S-100B Concentration Is Not Related to Neurocognitive Performance in the First Month after Mild Traumatic Brain Injury

Prognostic Value of S-100β Protein for Prediction of Post-Concussion Symptoms after a Mild Traumatic Brain Injury: Systematic Review and Meta-Analysis

This systematic review and meta-analysis aimed to determine the prognostic value of S-100β protein to identify patients with post-concussion symptoms after a mild traumatic brain injury (mTBI). A search strategy was submitted to seven databases from their inception to October 2016. Individual patient data were requested. Cohort studies evaluating the association between S-100β protein level and post-concussion symptoms assessed at least seven days after the mTBI were considered. Outcomes were dichotomized as persistent (≥3 months) or early (≥7 days <3 months). Our search strategy yielded 23,298 citations of which 29 studies including between seven and 223 patients (n = 2505) were included. Post-concussion syndrome (PCS) (16 studies) and neuropsychological symptoms (9 studies) were the most frequently assessed outcomes. The odds of having persistent PCS (odds ratio [OR] 0.62, 95% confidence interval [CI]: 0.34-1.12, p = 0.11, I² 0% [n = five studies]) in patients with an elevated S-100β protein serum level were not significantly different from those of patients with normal values while the odds of having early PCS (OR 1.67, 95% CI: 0.98-2.85, p = 0.06, I² 38% [n = five studies]) were close to statistical significance. Similarly, having an elevated S-100β protein serum level was not associated with the odds of returning to work at six months (OR 2.31, 95% CI: 0.50-10.64, p = 0.28, I² 22% [n = two studies]). Overall risk of bias was considered moderate. Results suggest that the prognostic biomarker S-100β protein has a low clinical value to identify patients at risk of persistent post-concussion symptoms. Variability in injury to S-100ß protein sample time, mTBI populations, and outcomes assessed could potentially explain the lack of association and needs further evaluation.

Characteristics of patients included and enrolled in studies on the prognostic value of serum biomarkers for prediction of postconcussion symptoms following a mild traumatic brain injury: a systematic review

OBJECTIVE

Mild traumatic brain injury (mTBI) has been insufficiently researched, and its definition remains elusive. Investigators are confronted by heterogeneity in patients, mechanism of injury and outcomes. Findings are thus often limited in generalisability and clinical application. Serum protein biomarkers are increasingly assessed to enhance prognostication of outcomes, but their translation into clinical practice has yet to be achieved. A systematic review was performed to describe the adult populations included and enrolled in studies that evaluated the prognostic value of protein biomarkers to predict postconcussion symptoms following an mTBI.

DATA SOURCES

Searches of MEDLINE, Embase, CENTRAL, CINAHL, Web of Science, PsycBITE and PsycINFO up to October 2016.

DATA SELECTION AND EXTRACTION

Two reviewers independently screened for potentially eligible studies, extracted data and assessed the overall quality of evidence by outcome using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

A total of 23 298 citations were obtained from which 166 manuscripts were reviewed. Thirty-six cohort studies (2812 patients) having enrolled between 7 and 311 patients (median 89) fulfilled our inclusion criteria. Most studies excluded patients based on advanced age (n=10 (28%)), neurological disorders (n=20 (56%)), psychiatric disorders (n=17 (47%)), substance abuse disorders (n=13 (36%)) or previous traumatic brain injury (n=10 (28%)). Twenty-one studies (58%) used at least two of these exclusion criteria. The pooled mean age of included patients was 39.3 (SD 4.6) years old (34 studies). The criteria used to define a mTBI were inconsistent. The most frequently reported outcome was postconcussion syndrome using the Rivermead Post-Concussion Symptoms Questionnaire (n=18 (50%)) with follow-ups ranging from 7 days to 5 years after the mTBI.

CONCLUSIONS

Most studies have recruited samples that are not representative and generalisable to the mTBI population. These exclusion criteria limit the potential use and translation of promising serum protein biomarkers to predict postconcussion symptoms.

Current status of fluid biomarkers in mild traumatic brain injury

Mild traumatic brain injury (mTBI) affects millions of people annually and is difficult to diagnose. Mild injury is insensitive to conventional imaging techniques and diagnoses are often made using subjective criteria such as self-reported symptoms. Many people who sustain a mTBI develop persistent post-concussive symptoms. Athletes and military personnel are at great risk for repeat injury which can result in second impact syndrome or chronic traumatic encephalopathy. An objective and quantifiable measure, such as a serum biomarker, is needed to aid in mTBI diagnosis, prognosis, return to play/duty assessments, and would further elucidate mTBI pathophysiology. The majority of TBI biomarker research focuses on severe TBI with few studies specific to mild injury. Most studies use a hypothesis-driven approach, screening biofluids for markers known to be associated with TBI pathophysiology. This approach has yielded limited success in identifying markers that can be used clinically, additional candidate biomarkers are needed. Innovative and unbiased methods such as proteomics, microRNA arrays, urinary screens, autoantibody identification and phage display would complement more traditional approaches to aid in the discovery of novel mTBI biomarkers.

