In Children and Youth with Mild and Moderate Traumatic Brain Injury, Glial Fibrillary Acidic Protein Out-Performs S100β in Detecting Traumatic Intracranial Lesions on Computed Tomography

Update on the role of S100B in traumatic brain injury in pediatric population: a meta-analysis

OBJECTIVE

Cranial computed tomography (CT) scan is the most widely used tool to rule out intracranial lesions after pediatric traumatic brain injury (TBI). However, in pediatric population, the radiation exposure can lead to an increased risk of hematological and brain neoplasm. Defined in 2019 National Institute for Health and Care Excellence (NICE) guidelines as "troponins for the brain", serum biomarkers measurements, particularly S100B, have progressively emerged as a supplementary tool in the management of TBI thanks to their capacity to predict intracranial post-traumatic lesions.

METHODS

This systematic review was conducted following the PRISMA protocol (preferred reporting items for systematic reviews and meta-analyses). No chronological limits of study publications were included. Studies reporting data from children with TBI undergoing serum S100B measurement and computed tomography (CT) scans were included.

RESULTS

Of 380 articles screened, 10 studies met the inclusion criteria. Patients admitted with mild-TBI in the Emergency Department (ED) were 1325 (80.25%). The overall pooled sensitivity and specificity were 98% (95% CI, 92-99%) and 45% (95% CI, 29-63%), respectively. The meta-analysis revealed a high negative predictive value (NVP) (99%; 95% CI, 94-100%) and a low positive predictive value (PPV) (41%; 95% CI, 16-79%). Area under the curve (AUC) was 76% (95% CI, 65-85%). The overall pooled negative predictive value (NPV) was 99% (95% CI, 99-100%).

CONCLUSIONS

The measurement of serum S100B in the diagnostic workflow of mTBI could help informed decision-making in the ED setting, potentially safely reducing the use of CT scan in the pediatric population. The high sensitivity and excellent negative predictive values look promising and seem to be close to the values found in adults. Despite this, it must be pointed out the high heterogeneity (> 90%) found among studies. In order for S100B to be regularly introduced in the pediatric workflow for TBI, it is important to conduct further studies to obtain cut-off levels based on pediatric reference intervals.

Systematic review and meta-analysis of observational studies evaluating glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCHL1) as blood biomarkers of mild acute traumatic brain injury (mTBI) or sport-related concussion (SRC) in adult subjects

INTRODUCTION

Neurotrauma is the leading cause of death in individuals <45 years old. Many of the published articles on UCHL1 and GFAP lack rigorous methods and reporting.

CONTENT

Due to the high heterogeneity between studies, we evaluated blood GFAP and UCHL1 levels in the same subjects. We determined the biomarker congruence among areas under the ROC curves (AUCs), sensitivities, specificities, and laboratory values in ng/L to avoid spurious results. The definitive meta-analysis included 1,880 subjects in eight studies. The items with the highest risk of bias were as follows: cut-off not prespecified and case-control design not avoided. The AUC of GFAP was greater than the AUC of UCHL1, with a lower prediction interval (PI) limit of 50.1 % for GFAP and 37.3 % for UCHL1, and a significantly greater percentage of GFAP Sp. The PI of laboratory results for GFAP and UCHL1 were 0.517-7,518 ng/L (diseased), 1.2-255 ng/L (nondiseased), and 3-4,180 vs. 3.2-1,297 ng/L, respectively.

SUMMARY

Only the GFAP positive cut-off (255 ng/L) appears to be reliable. The negative COs appear unreliable.

OUTLOOK

GFAP needs better standardization. However, the AUCs of the phospho-Tau and phospho-Tau/Tau proteins resulted not significantly lower than AUC of GFAP, but this result needs further verifications.

Blood Biomarkers for the Management of Mild Traumatic Brain Injury in Clinical Practice

BACKGROUND

Despite the use of validated guidelines in the management of mild traumatic brain injury (mTBI), processes to limit unnecessary brain scans are still not sufficient and need to be improved. The use of blood biomarkers represents a relevant adjunct to identify patients at risk for intracranial injury requiring computed tomography (CT) scan.

CONTENT

Biomarkers currently recommended in the management of mTBI in adults and children are discussed in this review. Protein S100 beta (S100B) is the best-documented blood biomarker due to its validation in large observational and interventional studies. Glial fibrillary acidic protein (GFAP) and ubiquitin carboxyterminal hydrolase L-1 (UCH-L1) have also recently demonstrated their usefulness in patients with mTBI. Preanalytical, analytical, and postanalytical performance are presented to aid in their interpretation in clinical practice. Finally, new perspectives on biomarkers and mTBI are discussed.

SUMMARY

In adults, the inclusion of S100B in Scandinavian and French guidelines has reduced the need for CT scans by at least 30%. S100B has significant potential as a diagnostic biomarker, but limitations include its rapid half-life, which requires blood collection within 3 h of trauma, and its lack of neurospecificity. In 2018, the FDA approved the use of combined determination of GFAP and UCH-L1 to aid in the assessment of mTBI. Since 2022, new French guidelines also recommend the determination of GFAP and UCH-L1 in order to target a larger number of patients (sampling within 12 h post-injury) and optimize the reduction of CT scans. In the future, new cut-offs related to age and promising new biomarkers are expected for both diagnostic and prognostic applications.

Performance of glial fibrillary acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase L1 (UCH-L1) biomarkers in predicting CT scan results and neurological outcomes in children with traumatic brain injury (BRAINI-2 paediatric study): protocol of a European prospective multicentre study

INTRODUCTION

In light of the burden of traumatic brain injury (TBI) in children and the excessive number of unnecessary CT scans still being performed, new strategies are needed to limit their use while minimising the risk of delayed diagnosis of intracranial lesions (ICLs). Identifying children at higher risk of poor outcomes would enable them to be better monitored. The use of the blood-based brain biomarkers glial fibrillar acidic protein (GFAP) and ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) could help clinicians in this decision. The overall aim of this study is to provide new knowledge regarding GFAP and UCH-L1 in order to improve TBI management in the paediatric population.

METHODS AND ANALYSIS

We will conduct a European, prospective, multicentre study, the BRAINI-2 paediatric study, in 20 centres in France, Spain and Switzerland with an inclusion period of 30 months for a total of 2880 children and adolescents included. To assess the performance of GFAP and UCH-L1 used separately and in combination to predict ICLs on CT scans (primary objective), 630 children less than 18 years of age with mild TBI, defined by a Glasgow Coma Scale score of 13-15 and with a CT scan will be recruited. To evaluate the potential of GFAP and UCH-L1 in predicting the prognosis after TBI (secondary objective), a further 1720 children with mild TBI but no CT scan as well as 130 children with moderate or severe TBI will be recruited. Finally, to establish age-specific reference values for GFAP and UCH-L1 (secondary objective), we will include 400 children and adolescents with no history of TBI.

ETHICS AND DISSEMINATION

This study has received ethics approval in all participating countries. Results from our study will be disseminated in international peer-reviewed journals. All procedures were developed in order to assure data protection and confidentiality.

TRIAL REGISTRATION NUMBER

NCT05413499.

S100B vs. "GFAP and UCH-L1" assays in the management of mTBI patients

OBJECTIVES

To compare for the first time the performance of "GFAP and UCH-L1" vs. S100B in a cohort of patients managed for mild traumatic brain injury (mTBI) according to actualized French guidelines.

METHODS

A prospective study was recently carried at the Emergency Department of Clermont-Ferrand University Hospital in France. Patients with mTBI presenting a medium risk of complications were enrolled. Blood S100B and "GFAP and UCHL-1" were sampled and measured according to French guidelines. S100B was measured in patients with samples within 3 h of trauma (Cobas®, Roche Diagnostics), while GFAP and UCHL-1 were measured in all patients (samples <3 h and 3-12 h) using another automated assay (i-STAT® Alinity, Abbott).

