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

mTBI Biological Biomarkers as Predictors of Postconcussion Syndrome-Review

Postconcussion syndrome (PCS) is one of the leading complications that may appear in patients after mild head trauma. Every day, thousands of people, regardless of age, gender, and race, are diagnosed in emergency departments due to head injuries. Traumatic Brain Injury (TBI) is a significant public health problem, impacting an estimated 1.5 million people in the United States and up to 69 million people worldwide each year, with 80% of these cases being mild. An analysis of the available research and a systematic review were conducted to search for a solution to predicting the occurrence of postconcussion syndrome. Particular biomarkers that can be examined upon admission to the emergency department after head injury were found as possible predictive factors of PCS development. Setting one unequivocal definition of PCS is still a challenge that causes inconsistent results. Neuron Specific Enolase (NSE), Glial Fibrillary Acidic Protein (GFAP), Ubiquitin C-terminal Hydrolase-L1 (UCH-L1), Serum Protein 100 B (s100B), and tau protein are found to be the best predictors of PCS development. The presence of all mentioned biomarkers is confirmed in severe TBI. All mentioned biomarkers are used as predictors of PCS. A combined examination of NSE, GFAP, UCH-1, S100B, and tau protein should be performed to detect mTBI and predict the development of PCS.

Lack of association between four biomarkers and persistent post-concussion symptoms after a mild traumatic brain injury

Approximately 15 % of individuals who sustained a mild Traumatic Brain Injury (TBI) develop persistent post-concussion symptoms (PPCS). We hypothesized that blood biomarkers drawn in the Emergency Department (ED) could help predict PPCS. The main objective of this project was to measure the association between four biomarkers and PPCS at 90 days post mild TBI. We conducted a prospective cohort study in seven Canadian EDs. Patients aged ≥ 14 years presenting to the ED within 24 h of a mild TBI who were discharged were eligible. Clinical data and blood samples were collected in the ED, and a standardized questionnaire was administered 90 days later to assess the presence of symptoms. The following biomarkers were analyzed: S100B protein, Neuron Specific Enolase (NSE), cleaved-Tau (c-Tau) and Glial Fibrillary Acidic Protein (GFAP). The primary outcome measure was the presence of PPCS at 90 days after trauma. Relative risks and Areas Under the Curve (AUC) were computed. A total of 595 patients were included, and 13.8 % suffered from PPCS at 90 days. The relative risk of PPCS was 0.9 (95 % CI: 0.5-1.8) for S100B ≥ 20 pg/mL, 1.0 (95 % CI: 0.6-1.5) for NSE ≥ 200 pg/mL, 3.4 (95 % CI: 0.5-23.4) for GFAP ≥ 100 pg/mL, and 1.0 (95 % CI: 0.6-1.8) for C-Tau ≥ 1500 pg/mL. AUC were 0.50, 0.50, 0.51 and 0.54, respectively. Among mild TBI patients, S100B protein, NSE, c-Tau or GFAP do not seem to predict PPCS. Future research testing of other biomarkers is needed to determine their usefulness in predicting PPCS.

Plasma von Willebrand Factor Is Elevated Hyperacutely After Mild Traumatic Brain Injury

Each year in the United States, ∼2.7 million persons seek medical attention for traumatic brain injury (TBI), of which ∼85% are characterized as being mild brain injuries. Many different cell types in the brain are affected in these heterogeneous injuries, including neurons, glia, and the brain vasculature. Efforts to identify biomarkers that reflect the injury of these different cell types have been a focus of ongoing investigation. We hypothesized that von Willebrand factor (vWF) is a sensitive biomarker for acute traumatic vascular injury and correlates with symptom severity post-TBI. To address this, blood was collected from professional boxing athletes (n = 17) before and within 30 min after competition. Plasma levels of vWF and neuron-specific enolase were measured using the Meso Scale Discovery, LLC. (MSD) electrochemiluminescence array-based multi-plex format (MSD, Gaithersburg, MD). Additional symptom and outcome data from boxers and patients, such as the Rivermead symptom scores (Rivermead Post Concussion Symptoms Questionnaire [RPQ-3]), were collected. We found that, subsequent to boxing bouts, there was a 1.8-fold increase in vWF levels within 30 min of injury (p < 0.0009). Moreover, fold-change in vWF correlates moderately (r = 0.51; p = 0.03) with the number of head blows. We also found a positive correlation (r = 0.69; p = 0.002) between fold-change in vWF and self-reported post-concussive symptoms, measured by the RPQ-3. The receiver operating curve analysis of vWF plasma levels and RPQ-3 scoring yielded a sensitivity of 94.12% and a specificity of 76.5% with an area under the curve of 83% for boxers after a fight compared to the pre-bout baseline. This study suggests that vWF is a potential blood biomarker measurable in the hyperacute period after blunt mild TBI. This biomarker may prove to be useful in diagnosing and monitoring traumatic vascular injury.

Prognostic factors for persistent symptoms in adults with mild traumatic brain injury: an overview of systematic reviews

BACKGROUND

Mild traumatic brain injury (mTBI) is an increasing public health problem, because of its persistent symptoms and several functional consequences. Understanding the prognosis of a condition is an important component of clinical decision-making and can help to guide the prevention of persistent symptoms following mTBI. The prognosis of mTBI has stimulated several empirical primary research papers and many systematic reviews leading to the identification of a wide range of factors. We aim to synthesize these factors to get a better understanding of their breadth and scope.

METHODS

We conducted an overview of systematic reviews. We searched in databases systematic reviews synthesizing evidence about the prognosis of persistent symptoms after mTBI in the adult population. Two reviewers independently screened all references and selected eligible reviews based on eligibility criteria. They extracted relevant information using an extraction grid. They also rated independently the risk of bias using the ROBIS tool. We synthesized evidence into a comprehensive conceptual map to facilitate the understanding of prognostic factors that have an impact on persistent post-concussion symptoms.

RESULTS

From the 3857 references retrieved in a database search, we included 25 systematic reviews integrating the results of 312 primary articles published between 1957 and 2019. We examined 35 prognostic factors from the systematics reviews. No single prognostic factor demonstrated convincing and conclusive results. However, age, sex, and multiple concussions showed an affirmatory association with persistent post-concussion outcomes in systematic reviews.

CONCLUSION

We highlighted the need for a comprehensive picture of prognostic factors related to persistent post-concussion symptoms. We believe that these prognostic factors would guide clinical decisions and research related to prevention and intervention regarding persistent post-concussion symptoms.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42020176676.

