Diagnostic accuracy of prehospital serum S100B and GFAP in patients with mild traumatic brain injury: a prospective observational multicenter cohort study - "the PreTBI I study"

Minor head injury in anticoagulated patients: performance of biomarkers S100B, NSE, GFAP, UCH-L1 and Alinity TBI in the detection of intracranial injury. A prospective observational study

OBJECTIVES

Data in literature indicate that in patients suffering a minor head injury (MHI), biomarkers serum levels could be effective to predict the absence of intracranial injury (ICI) on head CT scan. Use of these biomarkers in case of patients taking oral anticoagulants who experience MHI is very limited. We investigated biomarkers as predictors of ICI in anticoagulated patients managed in an ED.

METHODS

We conducted a single-cohort, prospective, observational study in an ED. Our structured clinical pathway included a first head CT scan, 24 h observation and a second CT scan. The outcome was delayed ICI (dICI), defined as ICI on the second CT scan after a first negative CT scan. We assessed the sensitivity (SE), specificity (SP), negative predictive value (NNV) and positive predictive value (PPV) of the biomarkers S100B, NSE, GFAP, UCH-L1 and Alinity TBI in order to identify dICI.

RESULTS

Our study population was of 234 patients with a negative first CT scan who underwent a second CT scan. The rate of dICI was 4.7 %. The NPV for the detection of dICI were respectively (IC 95 %): S100B 92.7 % (86.0-96.8 %,); ubiquitin C-terminal hydrolase-L1 (UCH-L1) 91.8 % (83.8-96.6 %); glial fibrillary protein (GFP) 100 % (83.2-100 %); TBI 100 % (66.4-100 %). The AUC for the detection of dICI was 0.407 for S100B, 0.563 for neuron-specific enolase (NSE), 0.510 for UCH-L1 and 0.720 for glial fibrillary acidic protein (GFAP), respectively.

CONCLUSIONS

The NPV of the analyzed biomarkers were high and they potentially could limit the number of head CT scan for detecting dICI in anticoagulated patients suffering MHI. GFAP and Alinity TBI seem to be effective to rule out a dCI, but future trials are needed.

Patients suffering traumatic brain injury: patient characteristics, prehospital triage, primary referral and mortality - A population-based follow-up study

BACKGROUND

Traumatic brain injury (TBI) is a potential high-risk condition, but appropriate care pathways, including prehospital triage and primary referral to a specialised neurosurgical centre, can improve neurological outcome and survival. The care pathway starts with layman triage, wherein the patient or bystander decides whether to contact a general practitioner (GP) or emergency services (1-1-2 call) as an entryway into the health care system. The GP or 112-health care professional then decides on the level of urgency and dispatches emergency medical services (EMS) when needed. Finally, a decision is made regarding referral of the TBI patient to a specialised neurotrauma centre or a local hospital. Recent studies have shown that injuries are generally more severe in patients entering the health care system through EMS (112-calls) than through GPs; however, no information exists on whether mortality and morbidity outcomes differ depending on the referral choice. The aim of this study was to examine triage pathways, including the method of entry into the health care system, as well as patient characteristics and place of primary referral, to determine the associated 30-day and 1-year mortality rates in TBI patients with confirmed intracranial lesions.

METHODS

This retrospective observational population-based follow-up study was conducted in the Central Denmark Region from 1 February 2017 to 31 January 2019. We included all adult patients who contacted hospitals and were ascribed a predefined TBI ICD-10 diagnosis code in the Danish National Patient Register. The obtained TBI cohort was merged with prehospital data from the Prehospital Emergency Medical Services, Central Denmark Region, and vital status from the Danish Civil Registration System. Binary logistic regression analysis of mortality was conducted. In all patients with TBI (including concussions), the primary outcome was primary referral to a specialised centre based on mode of entry ('GP/HCP', '112-call' or 'Unreferred') into the health care system. In the subgroup of patients with confirmed intracranial lesions, the secondary outcomes were the relative risk of death at day 30 and 1 year based on the place of primary referral.

