appearance. Hemoadsorption affected biomarker concentrations both during the treatment and over the ensuing 4 days after injury. Distinct changes in biomarker concentrations were also measured in survivor and nonsurvivor rats from the entire cohort of rats indicating biomarker patterns associated with survival and death after injury.

CONCLUSION

Blood purification by nonselective HA is an effective intervention to prevent death in a combined TBI/HS rat model. Hemoadsorption changed circulating concentrations of multiple inmmunologically active mediators during the treatment time frame and after treatment. Hemoadsorption has been safely implemented in human patients with sepsis and may be a treatment option after injury.

The Relationship between Serum Concentrations of Pro- and Anti-Inflammatory Cytokines and Nutritional Status in Patients with Traumatic Head Injury in the Intensive Care Unit

Background and objective: The aim of the present study was to examine the relationship between serum levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) and anti-inflammatory cytokines (IL-10) measured once at the baseline with changes in nutritional status of patients with traumatic head injury (THI) assessed at three consecutive times (24 h after admission, day 6 and day 13) during hospital stay in the intensive care unit (ICU). Materials and Methods: Sixty-four patients with THI were recruited for the current study (over 10 months). The nutritional status of the patients was determined within 24 h after admission and on days 6 and 13, using actual body weight, body composition analysis, and anthropometric measurements. The APACHE II score and SOFA score were also assessed within 24 h of admission and on days 6 and 13 of patients staying in the ICU. Circulatory serum levels of cytokines (IL-6, IL-1β, TNF-α, and IL-10) were assessed once within 24 h of admission. Results: The current study found a significant reduction in BMI, FBM, LBM, MAUAC, and APM, of THI patients with high serum levels the cytokines, over the course of time from the baseline to day 7 and to day 13 in patients staying in the ICU (p < 0.001). It was also found that patients with low levels of some studied cytokines had significant improvement in their nutritional status and clinical outcomes in term of MAUAC, APM, APACHE II score and SOFA score (p < 0.001 to p < 0.01). Conclusion: THI patients who had high serum levels of studied cytokines were more prone to develop a reduction of nutritional status in terms of BMI, FBM, LBM MAUAC and APM over the course of time from patient admission until day 13 of ICU admission.

An Exploratory Examination of Neonatal Cytokines and Chemokines as Predictors of Autism Risk: The Early Markers for Autism Study

BACKGROUND

The identification of an early biomarker for autism spectrum disorder (ASD) would improve the determination of risk, leading to earlier diagnosis and, potentially, earlier intervention and improved outcomes.

METHODS

Data were generated from the Early Markers for Autism study, a population-based case-control study of prenatal and neonatal biomarkers of ASD. Newborn bloodspots of children with ASD (n = 370), children with developmental delay (n = 140), and general population (GP) controls (n = 378) were analyzed for 42 different immune markers using a Luminex multiplex platform. Comparisons of immune marker concentrations between groups were examined using logistic regression and partial least squares discriminant analysis.

RESULTS

Children with ASD had significantly increased neonatal levels of interleukin-6 (IL-6) and IL-8 compared with GP controls. An increase in IL-8 was especially significant in the ASD group with early onset compared with the GP group, with an adjusted odds ratio of 1.97 (95% confidence interval, 1.39-2.83; p = .00014). In addition, children with ASD had significantly elevated levels of eotaxin-1, interferon-γ, and IL-12p70 relative to children with developmental delay. We observed no significant differences in levels of immune markers between the developmental delay and GP groups.

CONCLUSIONS

Elevated levels of some inflammatory markers in newborn bloodspots indicated a higher degree of immune activation at birth in children who were subsequently diagnosed with ASD. The data from this exploratory study suggest that with further expansion, the development of neonatal bloodspot testing for cytokine/chemokine levels might lead to the identification of biomarkers that provide an accurate assessment of ASD risk at birth.

