Biomarkers in traumatic brain injury

The neuroprotective effect of electro-acupuncture on cognitive recovery for patients with mild traumatic brain injury: A randomized controlled clinical trial

BACKGROUND

Traumatic brain injury (TBI) is a major health and socioeconomic problem that affects all societies. Consciousness disorder is a common complication after TBI while there is still no effective treatment currently. The aim of this study was to investigate the protective effect of electro-acupuncture (EA) on cognitive recovery for patients with mild TBI.

METHODS

A total of 83 patients with initial Glasgow coma scale score higher than 12 points were assigned into this study. Then patients were randomly divided into 2 groups: EA group and control group (group C). Patients in group EA received EA treatment at Neiguan and Shuigou for 2 weeks. At 0 minute before EA treatment (T1), 0 minute after EA treatment (T2), and 8 weeks after EA treatment (T3), level of neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), hypoxia inducible factor-1α (HIF-1α), and malondialdehyde were tested by enzyme-linked immunosorbent assay. The score of Montreal Cognitive Function Assessment (MoCA) and mini-mental state examination (MMSE) as well as cerebral oxygen saturation (rSO2) were detected at the same time.

RESULTS

Compared with the baseline at T1, the level of NSE, GFAP, HIF-1α, MDA, and rSO2 decreased, and the score of MoCA and MMSE increased in the 2 groups were significantly increased at T2-3 (P < .05). Compared with group C, the level of NSE, GFAP, HIF-1α, MDA, and rSO2 decreased, and the score of MoCA and MMSE increased were significantly increased at T2-3 in group EA; the difference were statistically significant (P < .05).

CONCLUSIONS

EA treatment could improve the cognitive recovery for patients with mild TBI and the potential mechanism may be related to improving cerebral hypoxia and alleviating brain injury.

Mild traumatic brain injury and sports-related concussion

Mild traumatic brain injury (mTBI) and concussion are equivalent terms for the sequela of injury to the head that disrupts brain functioning. Various forces may be causative from seemingly innocuous bumps to the head resulting from sports-related injuries to more severe blows to the head. However, the postconcussive motor, cognitive, emotional, and psychosocial sequelae can be just as devastating and long lasting, leading to loss of independent function and safe performance of activities. Taken together, they pose a significant challenge to recovery, requiring a multifaceted dynamic rehabilitative strategy. The current systems of health care pose challenges to suboptimal management of sports-related concussion (SRC) that goes beyond the acute injury, and into the school setting, failing to be identified by school staff, and inconsistencies in communicating medical information regarding school modifications, follow-up health services, or concussion-related educational services. Children who sustain SRC at different ages face different challenges. Young children face increased vulnerability due to SRC that coincides with periods of brain motor maturation and development.

Preliminary Evaluation of a Novel Point of Care Diagnostic Device for Sports-Related Concussion

OBJECTIVE

Visinin-like protein 1 (VILIP-1) is a neuron-specific calcium sensor protein rapidly released into blood after mild traumatic brain injury (mTBI) and may be a suitable biomarker for identification of sports-related concussion (SRC). The objective of the study is to test if quantification of a specific post-translationally modified (ubiquitinated) form of VILIP-1 (ubVILIP-1) from a fingerstick blood sample using a point of care (POC) lateral flow device (LFD) can be used to rapidly identify athletes with SRC.

DESIGN

Prospective cohort study.

SETTING

Side-line blood collection at football, soccer, and volleyball games/practices.

PARTICIPANTS

Division I athletes with/without SRC.

MAIN OUTCOME MEASURES

Blood ubVILIP-1 concentrations.

RESULTS

Data collected over 2 athletic seasons from non-SRC athletes (controls) show a small but statistically significant elevation of ubVILIP-1 over an individual season for male athletes (P = 0.02) dependent on sport (P = 0.014) and no significant changes in ubVILIP-1 levels between seasons. For SRC athletes, the data show ubVILIP-1 levels substantially increase above baseline as soon as 30 minutes postdiagnosis with peak concentrations and times postinjury that vary based on injury severity.

CONCLUSION

Results of the study suggest quantification of blood ubVILIP-1 levels measured using an LFD may provide an objective identification of athletes with SRC, setting the stage for further study with a larger number of SRC patients.