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.

Can Admission S-100β Predict the Extent of Brain Damage in Head Trauma Patients?

Background:

As has been shown previously, S-100β levels in serum can be a useful predictor of brain damage after head trauma. This pilot study was designed to investigate whether urine samples, which are much easier to obtain, could be used for the same purpose instead of serum samples.

Methods:

Ninety-six consecutive patients admitted with head trauma were recruited in the study. After exclusion of 54 patients, mostly because of significant additional trauma, S-100β levels were analyzed in serum and urine of 42 patients using a luminometric assay. A range for normal values was established based on samples from ten healthy volunteers.

Results:

S-100β serum levels increased proportional to the severity of the head trauma, as had been previously shown by several other groups. In many patients, initial increases in urine S-100β levels were seen later than in serum, after which the kinetics of S-100β levels in urine seemed to follow that established for serum levels. S-100β values in urine were on average about 54% lower in urine than in serum.

Conclusions:

S-100β levels in urine obtained on admission to the hospital are not a good indicator for the extent of brain damage. However, urine S-100β levels obtained at later time points might be a useful indicator for the development of secondary brain injury.

S-100β does not predict outcome after mild traumatic brain injury

OBJECTIVE

To determine the usefulness of S-100β, a marker for central nervous system damage, in the prediction of long-term outcomes after mild traumatic brain injury (MTBI) Hypothesis: Mid- and long-term outcomes of MTBI (i.e. 3, 6 and 12 months post-injury and return-to-work or school (RTWS)) may be predicted based on pre-injury and injury factors as well as S-100β.

METHODS

MTBI subjects without abnormal brain computed tomography requiring intervention, focal neurological deficits, seizures, amnesia > 24 hours and severe or multiple injuries were recruited at a level I trauma centre. Admission S-100β measurements and baseline Concussion Symptom Checklist were obtained. Symptoms and RTWS were re-assessed at follow-up visits (3-10 days and 3, 6 and 12 months). Outcomes included number of symptoms and RTWS at follow-up. Chi-square tests, linear and logistic regression models were used and p < 0.05 was considered statistically significant.

RESULTS

One hundred and fifty of 180 study subjects had S-100β results. Eleven per cent were unable to RTWS at 12 months. S-100β levels were not associated with post-concussive symptomatology at follow-up. In addition, no association was found between S-100β levels and RTWS.

CONCLUSION

Amongst MTBI patients, S-100β levels are not associated with prolonged post-concussive syndrome or the inability to RTWS.

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.

Biomarkers, genetics, and risk factors for concussion

It is estimated that between 1.6 and 3.8 million concussions occur annually in the United States. Although frequently regarded as benign, concussions can lead to multiple different adverse outcomes, including prolonged postconcussive symptoms, chronic traumatic encephalopathy, cognitive impairment, early onset dementia, movement disorders, psychiatric disorders, motor neuron disease, and even death. Therefore it is important to identify individuals with concussion to provide appropriate medical care and minimize adverse outcomes. Furthermore, it is important to identify individuals who are predisposed to sustaining a concussion or to having an adverse outcome after concussion. This article will discuss the current research on serum biomarkers for concussion, genetic influence on concussion, risk factors associated with concussion predisposition and poor outcome, and practical suggestions for the application of this information in clinical practice.

Computed tomography-estimated specific gravity at hospital admission predicts 6-month outcome in mild-to-moderate traumatic brain injury patients admitted to the intensive care unit

BACKGROUND

It is clear that patients with a severe traumatic brain injury (TBI) develop secondary, potentially lethal neurological deterioration. However, it is difficult to predict which patients with mild-to-moderate TBI (MM-TBI), even after intensive care unit (ICU) admission, will experience poor outcome at 6 months. Standard computed tomography (CT) imaging scans provide information that can be used to estimate specific gravity (eSG). We have previously demonstrated that higher eSG measurements in the standard CT reading were associated with poor outcomes after severe TBI. The aim of this study was to determine whether eSG of the intracranial content predicts 6-month outcome in MM-TBI.

METHODS

We analyzed admission clinical and CT scan data (including eSG) of 66 patients with MM-TBI subsequently admitted to our neurosurgical ICU. Primary outcome was defined as a Glasgow Outcome Scale score of 1 to 3 after 6 months. Discriminating power (area under the receiver operating characteristic curve [ROC-AUC], 95% confidence interval) of eSG to predict 6-month poor outcome was calculated. The correlation of eSG with the main ICU characteristics was then compared.