Meta-analysis of neuron specific enolase in predicting pediatric brain injury outcomes

A reliable biomarker has not been identified to predict the outcome of traumatic brain injury (TBI) in children. Therefore, the present systematic review and meta-analysis aimed to assess the association between neuron specific enolase (NSE) and traumatic brain injury (TBI) in children. Two independent reviewers searched electronic databases of EMBASE, Cochrane library, Medline and Scopus and then they summarized the results and did a quality control check. At the end, standardized mean difference (SMD) with 95 % confidence interval (CI) and performance of NSE were assessed. 10 studies were included in the present meta-analysis. Average serum (SMD=1.3; 95 % CI: 0.5 to 2.1; p=0.001) and CSF levels (SMD=2.45; 95 % CI: 1.04 to 3.8; p<0.0001) of NSE biomarker were significantly higher in children with TBI with unfavorable outcome compared with other children. Serum NSE had an area under the curve, sensitivity and specificity of 0.75 (95 % CI: 0.72 to 0.79), 0.74 (95 % CI: 0.64 to 0.82) and 0.69 (95 % CI: 0.59 to 0.77), respectively in prediction outcome of TBI. Positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio of serum NSE were 2.4 (95 % CI: 1.7 to 3.3), 0.38 (95 % CI: 0.26 to 0.55) and 6.0 (95 % CI: 3.0 to 12.0), respectively. The results show that the performance of NSE is in a moderate level in prediction of unfavorable outcome in children with TBI. However, data in this aspect is not sufficient and more studies are needed.

Role of Interleukin-10 in Acute Brain Injuries

Interleukin-10 (IL-10) is an important anti-inflammatory cytokine expressed in response to brain injury, where it facilitates the resolution of inflammatory cascades, which if prolonged causes secondary brain damage. Here, we comprehensively review the current knowledge regarding the role of IL-10 in modulating outcomes following acute brain injury, including traumatic brain injury (TBI) and the various stroke subtypes. The vascular endothelium is closely tied to the pathophysiology of these neurological disorders and research has demonstrated clear vascular endothelial protective properties for IL-10. In vitro and in vivo models of ischemic stroke have convincingly directly and indirectly shown IL-10-mediated neuroprotection; although clinically, the role of IL-10 in predicting risk and outcomes is less clear. Comparatively, conclusive studies investigating the contribution of IL-10 in subarachnoid hemorrhage are lacking. Weak indirect evidence supporting the protective role of IL-10 in preclinical models of intracerebral hemorrhage exists; however, in the limited number of clinical studies, higher IL-10 levels seen post-ictus have been associated with worse outcomes. Similarly, preclinical TBI models have suggested a neuroprotective role for IL-10; although, controversy exists among the several clinical studies. In summary, while IL-10 is consistently elevated following acute brain injury, the effect of IL-10 appears to be pathology dependent, and preclinical and clinical studies often paradoxically yield opposite results. The pronounced and potent effects of IL-10 in the resolution of inflammation and inconsistency in the literature regarding the contribution of IL-10 in the setting of acute brain injury warrant further rigorously controlled and targeted investigation.

Peripheral Inflammatory Markers and Antioxidant Response during the Post-Acute and Chronic Phase after Severe Traumatic Brain Injury

Traumatic brain injury (TBI) is a mechanical insult to the brain caused by external forces and associated with inflammation and oxidative stress. The patients may show different profiles of neurological recovery and a combination of oxidative damage and inflammatory processes can affect their courses. It is known that an overexpression of cytokines can be seen in peripheral blood in the early hours/days after the injury, but little is known about the weeks and months encompassing the post-acute and chronic phases. In addition, no information is available about the antioxidant responses mediated by the major enzymes that regulate reactive oxygen species levels: superoxide dismutase, catalase, peroxidases, and GSH-related enzymes. This study investigates the 6-month trends of inflammatory markers and antioxidant responses in 22 severe TBI patients with prolonged disorders of consciousness, consecutively recruited in a dedicated neurorehabilitation facility. Patients with a high degree of neurological impairment often show an uncertain outcome. In addition, the profiles of plasma activities were related to the neurological recovery after 12 months. Venous peripheral blood samples were taken blindly as soon as clinical signs and laboratory markers confirmed the absence of infections, 3 and 6 months later. The clinical and neuropsychological assessment continued up to 12 months. Nineteen patients completed the follow-up. In the chronic phase, persistent high plasma levels of cytokines can interfere with cognitive functioning and higher post-acute levels of cytokines [interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL1b, IL6] are associated with poorer cognitive recoveries 12 months later. Moreover, higher IFN-γ, higher TNF-α, and lower glutathione peroxidase activity are associated with greater disability. The results add evidence of persistent inflammatory response, provide information about long-term imbalance of antioxidant activity, and suggest that the over-production of cytokines and the alteration of the redox homeostasis in the post-acute phase might adversely affect the neurological and functional recovery. Inflammatory and antioxidant activity markers might offer a feasible way to highlight some of the processes opposing recovery after a severe TBI.

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.