RESULTS

For sampling <3 h, serum S100B correctly identifies intracranial lesions with a specificity of 25.7 % (95 % CI; 19.5-32.6 %), a sensitivity of 100 % (95 % CI; 66.4-100 %), and a negative predictive value of 100 % (95 % CI; 92.5-100 %). For sampling <12 h, plasma "GFAP and UCH-L1" levels correctly identify intracranial lesions with a specificity of 31.7 % (95 % CI; 25.7-38.2 %), a sensitivity of 100 % (95 % CI; 73.5-100 %), and a negative predictive value of 100 % (95 % CI; 95-100 %). Comparison of specificities (25.7 vs. 31.7 %) did not reveal a statistically significant difference (p=0.16).

CONCLUSIONS

We highlight the usefulness of measuring plasma "GFAP and UCH-L1" levels to target mTBI patients (sampling within 12 h post-injury) and optimize the reduction of CT scans.

Pediatric reference intervals for serum neurofilament light and glial fibrillary acidic protein using the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort

OBJECTIVES

Blood biomarkers have the potential to transform diagnosis and prognosis for multiple neurological indications. Establishing normative data is a critical benchmark in the analytical validation process. Normative data are important in children as little is known about how brain development may impact potential biomarkers. The objective of this study is to generate pediatric reference intervals (RIs) for serum neurofilament light (NfL), an axonal marker, and glial fibrillary acidic protein (GFAP), an astrocytic marker.

METHODS

Serum from healthy children and adolescents aged 1 to <19 years were obtained from the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) cohort. Serum NfL (n=300) and GFAP (n=316) were quantified using Simoa technology, and discrete RI (2.5th and 97.5th percentiles) and continuous RI (5th and 95th percentiles) were generated.

RESULTS

While there was no association with sex, there was a statistically significant (p<0.0001) negative association between age and serum NfL (Rho -0.400) and GFAP (Rho -0.749). Two statistically significant age partitions were generated for NfL: age 1 to <10 years (lower, upper limit; 3.13, 20.6 pg/mL) and 10 to <19 years (1.82, 7.44 pg/mL). For GFAP, three statistically significant age partitions were generated: age 1 to <3.5 years (80.4, 601 pg/mL); 3.5 to <11 years (50.7, 224 pg/mL); and 11 to <19 years (26.2, 119 pg/mL).

CONCLUSIONS

Taken together with the literature on adults, NfL and GFAP display U-shaped curves with high levels in infants, decreasing levels during childhood, a plateau during adolescence and early adulthood and increasing levels in seniors. These normative data are expected to inform future pediatric studies on the importance of age on neurological blood biomarkers.

Acute Fluid Biomarkers for Diagnosis and Prognosis in Children with Mild Traumatic Brain Injury: A Systematic Review

BACKGROUND AND OBJECTIVE

Fluid biomarkers have the potential to improve the accuracy of diagnosis and prognosis in children with mild traumatic brain injury. Our primary objective was to assess the diagnostic and prognostic utility of acute blood and fluid biomarkers in children with mild traumatic brain injury.

METHODS

We performed a systematic review of the published literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology. Fluid biomarker studies assessing pediatric mild traumatic brain injury diagnosis or prognosis were included if blood or fluids were sampled within 24 h of injury.

RESULTS

Thirty-two studies involving 4743 patients were included comprising 25 diagnostic studies and ten prognostic studies with three studies assessing both diagnosis and prognosis. Sixteen of the 25 diagnostic studies reported the area under the receiver operating characteristic curve (AUC) for predicting abnormal computed tomography scans of the head; S100 calcium binding protein B (S100B, N = 6 studies, AUC range 0.67-1.00), glial fibrillary acidic protein (N = 5, AUC range 0.41-0.85), ubiquitin C-terminal hydrolase (N = 3, AUC 0.59 and 0.83), neuron specific enolase (N = 1, AUC 0.99), total tau (N = 1, AUC 0.65), and interleukin-6 (N = 1, AUC 0.61). In four of the ten prognostic studies, increased acute serum S100B levels, tumor necrosis factor-α, or interleukin-8 were associated with post-concussive symptoms or fatigue from 3 to 12 months post-injury.

CONCLUSIONS

The largest amount of evidence supported the potential use of S100B, glial fibrillary acidic protein, and UCH-L1, but there was mixed accuracy for diagnosis and prognostication for all biomarkers in pediatric mTBI.

TXA does not affect levels of TBI-related biomarkers in blunt TBI with ICH: A secondary analysis of the prehospital TXA for TBI trial

BACKGROUND

Brain specific biomarkers such as glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCH-L1), and microtubule-associated protein-2 (MAP-2) have been identified as tools for diagnosis in traumatic brain injury (TBI). Tranexamic acid (TXA) has been shown to decrease mortality in patients with intracranial hemorrhage (ICH). The effect of TXA on these biomarkers is unknown. We investigated whether TXA affects levels of GFAP, UCH-L1, and MAP-2, and whether biomarker levels are associated with mortality in patients receiving TXA.

METHODS

Patients enrolled in the prehospital TXA for TBI trial had GFAP, UCHL-1 and MAP-2 levels drawn at 0 hour and 24 hours postinjury (n = 422). Patients with ICH from blunt trauma with a GCS <13 and SBP >90 were randomized to placebo, 2 g TXA bolus, or 1 g bolus +1 g/8 hours TXA infusion. Associations of TXA and 24-hour biomarker change were assessed with multivariate linear regression. Association of biomarkers with 28-day mortality was assessed with multivariate logistic regression. All models were controlled for age, GCS, ISS, and AIS head.

RESULTS

Administration of TXA was not associated with a change in biomarkers over 24 hours postinjury. Changes in biomarker levels were associated with AIS head and age. On admission, higher GFAP (odds ratio [OR], 1.75; confidence interval [CI], 1.31-2.38; p < 0.001) was associated with increased 28-day mortality. At 24 hours postinjury, higher levels of GFAP (OR, 2.09; CI, 1.37-3.30; p < 0.001 and UCHL-1 (OR, 2.98; CI, 1.77-5.25; p < 0.001) were associated with mortality. A change in UCH levels from 0 hour to 24 hours postinjury was also associated with increased mortality (OR, 1.68; CI, 1.15-2.49; p < 0.01).

CONCLUSION

Administration of TXA does not impact change in GFAP, UCHL-1, or MAP-2 during the first 24 hours after blunt TBI with ICH. Higher levels of GFAP and UCH early after injury may help identify patients at high risk for 28-day mortality.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

Prognostic and Diagnostic Utility of Serum Biomarkers in Pediatric Traumatic Brain Injury

Traumatic brain injury (TBI) remains a major cause of morbidity and death among the pediatric population. Timely diagnosis, however, remains a complex task because of the lack of standardized methods that permit its accurate identification. The aim of this study was to determine whether serum levels of brain injury biomarkers can be used as a diagnostic and prognostic tool in this pathology. This prospective, observational study collected and analyzed the serum concentration of neuronal injury biomarkers at enrollment, 24h and 48h post-injury, in 34 children ages 0-18 with pTBI and 19 healthy controls (HC). Biomarkers included glial fibrillary acidic protein (GFAP), neurofilament protein L (NfL), ubiquitin-C-terminal hydrolase (UCH-L1), S-100B, tau and tau phosphorylated at threonine 181 (p-tau181). Subjects were stratified by admission Glasgow Coma Scale score into two categories: a combined mild/moderate (GCS 9-15) and severe (GCS 3-8). Glasgow Outcome Scale-Extended (GOS-E) Peds was dichotomized into favorable (≤4) and unfavorable (≥5) and outcomes. Data were analyzed utilizing Prism 9 and R statistical software. The findings were as follows: 15 patients were stratified as severe TBI and 19 as mild/moderate per GCS. All biomarkers measured at enrollment were elevated compared with HC. Serum levels for all biomarkers were significantly higher in the severe TBI group compared with HC at 0, 24, and 48h. The GFAP, tau S100B, and p-tau181 had the ability to differentiate TBI severity in the mild/moderate group when measured at 0h post-injury. Tau serum levels were increased in the mild/moderate group at 24h. In addition, NfL and p-tau181 showed increased serum levels at 48h in the aforementioned GCS category. Individual biomarker performance on predicting unfavorable outcomes was measured at 0, 24, and 48h across different GOS-E Peds time points, which was significant for p-tau181 at 0h at all time points, UCH-L1 at 0h at 6-9 months and 12 months, GFAP at 48h at 12 months, NfL at 0h at 12 months, tau at 0h at 12 months and S100B at 0h at 12 months. We concluded that TBI leads to increased serum neuronal injury biomarkers during the first 0-48h post-injury. A biomarker panel measuring these proteins could aid in the early diagnosis of mild to moderate pTBI and may predict neurological outcomes across the injury spectrum.