Synaptamide Modulates Astroglial Activity in Mild Traumatic Brain Injury

At present, the study of the neurotropic activity of polyunsaturated fatty acid ethanolamides (N-acylethanolamines) is becoming increasingly important. N-docosahexaenoylethanolamine (synaptamide, DHEA) is a highly active metabolite of docosahexaenoic acid (DHA) with neuroprotective, synaptogenic, neuritogenic, and anti-inflammatory properties in the nervous system. Synaptamide tested in the present study was obtained using a chemical modification of DHA isolated from squid Berryteuthis magister liver. The results of this study demonstrate the effects of synaptamide on the astroglial response to injury in the acute (1 day) and chronic (7 days) phases of mild traumatic brain injury (mTBI) development. HPLC-MS study revealed several times increase of synaptamide concentration in the cerebral cortex and serum of experimental animals after subcutaneous administration (10 mg/kg/day). Using immunohistochemistry, it was shown that synaptamide regulates the activation of GFAP- and S100β-positive astroglia, reduce nNOS-positive immunostaining, and stimulates the secretion of neurotrophin BDNF. Dynamics of superoxide dismutase production in synaptamide treatment confirm the antioxidant efficacy of the test compound. We found a decrease in TBI biomarkers such as GFAP, S100β, and IL-6 in the blood serum of synaptamide-treated experimental animals using Western blot analysis. The results indicate the high therapeutic potential of synaptamide in reducing the severity of the brain damage consequences.

Progress Toward a Multiomic Understanding of Traumatic Brain Injury: A Review

Traumatic brain injury (TBI) is not a single disease state but describes an array of conditions associated with insult or injury to the brain. While some individuals with TBI recover within a few days or months, others present with persistent symptoms that can cause disability, neuropsychological trauma, and even death. Understanding, diagnosing, and treating TBI is extremely complex for many reasons, including the variable biomechanics of head impact, differences in severity and location of injury, and individual patient characteristics. Because of these confounding factors, the development of reliable diagnostics and targeted treatments for brain injury remains elusive. We argue that the development of effective diagnostic and therapeutic strategies for TBI requires a deep understanding of human neurophysiology at the molecular level and that the framework of multiomics may provide some effective solutions for the diagnosis and treatment of this challenging condition. To this end, we present here a comprehensive review of TBI biomarker candidates from across the multiomic disciplines and compare them with known signatures associated with other neuropsychological conditions, including Alzheimer’s disease and Parkinson’s disease. We believe that this integrated view will facilitate a deeper understanding of the pathophysiology of TBI and its potential links to other neurological diseases.

Post-Traumatic Epilepsy and Comorbidities: Advanced Models, Molecular Mechanisms, Biomarkers, and Novel Therapeutic Interventions

Post-traumatic epilepsy (PTE) is one of the most devastating long-term, network consequences of traumatic brain injury (TBI). There is currently no approved treatment that can prevent onset of spontaneous seizures associated with brain injury, and many cases of PTE are refractory to antiseizure medications. Post-traumatic epileptogenesis is an enduring process by which a normal brain exhibits hypersynchronous excitability after a head injury incident. Understanding the neural networks and molecular pathologies involved in epileptogenesis are key to preventing its development or modifying disease progression. In this article, we describe a critical appraisal of the current state of PTE research with an emphasis on experimental models, molecular mechanisms of post-traumatic epileptogenesis, potential biomarkers, and the burden of PTE-associated comorbidities. The goal of epilepsy research is to identify new therapeutic strategies that can prevent PTE development or interrupt the epileptogenic process and relieve associated neuropsychiatric comorbidities. Therefore, we also describe current preclinical and clinical data on the treatment of PTE sequelae. Differences in injury patterns, latency period, and biomarkers are outlined in the context of animal model validation, pathophysiology, seizure frequency, and behavior. Improving TBI recovery and preventing seizure onset are complex and challenging tasks; however, much progress has been made within this decade demonstrating disease modifying, anti-inflammatory, and neuroprotective strategies, suggesting this goal is pragmatic. Our understanding of PTE is continuously evolving, and improved preclinical models allow for accelerated testing of critically needed novel therapeutic interventions in military and civilian persons at high risk for PTE and its devastating comorbidities.