S100B protein as a screening tool for computed tomography findings after mild traumatic brain injury: Systematic review and meta-analysis

PRIMARY OBJECTIVE

To determine whether S100B protein in serum can predict intracranial lesions on computed tomography (CT) scan after mild traumatic brain injury (MTBI).

RESEARCH DESIGN

Systematic review and meta-analysis Methods and procedures: A literature search was conducted using Medline, Embase, Cochrane, Google Scholar, CINAHL, SUMSearch, Bandolier, Trip databases, bibliographies from identified articles and review article references. Eligible articles were defined as observational studies including patients with MTBI who underwent post-traumatic head CT scan and assessing the screening role of S100B protein.

MAIN OUTCOMES AND RESULTS

There was a significant positive association between S100B protein concentration and positive CT scan (22 studies, SMD = 1.92, 95% CI = 1.29-2.45, I² = 100%; p < 0.001). The pooled sensitivity and specificity values for a cut-point range = 0.16-0.20 µg L^-1 were 98.65 (95% CI = 95.53-101.77; I² = 0.0%) and 50.69 (95% CI = 40.69-60.69; I² = 76.3%), respectively. The threshold for serum S100B protein with 99.63 (95% CI = 96.00-103.25; I² = 0.0%) sensitivity and 46.94 (95% CI = 39.01-54.87; I² = 95.5%) specificity was > 0.20 µg L^-1.

CONCLUSIONS

After MTBI, serum S100B protein levels are significantly associated with the presence of intracranial lesions on CT scan. Measuring the protein could be useful in screening high risk MTBI patients and decreasing unnecessary CT examinations.

Clinical evidence of inflammation driving secondary brain injury: a systematic review

BACKGROUND

Despite advances in both prevention and treatment, traumatic brain injury (TBI) remains one of the most burdensome diseases; 2% of the US population currently lives with disabilities resulting from TBI. Recent advances in the understanding of inflammation and its impact on the pathophysiology of trauma have increased the interest in inflammation as a possible mediator in TBI outcome.

OBJECTIVES

The goal of this systematic review is to address the question: "What is the evidence in humans that inflammation is linked to secondary brain injury?" As the experimental evidence has been well described elsewhere, this review will focus on the clinical evidence for inflammation as a mechanism of secondary brain injury.

DATA SOURCES

Medline database (1996-Week 1 June 2014), Pubmed and Google Scholar databases were queried for relevant studies.

STUDY ELIGIBILITY CRITERIA

Studies were eligible if participants were adults and/or children who sustained moderate or severe TBI in the acute phase of injury, published in English. Studies published in the last decade (since 2004) were preferentially included. Trials could be observational or interventional in nature.

APPRAISAL AND SYNTHESIS METHODS

To address the quality of the studies retrieved, we applied the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) criteria to assess the limitations of the included studies.

RESULTS

Trauma initiates local central nervous system as well as systemic immune activation. Numerous observational studies describe elevation of pro-inflammatory cytokines that are associated with important clinical variables including neurologic outcome and mortality. A small number of clinical trials have included immunomodulating strategies, but no intervention to date has proven effective in improving outcomes after TBI.

LIMITATIONS

Inclusion of studies not initially retrieved by the search terms may have biased our results. Additionally, some reports may have been inadvertently excluded due to use of non-search term key words. Conclusions and Implications of Key Findings Clinical evidence of inflammation causing secondary brain injury in humans is gaining momentum. While inflammation is certainly present, it is not clear from the literature at what juncture inflammation becomes maladaptive, promoting secondary injury rather than facilitating repairand identifying patients with maladaptive inflammation (neuro-inflammation, systemic, or both) after TBI remains elusive. Direct agonism/antagonism represents an exciting target for future study.

LEVEL OF EVIDENCE

Systematic review, level III.

Biomarkers for the diagnosis and prognosis of mild traumatic brain injury/concussion