Serum GFAP - pediatric reference interval in a cohort of Danish children

OBJECTIVES

Glial fibrillary acidic protein (GFAP) in blood is an emerging biomarker of brain injury and neurological disease. Its clinical use in children is limited by the lack of a reference interval (RI). Thus, the aim of the present study was to establish an age-dependent continuous RI for serum GFAP in children.

METHODS

Excess serum from routine allergy testing of 391 children, 0.4-17.9 years of age, was measured by a single-molecule array (Simoa) assay. A continuous RI was modelled using non-parametric quantile regression and presented both graphically and tabulated as discrete one-year RIs based on point estimates from the model.

RESULTS

Serum GFAP showed a strong age-dependency with declining levels and variability from infants to adolescents. The estimated median level decreased 66 % from four months to five years of age and another 65 % from five years to 17.9 years of age. No gender difference was observed.

CONCLUSIONS

The study establishes an age-dependent RI for serum GFAP in children showing high levels and variability in the first years of life.

Do astrocytes act as immune cells after pediatric TBI?

Astrocytes are in contact with the vasculature, neurons, oligodendrocytes and microglia, forming a local network with various functions critical for brain homeostasis. One of the primary responders to brain injury are astrocytes as they detect neuronal and vascular damage, change their phenotype with morphological, proteomic and transcriptomic transformations for an adaptive response. The role of astrocytic responses in brain dysfunction is not fully elucidated in adult, and even less described in the developing brain. Children are vulnerable to traumatic brain injury (TBI), which represents a leading cause of death and disability in the pediatric population. Pediatric brain trauma, even with mild severity, can lead to long-term health complications, such as cognitive impairments, emotional disorders and social dysfunction later in life. To date, the underlying pathophysiology is still not fully understood. In this review, we focus on the astrocytic response in pediatric TBI and propose a potential immune role of the astrocyte in response to trauma. We discuss the contribution of astrocytes in the local inflammatory cascades and secretion of various immunomodulatory factors involved in the recruitment of local microglial cells and peripheral immune cells through cerebral blood vessels. Taken together, we propose that early changes in the astrocytic phenotype can alter normal development of the brain, with long-term consequences on neurological outcomes, as described in preclinical models and patients.

Concussion: Beyond the Cascade

Sport concussion affects millions of athletes each year at all levels of sport. Increasing evidence demonstrates clinical and physiological recovery are becoming more divergent definitions, as evidenced by several studies examining blood-based biomarkers of inflammation and imaging studies of the central nervous system (CNS). Recent studies have shown elevated microglial activation in the CNS in active and retired American football players, as well as in active collegiate athletes who were diagnosed with a concussion and returned to sport. These data are supportive of discordance in clinical symptomology and the inflammatory response in the CNS upon symptom resolution. In this review, we will summarize recent advances in the understanding of the inflammatory response associated with sport concussion and broader mild traumatic brain injury, as well as provide an outlook for important research questions to better align clinical and physiological recovery.

Examining four blood biomarkers for the detection of acute intracranial abnormalities following mild traumatic brain injury in older adults

Blood-based biomarkers have been increasingly studied for diagnostic and prognostic purposes in patients with mild traumatic brain injury (MTBI). Biomarker levels in blood have been shown to vary throughout age groups. Our aim was to study four blood biomarkers, glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCH-L1), neurofilament light (NF-L), and total tau (t-tau), in older adult patients with MTBI. The study sample was collected in the emergency department in Tampere University Hospital, Finland, between November 2015 and November 2016. All consecutive adult patients with head injury were eligible for inclusion. Serum samples were collected from the enrolled patients, which were frozen and later sent for biomarker analyses. Patients aged 60 years or older with MTBI, head computed tomography (CT) imaging, and available biomarker levels were eligible for this study. A total of 83 patients (mean age = 79.0, SD = 9.58, range = 60-100; 41.0% men) were included in the analysis. GFAP was the only biomarker to show statistically significant differentiation between patients with and without acute head CT abnormalities [U₍₈₃₎ = 280, p < 0.001, r = 0.44; area under the curve (AUC) = 0.79, 95% CI = 0.67-0.91]. The median UCH-L1 values were modestly greater in the abnormal head CT group vs. normal head CT group [U ₍₈₃₎ = 492, p = 0.065, r = 0.20; AUC = 0.63, 95% CI = 0.49-0.77]. Older age was associated with biomarker levels in the normal head CT group, with the most prominent age associations being with NF-L (r = 0.56) and GFAP (r = 0.54). The results support the use of GFAP in detecting abnormal head CT findings in older adults with MTBIs. However, small sample sizes run the risk for producing non-replicable findings that may not generalize to the population and do not translate well to clinical use. Further studies should consider the potential effect of age on biomarker levels when establishing clinical cut-off values for detecting head CT abnormalities.

REFINEMENT OF SALIVA MI-RNA BIOMARKERS FOR SPORT-RELATED CONCUSSION

ABSTRACT Introduction: The changes in brain structure caused by a sports-related concussion may initially be indistinguishable, however, the irreversible deleterious effects are noted in the long term. An early diagnosis may provide the patient with a better recovery chance and increased survival. For this purpose, this paper studies the feasibility of a diagnosis for concussion by microRNA (mi-RNA) biomarkers contained in the saliva of athletes. Objective: Verify whether salivary miRNAs could be considered good biomarkers for sports concussion. Methodology: Salivary mi-RNA levels were determined from 120 saliva samples of 120 players. There were 43 with a diagnosis of concussion and 77 without a diagnosis of concussion. Samples from players with a concussion were collected 30 minutes prior to activity, samples from individuals who did not engage in physical activity were also compared. Results: On the evaluation of 30 miRNA from individuals with a concussion between contact and non-contact sports there was high detection reliability(P<.05). Both miR-532-5p and miR-182-5p showed reduced amounts of physical activity. The miRNA-532-5p and miRNA-182-5p show significant results among 43 subjects from pre-exercise to post-exercise. The miRNA-4510 showed a significant result (p < 0.05) between contact and non-contact sport types. The amount of miRNA-4510 expanded in 20 individuals in the contact sport at post-exercise but remained normal in the non-contact sports group. Conclusion: The salivary miRNAs are reliable biomarkers for concussion. Evidence Level II; Therapeutic Studies – Investigating the results.

Concussion severity and functional outcome using biomarkers in children and youth involved in organized sports, recreational activities and non-sport related incidents

This prospective multicenter study evaluated differences in concussion severity and functional outcome using glial and neuronal biomarkers glial Fibrillary Acidic (GFAP) and Ubiquitin C-terminal Hydrolase (UCH-L1) in children and youth involved in non-sport related trauma, organized sports, and recreational activities. Children and youth presenting to three Level 1 trauma centersfollowing blunt head trauma with a GCS 15 with a verified diagnosis of a concussion were enrolled within 6 hours of injury. Traumatic intracranial lesions on CT scan and functional outcome within 3 months of injury were evaluated. 131 children and youth with concussion were enrolled, 81 in the no sports group, 22 in the organized sports group and 28 in the recreational activities group. Median GFAP levels were 0.18, 0.07, and 0.39 ng/mL in the respective groups (p = 0.014). Median UCH-L1 levels were 0.18, 0.27, and 0.32 ng/mL respectively (p = 0.025). A CT scan of the head was performed in 110 (84%) patients. CT was positive in 5 (7%), 4 (27%), and 5 (20%) patients, respectively. The AUC for GFAP for detecting +CT was 0.84 (95%CI 0.75-0.93) and for UCH-L1 was 0.82 (95%CI 0.71-0.94). In those without CT lesions, elevations in UCH-L1 were significantly associated with unfavorable 3-month outcome. Concussions in the 3 groups were of similar severity and functional outcome. GFAP and UCH-L1 were both associated with severity of concussion and intracranial lesions, with the most elevated concentrations in recreational activities .