RESULTS

Of 5,257 first TBI hospital contacts of adult patients included in the cohort, 1,430 (27.2%) entered the health care system via 1-1-2 emergency medical calls. TBI patients triaged by 112-calls were more likely to receive the highest level of emergency response (15.6% vs. 50.3%; p < 0.001) and second-tier resources and were more frequently referred directly to a specialised centre than were patients entering through GPs or other health care personnel. In the subgroup of 1188/5257 (22.4%) patients with confirmed intracranial lesions, we found no difference in the risk ratio of 30 day (RR 1.04 (95%CI 0.65-1.63)) or 1 year (RR 0.96 (95%CI 0.72-1.25)) all-cause mortality between patients primarily referred to a regional hospital or to a specialised centre when adjusting for age, sex, comorbidities, antiplatelet/anticoagulant treatment and type of intracranial lesions.

CONCLUSION

TBI patients mainly enter the health system by contact with GPs or other health care professionals. However, patients entering through 112-calls are more frequently triaged directly to specialised centres. We were unable to demonstrate any significant difference in the adjusted 30-day and 1-year mortality based on e primary referral to a specialised centre. The inability to demonstrate an effect on mortality based on primary referral to a specialised centre may reflect a lack of clinical data in the registries used. Considerable differences may exist in nondocumented baseline characteristics (i.e., GCS, blood pressure and injury severity) between the groups and may limit conclusions about differences in mortality. Further research providing high-quality evidence on the effect of primary referral is needed to secure early neurosurgical interventions in TBI patients.

An overview of mild traumatic brain injuries and emerging therapeutic targets

The majority of traumatic brain injuries (TBIs), approximately 90%, are classified as mild (mTBIs). Globally, an estimated 4 million injuries occur each year from concussions or mTBIs, highlighting their significance as a public health crisis. TBIs can lead to substantial long-term health consequences, including an increased risk of developing Alzheimer's Disease, Parkinson's Disease (PD), chronic traumatic encephalopathy (CTE), and nearly doubling one's risk of suicide. However, the current management of mTBIs in clinical practice and the available treatment options are limited. There exists an unmet need for effective therapy. This review addresses various aspects of mTBIs based on the most up-to-date literature review, with the goal of stimulating translational research to identify new therapeutic targets and improve our understanding of pathogenic mechanisms. First, we provide a summary of mTBI symptomatology and current diagnostic parameters such as the Glasgow Coma Scale (GCS) for classifying mTBIs or concussions, as well as the utility of alternative diagnostic parameters, including imaging techniques like MRI with diffusion tensor imaging (DTI) and serum biomarkers such as S100B, NSE, GFAP, UCH-L1, NFL, and t-tau. Our review highlights several pre-clinical concussion models employed in the study of mTBIs and the underlying cellular mechanisms involved in mTBI-related pathogenesis, including axonal damage, demyelination, inflammation, and oxidative stress. Finally, we examine a selection of new therapeutic targets currently under investigation in pre-clinical models. These targets may hold promise for clinical translation and address the pressing need for more effective treatments for mTBIs.

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.

Management of traumatic brain injury in adult-A cross-sectional national study

Background

Mild traumatic brain injury (mTBI) is a common cause for seeking care. Previous studies have shown considerable variations in TBI management. New guidelines may have influenced management routines.

Methods

This is a descriptive cross-sectional study, collecting data through structured questionnaires. All Swedish emergency hospitals that manage and treat adult patients with mTBI (Reaction Level Scale [RLS] 1-3, Glasgow Coma Scale [GCS] 13-15, age > 18 years) for the initial 24 h after injury were included in this study.

Results

The response rate among hospitals fulfilling the study criteria's was 61/67 (91%). We observed a distinct predominance of nonspecialists being responsible for the initial management of these patients, with general surgeons and ED-physicians being the dominating specialties. A total of 45/61 (74%) of the hospitals use a guideline when managing TBI, with 12 hospitals (20%) stating that no guideline was used.