Biofluid Biomarkers in Traumatic Brain Injury: A Systematic Scoping Review

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

The Current State of Traumatic Brain Injury Biomarker Measurement Methods

Traumatic brain injury (TBI) is associated with high rates of morbidity and mortality partially due to the limited tools available for diagnosis and classification. Measuring panels of protein biomarkers released into the bloodstream after injury has been proposed to diagnose TBI, inform treatment decisions, and monitor the progression of the injury. Being able to measure these protein biomarkers at the point-of-care would enable assessment of TBIs from the point-of-injury to the patient's hospital bedside. In this review, we provide a detailed discussion of devices reported in the academic literature and available on the market that have been designed to measure TBI protein biomarkers in various biofluids and contexts. We also assess the challenges associated with TBI biomarker measurement devices and suggest future research directions to encourage translation of these devices to clinical use.

A Biomarker for Concussion: The Good, the Bad, and the Unknown

BACKGROUND

Traumatic brain injury (TBI) is a significant cause of morbidity, mortality, and disability in the US, with >2.8 million patients presenting to the emergency department (ED) annually. However, the diagnosis of TBI is challenging and presents a number of difficulties, particularly at the mildest end of the spectrum: concussion. A number of groups have researched biomarkers to aid in the evaluation of TBI, and most recently in 2018 the Food and Drug Administration approved a new blood-based immunoassay biomarker using ubiquitin carboxyl hydrolase L1 and glial fibrillary acidic protein to aid in head computed tomography (CT) triage.

CONTENT

This review clarifies the practical challenges in assessing and implementing a new blood biomarker. It then examines the clinical context and need, as well as the evidence used to validate this new immunoassay.

SUMMARY

Concussion is a multifaceted diagnosis with a need for biomarkers to assist in diagnostic and prognostic assessment. Recent articles in the lay press have revealed misunderstanding about the function of this new test, expressing hopes that this biomarker serves patients at the mildest end of the spectrum and is useful for athletes and children. None of these assumptions are correct, as this biomarker has been evaluated in patients only at the moderate end of the spectrum and has been validated only in adults presenting to the ED who have already been triaged to receive head CT, not in athletes or children. The next steps for this assay should consider clinical work flow and clarifying its intended use, including integration with existing triage methods, and validating the assay for a broader population.

Thorough overview of ubiquitin C-terminal hydrolase-L1 and glial fibrillary acidic protein as tandem biomarkers recently cleared by US Food and Drug Administration for the evaluation of intracranial injuries among patients with traumatic brain injury

Traumatic brain injury (TBI) is a major cause of mortality and morbidity affecting all ages. It remains to be a diagnostic and therapeutic challenge, in which, to date, there is no Food and Drug Administration‐approved drug for treating patients suffering from TBI. The heterogeneity of the disease and the associated complex pathophysiology make it difficult to assess the level of the trauma and to predict the clinical outcome. Current injury severity assessment relies primarily on the Glasgow Coma Scale score or through neuroimaging, including magnetic resonance imaging and computed tomography scans. Nevertheless, such approaches have certain limitations when it comes to accuracy and cost efficiency, as well as exposing patients to unnecessary radiation. Consequently, extensive research work has been carried out to improve the diagnostic accuracy of TBI, especially in mild injuries, because they are often difficult to diagnose. The need for accurate and objective diagnostic measures led to the discovery of biomarkers significantly associated with TBI. Among the most well‐characterized biomarkers are ubiquitin C‐terminal hydrolase‐L1 and glial fibrillary acidic protein. The current review presents an overview regarding the structure and function of these distinctive protein biomarkers, along with their clinical significance that led to their approval by the US Food and Drug Administration to evaluate mild TBI in patients.

Higher pyruvate levels after Achilles tendon rupture surgery could be used as a prognostic biomarker of an improved patient outcome

PURPOSE

The primary aim of this study was to assess the relationship between the metabolites lactate and pyruvate in the healing tendon after Achilles tendon rupture (ATR) and patient-reported outcome at 6 and 12 months. A secondary aim was to evaluate which underlying factors regulate lactate and pyruvate concentrations.

METHODS

Lactate and pyruvate concentrations were measured two weeks post-operatively in both the healing- and healthy Achilles tendon in 109 patients (90 men, 19 women; mean age 40 ± 7.9 years). Patient demographics, degree of physical activity, timing of surgery, operation time, patient-reported loading and step counts were investigated in relation to metabolite concentrations. At 6 and 12 months, the Achilles tendon Total Rupture Score (ATRS) questionnaire was used to assess patient outcome.