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

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

Biomarkers in Moderate to Severe Pediatric Traumatic Brain Injury: A Review of the Literature

BACKGROUND

Despite decades of research, outcomes in pediatric traumatic brain injury (pTBI) remain highly variable. Brain biofluid-specific biomarkers from pTBI patients may allow us to diagnose and prognosticate earlier and with a greater degree of accuracy than conventional methods. This manuscript reviews the evidence surrounding current brain-specific biomarkers in pTBI and assesses the temporal relationship between the natural history of the traumatic brain injury (TBI) and measured biomarker levels.

METHODS

A literature search was conducted in the Ovid, PubMed, MEDLINE, and Cochrane databases seeking relevant publications. The study selection and screening process were documented in a Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram. Extraction forms included developmental stages of patients, type and biofluid source of biomarkers, brain injury type, and other relevant data.

RESULTS

The search strategy identified 443 articles, of which 150 examining the biomarkers of our interest were included. The references retrieved were examined thoroughly and discussed at length with a pediatric neurocritical care intensivist specializing in pTBI and a Ph.D. scientist with a high degree of involvement in TBI biomarker research, authoring a vast amount of literature in this field.

CONCLUSIONS

TBI biomarkers might serve as valuable tools in the diagnosis and prognosis of pTBI. However, while each biomarker has its advantages, they are not without limitations, and therefore, further research is critical in pTBI biomarkers.

GFAP and S100B: What You Always Wanted to Know and Never Dared to Ask

Traumatic brain injury (TBI) is a major global health issue, with outcomes spanning from intracranial bleeding, debilitating sequelae, and invalidity with consequences for individuals, families, and healthcare systems. Early diagnosis of TBI by testing peripheral fluids such as blood or saliva has been the focus of many research efforts, leading to FDA approval for a bench-top assay for blood GFAP and UCH-L1 and a plasma point-of-care test for GFAP. The biomarker S100B has been included in clinical guidelines for mTBI (mTBI) in Europe. Despite these successes, several unresolved issues have been recognized, including the robustness of prior data, the presence of biomarkers in tissues beyond the central nervous system, and the time course of biomarkers in peripheral body fluids. In this review article, we present some of these issues and provide a viewpoint derived from an analysis of existing literature. We focus on two astrocytic proteins, S100B and GFAP, the most commonly employed biomarkers used in mTBI. We also offer recommendations that may translate into a broader acceptance of these clinical tools.

Traumatic Brain Injury in Children: Glial fibrillary Acidic Protein and Clinical Outcomes

OBJECTIVES

Glial fibrillary acidic protein (GFAP) is a neuronal protein released after traumatic brain injury (TBI) and detectable in serum samples. GFAP correlates with symptom severity in adults and may be a marker of brain injury in children with milder symptoms or preverbal children.

METHODS

GFAP was examined in children with severe TBI (initial Glasgow Coma Scale score <8), with mild TBI (Glasgow Coma Scale score 14/15), and at 0 to 4 and at 10 to 14 days after TBI and was compared with healthy age-matched controls. Mechanism, time points from injury, and symptoms were recorded.

RESULTS

The study enrolled 208 children including 110 with TBI (n = 104 mild, 6 severe) and controls (n = 98). GFAP was higher in mild TBI than in controls and highest in the severe TBI cohort, with a maximum value at 6 hours from injury. Vomiting was significantly associated with higher GFAP levels, but no association was found with amnesia, loss of consciousness, and the Sports Concussion Assessment Tool. Children reporting >1-point changes from their preinjury functioning on the Post-Concussive Symptom Inventory had higher initial GFAP but not total Post-Concussive Symptom Inventory score changes.

CONCLUSIONS

GFAP identifies children with TBI, even at the milder end of the spectrum, and is strongly associated with postinjury vomiting. It may be a useful marker of pediatric TBI; however, sampling is time critical.

Evaluation of Glial and Neuronal Blood Biomarkers Compared With Clinical Decision Rules in Assessing the Need for Computed Tomography in Patients With Mild Traumatic Brain Injury

IMPORTANCE

In 2018, the combination of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase (UCH-L1) levels became the first US Food and Drug Administration-approved blood test to detect intracranial lesions after mild to moderate traumatic brain injury (MTBI). How this blood test compares with validated clinical decision rules remains unknown.

OBJECTIVES

To compare the performance of GFAP and UCH-L1 levels vs 3 validated clinical decision rules for detecting traumatic intracranial lesions on computed tomography (CT) in patients with MTBI and to evaluate combining biomarkers with clinical decision rules.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study from a level I trauma center enrolled adults with suspected MTBI presenting within 4 hours of injury. The clinical decision rules included the Canadian CT Head Rule (CCHR), New Orleans Criteria (NOC), and National Emergency X-Radiography Utilization Study II (NEXUS II) criteria. Emergency physicians prospectively completed data forms for each clinical decision rule before the patients' CT scans. Blood samples for measuring GFAP and UCH-L1 levels were drawn, but laboratory personnel were blinded to clinical results. Of 2274 potential patients screened, 697 met eligibility criteria, 320 declined to participate, and 377 were enrolled. Data were collected from March 16, 2010, to March 5, 2014, and analyzed on August 11, 2021.

MAIN OUTCOMES AND MEASURES

The presence of acute traumatic intracranial lesions on head CT scan (positive CT finding).

RESULTS

Among enrolled patients, 349 (93%) had a CT scan performed and were included in the analysis. The mean (SD) age was 40 (16) years; 230 patients (66%) were men, 314 (90%) had a Glasgow Coma Scale score of 15, and 23 (7%) had positive CT findings. For the CCHR, sensitivity was 100% (95% CI, 82%-100%), specificity was 33% (95% CI, 28%-39%), and negative predictive value (NPV) was 100% (95% CI, 96%-100%). For the NOC, sensitivity was 100% (95% CI, 82%-100%), specificity was 16% (95% CI, 12%-20%), and NPV was 100% (95% CI, 91%-100%). For NEXUS II, sensitivity was 83% (95% CI, 60%-94%), specificity was 52% (95% CI, 47%-58%), and NPV was 98% (95% CI, 94%-99%). For GFAP and UCH-L1 levels combined with cutoffs at 67 and 189 pg/mL, respectively, sensitivity was 100% (95% CI, 82%-100%), specificity was 25% (95% CI, 20%-30%), and NPV was 100%; with cutoffs at 30 and 327 pg/mL, respectively, sensitivity was 91% (95% CI, 70%-98%), specificity was 20% (95% CI, 16%-24%), and NPV was 97%. The area under the receiver operating characteristic curve (AUROC) for GFAP alone was 0.83; for GFAP plus NEXUS II, 0.83; for GFAP plus NOC, 0.85; and for GFAP plus CCHR, 0.88. The AUROC for UCH-L1 alone was 0.72; for UCH-L1 plus NEXUS II, 0.77; for UCH-L1 plus NOC, 0.77; and for UCH-L1 plus CCHR, 0.79. The GFAP biomarker alone (without UCH-L1) contributed the most improvement to the clinical decision rules.

CONCLUSIONS AND RELEVANCE

In this cohort study, the CCHR, the NOC, and GFAP plus UCH-L1 biomarkers had equally high sensitivities, and the CCHR had the highest specificity. However, using different cutoff values reduced both sensitivity and specificity of GFAP plus UCH-L1. Use of GFAP significantly improved the performance of the clinical decision rules, independently of UCH-L1. Together, the CCHR and GFAP had the highest diagnostic performance.