Conclusion

In general, established guidelines are used for the management of TBI in Sweden. However, some of these are outdated and several hospitals used local guidelines not based upon reliable evidence-based methodology. Most patients with TBI are managed by nonspecialist doctors, stressing the need of a reliable guideline.

The S100B Protein: A Multifaceted Pathogenic Factor More Than a Biomarker

S100B is a calcium-binding protein mainly concentrated in astrocytes in the nervous system. Its levels in biological fluids are recognized as a reliable biomarker of active neural distress, and more recently, mounting evidence points to S100B as a Damage-Associated Molecular Pattern molecule, which, at high concentration, triggers tissue reactions to damage. S100B levels and/or distribution in the nervous tissue of patients and/or experimental models of different neural disorders, for which the protein is used as a biomarker, are directly related to the progress of the disease. In addition, in experimental models of diseases such as Alzheimer's and Parkinson's diseases, amyotrophic lateral sclerosis, multiple sclerosis, traumatic and vascular acute neural injury, epilepsy, and inflammatory bowel disease, alteration of S100B levels correlates with the occurrence of clinical and/or toxic parameters. In general, overexpression/administration of S100B worsens the clinical presentation, whereas deletion/inactivation of the protein contributes to the amelioration of the symptoms. Thus, the S100B protein may be proposed as a common pathogenic factor in different disorders, sharing different symptoms and etiologies but appearing to share some common pathogenic processes reasonably attributable to neuroinflammation.

The chronic stress risk phenotype mirrored in the human retina as a neurodegenerative condition

The brain is the key organ that orchestrates the stress response which translates to the retina. The retina is an extension of the brain and retinal symptoms in subjects with neurodegenerative diseases substantiated the eye as a window to the brain. The retina is used in this study to determine whether chronic stress reflects neurodegenerative signs indicative of neurodegenerative conditions. A 3-year prospective cohort (n = 333; aged 46 ± 9 years) was stratified into stress-phenotype cases (n = 212) and controls (n = 121) by applying the Malan stress-phenotype index. Neurodegenerative risk markers included ischemia (astrocytic S100 calcium-binding protein B/S100B); 24h blood pressure, proteomics; inflammation (tumor-necrosis-factor-α/TNF-α); neuronal damage (neuron-specific-enolase); anti-apoptosis of retinal-ganglion-cells (beta-nerve-growth-factor), astrocytic activity (glial-fibrillary-acidic-protein); hematocrit (viscosity) and retinal follow-up data [vessels; stress-optic-neuropathy]. Stress-optic-neuropathy risk was calculated from two indices: a newly derived diastolic-ocular-perfusion-pressure cut-point ≥68 mmHg relating to the stress-phenotype; combined with an established cup-to-disc ratio cut-point ≥0.3. Higher stress-optic-neuropathy (39% vs. 17%) and hypertension (73% vs. 16%) prevalence was observed in the stress-phenotype cases vs. controls. Elevated diastolic-ocular-perfusion-pressure, indicating hypoperfusion, was related to arterial narrowing and trend for ischemia increases in the stress-phenotype. Ischemia in the stress-phenotype at baseline, follow-up and 3-yr changes was related to consistent inflammation (TNF-α and cytokine-interleukin-17-receptor-A), neuron-specific-enolase increases, consistent apoptosis (chitinase 3-like-1, low beta-nerve-growth-factor), glial-fibrillary-acidic-protein decreases, elevated viscosity, vein widening as risk marker of endothelial dysfunction in the blood-retinal-barrier, lower vein count, and elevated stress-optic-neuropathy. The stress-phenotype and related neurodegenerative signs of ongoing brain ischemia, apoptosis and endothelial dysfunction compromised blood-retinal-barrier permeability and optic nerve integrity. In fact, the stress-phenotype could identify persons at high risk of neurodegeneration to indicate a neurodegenerative condition.