RESULTS

The mean number of steps taken during the post-operative days 1-10 was the only factor significantly related to the mean concentration of lactate (R² = 0.34, p = 0.038), and pyruvate (R² = 0.46, p = 0.006). Pyruvate was demonstrated as the only factor significantly associated with ATRS at both 6 months (R² = 0.32, p = 0.003) and at 12 months (R² = 0.37, p = 0.004) using multiple linear regression.

CONCLUSION

The mean concentration of pyruvate during early ATR healing may predict patient outcome at 6 and 12 months post-operatively and possibly be used as a biomarker of healing. Early mobilization with an increased number of steps taken is an important clinical strategy to improve the metabolite concentrations during healing.

LEVEL OF EVIDENCE

III.

Simultaneous Determination of Eight Urinary Metabolites by HPLC-MS/MS for Noninvasive Assessment of Traumatic Brain Injury

Traumatic brain injury (TBI) is a serious public health concern for which sensitive and objective diagnostic methods remain lacking. While advances in neuroimaging have improved diagnostic capabilities, the complementary use of molecular biomarkers can provide clinicians with additional insight into the nature and severity of TBI. In this study, a panel of eight metabolites involved in distinct pathophysiological processes related to concussion was quantified using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Specifically, the newly developed method can simultaneously determine urinary concentrations of glutamic acid, homovanillic acid, 5-hydroxyindoleacetic acid, methionine sulfoxide, lactic acid, pyruvic acid, N-acetylaspartic acid, and F_2α-isoprostane without intensive sample preparation or preconcentration. The method was systematically validated to assess sensitivity (method detection limits: 1-20 μg/L), accuracy (81-124% spike recoveries in urine), and reproducibility (relative standard deviation: 4-12%). The method was ultimately applied to a small cohort of urine specimens obtained from healthy college student volunteers. The method presented here provides a new technique to facilitate future work aiming to assess the clinical efficacy of these putative biomarkers for noninvasive assessment of TBI.

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

INTRODUCTION

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSION

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

Biomarkers in Traumatic Spinal Cord Injury—Technical and Clinical Considerations: A Systematic Review

Objective. To examine (1) if serological or cerebrospinal fluid (CSF) biomarkers can be used as diagnostic and/or prognostic tools in patients with spinal cord injury (SCI) and (2) if literature provides recommendations regarding timing and source of biomarker evaluation. Data Sources. A systematic literature search to identify studies reporting on diagnostic and prognostic blood and/or CSF biomarkers in SCI was conducted in PubMed/MEDLINE, CINAHL, Science Direct, The Cochrane Library, ISI Web of Science, and PEDro. Study Selection. Clinical trials, cohort, and pilot studies on patients with traumatic SCI investigating at least one blood or CSF biomarker were included. Following systematic screening, 19 articles were included in the final analysis. PRISMA guidelines were followed to conduct this review. Data Extraction. Independent extraction of articles was completed by 2 authors using predefined inclusion criteria and study quality indicators. Data Synthesis. Nineteen studies published between 2002 and April 2019 with 1596 patients were included in the systematic review. In 14 studies, blood biomarkers were measured, 4 studies investigated CSF biomarkers, and 1 study used both blood and CSF samples. Conclusions. Serum/CSF concentrations of several biomarkers (S100b, IL-6, GFAP, NSE, tau, TNF-α, IL-8, MCP-1, pNF-H, and IP-10) following SCI are highly time dependent and related to injury severity. Future studies need to validate these markers as true biomarkers and should control for secondary complications associated with SCI. A deeper understanding of secondary pathophysiological events after SCI and their effect on biomarker dynamics may improve their clinical significance as surrogate parameters in future clinical studies.

Metabolomics and Biomarker Discovery in Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the leading causes of disability and mortality worldwide. The TBI pathogenesis can induce broad pathophysiological consequences and clinical outcomes attributed to the complexity of the brain. Thus, the diagnosis and prognosis are important issues for the management of mild, moderate, and severe forms of TBI. Metabolomics of readily accessible biofluids is a promising tool for establishing more useful and reliable biomarkers of TBI than using clinical findings alone. Metabolites are an integral part of all biochemical and pathophysiological pathways. Metabolomic processes respond to the internal and external stimuli resulting in an alteration of metabolite concentrations. Current high-throughput and highly sensitive analytical tools are capable of detecting and quantifying small concentrations of metabolites, allowing one to measure metabolite alterations after a pathological event when compared to a normal state or a different pathological process. Further, these metabolic biomarkers could be used for the assessment of injury severity, discovery of mechanisms of injury, and defining structural damage in the brain in TBI. Metabolic biomarkers can also be used for the prediction of outcome, monitoring treatment response, in the assessment of or prognosis of post-injury recovery, and potentially in the use of neuroplasticity procedures. Metabolomics can also enhance our understanding of the pathophysiological mechanisms of TBI, both in primary and secondary injury. Thus, this review presents the promising application of metabolomics for the assessment of TBI as a stand-alone platform or in association with proteomics in the clinical setting.