RESULTS

Univariate and stepwise multivariate analyses showed an independent association between eSG and 6-month poor outcome (P = 0.001). ROC-AUC of eSG for the prediction of 6-month outcomes was 0.87 (confidence interval: 0.77-0.96). Admission eSG values were correlated with the main ICU characteristics, specifically 14-day mortality (P = 0.004), length of mechanical ventilation (P = 0.01), length of ICU stay (P = 0.045), and ICU procedures such as intracranial pressure monitoring (P < 0.001).

CONCLUSIONS

In this MM-TBI cohort admitted to the ICU, eSG of routine CT scans was correlated with mortality, ICU severity, and predicted 6-month poor outcome. An external validation with studies that include the spectrum of TBI severities is warranted to confirm our results.

Time-dependent changes in serum biomarker levels after blast traumatic brain injury

Neuronal and glial proteins detected in the peripheral circulating blood after injury can reflect the extent of the damage caused by blast traumatic brain injury (bTBI). The temporal pattern of their serum levels can further predict the severity and outcome of the injury. As part of characterizing a large-animal model of bTBI, we determined the changes in the serum levels of S100B, neuron-specific enolase (NSE), myelin basic protein (MBP), and neurofilament heavy chain (NF-H). Blood samples were obtained prior to injury and at 6, 24, 72 h, and 2 weeks post-injury from animals with different severities of bTBI; protein levels were determined using reverse phase protein microarray (RPPM) technology. Serum levels of S100B, MBP, and NF-H, but not NSE, showed a time-dependent increase following injury. The detected changes in S100B and MBP levels showed no correlation with the severity of the injury. However, serum NF-H levels increased in a unique, rapid manner, peaking at 6 h post-injury only in animals exposed to severe blast with poor clinical and pathological outcomes. We conclude that the sudden increase in serum NF-H levels following bTBI may be a useful indicator of injury severity. If additional studies verify our findings, the observed early peak of serum NF-H levels can be developed into a useful diagnostic tool for predicting the extent of damage following bTBI.

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.

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.

[Can serum protein S100beta predict neurological deterioration after moderate or minor traumatic brain injury?]

INTRODUCTION

Patients with moderate traumatic brain injury (TBI) (Glasgow Coma Scale, GCS, 9-13) or minor TBI (GCS 14-15) are at risk for subsequent neurological deterioration. Serum protein S-100 is believed to reflect brain damage following TBI. In patients with normal or minor CT scan abnormalities on admission, we tested whether the determination of serum protein S-100 beta could predict secondary neurological deterioration.

METHODS

Sixty-seven patients with moderate or minor TBI were prospectively studied. Serum samples were collected on admission within 12 hours postinjury to measure serum protein S-100 levels. Neurological outcome was assessed up to seven days after trauma. Secondary neurological deterioration was defined as two points or more decrease from the initial GCS, or any treatment for neurological deterioration.

RESULTS

Nine patients had a secondary neurological deterioration after trauma. No differences in serum levels of protein S-100 were found between these patients and those without neurological aggravation (n=58 patients): 0.93 microg/l (0.14-4.85) vs 0.39 microg/l (0.04-6.40), respectively. The proportion of patients with abnormal levels of serum protein S-100 at admission according to two admitted cut-off levels (>0.1 and >0.5 microg/l) was comparable between the two groups of patients. Elevated serum levels of protein S-100 were found in patients with Injury Severity Score (ISS) of more than 16 (n=23 patients): 1.26 microg/l (0.14-6.40) vs 0.22 microg/l (0.04-6.20) in patients with ISS less than 16 (n=44 patients).

DISCUSSION

The dosage of serum protein S-100 on admission failed to predict patients at risk for neurological deterioration after minor or moderate TBI. Extracranial injuries can increase serum protein S-100 levels, then limiting the usefulness of this dosage in this clinical setting.

Serum cleaved tau does not predict postconcussion syndrome after mild traumatic brain injury

OBJECTIVES

Our objective was to determine if the biomarker for axonal injury, serum cleaved tau (C-tau), predicts postconcussion syndrome (PCS) in adults after mild traumatic brain injury (mTBI).

METHODS

C-tau was measured from blood obtained in the emergency department. Outcome was assessed at 3 months post injury using the Rivermead Postconcussion Symptoms Questionnaire and Acute Medical Outcomes SF-36v2 Health Survey (SF-36).