Identifying prioritization criteria for patients with mtbi waiting for multidisciplinary rehabilitation services: A Delphi study

INTRODUCTION

Rehabilitation service providers must take into account prognostic factors when making clinical decisions, which includes using these factors as prioritization criteria. The goal of this study was to establish consensus on patient prioritization criteria based on prognostic factors related to persistent symptoms for patients with mild traumatic brain injury (mTBI) waiting for outpatient specialized rehabilitation services.

MATERIALS AND METHODS

We conducted a Delphi survey involving clinicians, researchers, decision makers, and patients. Before the survey, we presented the results of an overview of systematic reviews summarizing the evidence on prognostic factors related to post-concussion symptoms.

RESULTS

After two rounds, the 17 experts reached consensus on the inclusion of 12 prioritization criteria: acute stress disorder, anxiety and depression, baseline mental and physical health, functional impacts and difficulties in performing daily habits after the trauma, motivation to receive services, multiple concussions, prior neurological problems, PTSD, quality of sleep, return to work failures, somatic complaints, suicidal ideation.

CONCLUSION

Healthcare stakeholders must consider a wide range of factors to guide clinical decision-making, including about access to care and patient prioritization. This study shows that the Delphi technique can be used to reach consensus on such decisions regarding patients with mTBI who are waiting for outpatient specialized rehabilitation services.

Sex Differences in Cerebral Blood Flow and Serum Inflammatory Cytokines and Their Relationships in Mild Traumatic Brain Injury

This study aimed to investigate sex differences in cerebral blood flow (CBF) and serum inflammatory cytokines, as well as their correlations in patients with acute-stage mild traumatic brain injury (mTBI). Forty-one patients with mTBI and 23 matched healthy controls underwent 3D-pseudo-continuous arterial spin labeling imaging on 3T magnetic resonance imaging. The patients underwent cognitive evaluations and measurement of a panel of ten serum cytokines: interleukin (IL)-1I, IL-4, IL-6, IL-8, IL-10, IL-12, C–C motif chemokine ligand 2, interferon-gamma, nerve growth factor-beta (β-NGF), and tumor necrosis factor-alpha (TNF-α). Spearman rank correlation analysis was performed to evaluate the relationship between inflammation levels and CBF. We found that both male and female patients showed increased IL-1L and IL-6 levels. Female patients also demonstrated overexpression of IL-8 and low expression of IL-4. As for CBF levels, three brain regions [the right superior frontal gyrus (SFG_R), left putamen, and right precuneus] increased in male patients while three brain regions [the right superior temporal gyrus (STG_R), left middle occipital gyrus, and right postcentral (PoCG_R)] decreased in female patients. Furthermore, the STG_R in female controls was positively correlated with β-NGF while the right PoCG_R in female patients was negatively correlated with IL-8. In addition, compared with male patients, female patients showed decreased CBF in the right pallidum, which was negatively correlated with IL-8. These findings revealed abnormal expression of serum inflammatory cytokines and CBF levels post-mTBI. Females may be more sensitive to inflammatory and CBF changes and thus more likely to get cognitive impairment. This may suggest the need to pay closer attention to the female mTBI group.

Effect of erythropoietin administration on expression of mRNA brain-derived Neutrophic factor, levels of stromal cell-derived Factor-1, and neuron specific enolase in brain injury model Sprague Dawley

BACKGROUND

Traumatic brain injury (TBI) is a complicated condition that is the primary cause of death and disability in children and young adults in developed countries. Various kinds of therapy have been carried out in the management of brain injury, one of which is the administration of erythropoietin (EPO). There are not many studies in Indonesia have proven that EPO administration is effective on parameters such as stromal cell-derived factor 1 (SDF-1), brain-derived neurotrophic factor (BDNF mRNA), and neuron-specific enolase (NSE) in brain injury patients. The purpose of this study was to see how EPO affected BDNF mRNA expression, SDF-1 serum levels, and NSE levels in experimental rats with TBI.

METHODS

This study was conducted using a rat head injury model. Fifteen rats were randomly assigned to one of three groups: A, B, or C. EPO was administered subcutis with a dose of 30.000 U/kg. Blood samples were taken after brain injury (H0), 12 h (H12), and 24 h (H24) after brain injury. Serum level of SDF-1 and NSE were measured using mRNA BDNF gene expression was measured with Real-Time-PCR, and ELISA.

RESULTS

This study found EPO increase BDNF mRNA expression in group C at H-12 (7,92 ± 0.51 vs 6.45 ± 0.33) compared to group B, and at H-24 (9.20 ± 0.56 vs 7.22 ± 0.19); increase SDF-1 levels in group C at H-12 (7,56 ± 0,54) vs 4,62 ± 0,58) compared to group B, and at H-24 (11,32 ± 4,55 vs 2,55 ± 0,70); decrease serum NSE levels in group C at H-12 (17,25 ± 2,02 vs 29,65 ± 2,33) compare to group B and at H-24 (12,14 ± 2,61 vs 37,31 ± 2,76); the values are significantly different with p < 0,05.

CONCLUSION

EPO may have neuroprotective and anti-inflammatory properties in TBI by increasing mRNA BDNF expression and serum SDF-1 levels, and decrease serum NSE levels.

Biofluid Biomarkers in Traumatic Brain Injury: A Systematic Scoping Review

Emerging evidence suggests that biofluid-based biomarkers have diagnostic and prognostic potential in traumatic brain injuries (TBI). However, owing to the lack of a conceptual framework or comprehensive review, it is difficult to visualize the breadth of materials that might be available. We conducted a systematic scoping review to map and categorize the evidence regarding biofluid-based biochemical markers of TBI. A comprehensive search was undertaken in January 2019. Of 25,354 records identified through the literature search, 1036 original human studies were included. Five hundred forty biofluid biomarkers were extracted from included studies and classified into 19 distinct categories. Three categories of biomarkers including cytokines, coagulation tests, and nerve tissue proteins were investigated more than others and assessed in almost half of the studies (560, 515, and 502 from 1036 studies, respectively). S100 beta as the most common biomarker for TBI was tested in 21.2% of studies (220 articles). Cortisol was the only biomarker measured in blood, cerebrospinal fluid, urine, and saliva. The most common sampling time was at admission and within 24 h of injury. The included studies focused mainly on biomarkers from blood and central nervous system sources, the adult population, and severe and blunt injuries. The most common outcome measures used in studies were changes in biomarker concentration level, Glasgow coma scale, Glasgow outcome scale, brain computed tomography scan, and mortality rate. Biofluid biomarkers could be clinically helpful in the diagnosis and prognosis of TBI. However, there was no single definitive biomarker with accurate characteristics. The present categorization would be a road map to investigate the biomarkers of the brain injury cascade separately and detect the most representative biomarker of each category. Also, this comprehensive categorization could provide a guiding framework to design combined panels of multiple biomarkers.