Pyruvate and lactate as local prognostic biomarkers of patient outcome after achilles tendon rupture

BACKGROUND

Acute Achilles tendon rupture (ATR) is a frequently disabling injury, which exhibits unclear variability in long-term functional and patient-reported outcomes. Biomarkers from early healing, which have been shown to be prognostic of long-term outcome would facilitate the development of improved treatment methods.

HYPOTHESIS/PURPOSE

The aim of this study was to assess essential metabolites pyruvate and its product lactate, as early biomarkers in relation to long-term functional- and patient-reported outcome after ATR.

STUDY DESIGN

Prospective cohort study.

METHODS

A total of 124 patients (103 men, 21 women; mean age 40 ± 7 years) with ATR, treated with uniform anesthetic and surgical technique, were prospectively assessed. At two weeks post-injury pyruvate and lactate concentrations were assessed in both the injured and uninjured limbs using microdialysis followed by enzymatic quantification. The ratios of the concentration in the injured versus uninjured limb of pyruvate (pyruvate-r) and lactate (lactate-r) were calculated as well as the lactate/pyruvate ratios (L/P-r). At 12 months, patient-reported outcome was examined using self-reported questionnaires; Achilles tendon Total Rupture Score (ATRS), Foot and Ankle Outcome Score (FAOS), and physical activity score. At 12 months, functional outcome was studied using the validated heel-rise test.

RESULTS

Elevated pyruvate-r, at two weeks, was significantly associated with total ATRS (R = 0.254, P = 0.028), less loss in physical activity (R = 0.241, P = 0.039), less experience of pain in FAOS (R = 0.275, P = 0.032), and a higher number of heel-rise repetitions on injured side (R = 0.230, P = 0.040) at 12 months. Increased lactate-r was related with less strength limitations in the calf (R = 0.283, P = 0.011), while the elevated lactate-pyruvate ratio, notably, was related to more limitations in walking on uneven surface (R = -0,243, P = 0.027). The findings were verified by multiple linear regression taking confounding factors into consideration.

CONCLUSION

This study established that the metabolite pyruvate is a good potential biomarker, prognostic of patient outcome at the one-year follow-up after ATR surgery. These novel findings suggest that local biomarkers could be developed at an early-stage screen for new ATR treatments.

Serum Amyloid A Protein as a Potential Biomarker for Severity and Acute Outcome in Traumatic Brain Injury

Traumatic brain injury (TBI) causes a wide variety of neuroinflammatory events. These neuroinflammatory events depend, to a greater extent, on the severity of the damage. Our previous studies have shown that the liver produces serum amyloid A (SAA) at high levels in the initial hours after controlled cortical impact (CCI) injury in mice. Clinical studies have reported detectable SAA in the plasma of brain injury patients, but it is not clear if SAA levels depend on TBI severity. To evaluate this question, we performed a mild to severe CCI injury in wild-type mice. We collected blood samples and brains at 1, 3, and 7 days after injury for protein detection by western blotting, enzyme-linked immunosorbent assay, or immunohistochemical analysis. Our results showed that severe CCI injury compared to mild CCI injury or sham mice caused an increased neuronal death, larger lesion volume, increased microglia/macrophage density, and augmented neutrophil infiltration. Furthermore, we found that the serum levels of SAA protein ascended in the blood in correlation with high neuroinflammatory and neurodegenerative responses. Altogether, these results suggest that serum SAA may be a novel neuroinflammation-based, and severity-dependent, biomarker for acute TBI.