Towards exploring current challenges and future opportunities relating to the prehospital triage of patients with traumatic brain injury: a mixed-methods study protocol

INTRODUCTION

Traumatic brain injury (TBI) is a major global health burden that results in disability and loss of health. Identifying those patients who require specialist neuroscience care can be challenging due to the low accuracy of existing prehospital trauma triage tools. Despite the widespread use of decision aids to 'rule out' TBI in hospitals, they are not widely used in the prehospital environment. We aim to provide a snapshot of current prehospital practices in the UK, and to explore facilitators and challenges that may be encountered when adopting new tools for decision support.

METHODS AND ANALYSIS

A mixed-methods study will be conducted using a convergent design approach. In the first phase, we will conduct a national survey of current practice in which every participating ambulance service in the UK will receive an online questionnaire, and only one response is required. In the second phase, semistructured interviews will be conducted to explore the perceptions of ambulance service personnel regarding the implementation of new triage methods that may enhance triage decisions. The survey questions and the interview topic guide were piloted and externally reviewed. Quantitative data will be summarised using descriptive statistics; qualitative data will be analysed thematically.

ETHICS AND DISSEMINATION

This study has been approved by the Health Research Authority (REC reference 22/HRA/2035). Our findings may inform the design of future care pathways and research as well as identify challenges and opportunities for future development of prehospital triage tools for patients with suspected TBI. Our findings will be published in peer-reviewed journals, relevant national and international conferences, and will be included in a PhD thesis.

Double Blast Wave Primary Effect on Synaptic, Glymphatic, Myelin, Neuronal and Neurovascular Markers

Explosive blasts are associated with neurological consequences as a result of blast waves impact on the brain. Yet, the neuropathologic and molecular consequences due to blast waves vs. blunt-TBI are not fully understood. An explosive-driven blast-generating system was used to reproduce blast wave exposure and examine pathological and molecular changes generated by primary wave effects of blast exposure. We assessed if pre- and post-synaptic (synaptophysin, PSD-95, spinophilin, GAP-43), neuronal (NF-L), glymphatic (LYVE1, podoplanin), myelin (MBP), neurovascular (AQP4, S100β, PDGF) and genomic (DNA polymerase-β, RNA polymerase II) markers could be altered across different brain regions of double blast vs. sham animals. Twelve male rats exposed to two consecutive blasts were compared to 12 control/sham rats. Western blot, ELISA, and immunofluorescence analyses were performed across the frontal cortex, hippocampus, cerebellum, and brainstem. The results showed altered levels of AQP4, S100β, DNA-polymerase-β, PDGF, synaptophysin and PSD-95 in double blast vs. sham animals in most of the examined regions. These data indicate that blast-generated changes are preferentially associated with neurovascular, glymphatic, and DNA repair markers, especially in the brainstem. Moreover, these changes were not accompanied by behavioral changes and corroborate the hypothesis for which an asymptomatic altered status is caused by repeated blast exposures.

Post-Concussion Symptoms Rule: Derivation and Validation of a Clinical Decision Rule for Early Prediction of Persistent Symptoms after a Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is a common problem. Depending on diagnostic criteria, 13 to 62% of those patients develop persistent post-concussion symptoms (PPCS). The main objective of this prospective multi-center study is to derive and validate a clinical decision rule (CDR) for the early prediction of PPCS. Patients aged ≥14 years were included if they presented to one of our seven participating emergency departments (EDs) within 24 h of an mTBI. Clinical data were collected in the ED, and symptom evolution was assessed at 7, 30 and 90 days post-injury using the Rivermead Post-Concussion Questionnaire (RPQ). The primary outcome was PPCS at 90 days after mTBI. A predictive model called the Post-Concussion Symptoms Rule (PoCS Rule) was developed using the methodological standards for CDR. Of the 1083 analyzed patients (471 and 612 for the derivation and validation cohorts, respectively), 15.6% had PPCS. The final model included the following factors assessed in the ED: age, sex, history of prior TBI or mental health disorder, headache in ED, cervical sprain and hemorrhage on computed tomography. The 7-day follow-up identified additional risk factors: headaches, sleep disturbance, fatigue, sensitivity to light, and RPQ ≥21. The PoCS Rule had a sensitivity of 91.4% and 89.6%, a specificity of 53.8% and 44.7% and a negative predictive value of 97.2% and 95.8% in the derivation and validation cohorts, respectively. The PoCS Rule will help emergency physicians quickly stratify the risk of PPCS in mTBI patients and better plan post-discharge resources.