Effects of Memantine in Patients with Traumatic Brain Injury: A Systematic Review

Traumatic brain injury (TBI) affects millions of people around the world and amongst other effects, causes cognitive decline, neurodegenerative disease and increased risk of seizures and sensory disturbances. Excitotoxicity and apoptosis occur after TBI and are mediated through the N-methyl-D-aspartate (NMDA)-type glutamate receptor. Memantine is effective in blocking excessive activity of NMDA-type glutamate receptors and reduces the progression of dementia and may have benefits after TBI. Here, we performed a systematic review of the literature to evaluate whether memantine is effective in improving outcomes, including cognitive function in patients with TBI. Our search yielded only 4 randomized control trials (RCTs) that compared the effects of memantine to placebos, standard treatment protocols or piracetam. A single RCT reported that serum neuron-specific enolase (NSE) levels were significantly reduced (p = 0.009) in the memantine compared to the control group, and this coincided with reported significant day-to-day improvements in Glasgow Coma Scale (GCS) for patients receiving memantine. The remaining RCTs investigated the effects of memantine on cognitive function using 26 standardized tests for assessing cognition function. One RCT reported significant improvements in cognitive function across all domains whilst the other two RCTs, reported that patients in the memantine group underperformed in all cognitive outcome measures. This review shows that despite laboratory and clinical evidence reporting reduced serum NSE and improved GCS, supporting the existence of the neuroprotective properties, there is a lack of reported evidence from RCTs to suggest that memantine directly leads to cognitive improvements in TBI patients.

Serum Cleaved Tau Protein and Clinical Outcome in Patients with Minor Head Trauma

INTRODUCTION

Minor head trauma is due to the transfer of a mechanical energy to the brain caused by a traumatic event. The present study was accomplished aiming to investigate the cleaved tau protein (CTP) as a brain injury biomarker among patients with minor head trauma.

PATIENTS AND METHODS

This observational study was performed on patients with minor head trauma in 2017 who referred to emergency department of Imam Khomeini Hospital and Golestan Hospital of Ahvaz, Iran. The patients over the age of 16 years old with minor head trauma, who had computed tomography (CT) scan at most 10 hrs after the incident, and consented to participate in the study, were enrolled. C-tau evaluation was performed by the enzyme-linked immunosorbent assay (ELISA) method with monoclonal antibodies detecting the C-tau marker. Investigation of the injury after 3 months of minor head trauma was conducted using a post-concussion syndrome questionnaire (RPCS).

RESULTS

In this study, 86 patients were evaluated. CTP was positive in 14% of the patients and the results revealed that there was a significant relationship between traumatic brain injury (TBI) and positive CTP (p < 0.0001). The CTP had a sensitivity and specificity of, respectively, 92% and 100% in detecting intracranial trauma. In addition, positive and negative predictive powers for this marker were 100% and 98%, respectively.

CONCLUSION

In general, contrary to previous studies, the findings of this study suggest that evaluation of the CTP levels can be a strong biomarker with high sensitivity and specificity in detecting TBI.

Novel Mouse Tauopathy Model for Repetitive Mild Traumatic Brain Injury: Evaluation of Long-Term Effects on Cognition and Biomarker Levels After Therapeutic Inhibition of Tau Phosphorylation

Traumatic brain injury (TBI) is a risk factor for a group of neurodegenerative diseases termed tauopathies, which includes Alzheimer's disease and chronic traumatic encephalopathy (CTE). Although TBI is stratified by impact severity as either mild (m), moderate or severe, mTBI is the most common and the most difficult to diagnose. Tauopathies are pathologically related by the accumulation of hyperphosphorylated tau (P-tau) and increased total tau (T-tau). Here we describe: (i) a novel human tau-expressing transgenic mouse model, TghTau/PS1, to study repetitive mild closed head injury (rmCHI), (ii) quantitative comparison of T-tau and P-tau from brain and plasma in TghTau/PS1 mice over a 12 month period following rmCHI (and sham), (iii) the usefulness of P-tau as an early- and late-stage blood-based biochemical biomarker for rmCHI, (iii) the influence of kinase-targeted therapeutic intervention on rmCHI-associated cognitive deficits using a combination of lithium chloride (LiCl) and R-roscovitine (ros), and (iv) correlation of behavioral and cognitive changes with concentrations of the brain and blood-based T-tau and P-tau. Compared to sham-treated mice, behavior changes and cognitive deficits of rmCHI-treated TghTau/PS1 mice correlated with increases in both cortex and plasma T-tau and P-tau levels over 12 months. In addition, T-tau, but more predominantly P-tau, levels were significantly reduced in the cortex and plasma by LiCl + ros approaching the biomarker levels in sham and drug-treated sham mice (the drugs had only modest effects on the T-tau and P-tau levels in sham mice) throughout the 12 month study period. Furthermore, although we also observed a reversal of the abnormal behavior and cognitive deficits in the drug-treated rmCHI mice (compared to the untreated rmCHI mice) throughout the time course, these drug-treated effects were most pronounced up until 10 and 12 months where the abnormal behavior and cognition deficits began to gradually increase. These studies describe: (a) a translational relevant animal model for TBI-linked tauopathies, and (b) utilization of T-tau and P-tau as rmCHI biomarkers in plasma to monitor novel therapeutic strategies and treatment regimens for these neurodegenerative diseases.

Prevalence of Postconcussion Syndrome after Mild Traumatic Brain Injury in Young Adults from a Single Neurosurgical Center in East Coast of Malaysia

Context:

Postconcussion syndrome (PCS) is a set of symptoms occurred after a mild traumatic brain injury (MTBI). Aims: This study aims to determine the prevalence of PCS in a young adult population from a single Neurological Centre in Malaysia's East Coast and to evaluate the factors associated with PCS in MTBI patients.