In search of antiepileptogenic treatments for post-traumatic epilepsy

Post-traumatic epilepsy (PTE) is diagnosed in 20% of individuals with acquired epilepsy, and can impact significantly the quality of life due to the seizures and other functional or cognitive and behavioral outcomes of the traumatic brain injury (TBI) and PTE. There is no available antiepileptogenic or disease modifying treatment for PTE. Animal models of TBI and PTE have been developed, offering useful insights on the value of inflammatory, neurodegenerative pathways, hemorrhages and iron accumulation, calcium channels and other target pathways that could be used for treatment development. Most of the existing preclinical studies test efficacy towards pathologies of functional recovery after TBI, while a few studies are emerging testing the effects towards induced or spontaneous seizures. Here we review the existing preclinical trials testing new candidate treatments for TBI sequelae and PTE, and discuss future directions for efforts aiming at developing antiepileptogenic and disease-modifying treatments.

Current trends in biomarker discovery and analysis tools for traumatic brain injury

Traumatic brain injury (TBI) affects 1.7 million people in the United States each year, causing lifelong functional deficits in cognition and behavior. The complex pathophysiology of neural injury is a primary barrier to developing sensitive and specific diagnostic tools, which consequentially has a detrimental effect on treatment regimens. Biomarkers of other diseases (e.g. cancer) have provided critical insight into disease emergence and progression that lend to developing powerful clinical tools for intervention. Therefore, the biomarker discovery field has recently focused on TBI and made substantial advancements to characterize markers with promise of transforming TBI patient diagnostics and care. This review focuses on these key advances in neural injury biomarkers discovery, including novel approaches spanning from omics-based approaches to imaging and machine learning as well as the evolution of established techniques.

Variation in Candidate Traumatic Brain Injury Biomarker Genes Are Associated with Gross Neurological Outcomes after Severe Traumatic Brain Injury

Diagnostic and prognostic biomarkers of traumatic brain injury (TBI) are actively being pursued; potential candidates include glial fibrillary acid protein (GFAP), S100 calcium-binding protein B (S100B), and ubiquitin C-terminal hydrolase L1 (UCHL1), two of which the United States Food and Drug Administration (FDA) recently approved for marketing of blood tests for adult concussion. The relationship between biomarker-encoding genes and TBI outcomes remains unknown. This pilot study explores variation in 18 single nucleotide polymorphisms (SNPs) in biomarker-encoding genes as predictors of neurological outcome in a population of adults with severe TBI. Participants (n = 305) were assessed using the Glasgow Outcome Scale (GOS) at 3, 6, 12, and 24 months post-injury. Multivariate logistical regression was used to calculate the odds ratio (OR) and determine the odds of having a lower score on the GOS ( = 1-2 vs. 3-5) based on variant allele presence, while controlling for confounders. Possession of the variant allele of one S100B SNP (rs1051169) was associated with higher scores on the GOS at 3 months (OR = 0.39; p = 0.04), 6 months (OR = 0.34; p = 0.02), 12 months (OR = 0.32; p = 0.02), and 24 months (OR = 0.30; p = 0.02) post-severe TBI. The relationship among these polymorphisms, protein levels, and biomarker utility, merits examination. These findings represent a novel contribution to the evidence that can inform future studies aimed at enhancing interpretation of biomarker data, identifying novel biomarkers, and ultimately harnessing this information to improve clinical outcomes and personalize care.

Neuronal Enriched Extracellular Vesicle Proteins as Biomarkers for Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of injury-related death throughout the world and lacks effective treatment. Surviving TBI patients often develop neuropsychiatric symptoms, and the molecular mechanisms underlying the neuronal damage and recovery following TBI are not well understood. Extracellular vesicles (EVs) are membranous nanoparticles that are divided into exosomes (originating in the endosomal/multi-vesicular body [MVB] system) and microvesicles (larger EVs produced through budding of the plasma membrane). Both types of EVs are generated by all cells and are secreted into the extracellular environment, and participate in cell-to-cell communication and protein and RNA delivery. EVs enriched for neuronal origin can be harvested from peripheral blood samples and their contents quantitatively examined as a window to follow potential changes occurring in brain. Recent studies suggest that the levels of exosomal proteins and microRNAs (miRNAs) may represent novel biomarkers to support the clinical diagnosis and potential response to treatment for neurological disorders. In this review, we focus on the biogenesis of EVs, their molecular composition, and recent advances in research of their contents as potential diagnostic tools for TBI.