RESULTS

Of 50 patients, there were 15 patients with detectable levels of C-tau, 10 patients with abnormal findings on initial head computed tomography (CT) and 22 patients with PCS. One-third of patients with detectable C-tau and 14.3% of patients without detectable C-tau had abnormal findings on head CT (P = .143). Serum C-tau was not detected more frequently in patients with PCS than those without, neither for all patients (P = .115) nor the subgroup with negative head CT (P = .253).

CONCLUSIONS

C-tau is a poor predictor of PCS after mTBI regardless of head CT result.

Biomarker evidence for mild central nervous system injury after surgically-induced circulation arrest

Previously, we identified 14-3-3 beta and zeta isoforms and proteolytic fragments of alpha-spectrin as proteins released from degenerating neurons that also rise markedly in cerebrospinal fluid (CSF) following experimental brain injury or ischemia in rodents, but these proteins have not been studied before as potential biomarkers for ischemic central nervous system injury in humans. Here we describe longitudinal analysis of these proteins along with the neuron-enriched hypophosphorylated neurofilament H (pNFH) and the deubiquitinating enzyme UCH-L1 in lumbar CSF samples from 19 surgical cases of aortic aneurysm repair, 7 involving cardiopulmonary bypass with deep hypothermic circulatory arrest (DHCA). CSF levels of the proteins were near the lower limit of detection by Western blot or enzyme-linked fluorescence immunoassay at the onset of surgical procedures, but increased substantially in a subset of cases, typically within 12-24 h. All cases involving DHCA were characterized by >3-fold elevations in CSF levels of the two 14-3-3 isoforms, UCH-L1, and pNFH. Six of 7 also exhibited marked increases in alpha-spectrin fragments generated by calpain, a protease known to trigger necrotic neurodegeneration. Among cases involving aortic cross-clamping but not DHCA, the proteins rose in CSF preferentially in the subset experiencing acute neurological complications. Our results suggest the neuron-enriched 14-3-3beta, 14-3-3zeta, pNFH, UCH-L1, and calpain-cleaved alpha-spectrin may serve as a panel of biomarkers with clinical potential for the detection and management of ischemic central nervous system injury, including for mild damage associated with surgically-induced circulation arrest.

Head injury outcome prediction: a role for protein S-100B?

INTRODUCTION

Prediction of the likely outcome of head injury from the outset would allow early rehabilitation to be targeted at those with most to gain. Clinical evaluation of a head injured patient may be confounded by intoxicants such as alcohol. Imaging modalities are insensitive (CT) or impractical (MR) for screening populations of such patients. A peripheral marker that reflected the extent of brain injury might offer an objective indication of likely adverse sequelae. This review evaluates the evidence for Protein S-100B as such a marker.

METHODS

A search of published literature revealed 18 studies designed to evaluate the relation between serum S-100B and measures of outcome after head injury.

RESULTS

A cut-off point of 2.5microg/L is related to dependent disability in those presenting with low conscious level, and may be a specific test for this. There appears to be a relation between initial serum S-100B concentration and measures of disability as well as post-concussion symptoms for those with seemingly mild injuries. There does not appear to be a relation between S-100B and measures of neuropsychological performance.

CONCLUSION

Patients with high levels of S-100B at initial assessment (>2.5microg/L) may represent a high risk group for disability after head trauma.

Serum biochemical markers for post-concussion syndrome in patients with mild traumatic brain injury

Mild traumatic brain injury (MTBI) is a major public health problem in the United States. A significant subset of MTBI patients develop persistent and distressing neurological, cognitive, and behavioral symptoms, known as the post-concussion syndrome (PCS). To date, multiple studies have assessed the relationship between brain-related proteins found in the serum at the time of injury, and the development of PCS. We conducted a systematic review of prospective cohort studies that assessed the ability of serum biochemical markers to predict PCS after MTBI. A total of 11 studies assessing three different potential biochemical markers of PCS--S100 proteins, neuron-specific enolase (NSE), and cleaved Tau protein (CTP)--met selection criteria. Of these markers, S100 appeared to be the best researched. We conclude that no biomarker has consistently demonstrated the ability to predict PCS after MTBI. A combination of clinical factors in conjunction with biochemical markers may be necessary to develop a comprehensive decision rule that more accurately predicts PCS after MTBI.

The Use of Serum Biomarkers to Predict Outcome After Traumatic Brain Injury in Adults and Children

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in adults and children. Predicting outcome after TBI is difficult, but it is important for acute management, counseling of family members, and provision of rehabilitation services. Serum biomarkers may be useful alone or in combination with clinical variables to predict outcome after TBI. This article reviews the potential uses of serum biomarkers for the clinician, current literature related to the use of serum biomarkers for outcome prediction after adult and pediatric TBI, limitations of the literature, and future direction for this field.