Settings and Design:

This was a cross-sectional study conducted in a Neurological Centre at Hospital Tengku Ampuan Afzan, Kuantan, Pahang, Malaysia, from January 2016 to December 2016.

Subjects and Methods:

A total of 209 patients; 133 males and 76 females, in the age range of 16–84 years, were randomly recruited for this study. All the selected patients were subjected to the checklist for diagnosis of PCS as per International Statistical Classification of Diseases and Related Health Problems 10^th edition classification at a 2-week interval.

Statistical Analysis Used:

Descriptive statistic and Multivariable Logistic Regression Model were used for frequency and percentage analyses of categorical variables, using SPSS version 23.0.

Results:

Only 20 patients were identified with PCS. There were more female (70%) patients with PCS than the male (30%) patients. The prevalence of PCS for 2 weeks, 3 and 6 months since injuries were 9.6%, 8.1%, and 8.1% respectively. Majority (80%) of the patients were found to have PCS due to road traffic accidents, while the remaining were attributed to assault (15%), and falls (5%). Among the sample population, 25% were smokers, while 10% of them had either skull fracture or premorbidity.

Conclusion:

Less than 10% of patients with MTBI had PCS after 6 months’ following trauma. None of the variables tested were significant factors for the development of PCS symptoms.

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.

Effects of concussion on the blood-brain barrier in humans and rodents

Traumatic brain injury and the long-term consequences of repeated concussions constitute mounting concerns in the United States, with 5.3 million individuals living with a traumatic brain injury-related disability. Attempts to understand mechanisms and possible therapeutic approaches to alleviate the consequences of repeat mild concussions or traumatic brain injury on cerebral vasculature depend on several aspects of the trauma, including: (1) the physical characteristics of trauma or insult that result in damage; (2) the time “window” after trauma in which neuropathological features develop; (3) methods to detect possible breakdown of the blood–brain barrier; and (4) understanding different consequences of a single concussion as compared with multiple concussions. We review the literature to summarize the current understanding of blood–brain barrier and endothelial cell changes post-neurotrauma in concussions and mild traumatic brain injury. Attention is focused on concussion and traumatic brain injury in humans, with a goal of pointing out the gaps in our knowledge and how studies of rodent model systems of concussion may help in filling these gaps. Specifically, we focus on disruptions that concussion causes to the blood–brain barrier and its multifaceted consequences. Importantly, the magnitude of post-concussion blood–brain barrier dysfunction may influence the time course and extent of neuronal recovery; hence, we include in this review comparisons of more severe traumatic brain injury to concussion where appropriate. Finally, we address the important, and still unresolved, issue of how best to detect possible breakdown in the blood–brain barrier following neurotrauma by exploring intravascular tracer injection in animal models to examine leakage into the brain parenchyma.

Local and distant trauma after hypervelocity ballistic impact to the pig hind limb

The development of high-energy weapons could increase the velocity of projectiles to well over 1000 m/s. The nature of the injuries caused by the ballistic impact of projectiles at velocities much faster than 1000 m/s is unclear. This study characterizes the mechanical and biochemical alterations caused by high-speed ballistic impact generated by spherical steel ball to the hind limbs of the pig. That the local and distal injuries caused by hypervelocity ballistic impact to the living body are also identified. It is showed that the severity of the injury was positively correlated with the velocity of the projectile. And 4000 m/s seems to be the critical velocity for the 5.6 mm spherical steel ball, which would cause severe damage to either local or distal organs, as below that speed the projectile penetrated the body while above that speed it caused severe damage to the body. In addition, vaporization prevented the projectile from penetrating the body and the consequent pressure wave seems to be the causal factor for the distant damage.

Diffusion Tensor Imaging Findings in Post-Concussion Syndrome Patients after Mild Traumatic Brain Injury: A Systematic Review

Objectives

To review the evidence for the use of diffusion tensor imaging (DTI) parameters in the human brain as a diagnostic tool for and predictor of post-concussion syndrome (PCS) after a mild traumatic brain injury (mTBI).

Design

Systematic review.

Data sources

All relevant studies in AMED, Embase, MEDLINE, Ovid, PubMed, Scopus, and Web of Science through 20 May, 2016.

Study selection

Studies that analyze traditional DTI measures [fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD)] and the severity of PCS symptoms or the development of PCS in humans after an mTBI.

Data extraction

Population studied, patient source, mTBI diagnosis method, PCS diagnosis method, DTI values measured, significant findings, and correlation between DTI findings and PCS.

Data synthesis

Ten studies investigated correlations between DTI values and PCS symptom severity or between DTI values and the development of PCS in mTBI patients. Decreased FA and increased MD and RD were associated with the development and severity of PCS. AD was not found to change significantly. Brain regions found to have significant changes in DTI parameters varied from study to study, although the corpus callosum was most frequently cited as having abnormal DTI parameters in PCS patients.

Conclusion

DTI abnormalities correlate with PCS incidence and symptom severity, as well as indicate an increased risk of developing PCS after mTBI. Abnormal DTI findings should prompt investigation of the syndrome to ensure optimal symptom management at the earliest stages. Currently, there is no consensus in the literature about the use of one DTI parameter in a specific region of the brain as a biomarker for PCS because no definite trends for DTI parameters in PCS subjects have been identified. Further research is required to establish a standard biomarker for PCS.

Utility of neuron-specific enolase in traumatic brain injury; relations to S100B levels, outcome, and extracranial injury severity

BACKGROUND

In order to improve assessment and outcome prediction in patients suffering from traumatic brain injury (TBI), cerebral protein levels in serum have been suggested as biomarkers of injury. However, despite much investigation, biomarkers have yet to reach broad clinical utility in TBI. This study is a 9-year follow-up and clinical experience of the two most studied proteins, neuron-specific enolase (NSE) and S100B, in a neuro-intensive care TBI population. Our aims were to investigate to what extent NSE and S100B, independently and in combination, could predict outcome, assess injury severity, and to investigate if the biomarker levels were influenced by extracranial factors.

METHODS

All patients treated at the neuro-intensive care unit at Karolinska University Hospital, Stockholm, Sweden between 2005 and 2013 with at least three measurements of serum S100B and NSE (sampled twice daily) were retrospectively included. In total, 417 patients fulfilled the criteria. Parameters were extracted from the computerized hospital charts. Glasgow Outcome Score (GOS) was used to assess long-term functional outcome. Univariate, and multivariate, regression models toward outcome and what explained the high levels of the biomarkers were performed. Nagelkerke's pseudo-R(2) was used to illustrate the explained variance of the different models. A sliding window assessed biomarker correlation to outcome and multitrauma over time.