The diagnostic accuracy of prehospital triage tools in identifying patients with traumatic brain injury: A systematic review

INTRODUCTION

Prehospital care providers are usually the first responders for patients with traumatic brain injury (TBI). Early identification of patients with TBI enables them to receive trauma centre care, which improves outcomes. Two recent systematic reviews concluded that prehospital triage tools for undifferentiated major trauma have low accuracy. However, neither review focused specifically on patients with suspected TBI. Therefore, we aimed to systematically review the existing evidence on the diagnostic performance of prehospital triage tools for patients with suspected TBI.

METHODS

A comprehensive search of the current literature was conducted using Medline, EMBASE, CINAHL Plus and the Cochrane library (inception to 1st June 2021). We also searched Google Scholar, OpenGrey, pre-prints (MedRxiv) and dissertation databases. We included all studies published in English language evaluating the accuracy of prehospital triage tools for TBI. We assessed methodological quality and risk of bias using a modified Quality Assessment of Diagnostic Studies (QUADAS-2) tool. Two reviewers independently performed searches, screened titles and abstracts and undertook methodological quality assessments. Due to the heterogeneity in the population of interest and prehospital triage tools used, a narrative synthesis was undertaken.

RESULTS

The initial search identified 1787 articles, of which 8 unique eligible studies met the inclusion criteria (5 retrospective, 2 prospective, 1 mixed). Overall, sensitivity of triage tools studied ranged from 19.8% to 87.9% for TBI identification. Specificity ranged from 41.4% to 94.4%. Two decision tools have been validated more than once: HITS-NS (2 studies, sensitivity 28.3-32.6%, specificity 89.1-94.4%) and the Field Triage Decision Scheme (4 studies, sensitivity 19.8-64.5%, specificity 77.4%-93.1%). Existing tools appear to systematically under-triage older patients.

CONCLUSION

Further efforts are needed to improve and optimise prehospital triage tools. Consideration of additional predictors (e.g., biomarkers, clinical decision aids and paramedic judgement) may be required to improve diagnostic accuracy.

The Potential of S100 Calcium-Binding Protein B and Glial Fibrillary Acid Protein in Predicting the Intracranial Lesions in Mild Traumatic Brain Injury: A Systematic Review of Literature

ABSTRACT AIM: To summarize the current evidence of S100B and GFAP in predicting intracranial lesions after mTBI. MATERIAL AND METHODS: We searched publications on biomarkers in mTBI from Web of Science, PubMed, and Scopus between January 1990 and July 2021. We included RCTs, cohort, case control, and cross-sectional studies that involved patients with acute closed mTBI in all age group in which head CT scan and blood-based biomarkers (GFAP and S100B) examination were conducted under 24 hours. This study was registered in Open Science Framework. RESULTS: The initial search identified 4.937 article, in which 127 were included for full-text assessment. A total of 16 articles were finally included. No RCT was found in literature searching. Thirteen studies were studying S100B and three studies were studying GFAP. Nine out of 13 S100B studies shows a promising result with ≥ 95% sensitivity for detecting intracranial lesions.  Majorities (11 /13) studies of  S100B confirmed that S100B reduced the unnecessary usage of CT scan. GFAP concentration significantly increased in CT+ patient than CT- patient. No specific GFAP cut off value between the studies was found. CONCLUSION: The result showed that S100B and GFAP had potential to predict the occurrence of intracranial lesions. Variance between methodologies and cut off value hindered the quality of evidence, especially in GFAP. KEYWORDS: mild traumatic brain injury, S100B, GFAP.