Decreases in Dorsal Cervical Spinal Cord White Matter Tract Integrity Are Associated with Elevated Levels of Serum MicroRNA Biomarkers in NCAA Division I Collegiate Football Players

This prospective, controlled, observational cohort study assessed the performance of a novel panel of serum microRNA (miRNA) biomarkers relative to findings on cervical spinal cord magnetic resonance imaging (MRI) in collegiate football players. There were 44 participants included in the study: 30 non-athlete control subjects and 14 male collegiate football athletes participating in a Division I Football Bowl Subdivision of the National Collegiate Athletic Association. Diffuse tensor MRI and blood samples were acquired within the week before the athletic season began and within the week after the last game of the season. All miRNAs were significantly higher in athletes regardless of their fractional anisotropy (FA) values (p < 0.001), even those considered to be in the “normal” range of FA for white and gray matter integrity in the cervical spinal cord. miRNA biomarkers were most significantly correlated with FA of the white matter (WM) tracts of the dorsal (posterior) spinal cord; particularly, the fasciculus gracilis, fasciculus cuneatus, lateral corticospinal tract, rubrospinal tract, lateral reticulospinal tract, spinal lemniscus, and spinothalamic and -reticular tracts. Areas under the curve for miRNA biomarkers predicting lower FA of WM dorsal (posterior) cervical spinal tracts, therefore lower white matter integrity (connectivity), were miR-505* = 0.75 (0.54–0.96), miR-30d = 0.74 (0.52–0.95), and miR-92a = 0.75 (0.53–0.98). Should these findings be replicated in a larger cohort of athletes, these markers could potentially serve as measures of neuroimaging abnormalities in athletes at risk for concussion and subconcussive injuries to the cervical spinal cord.

A blood biomarker and clinical correlation cohort study protocol to diagnose sports-related concussion and monitor recovery in elite rugby

Introduction

In professional rugby, sports-related concussion (SRC) remains the most frequent time loss injury. Therefore, accurately diagnosing SRC and monitoring player recovery, through a multi-modal assessment process, is critical to SRC management. In this protocol study, we aim to assess SRC over multiple time points post-injury to determine the value of multi-modal assessments to monitor player recovery. This is of significance to minimise premature return-to-play and, ultimately, to reduce the long-term effects associated with SRC. The study will also establish the logistics of implementing such a study in a professional setting to monitor a player's SRC recovery.

Methods and analysis

All players from the participating professional rugby club within the Irish Rugby Football Union are invited to participate in the current study. Player assessment includes head injury assessment (HIA), neuropsychometric assessment (ImPACT), targeted biomarker analysis and untargeted biomarker analysis. Baseline HIA, ImPACT, and blood draws are performed prior to the start of playing season. During the baseline tests, player's complete consent forms and an SRC history questionnaire. Subsequently, any participant that enters the HIA process over the playing season due to a suspected SRC will be clinically assessed (HIA and ImPACT) and their blood will be drawn within 3 days of injury, 6 days post-injury, and 13 days post-injury.

Ethics and dissemination

Ethical approval was attained from the Science and Engineering Research Ethics Committee, University of Limerick (Approval Code: 2018_06_11_S&E). On completion of the study, further manuscripts will be published to present the results of the tests and their ability to measure player recovery from SRC.

Trial registration number

NCT04485494.

Association Between Proteomic Blood Biomarkers and DTI/NODDI Metrics in Adolescent Football Players: A Pilot Study

While neuroimaging and blood biomarker have been two of the most active areas of research in the neurotrauma community, these fields rarely intersect to delineate subconcussive brain injury. The aim of the study was to examine the association between diffusion MRI techniques [diffusion tensor imaging (DTI) and neurite orientation/dispersion density imaging (NODDI)] and brain-injury blood biomarker levels [tau, neurofilament-light (NfL), glial-fibrillary-acidic-protein (GFAP)] in high-school football players at their baseline, aiming to detect cumulative neuronal damage from prior seasons. Twenty-five football players were enrolled in the study. MRI measures and blood samples were obtained during preseason data collection. The whole-brain, tract-based spatial statistics was conducted for six diffusion metrics: fractional anisotropy (FA), mean diffusivity (MD), axial/radial diffusivity (AD, RD), neurite density index (NDI), and orientation dispersion index (ODI). Five players were ineligible for MRIs, and three serum samples were excluded due to hemolysis, resulting in 17 completed set of diffusion metrics and blood biomarker levels for association analysis. Our permutation-based regression model revealed that serum tau levels were significantly associated with MD and NDI in various axonal tracts; specifically, elevated serum tau levels correlated to elevated MD (p = 0.0044) and reduced NDI (p = 0.016) in the corpus callosum and surrounding white matter tracts (e.g., longitudinal fasciculus). Additionally, there was a negative association between NfL and ODI in the focal area of the longitudinal fasciculus. Our data suggest that high school football players may develop axonal microstructural abnormality in the corpus callosum and surrounding white matter tracts, such as longitudinal fasciculus. A future study is warranted to determine the longitudinal multimodal relationship in response to repetitive exposure to sports-related head impacts.

Persistent Neurovascular Unit Dysfunction: Pathophysiological Substrate and Trigger for Late-Onset Neurodegeneration After Traumatic Brain Injury

Traumatic brain injury (TBI) represents one of the major causes of death worldwide and leads to persisting neurological deficits in many of the survivors. One of the most significant long-term sequelae deriving from TBI is neurodegenerative disease, which is a group of incurable diseases that impose a heavy socio-economic burden. However, mechanisms underlying the increased susceptibility of TBI to neurodegenerative disease remain elusive. The neurovascular unit (NVU) is a functional unit composed of neurons, neuroglia, vascular cells, and the basal lamina matrix. The key role of NVU dysfunction in many central nervous system diseases has been revealed. Studies have proved the presence of prolonged structural and functional abnormalities of the NVU after TBI. Moreover, growing evidence suggests impaired NVU function is also implicated in neurodegenerative diseases. Therefore, we propose the Neurovascular Unit Dysfunction (NVUD) Hypothesis, in which the persistent NVU dysfunction is thought to underlie the development of post-TBI neurodegeneration. We deduce NVUD Hypothesis through relational inference and supporting evidence, and suggest continued NVU abnormalities following TBI serve as the pathophysiological substrate and trigger yielding chronic neuroinflammation, proteinopathies and oxidative stress, consequently leading to the progression of neurodegenerative diseases. The NVUD Hypothesis may provide potential treatment and prevention strategies for TBI and late-onset neurodegenerative diseases.

The value of glial fibrillary acidic protein levels in the diagnosis and prognosis of subarachnoid hemorrhage

Background:

Subarachnoid hemorrhages is an important emergency condition due to its high morbidity and mortality. Early diagnosis and rapid intervention are very important to prevent poor clinical outcome of this disease.

Objective:

The aim of this study was to determine the value of glial fibrillary acidic protein in the diagnosis and prognosis of subarachnoid hemorrhage.

Methods:

Patients presenting to the emergency department and undergoing computerized tomography and/or lumbar puncture due to suspicion of subarachnoid hemorrhage were included in this prospective study. Based on the computerized tomography–lumbar puncture results, cases were divided into subarachnoid hemorrhage group and non–subarachnoid hemorrhage control group. Subarachnoid hemorrhage patients were classified on the basis of severity of subarachnoid hemorrhage and were classified as good or poor clinical outcome groups based on Glasgow Outcome Scores. Glial fibrillary acidic protein levels were then compared.

Results:

A total of 111 patients were evaluated due to suspicion of subarachnoid hemorrhage and diagnosed with subarachnoid hemorrhage (n = 73) or without subarachnoid hemorrhage (n = 38). Cerebrospinal fluid glial fibrillary acidic protein levels were significantly higher in the subarachnoid hemorrhage group than in the non–subarachnoid hemorrhage group (p < 0.001) (median (25%–75%): 11.62 (2.64–68.04) and 2.26 (1.5–4.83), respectively). Serum glial fibrillary acidic protein levels of the subarachnoid hemorrhage patients with poor clinical outcomes were higher than those of subarachnoid hemorrhage patients with good clinical outcomes (p = 0.003) and cerebrospinal fluid glial fibrillary acidic protein levels were similar (p = 0.379). Glial fibrillary acidic protein levels at the time of presentation exhibited a low level of correlation with Glasgow coma score, World Federation of Neurological Surgeons scale, Hunter–Hess Scale, Ogilvy–Carter Scale, Glasgow Outcome Score, and modified Rankin score.