RESULTS

S100B was found a better predictor of outcome as compared to NSE (area under the curve (AUC) samples, the first 48 hours had Nagelkerke's pseudo-R(2) values of 0.132 and 0.038, respectively), where the information content of S100B peaks at approximately 1 day after trauma. In contrast, although both biomarkers were independently correlated to outcome, NSE had limited additional predictive capabilities in the presence of S100B in multivariate models, due to covariance between the two biomarkers (correlation coefficient 0.673 for AUC 48 hours). Moreover, NSE was to a greater extent correlated to multitrauma the first 48 hours following injury, whereas the effect of extracerebral trauma on S100B levels appears limited to the first 12 hours.

CONCLUSIONS

While both biomarkers are independently correlated to long-term functional outcome, S100B is found a more accurate outcome predictor and possibly a more clinically useful biomarker than NSE for TBI patients.

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.

Arterial Spin Labeling Magnetic Resonance Perfusion for Traumatic Brain Injury: Technical Challenges and Potentials

Traumatic brain injury (TBI), including concussion, is a public health concern, as it affects over 1.7 million persons in the United States per year. Yet, the diagnosis of TBI, particularly mild TBI (mTBI), can be controversial, as neuroimaging findings can be sparse on conventional magnetic resonance and computed tomography examinations, and when present, often poorly correlate with clinical signs and symptoms. Furthermore, the discussion of TBI, concussion, and head impact exposure is immediately complicated by the many differing opinions of what constitutes each, their respective severities, and how the underlying biomechanics of the inciting head impact might alter the distribution, severity, and prognosis of the underlying brain injury. Advanced imaging methodologies hold promise in improving the sensitivity and detectability of associated imaging biomarkers that might better correlate with patient outcome and prognostication, allowing for improved triage and therapeutic guidance in the setting of TBI, particularly in mTBI. This work will examine the defining symptom complex associated with mTBI and explore changes in cerebral blood flow measured by arterial spin labeling, as a potential imaging biomarker for TBI, and briefly correlate these observations with findings identified by single photon emission computed tomography and positron emission tomography imaging.

The long-term effects of repetitive mild head injuries in sports

At least 300 000 sports-related concussions occur in the United States annually. With millions of American athletes, the long-term effects of repeated concussion or mild traumatic brain injury are an important topic. Unfortunately, there is a lack of strong data on the causality or prevalence of long-term effects among athletes. Chronic traumatic encephalopathy (CTE), a progressive neurodegenerative tauopathy, with associated clinical, behavioral, and neuropathological findings, is an important clinical entity in need of further study. Diffusion tensor imaging can elucidate trauma-induced white matter damage, but the diagnosis of CTE cannot be proven until postmortem neuropathology shows characteristic neurofibrillary and astrocytic tangles. Concern exists that athletes subject to repeated concussive and even subconcussive blows may be at risk of CTE, but no definitive data exist due to the difficulty in diagnosis. Animal models suggest that mild traumatic brain injuries lead to primarily a metabolic derangement with increased excitotoxic neurotransmitter release, extracellular potassium, and intracellular calcium. Further understanding of the underlying pathophysiology may eventually lead to better therapeutic and diagnostic options for the treating clinician.

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.

Predictors of postconcussion syndrome after sports-related concussion in young athletes: a matched case-control study

OBJECT Sport-related concussion (SRC) is a major public health problem. Approximately 90% of SRCs in high school athletes are transient; symptoms recover to baseline within 1 week. However, a small percentage of patients remain symptomatic several months after injury, with a condition known as postconcussion syndrome (PCS). The authors aimed to identify risk factors for PCS development in a cohort of exclusively young athletes (9-18 years of age) who sustained SRCs while playing a sport. METHODS The authors conducted a retrospective case-control study by using the Vanderbilt Sports Concussion Clinic database. They identified 40 patients with PCS and matched them by age at injury and sex to SRC control patients (1 PCS to 2 control). PCS patients were those experiencing persistent symptoms at 3 months after an SRC. Control patients were those with documented resolution of symptoms within 3 weeks of an SRC. Data were collected in 4 categories: 1) demographic variables; 2) key medical, psychiatric, and family history; 3) acute-phase postinjury symptoms (at 0-24 hours); and 4) subacute-phase postinjury features (at 0-3 weeks). The chi-square Fisher exact test was used to assess categorical variables, and the Mann-Whitney U-test was used to evaluate continuous variables. Forward stepwise regression models (Pin = 0.05, Pout = 0.10) were used to identify variables associated with PCS. RESULTS PCS patients were more likely than control patients to have a concussion history (p = 0.010), premorbid mood disorders (p = 0.002), other psychiatric illness (p = 0.039), or significant life stressors (p = 0.036). Other factors that increased the likelihood of PCS development were a family history of mood disorders, other psychiatric illness, and migraine. Development of PCS was not predicted by race, insurance status, body mass index, sport, helmet use, medication use, and type of symptom endorsement. A final logistic regression analysis of candidate variables showed PCS to be predicted by a history of concussion (OR 1.8, 95% CI 1.1-2.8, p = 0.016), preinjury mood disorders (OR 17.9, 95% CI 2.9-113.0, p = 0.002), family history of mood disorders (OR 3.1, 95% CI 1.1-8.5, p = 0.026), and delayed symptom onset (OR 20.7, 95% CI 3.2-132.0, p < 0.001). CONCLUSIONS In this age- and sex-matched case-control study of risk factors for PCS among youth with SRC, risk for development of PCS was higher in those with a personal and/or family history of mood disorders, other psychiatric illness, and migraine. These findings highlight the unique nature of SRC in youth. For this population, providers must recognize the value of establishing the baseline health and psychiatric status of children and their primary caregivers with regard to symptom reporting and recovery expectations. In addition, delayed symptom onset was an unexpected but strong risk factor for PCS in this cohort. Delayed symptoms could potentially result in late removal from play, rest, and care by qualified health care professionals. Taken together, these results may help practitioners identify young athletes with concussion who are at a greater danger for PCS and inform larger prospective studies for validation of risk factors from this cohort.