Temporal Changes in Serum S100B Levels From Prehospital to Early In-Hospital Sampling in Patients Suffering Traumatic Brain Injury

Background

The biomarker S100B is used for the rule-out of intracranial lesions in patients with mild traumatic brain injury (TBI) and is suggested for prehospital use in Europe. Early kinetics of S100B are not exhaustively investigated in human TBI. This post hoc descriptive study of the data from the PreTBI studies aimed to characterize the early temporal changes of S100B using two-sample timepoints.

Materials and Methods

Two consecutive blood samples were taken prehospital and in-hospital after injury and assayed for S100B. The endpoint adjudication of the outcome intracranial lesion was done by the evaluation of electronic medical patient journals. The data were analyzed using descriptive statistics, scatterplots, and temporal changes estimated by the locally weighted scatterplot smoothing (LOWESS) regression line.

Results

A total of 592 adult patients with TBI were included; 566 with Glasgow Coma Scale (GCS) 14-15, 20 with GCS 9-13, and 6 with GCS 3-8. Intracranial lesions were diagnosed in 44/566 (7.4%) of patients. In 90% of patients, S100B concentrations decreased from prehospital to in-hospital sampling. The mean decrease was−0.34 μg/L. S100B concentrations seem to decline already within 60 min. Patients sampled very close to trauma and patients suffering intracranial lesions may express a slight incline before this decline. Temporal changes of S100B did not differ in patients >65 years of age, in antiplatelet/-coagulant treatment, alcohol intoxicated, or suffering extra-cranial injuries.

Conclusion

S100B concentrations may peak earlier than expected from previous studies of temporal changes in human TBI. Patterns of S100B stand robust to parameters stated as limiting factors to the use for early rule-out of intracranial lesions in the current guidelines. Further studies are needed to investigate the ultra-early temporal profiles of other novel TBI biomarkers to assess prehospital applicability and optimal diagnostic performance in TBI.

S100B, GFAP, UCH-L1 and NSE as predictors of abnormalities on CT imaging following mild traumatic brain injury: a systematic review and meta-analysis of diagnostic test accuracy

Biomarkers such as calcium channel binding protein S100 subunit beta (S100B), glial fibrillary acidic protein (GFAP), ubiquitin c-terminal hydrolase L1 (UCH-L1) and neuron-specific enolase (NSE) have been proposed to aid in screening patients presenting with mild traumatic brain injury (mTBI). As such, we aimed to characterise their accuracy at various thresholds. MEDLINE, SCOPUS and EMBASE were searched, and articles reporting the diagnostic performance of included biomarkers were eligible for inclusion. Risk of bias was assessed using the QUADAS-II criteria. A meta-analysis was performed to assess the predictive value of biomarkers for imaging abnormalities on CT. A total of 2939 citations were identified, and 38 studies were included. Thirty-two studies reported data for S100B. At its conventional threshold of 0.1 μg/L, S100B had a pooled sensitivity of 91% (95%CI 87-94) and a specificity of 30% (95%CI 26-34). The optimal threshold for S100B was 0.72 μg/L, with a sensitivity of 61% (95% CI 50-72) and a specificity of 69% (95% CI 64-74). Nine studies reported data for GFAP. The optimal threshold for GFAP was 626 pg/mL, at which the sensitivity was 71% (95%CI 41-91) and specificity was 71% (95%CI 43-90). Sensitivity of GFAP was maximised at a threshold of 22 pg/mL, which had a sensitivity of 93% (95%CI 73-99) and a specificity of 36% (95%CI 12-68%). Three studies reported data for NSE and two studies for UCH-L1, which precluded meta-analysis. There is evidence to support the use of S100B as a screening tool in mild TBI, and potential advantages to the use of GFAP, which requires further investigation.