Conclusion:

Cerebrospinal fluid glial fibrillary acidic protein levels may be a valuable diagnostic parameter at the time of presentation for diagnosis of subarachnoid hemorrhage. And also serum glial fibrillary acidic protein levels may be useful in predicting subarachnoid hemorrhage patients with poor clinical outcomes.

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

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

Elevated markers of brain injury as a result of clinically asymptomatic high-acceleration head impacts in high-school football athletes

OBJECTIVE

This prospective observational cohort study of high-school football athletes was performed to determine if high-acceleration head impacts (HHIs) that do not result in clinically diagnosed concussion still lead to increases in serum levels of biomarkers indicating traumatic brain injury (TBI) in asymptomatic athletes and to determine the longitudinal profile of these biomarkers over the course of the football season.

METHODS

Sixteen varsity high-school football athletes underwent baseline neurocognitive testing and blood sampling for the biomarkers tau, ubiquitin C-terminal hydrolase L1 (UCH-L1), neurofilament light protein (NF-L), glial fibrillary acidic protein (GFAP), and spectrin breakdown products (SBDPs). All athletes wore helmet-based accelerometers to measure and record head impact data during all practices and games. At various time points during the season, 6 of these athletes met the criteria for HHI (linear acceleration > 95g and rotational acceleration > 3760 rad/sec2); in these athletes a second blood sample was drawn at the end of the athletic event during which the HHI occurred. Five athletes who did not meet the criteria for HHI underwent repeat blood sampling following the final game of the season. In a separate analysis, all athletes who did not receive a diagnosis of concussion during the season (n = 12) underwent repeat neurocognitive testing and blood sampling after the end of the season.

RESULTS

Total tau levels increased 492.6% ± 109.8% from baseline to postsession values in athletes who received an HHI, compared with 164% ± 35% in athletes who did not receive an HHI (p = 0.03). Similarly, UCH-L1 levels increased 738.2% ± 163.3% in athletes following an HHI, compared with 237.7% ± 71.9% in athletes in whom there was no HHI (p = 0.03). At the end of the season, researchers found that tau levels had increased 0.6 ± 0.2 pg/ml (p = 0.003) and UCH-L1 levels had increased 144.3 ± 56 pg/ml (p = 0.002). No significant elevations in serum NF-L, GFAP, or SBDPs were seen between baseline and end-of-athletic event or end-of-season sampling (for all, p > 0.05).

CONCLUSIONS

In this pilot study on asymptomatic football athletes, an HHI was associated with increased markers of neuronal (UCH-L1) and axonal (tau) injury when compared with values in control athletes. These same markers were also increased in nonconcussed athletes following the football season.

Clinical Use of the Calcium-Binding S100B Protein, a Biomarker for Head Injury

S100B is a calcium-binding protein most abundant in neuronal tissue. It is expressed in glial cells and Schwann cells and exerts both intra- and extracellular effects. Depending on the concentration, secreted S100B exerts either trophic or toxic effects. Its functions have been extensively studied but are still not fully understood. It can be measured in cerebrospinal fluid and in blood, and increased S100B level in blood can be seen after, e.g., traumatic brain injury, certain neurodegenerative disorders, and malignant melanoma. This chapter provides a short background of protein S100B, commercially available methods of analysis, and its clinical use, especially as a biomarker in minor head injury.

Evaluating glial and neuronal blood biomarkers GFAP and UCH-L1 as gradients of brain injury in concussive, subconcussive and non-concussive trauma: a prospective cohort study

OBJECTIVES

To evaluate the ability of glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase (UCH-L1) to detect concussion in children and adult trauma patients with a normal mental status and assess biomarker concentrations over time as gradients of injury in concussive and non-concussive head and body trauma.

DESIGN

Large prospective cohort study.

SETTING

Three level I trauma centres in the USA.

PARTICIPANTS

Paediatric and adult trauma patients of all ages, with and without head trauma, presenting with a normal mental status (Glasgow Coma Scale score of 15) within 4 hours of injury. Rigorous screening for concussive symptoms was conducted. Of 3462 trauma patients screened, 751 were enrolled and 712 had biomarker data. Repeated blood sampling was conducted at 4, 8, 12, 16, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168 and 180 hours postinjury in adults.

MAIN OUTCOMES

Detection of concussion and gradients of injury in children versus adults by comparing three groups of patients: (1) those with concussion; (2) those with head trauma without overt signs of concussion (non-concussive head trauma controls) and (3) those with peripheral (body) trauma without head trauma or concussion (non-concussive body trauma controls).

RESULTS

A total of 1904 samples from 712 trauma patients were analysed. Within 4 hours of injury, there were incremental increases in levels of both GFAP and UCH-L1 from non-concussive body trauma (lowest), to mild elevations in non-concussive head trauma, to highest levels in patients with concussion. In concussion patients, GFAP concentrations were significantly higher compared with body trauma controls (p<0.001) and with head trauma controls (p<0.001) in both children and adults, after controlling for multiple comparisons. However, for UCH-L1, there were no significant differences between concussion patients and head trauma controls (p=0.894) and between body trauma and head trauma controls in children. The AUC for initial GFAP levels to detect concussion was 0.80 (0.73-0.87) in children and 0.76 (0.71-0.80) in adults. This differed significantly from UCH-L1 with AUCs of 0.62 (0.53-0.72) in children and 0.69 (0.64-0.74) in adults.

CONCLUSIONS

In a cohort of trauma patients with normal mental status, GFAP outperformed UCH-L1 in detecting concussion in both children and adults. Blood levels of GFAP and UCH-L1 showed incremental elevations across three injury groups: from non-concussive body trauma, to non-concussive head trauma, to concussion. However, UCH-L1 was expressed at much higher levels than GFAP in those with non-concussive trauma, particularly in children. Elevations in both biomarkers in patients with non-concussive head trauma may be reflective of a subconcussive brain injury. This will require further study.

Elevations in MicroRNA Biomarkers in Serum Are Associated with Measures of Concussion, Neurocognitive Function, and Subconcussive Trauma over a Single National Collegiate Athletic Association Division I Season in Collegiate Football Players

This prospective controlled observational cohort study assessed the performance of a novel panel of serum microRNA (miRNA) biomarkers on indicators of concussion, subconcussive impacts, and neurocognitive function in collegiate football players over the playing season. Male collegiate student football athletes participating in a Division I Football Bowl Subdivision of the National Collegiate Athletic Association (NCAA) were enrolled. There were a total of 53 participants included in the study, 30 non-athlete control subjects and 23 male collegiate student football athletes. Neurocognitive assessments and blood samples were taken within the week before the athletic season began and within the week after the last game of the season and measured for a panel of pre-selected miRNA biomarkers. All the athletes had elevated levels of circulating miRNAs at the beginning of the season compared with control subjects (p < 0.001). Athletes with the lowest standard assessment of concussion (SAC) scores at the beginning of the season had the highest levels of miRNAs. The area under the curve (AUC) for predicting pre-season SAC scores were miR-195 (0.90), miR-20a (0.89), miR-151-5p (0.86), miR-505* (0.85), miR-9-3p (0.77), and miR-362-3p (0.76). In athletes with declining neurocognitive function over the season, concentrations of miRNAs increased over same period. There were significant negative correlations with miR-505* (p = 0.011), miR-30d (p = 0.007), miR-92 (p = 0.033), and (p = 0.008). The miRNAs correlating with balance problems were miR-505* (p = 0.007), miR-30d (p = 0.028), and miR-151-5p (p = 0.023). Those correlating with poor reaction times were miR-20a (0.043), miR-505* (p = 0.049), miR-30d (p = 0.031), miR-92 (p = 0.015), and miR-151-5p (p = 0.044). Select miRNAs were associated with baseline concussion assessments at the beginning of the season and with neurocognitive changes from pre to post-season in collegiate football players. Should these findings be replicated in a larger cohort of athletes, these markers could potentially serve as measures of neurocognitive status in athletes at risk for concussion and subconcussive injuries.