A review of the neuro- and systemic inflammatory responses in post concussion symptoms: Introduction of the "post-inflammatory brain syndrome" PIBS

Post-concussion syndrome is an aggregate of symptoms that commonly present together after head injury. These symptoms, depending on definition, include headaches, dizziness, neuropsychiatric symptoms, and cognitive impairment. However, these symptoms are common, occurring frequently in non-head injured controls, leading some to question the existence of post-concussion syndrome as a unique syndrome. Therefore, some have attempted to explain post-concussion symptoms as post-traumatic stress disorder, as they share many similar symptoms and post-traumatic stress disorder does not require head injury. This explanation falls short as patients with post-concussion syndrome do not necessarily experience many key symptoms of post-traumatic stress disorder. Therefore, other explanations must be sought to explain the prevalence of post-concussion like symptoms in non-head injury patients. Many of the situations in which post-concussion syndrome like symptoms may be experienced such as infection and post-surgery are associated with systemic inflammatory responses, and even neuroinflammation. Post-concussion syndrome itself has a significant neuroinflammatory component. In this review we examine the evidence of neuroinflammation in post-concussion syndrome and the potential role systemic inflammation plays in post-concussion syndrome like symptoms. We conclude that given the overlap between these conditions and the role of inflammation in their etiologies, a new term, post-inflammatory brain syndromes (PIBS), is necessary to describe the common outcomes of many different inflammatory insults. The concept of post-concussion syndrome is in its evolution therefore, the new term post-inflammatory brain syndromes provides a better understanding of etiology of its wide-array of symptoms and the wide array of conditions they can be seen in.

S100B blood levels and childhood trauma in adolescent inpatients

BACKGROUND

Serum levels of the astrocytic protein S100B have been reported to indicate disruption of the blood-brain barrier. In this study, we investigated the relationship between S100B levels and childhood trauma in a child psychiatric inpatient unit.

METHOD

Levels of S100B were measured in a group of youth with mood disorders or psychosis with and without history of childhood trauma as well as in healthy controls. Study participants were 93 inpatient adolescents admitted with a diagnosis of psychosis (N = 67), or mood disorder (N = 26) and 22 healthy adolescents with no history of trauma or psychiatric illness. Childhood trauma was documented using the Life Events Checklist (LEC) and Adverse Child Experiences (ACE).

RESULTS

In a multivariate regression model, suicidality scores and trauma were the only two variables which were independently related to serum S100B levels. Patients with greater levels of childhood trauma had significantly higher S100B levels even after controlling for intensity of suicidal ideation. Patients with psychotic diagnoses and mood disorders did not significantly differ in their levels of S100B. Patients exposed to childhood trauma were significantly more likely to have elevated levels of S100B (p < .001) than patients without trauma, and patients with trauma had significantly higher S100B levels (p < .001) when compared to the control group. LEC (p = 0.046), and BPRS-C suicidality scores (p = 0.001) significantly predicted S100B levels.

CONCLUSIONS

Childhood trauma can potentially affect the integrity of the blood-brain barrier as indicated by associated increased S100B levels.

The prognostic value of serum neuron-specific enolase in traumatic brain injury: systematic review and meta-analysis

BACKGROUND

Several studies have suggested that neuron-specific enolase (NSE) in serum may be a biomarker of traumatic brain injury. However, whether serum NSE levels correlate with outcomes remains unclear. The purpose of this review was to evaluate the prognostic value of serum NSE protein after traumatic brain injury.

METHODS

PubMed and Embase were searched for relevant studies published up to October 2013. Full-text publications on the relationship of NSE to TBI were included if the studies concerned patients with closed head injury, NSE levels in serum after injury, and Glasgow Outcome Scale (GOS) or Extended GOS (GOSE) scores or mortality. Study design, inclusion criteria, assay, blood sample collection time, NSE cutoff, sensitivity and specificity of NSE for mortality prediction (if sufficient information was provided to calculate these values), and main outcomes were recorded.

RESULTS

Sixteen studies were eligible for the current meta-analysis. In the six studies comparing NSE concentrations between TBI patients who died and those who survived, NSE concentrations correlated with mortality (M.D. 0.28, 95% confidence interval (CI), 0.21 to 0.34; I2 55%). In the eight studies evaluating GOS or GOSE, patients with unfavorable outcomes had significantly higher NSE concentrations than those with favorable outcomes (M.D. 0.24, 95% CI, 0.17 to 0.31; I2 64%). From the studies providing sufficient data, the pooled sensitivity and specificity for mortality were 0.79 and 0.50, and 0.72 and 0.66 for unfavorable neurological prognosis, respectively. The areas under the SROC curve (AUC) of NSE concentrations were 0.73 (95% CI, 0.66-0.80) for unfavorable outcome and 0.76 (95% CI, 0.62-0.90) for mortality.

CONCLUSIONS

Mortality and unfavorable outcome were significantly associated with greater NSE concentrations. In addition, NSE has moderate discriminatory ability to predict mortality and neurological outcome in TBI patients. The optimal discrimination cutoff values and optimal sampling time remain uncertain because of significant variations between studies.

Traumatic white matter injury and glial activation: from basic science to clinics

An improved understanding and characterization of glial activation and its relationship with white matter injury will likely serve as a novel treatment target to curb post injury inflammation and promote axonal remyelination after brain trauma. Traumatic brain injury (TBI) is a significant public healthcare burden and a leading cause of death and disability in the United States. Particularly, traumatic white matter (WM) injury or traumatic axonal injury has been reported as being associated with patients' poor outcomes. However, there is very limited data reporting the importance of glial activation after TBI and its interaction with WM injury. This article presents a systematic review of traumatic WM injury and the associated glial activation, from basic science to clinical diagnosis and prognosis, from advanced neuroimaging perspective. It concludes that there is a disconnection between WM injury research and the essential role of glia which serve to restore a healthy environment for axonal regeneration following WM injury. Particularly, there is a significant lack of non-invasive means to characterize the complex pathophysiology of WM injury and glial activation in both animal models and in humans. An improved understanding and characterization of the relationship between glia and WM injury will likely serve as a novel treatment target to curb post injury inflammation and promote axonal remyelination.