Lipidomics Reveals Changes in Metabolism, Indicative of Anesthetic-Induced Neurotoxicity in Developing Brains

Numerous studies have demonstrated that treatment with high dose anesthetics for a prolonged duration induces brain injury in infants. However, whether anesthetic treatment leading to neurotoxicity is associated with alterations in lipid metabolism and homeostasis is still unclear. This review first outlines the lipidomics tools for analysis of lipid molecular species that can inform alterations in lipid species after anesthetic exposure. Then the available data indicating anesthetics cause changes in lipid profiles in the brain and serum of infant monkeys in preclinical studies are summarized, and the potential mechanisms leading to the altered lipid metabolism and their association with anesthetic-induced brain injury are also discussed. Finally, whether lipid changes identified in serum of infant monkeys can serve as indicators for the early detection of anesthetic-induced brain injury is described. We believe extensive studies on alterations in lipids after exposure to anesthetics will allow us to better understand anesthetic-induced neurotoxicity, unravel its underlying biochemical mechanisms, and develop powerful biomarkers for early detection/monitoring of the toxicity.

Biofluid biomarkers of traumatic brain injury

PRIMARY OBJECTIVE

The purpose of this paper is to review the clinical and research utility and applications of blood, cerebrospinal fluid (CSF), and cerebral microdialysis biomarkers in traumatic brain injury (TBI).

RESEARCH DESIGN

Not applicable.

METHODS AND PROCEDURES

A selective review was performed on these biofluid biomarkers in TBI.

MAIN OUTCOME AND RESULTS

Neurofilament heavy chain protein (NF-H), glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase-L1 (UCHL1), neuron-specific enolase (NSE), myelin basic protein (MBP), tau, and s100β blood biomarkers are elevated during the acute phase of severe head trauma but have key limitations in their research and clinical applications to mild TBI (mTBI). CSF biomarkers currently provide the best reflection of the central nervous system (CNS) pathobiological processes in TBI. Both animal and human studies of TBI have demonstrated the importance of serial sampling of biofluids and suggest that CSF biomarkers may be better equipped to characterize both TBI severity and temporal profiles.

CONCLUSIONS

The identification of biofluid biomarkers could play a vital role in identifying, diagnosing, and treating the underlying individual pathobiological changes of TBI. CNS-derived exosomes analyzed by ultra-high sensitivity detection methods have the potential to identify blood biomarkers for the range of TBI severity and time course.

A blood-based biomarker panel to risk-stratify mild traumatic brain injury

Mild traumatic brain injury (TBI) accounts for the vast majority of the nearly two million brain injuries suffered in the United States each year. Mild TBI is commonly classified as complicated (radiographic evidence of intracranial injury) or uncomplicated (radiographically negative). Such a distinction is important because it helps to determine the need for further neuroimaging, potential admission, or neurosurgical intervention. Unfortunately, imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI) are costly and not without some risk. The purpose of this study was to screen 87 serum biomarkers to identify a select panel of biomarkers that would predict the presence of intracranial injury as determined by initial brain CT. Serum was collected from 110 patients who sustained a mild TBI within 24 hours of blood draw. Two models were created. In the broad inclusive model, 72kDa type IV collagenase (MMP-2), C-reactive protein (CRP), creatine kinase B type (CKBB), fatty acid binding protein-heart (hFABP), granulocyte-macrophage colony-stimulating factor (GM-CSF) and malondialdehyde modified low density lipoprotein (MDA-LDL) significantly predicted injury visualized on CT, yielding an overall c-statistic of 0.975 and a negative predictive value (NPV) of 98.6. In the parsimonious model, MMP-2, CRP, and CKBB type significantly predicted injury visualized on CT, yielding an overall c-statistic of 0.964 and a negative predictive value (NPV) of 97.2. These results suggest that a serum based biomarker panel can accurately differentiate patients with complicated mild TBI from those with uncomplicated mild TBI. Such a panel could be useful to guide early triage decisions, including the need for further evaluation or admission, especially in those environments in which resources are limited.

Heart rate variability and serum level of insulin-like growth factor-1 are correlated with symptoms of emotional disorders in patients suffering a mild traumatic brain injury

OBJECTIVE

Patients who have experienced a mild traumatic brain injury (mTBI) are susceptible to symptoms of anxiety or depression. To explore the potential biomarkers for emotional disorders in mTBI patients, we analyzed the frequency domain of heart rate variability (HRV) and serum concentrations of four neurohormones.