Mild traumatic brain injury (mTBI) results from a transfer of mechanical energy into the brain from traumatic events such as rapid acceleration/deceleration, a direct impact to the head, or an explosive blast. Transfer of energy into the brain can cause structural, physiological, and/or functional changes in the brain that may yield neurological, cognitive, and behavioral symptoms that can be long-lasting. Because mTBI can cause these symptoms in the absence of positive neuroimaging findings, its diagnosis can be subjective and often is based on self-reported neurological symptoms. Further, proper diagnosis can be influenced by the motivation to conceal or embellish signs and/or an inability of the patient to notice subtle dysfunctions or alterations of consciousness. Therefore, appropriate diagnosis of mTBI would benefit from objective indicators of injury. Concussion and mTBI are often used interchangeably, with concussion being primarily used in sport medicine, whereas mTBI is used in reference to traumatic injury. This review provides a critical assessment of the status of current biomarkers for the diagnosis of human mTBI. We review the status of biomarkers that have been tested in TBI patients with injuries classified as mild, and introduce a new concept for the discovery of biomarkers (termed symptophenotypes) to predict common and unique symptoms of concussion. Finally, we discuss the need for biomarker/biomarker signatures that can detect mTBI in the context of polytrauma, and to assess the consequences of repeated injury on the development of secondary injury syndrome, prolongation of post-concussion symptoms, and chronic traumatic encephalopathy.

The role of markers of inflammation in traumatic brain injury

Within minutes of a traumatic impact, a robust inflammatory response is elicited in the injured brain. The complexity of this post-traumatic squeal involves a cellular component, comprising the activation of resident glial cells, microglia, and astrocytes, and the infiltration of blood leukocytes. The second component regards the secretion immune mediators, which can be divided into the following sub-groups: the archetypal pro-inflammatory cytokines (Interleukin-1, Tumor Necrosis Factor, Interleukin-6), the anti-inflammatory cytokines (IL-4, Interleukin-10, and TGF-beta), and the chemotactic cytokines or chemokines, which specifically drive the accumulation of parenchymal and peripheral immune cells in the injured brain region. Such mechanisms have been demonstrated in animal models, mostly in rodents, as well as in human brain. Whilst the humoral immune response is particularly pronounced in the acute phase following Traumatic brain injury (TBI), the activation of glial cells seems to be a rather prolonged effect lasting for several months. The complex interaction of cytokines and cell types installs a network of events, which subsequently intersect with adjacent pathological cascades including oxidative stress, excitotoxicity, or reparative events including angiogenesis, scarring, and neurogenesis. It is well accepted that neuroinflammation is responsible of beneficial and detrimental effects, contributing to secondary brain damage but also facilitating neurorepair. Although such mediators are clear markers of immune activation, to what extent cytokines can be defined as diagnostic factors reflecting brain injury or as predictors of long term outcome needs to be further substantiated. In clinical studies some groups reported a proportional cytokine production in either the cerebrospinal fluid or intraparenchymal tissue with initial brain damage, mortality, or poor outcome scores. However, the validity of cytokines as biomarkers is not broadly accepted. This review article will discuss the evidence from both clinical and laboratory studies exploring the validity of immune markers as a correlate to classification and outcome following TBI.

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.

The role of markers of inflammation in traumatic brain injury

Within minutes of a traumatic impact, a robust inflammatory response is elicited in the injured brain. The complexity of this post-traumatic squeal involves a cellular component, comprising the activation of resident glial cells, microglia, and astrocytes, and the infiltration of blood leukocytes. The second component regards the secretion immune mediators, which can be divided into the following sub-groups: the archetypal pro-inflammatory cytokines (Interleukin-1, Tumor Necrosis Factor, Interleukin-6), the anti-inflammatory cytokines (IL-4, Interleukin-10, and TGF-beta), and the chemotactic cytokines or chemokines, which specifically drive the accumulation of parenchymal and peripheral immune cells in the injured brain region. Such mechanisms have been demonstrated in animal models, mostly in rodents, as well as in human brain. Whilst the humoral immune response is particularly pronounced in the acute phase following Traumatic brain injury (TBI), the activation of glial cells seems to be a rather prolonged effect lasting for several months. The complex interaction of cytokines and cell types installs a network of events, which subsequently intersect with adjacent pathological cascades including oxidative stress, excitotoxicity, or reparative events including angiogenesis, scarring, and neurogenesis. It is well accepted that neuroinflammation is responsible of beneficial and detrimental effects, contributing to secondary brain damage but also facilitating neurorepair. Although such mediators are clear markers of immune activation, to what extent cytokines can be defined as diagnostic factors reflecting brain injury or as predictors of long term outcome needs to be further substantiated. In clinical studies some groups reported a proportional cytokine production in either the cerebrospinal fluid or intraparenchymal tissue with initial brain damage, mortality, or poor outcome scores. However, the validity of cytokines as biomarkers is not broadly accepted. This review article will discuss the evidence from both clinical and laboratory studies exploring the validity of immune markers as a correlate to classification and outcome following TBI.