Functionally-detected cognitive impairment in high school football players without clinically-diagnosed concussion

Head trauma and concussion in football players have recently received considerable media attention. Postmortem evidence suggests that accrual of damage to the brain may occur with repeated blows to the head, even when the individual blows fail to produce clinical symptoms. There is an urgent need for improved detection and characterization of head trauma to reduce future injury risk and promote development of new therapies. In this study we examined neurological performance and health in the presence of head collision events in high school football players, using longitudinal measures of collision events (the HIT(™) System), neurocognitive testing (ImPACT(™)), and functional magnetic resonance imaging MRI (fMRI). Longitudinal assessment (including baseline) was conducted in 11 young men (ages 15-19 years) participating on the varsity and junior varsity football teams at a single high school. We expected and observed subjects in two previously described categories: (1) no clinically-diagnosed concussion and no changes in neurological behavior, and (2) clinically-diagnosed concussion with changes in neurological behavior. Additionally, we observed players in a previously undiscovered third category, who exhibited no clinically-observed symptoms associated with concussion, but who demonstrated measurable neurocognitive (primarily visual working memory) and neurophysiological (altered activation in the dorsolateral prefrontal cortex [DLPFC]) impairments. This new category was associated with significantly higher numbers of head collision events to the top-front of the head, directly above the DLPFC. The discovery of this new category suggests that more players are suffering neurological injury than are currently being detected using traditional concussion-assessment tools. These individuals are unlikely to undergo clinical evaluation, and thus may continue to participate in football-related activities, even when changes in brain physiology (and potential brain damage) are present, which will increase the risk of future neurological injury.

Evidence That the Blood Biomarker SNTF Predicts Brain Imaging Changes and Persistent Cognitive Dysfunction in Mild TBI Patients

Although mild traumatic brain injury (mTBI), or concussion, is not typically associated with abnormalities on computed tomography (CT), it nevertheless causes persistent cognitive dysfunction for many patients. Consequently, new prognostic methods for mTBI are needed to identify at risk cases, especially at an early and potentially treatable stage. Here, we quantified plasma levels of the neurodegeneration biomarker calpain-cleaved αII-spectrin N-terminal fragment (SNTF) from 38 participants with CT-negative mTBI, orthopedic injury (OI), and normal uninjured controls (UCs) (age range 12–30 years), and compared them with findings from diffusion tensor imaging (DTI) and long-term cognitive assessment. SNTF levels were at least twice the lower limit of detection in 7 of 17 mTBI cases and in 3 of 13 OI cases, but in none of the UCs. An elevation in plasma SNTF corresponded with significant differences in fractional anisotropy and the apparent diffusion coefficient in the corpus callosum and uncinate fasciculus measured by DTI. Furthermore, increased plasma SNTF on the day of injury correlated significantly with cognitive impairment that persisted for at least 3 months, both across all study participants and also among the mTBI cases by themselves. The elevation in plasma SNTF in the subset of OI cases, accompanied by corresponding white matter and cognitive abnormalities, raises the possibility of identifying undiagnosed cases of mTBI. These data suggest that the blood level of SNTF on the day of a CT-negative mTBI may identify a subset of patients at risk of white matter damage and persistent disability. SNTF could have prognostic and diagnostic utilities in the assessment and treatment of mTBI.

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.

Serum cleaved tau protein and traumatic mild head injury: a preliminary study in the Thai population

PURPOSE

To determine the correlation between serum cleaved tau protein and traumatic mild head injury (MHI) (GCS 13-15).

METHODS

A prospective observational study was conducted. Blood specimens from 12 healthy persons and 44 adult patients with traumatic MHI were collected in the emergency department to measure the cleaved tau protein level using a Human Tau phosphoSerine 396 ELISA kit. A brain computed tomography (CT) scan was done in all patients. The serum cleaved tau protein level was considered positive at a cut-off point of 0.1 pg/ml. An intracranial lesion was defined as any abnormality detected by brain CT scan.

RESULTS

The mean age of the traumatic MHI patients was 34.9 ± 15.6 years (range 15-74). The median GCS was 15. The median time from injury to arrival at the emergency department was 30 min. There were 11 intracranial lesions detected by brain CT scan (25.0 %). Serum cleaved tau protein was not detected in either healthy or traumatic MHI patients.

CONCLUSION

As it was uncorrelated with traumatic MHI, serum cleaved tau protein proved to be an unreliable biomarker to use in the early detection of and decision-making for traumatic MHI patients at the emergency department.

Biomarkers for the clinical differential diagnosis in traumatic brain injury--a systematic review

Rapid triage and decision-making in the treatment of traumatic brain injury (TBI) present challenging dilemma in "resource poor" environments such as the battlefield and developing areas of the world. There is an urgent need for additional tools to guide treatment of TBI. The aim of this review is to establish the possible use of diagnostic TBI biomarkers in (1) identifying diffuse and focal brain injury and (2) assess their potential for determining outcome, intracranial pressure (ICP), and responses to therapy. At present, there is insufficient literature to support a role for diagnostic biomarkers in distinguishing focal and diffuse injury or for accurate determination of raised ICP. Presently, neurofilament (NF), S100β, glial fibrillary acidic protein (GFAP), and ubiquitin carboxyl terminal hydrolase-L1 (UCH-L1) seemed to have the best potential as diagnostic biomarkers for distinguishing focal and diffuse injury, whereas C-tau, neuron-specific enolase (NSE), S100β, GFAP, and spectrin breakdown products (SBDPs) appear to be candidates for ICP reflective biomarkers. With the combinations of different pathophysiology related to each biomarker, a multibiomarker analysis seems to be effective and would likely increase diagnostic accuracy. There is limited research focusing on the differential diagnostic properties of biomarkers in TBI. This fact warrants the need for greater efforts to innovate sensitive and reliable biomarkers. We advocate awareness and inclusion of the differentiation of injury type and ICP elevation in further studies with brain injury biomarkers.

Application of blood-based biomarkers in human mild traumatic brain injury

Traumatic Brain Injury (TBI) is a global health concern. The majority of TBI's are mild, yet our ability to diagnose and treat mild traumatic brain injury (mTBI) is lacking. This deficiency results from a variety of issues including the difficulty in interpreting ambiguous clinically presented symptoms, and ineffective imaging techniques. Thus, researchers have begun to explore cellular and molecular based approaches to improve both diagnosis and prognosis. This has been met with a variety of challenges, including difficulty in relating biological markers to current clinical symptoms, and overcoming our lack of fundamental understanding of the pathophysiology of mTBI. However, recent adoption of high throughput technologies and a change in focus from the identification of single to multiple markers has given just optimism to mTBI research. The purpose of this review is to highlight a number of current experimental peripheral blood biomarkers of mTBI, as well as comment on the issues surrounding their clinical application and utility.