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

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

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

STUDY SELECTION

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

DATA EXTRACTION

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

RESULTS

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

LIMITATIONS

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

CONCLUSIONS

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

Serum S100B Levels Can Predict Computed Tomography Findings in Paediatric Patients with Mild Head Injury

Introduction

Traumatic brain injuries (TBIs) are very common in paediatric populations, in which they are also a leading cause of death. Computed tomography (CT) overuse in these populations results in ionization radiation exposure, which can lead to lethal malignancies. The aims of this study were to investigate the accuracy of serum S100B levels with respect to the detection of cranial injury in children with mild TBI and to determine whether decisions regarding the performance of CT can be made based on biomarker levels alone.

Materials and Methods

This was a single-center prospective cohort study that was carried out from December 2016 to December 2017. A total of 80 children with mild TBI who met the inclusion criteria were included in the study. The patients were between 2 and 16 years of age. We determined S100B protein levels and performed head CTs in all the patients.

Results

Patients with cranial injury, as detected by CT, had higher S100B protein levels than those without cranial injury (p < 0.0001). We found that patients with cranial injury (head CT+) had higher mean S100B protein levels (0.527 μg L⁻¹, 95% confidence interval (CI) 0.447–0.607 μg L⁻¹) than did patients without cranial injury (head CT−) (0.145 μg L⁻¹, 95% CI 0.138–0.152 μg L⁻¹). Receiver operating characteristic (ROC) curve analysis clearly showed that S100B protein levels differed between patients with and without cranial injury at 3 hours after TBI (AUC = 0.893, 95% CI 0.786–0.987, p = 0.0001).

Conclusion

Serum S100B levels cannot replace clinical examinations or CT as tools for identifying paediatric patients with mild head injury; however, serum S100B levels can be used to identify low-risk patients to prevent such patients from being exposed to radiation unnecessarily.

A Systematic Review of the Usefulness of Glial Fibrillary Acidic Protein for Predicting Acute Intracranial Lesions following Head Trauma

Background

The extensive use of computed tomography (CT) after acute head injury is costly and carries potential iatrogenic risk. This systematic review examined the usefulness of blood-based glial fibrillary acidic protein (GFAP) for predicting acute trauma-related CT-positive intracranial lesions following head trauma. The main objective was to summarize the current evidence on blood-based GFAP as a potential screening test for acute CT-positive intracranial lesions following head trauma.

Methods

We screened MEDLINE, EMBASE, PsychInfo, CINAHL, Web of Science, the Cochrane Database, Scopus, Clinical Trials, OpenGrey, ResearchGate, and the reference lists of eligible publications for original contributions published between January 1980 and January 2017. Eligibility criteria included: (i) population: human head and brain injuries of all severities and ages; (ii) intervention: blood-based GFAP measurement ≤24 h post-injury; and (iii) outcome: acute traumatic lesion on non-contrast head CT ≤24 h post-injury. Three authors completed the publication screening, data extraction, and quality assessment of eligible articles.

Results

The initial search identified 4,706 articles, with 51 eligible for subsequent full-text assessment. Twenty-seven articles were ultimately included. Twenty-four (89%) studies reported a positive association between GFAP level and acute trauma-related intracranial lesions on head CT. The area under the receiver operating characteristic curve for GFAP prediction of intracranial pathology ranged from 0.74 to 0.98 indicating good to excellent discrimination. GFAP seemed to discriminate mass lesions and diffuse injury, with mass lesions having significantly higher GFAP levels. There was considerable variability between the measured GFAP averages between studies and assays. No well-designed diagnostic studies with specific GFAP cutoff values predictive of acute traumatic intracranial lesions have been published.

Conclusion

Intracranial CT-positive trauma lesions were associated with elevated GFAP levels in the majority of studies. Methodological heterogeneity in GFAP assessments and the lack of well-designed diagnostic studies with commercially validated GFAP platforms hinder the level of evidence, and variability in levels of GFAP with no clearly established cutoff for abnormality limit the clinical usefulness of the biomarker. However, blood-based GFAP holds promise as a means of screening for acute traumatic CT-positive lesion following head trauma.

Prospective Assessment of Acute Blood Markers of Brain Injury in Sport-Related Concussion

There is a pressing need to identify objective biomarkers for the assessment of sport-related concussion (SRC) to reduce the reliance on clinical judgment for the management of these injuries. The goal of the current study was to prospectively establish the acute effects of SRC on serum levels of S100 calcium-binding protein beta (S100B), glial fibrillary acidic protein (GFAP), and ubiquitin C-terminal hydrolase-L1 (UCH-L1). Collegiate and high school football players were enrolled and provided blood at pre-season. Injured athletes participated in follow-up visits at ∼6 and 24-48 h following documented SRC (n = 32). Uninjured football players participated in similar follow-up visits and served as controls (n = 29). The median time between injury and blood collection was 2 h (6 h visit) and 22.5 h (24-48 h visit) in concussed athletes. Concussed athletes had significantly elevated UCH-L1 levels at the 6 h visit relative to pre-season levels (Z = 2.22, p = 0.03) and levels in control athletes (Z = 3.02, p = 0.003). Concussed athletes also had elevated S100B at 6 h relative to pre-season (Z = 2.07, p = 0.04) and controls (Z = 2.75, p = 0.006). Both markers showed fair discrimination between concussed and control athletes (UCH-L1 area under receiver operating characteristic curve [AUC] [95% CI] = 0.74 [0.61-0.88], S100B AUC = 0.72 [0.58-0.87]). Percent-change of UCH-L1 and S100B at 6 h relative to pre-season also showed fair discrimination (AUC = 0.79 [0.66-0.92] and AUC = 0.77 [0.64-0.90]). GFAP levels did not differ between groups or in concussed athletes relative to pre-season. This study provides prospective evidence of significant increases in serum levels of UCH-L1 and S100B during the early acute period following SRC, and lays the foundation for future studies examining the clinical potential for blood-based biomarkers in the early detection of concussion.

Phase I randomized clinical trial of N-acetylcysteine in combination with an adjuvant probenecid for treatment of severe traumatic brain injury in children

Background

There are no therapies shown to improve outcome after severe traumatic brain injury (TBI) in humans, a leading cause of morbidity and mortality. We sought to verify brain exposure of the systemically administered antioxidant N-acetylcysteine (NAC) and the synergistic adjuvant probenecid, and identify adverse effects of this drug combination after severe TBI in children.

Methods

IRB-approved, randomized, double-blind, placebo controlled Phase I study in children 2 to 18 years-of-age admitted to a Pediatric Intensive Care Unit after severe TBI (Glasgow Coma Scale [GCS] score ≤8) requiring an externalized ventricular drain for measurement of intracranial pressure (ICP). Patients were recruited from November 2011-August 2013. Fourteen patients (n = 7/group) were randomly assigned after obtaining informed consent to receive probenecid (25 mg/kg load, then 10 mg/kg/dose q6h×11 doses) and NAC (140 mg/kg load, then 70 mg/kg/dose q4h×17 doses), or placebos via naso/orogastric tube. Serum and CSF samples were drawn pre-bolus and 1–96 h after randomization and drug concentrations were measured via UPLC-MS/MS. Glasgow Outcome Scale (GOS) score was assessed at 3 months.

Results

There were no adverse events attributable to drug treatment. One patient in the placebo group was withdrawn due to adverse effects. In the treatment group, NAC concentrations ranged from 16,977.3±2,212.3 to 16,786.1±3,285.3 in serum and from 269.3±113.0 to 467.9±262.7 ng/mL in CSF, at 24 to 72 h post-bolus, respectively; and probenecid concentrations ranged from 75.4.3±10.0 to 52.9±25.8 in serum and 5.4±1.0 to 4.6±2.1 μg/mL in CSF, at 24 to 72 h post-bolus, respectively (mean±SEM). Temperature, mean arterial pressure, ICP, use of ICP-directed therapies, surveillance serum brain injury biomarkers, and GOS at 3 months were not different between groups.