Sports-related concussion testing

Due to the recent focus on concussion in sports, a number of tests have been developed to diagnose and manage concussion. While each test measures different brain functions, no single test has been shown to quickly and reliably assess concussion in all cases. In addition, most of the current concussion tests have not been validated by scientific investigation. This review identifies the pros and cons of the most commonly used noninvasive tests for concussion in order to provide a more complete picture of the resources that are available for concussion testing. The potential utility of research tools such as the head impact telemetry system, advanced magnetic resonance imaging protocols, and biomarkers are discussed in the context of the currently employed tools.

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.

Serum-based protein biomarkers in blast-induced traumatic brain injury spectrum disorder

The biological consequences of exposure to explosive blast are extremely complex. Serum protein biomarkers in blast-induced traumatic brain injury (bTBI) can aid in determining injury severity, monitoring progress, and predicting outcome. Exposure to blast results in varying degrees of physical injury. Explosive blast can also induce psychological stress that can contribute to or amplify the extent of physical damage. Given the complexity, scale of injury, and variety of symptoms, bTBI may be best described as a spectrum disorder. In this focused review, we summarize the status of serum protein biomarkers in bTBI in the context of the classification and pathological changes of other forms of TBI. Finally, we recommend specific and easily implementable measures to accelerate serum protein biomarker discovery and validation in bTBI.

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.

Concussions: What a neurosurgeon should know about current scientific evidence and management strategies

BACKGROUND

There has been a tremendous amount of interest focused on the topic of concussions over the past few decades. Neurosurgeons are frequently consulted to manage patients with mild traumatic brain injuries (mTBI) that have radiographic evidence of cerebral injury. These injuries share significant overlap with concussions, injuries that typically do not reveal radiographic evidence of structural injury, in the realms of epidemiology, pathophysiology, outcomes, and management. Further, neurosurgeons often manage patients with extracranial injuries that have concomitant concussions. In these cases, neurosurgeons are often the only "concussion experts" that patients encounter.

RESULTS

The literature has been reviewed and data have been synthesized on the topic including sections on historical background, epidemiology, pathophysiology, diagnostic advances, clinical sequelae, and treatment suggestions, with neurosurgeons as the intended target audience.

CONCLUSIONS

Neurosurgeons should have a fundamental knowledge of the scientific evidence that has developed regarding concussions and be prepared to guide patients with treatment plans.

Translating biomarkers research to clinical care: applications and issues for rehabilomics

Traumatic brain injury is a leading cause of morbidity and mortality in adults and children in the United States. Despite steady improvement in our understanding of the pathophysiology of acquired brain injuries, there has been remarkably little improvement in brain injury therapies and/or pharmacologic treatments over the past decade. One of the reasons may be the inability to properly stratify subjects for clinical trials and/or to have real-time assessment of the effectiveness of a given intervention. It has been recognized for several decades that serum biomarkers may allow for more objective subject stratification as well as act as surrogate markers of treatment efficacy. Despite numerous studies, however, biomarkers are not currently part of clinical practice in either acquired brain injury or other neurologic or musculoskeletal disorders. The goals of this review article, therefore, are to use traumatic brain injury as a example to discuss the use of biomarkers in clinical and randomized controlled trials; to briefly discuss the field of neuroproteomics and its interface with neurologic interventions; and to provide an overview of the collaborative pathway between academia and industry, which needs to be an integral part of the translation of biomarkers from the bench to the bedside in any clinical population. Introduction of the concept of rehabilomics and implications of biomarker use for the physical medicine and rehabilitation physician also are discussed.

Neuron-specific enolase, S100B, and glial fibrillary acidic protein levels as outcome predictors in patients with severe traumatic brain injury

BACKGROUND

The availability of markers able to provide an early insight related to prognostic and functional outcome of patients with traumatic brain injury (TBI) are limited.

OBJECTIVE

The relationship of clinical outcome with CSF neuron-specific enolase (NSE), S100B and glial fibrillary acidic protein (GFAP) levels in patients with severe TBI was investigated.

METHODS

Twenty patients with severe TBI (7 days at unit care) and controls were studied. Patients were grouped according to the outcome: (1) nonsurvival (n=5): patients who died; (2) survival A (n=15): CSF sampled between 1st and 3rd day from patients who survived after hospital admission; and (3) survival B (n=7): CSF sampled between 4th and 7th day from patients who survived after hospital admission and were maintained with intraventricular catheter up to 7 days.

RESULTS

Up to 3 days, S100B and NSE levels (ng/mL) were significantly elevated in the nonsurvival compared with survival A group (S100: 12.45 ± 5.46 vs 5.64 ± 3.36; NSE: 313.20 ± 45.51 vs 107.80 ± 112.10). GFAP levels did not differ between groups. In the survival B group S100B, GFAP, and NSE levels were still elevated compared with control (4.59 ± 2.19, 2.48 ± 2.55, and 89.80 ± 131.10, respectively). To compare S100B and NSE for the prediction of nonsurvival and survival patients we performed receiver operating characteristic curves. At admission, CSF NSE level predicts brain death more accurately than S100B.

CONCLUSION

Early elevations (up to 3 days) of S100B and NSE secondary to severe TBI predict deterioration to brain death. However, this feature was more prominently associated with NSE than S100B.

Biomarkers associated with diffuse traumatic axonal injury: exploring pathogenesis, early diagnosis, and prognosis

BACKGROUND

Diffuse traumatic axonal injury (dTAI) is a significant pathologic feature of traumatic brain injury and is associated with substantial mortality and morbidity. It is still a challenge for clinicians to make an early diagnosis of dTAI and generate accurate prognosis and direct therapeutic decisions because most patients rapidly progress to coma after trauma and because specific neurologic symptoms and focal lesions detectable with current routine imaging techniques are absent. To address these issues, many investigations have sought to identify biomarkers of dTAI.

METHODS

This article is a review of the pertinent medical literature.

RESULTS

From the perspective of the pathophysiology of dTAI, we reviewed several biomarkers that are associated with structural damage and biochemical cascades in the secondary injury or repair response to traumatic brain injury. Although some biomarkers are not specific to dTAI, they are nevertheless useful in elucidating its pathogenesis, making early diagnosis possible, predicting outcomes, and providing candidate targets for novel therapeutic strategies.

CONCLUSIONS

The availability of biomarker data, clinical case histories, and radiologic information can improve our current ability to diagnose and monitor pathogenic conditions and predict outcomes in patients with dTAI.