Conclusions

Treatment resulted in detectable concentrations of NAC and probenecid in CSF and was not associated with undesirable effects after TBI in children.

Trial registration

ClinicalTrials.gov NCT01322009

Neuronal Biomarker Ubiquitin C-Terminal Hydrolase Detects Traumatic Intracranial Lesions on Computed Tomography in Children and Youth with Mild Traumatic Brain Injury

This study examined the performance of serum ubiquitin C-terminal hydrolase (UCH-L1) in detecting traumatic intracranial lesions on computed tomography (CT) scan (+CT) in children and youth with mild and moderate TBI (mmTBI) and assessed its performance in trauma control patients without head trauma. This prospective cohort study enrolled children and youth presenting to three level 1 trauma centers after blunt head trauma and a Glasgow Coma Scale (GCS) score of 9-15 as well as trauma control patients with GCS 15 that did not have blunt head trauma. The primary outcome measure was the presence of intracranial lesions on initial CT scan. Blood samples were obtained in all patients within 6 h of injury and measured by enzyme-linked immunosorbent assay ELISA for UCH-L1 (ng/mL). A total of 256 children and youth were enrolled in the study and had serum samples drawn within 6 h of injury for analysis; 196 had blunt head trauma and 60 were trauma controls. CT scan of the head was performed in 151 patients and traumatic intracranial lesions on CT scan were evident in 17 (11%), all of whom had a GCS of 13-15. The area under the receiver operating characteristic curve (AUC) for UCH-L1 in detecting children and youth with traumatic intracranial lesions on CT was 0.83 (95% confidence interval [CI], 0.73-0.93). In those presenting with a GCS of 15, the AUC for detecting lesions was 0.83 (95% CI, 0.72-0.94). Similarly, in children under 5 years of age, the AUC was 0.79 (95% CI, 0.59-1.00). Performance for detecting intracranial lesions at a UCH-L1 cut-off level of 0.18 ng/mL yielded a sensitivity of 100%, a specificity of 47%, and a negative predictive value of 100%. UCH-L1 showed good performance in infants and toddlers younger than 5 years and performed well in children and youth with a GCS score of 15. Before clinical application, further study in larger cohort of children and youth with mild TBI is warranted.

Potential Blood-based Biomarkers for Concussion

Mounting research in the field of sports concussion biomarkers has led to a greater understanding of the effects of brain injury from sports. A recent systematic review of clinical studies examining biomarkers of brain injury following sports-related concussion established that almost all studies have been published either in or after the year 2000. In an effort to prevent chronic traumatic encephalopathy and long-term consequences of concussion, early diagnostic and prognostic tools are becoming increasingly important; particularly in sports and in military personnel, where concussions are common occurrences. Early and tailored management of athletes following a concussion with biomarkers could provide them with the best opportunity to avoid further injury. Should blood-based biomarkers for concussion be validated and become widely available, they could have many roles. For instance, a point-of-care test could be used on the field by trained sport medicine professionals to help detect a concussion. In the clinic or hospital setting, it could be used by clinicians to determine the severity of concussion and be used to screen players for neuroimaging (computed tomography and/or magnetic resonance imaging) and further neuropsychological testing. Furthermore, biomarkers could have a role in monitoring progression of injury and recovery and in managing patients at high risk of repeated injury by being incorporated into guidelines for return to duty, work, or sports activities. There may even be a role for biomarkers as surrogate measures of efficacy in the assessment of new treatments and therapies for concussion.

Biomarkers of Traumatic Brain Injury: Temporal Changes in Body Fluids

Traumatic brain injuries (TBIs) are caused by a hit to the head or a sudden acceleration/deceleration movement of the head. Mild TBIs (mTBIs) and concussions are difficult to diagnose. Imaging techniques often fail to find alterations in the brain, and computed tomography exposes the patient to radiation. Brain-specific biomolecules that are released upon cellular damage serve as another means of diagnosing TBI and assessing the severity of injury. These biomarkers can be detected from samples of body fluids using laboratory tests. Dozens of TBI biomarkers have been studied, and research related to them is increasing. We reviewed the recent literature and selected 12 biomarkers relevant to rapid and accurate diagnostics of TBI for further evaluation. The objective was especially to get a view of the temporal profiles of the biomarkers’ rise and decline after a TBI event. Most biomarkers are rapidly elevated after injury, and they serve as diagnostics tools for some days. Some biomarkers are elevated for months after injury, although the literature on long-term biomarkers is scarce. Clinical utilization of TBI biomarkers is still at a very early phase despite years of active research.

Are UCH-L1 and GFAP promising biomarkers for children with mild traumatic brain injury?

OBJECTIVES

To compare serum biomarker levels between children with mild traumatic brain injury (mTBI) and orthopaedic injury (OI), acutely following injury. Secondarily, to explore the association between biomarker levels and symptom burden over 1 month post-injury.

METHODS

This was a prospective cohort study of children aged 11-16 years who presented to the emergency department within 6 hours of sustaining mTBI or isolated extremity OI. Serum was drawn at the time of study enrollment and levels of ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) and glial fibrillary acid protein (GFAP) were analysed. Symptom burden was assessed by the Post-Concussion Symptom Scale (PCSS) acutely following injury and at three subsequent time points over 1 month.

RESULTS

Twenty-five children with mTBI and 20 children with OI were enrolled. The average age for the overall cohort was 13 (± 1.6) years and the majority were male and injured playing sports. GFAP levels and PCSS scores were significantly higher acutely following mTBI vs OI (p < 0.01). There was not a significant group difference in UCH-L1 levels. Neither GFAP nor UCH-L1 were predictive of PCSS scores over the 1month post-injury.

CONCLUSIONS

GFAP may be a promising diagnostic tool for children with mTBI. Additional approaches are needed to predict symptom severity and persistence.

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

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

Performance of Glial Fibrillary Acidic Protein in Detecting Traumatic Intracranial Lesions on Computed Tomography in Children and Youth With Mild Head Trauma

OBJECTIVES

This study examined the performance of serum glial fibrillary acidic protein (GFAP) in detecting traumatic intracranial lesions on computed tomography (CT) scan in children and youth with mild and moderate traumatic brain injury (TBI) and assessed its performance in trauma control patients without head trauma.

METHODS

This prospective cohort study enrolled children and youth presenting to three Level I trauma centers following blunt head trauma with Glasgow Coma Scale (GCS) scores of 9 to 15, as well as trauma control patients with GCS scores of 15 who did not have blunt head trauma. The primary outcome measure was the presence of intracranial lesions on initial CT scan. Blood samples were obtained in all patients within 6 hours of injury and measured by enzyme-linked immunosorbent assay for GFAP (ng/mL).

RESULTS

A total of 257 children and youth were enrolled in the study and had serum samples drawn within 6 hours of injury for analysis: 197 had blunt head trauma and 60 were trauma controls. CT scan of the head was performed in 152 patients and traumatic intracranial lesions on CT scan were evident in 18 (11%), all of whom had GCS scores of 13 to 15. When serum levels of GFAP were compared in children and youth with traumatic intracranial lesions on CT scan to those without CT lesions, median GFAP levels were significantly higher in those with intracranial lesions (1.01, interquartile range [IQR] = 0.59 to 1.48) than those without lesions (0.18, IQR = 0.06 to 0.47). The area under the receiver operating characteristic curve (AUC) for GFAP in detecting children and youth with traumatic intracranial lesions on CT was 0.82 (95% confidence interval [CI] = 0.71 to 0.93). In those presenting with GCS scores of 15, the AUC for detecting lesions was 0.80 (95% CI = 0.68 to 0.92). Similarly, in children under 5 years old the AUC was 0.83 (95% CI = 0.56 to 1.00). Performance for detecting intracranial lesions at a GFAP cutoff level of 0.15 ng/mL yielded a sensitivity of 94%, a specificity of 47%, and a negative predictive value of 98%.

CONCLUSIONS

In children and youth of all ages, GFAP measured within 6 hours of injury was associated with traumatic intracranial lesions on CT and with severity of TBI. Further study is required to validate these findings before clinical application.