METHODS

We assessed mTBI patients on their first visit and follow-up. Symptoms were evaluated by the Beck Anxiety Inventory and the Beck Depression Inventory, respectively. Serum levels of adrenocorticotropic hormone (ACTH), melatonin, cortisol, and insulin-like growth factor (IGF)-1 and HRV follow-ups were measured and compared.

RESULTS

mTBI patients were more vulnerable to symptoms of anxiety or depression than healthy controls. Reduced HRV was noted in mTBI patients compared to healthy controls. The mTBI patients demonstrated higher serum levels of ACTH, lower IGF-1 compared to healthy controls. In correlation analysis, only IGF-1 was positively correlated with HRV in mTBI patients. Both HRV and IGF-1 were correlated with symptom of depression while only HRV was correlated with symptom of anxiety in mTBI patients.

CONCLUSIONS

We infer that HRV may be more significantly correlated with emotional disorders than is IGF-1 in mTBI patients.

SIGNIFICANCE

The study is relevant for specific diagnostic markers in mTBI patients.

Comparative Assessment of the Prognostic Value of Biomarkers in Traumatic Brain Injury Reveals an Independent Role for Serum Levels of Neurofilament Light

Traumatic brain injury (TBI) is a common cause of death and disability, worldwide. Early determination of injury severity is essential to improve care. Neurofilament light (NF-L) has been introduced as a marker of neuroaxonal injury in neuroinflammatory/-degenerative diseases. In this study we determined the predictive power of serum (s-) and cerebrospinal fluid (CSF-) NF-L levels towards outcome, and explored their potential correlation to diffuse axonal injury (DAI). A total of 182 patients suffering from TBI admitted to the neurointensive care unit at a level 1 trauma center were included. S-NF-L levels were acquired, together with S100B and neuron-specific enolase (NSE). CSF-NF-L was measured in a subcohort (n = 84) with ventriculostomies. Clinical and neuro-radiological parameters, including computerized tomography (CT) and magnetic resonance imaging, were included in the analyses. Outcome was assessed 6 to 12 months after injury using the Glasgow Outcome Score (1-5). In univariate proportional odds analyses mean s-NF-L, -S100B and -NSE levels presented a pseudo-R2 Nagelkerke of 0.062, 0.214 and 0.074 in correlation to outcome, respectively. In a multivariate analysis, in addition to a model including core parameters (pseudo-R2 0.33 towards outcome; Age, Glasgow Coma Scale, pupil response, Stockholm CT score, abbreviated injury severity score, S100B), S-NF-L yielded an extra 0.023 pseudo-R2 and a significantly better model (p = 0.006) No correlation between DAI or CT assessed-intracranial damage and NF-L was found. Our study thus demonstrates that S-NF-L correlates to TBI outcome, even if used in models with S100B, indicating an independent contribution to the prediction, perhaps by reflecting different pathophysiological processes, not possible to monitor using conventional neuroradiology. Although we did not find a predictive value of NF-L for DAI, this cannot be completely excluded. We suggest further studies, with volume quantification of axonal injury, and a prolonged sampling time, in order to better determine the connection between NF-L and DAI.

Why have we not yet developed a simple blood test for TBI?

In recent years, traumatic brain injury (TBI) has emerged as a rapidly growing public health challenge. Annually, approximately 1.7 million people will sustain a TBI in the USA and WHO has named TBI the leading cause of death and disability in young adults worldwide, predicting it will become the third leading cause of death in the general population by 2020. The medical community currently relies on clinical examination and various neuroimaging modalities for the diagnosis of TBI; however, these methodologies are often confounded by altered patient mental status and are particularly poor at identifying mild-to-moderate injury. Despite decades of basic and clinical research, and the identification of hundreds of biochemical markers, presently there is no blood test to objectively assess TBI severity. Recent work suggests treatment-induced variance in the brain's glymphatic clearance may be responsible for the breakdown between biomarker discovery and clinical translation.

The prehospital management of traumatic brain injury

Traumatic brain injury (TBI) is an important cause of death and disability, particularly in younger populations. The prehospital evaluation and management of TBI is a vital link between insult and definitive care and can have dramatic implications for subsequent morbidity. Following a TBI the brain is at high risk for further ischemic injury, with prehospital interventions targeted at reducing this secondary injury while optimizing cerebral physiology. In the following chapter we discuss the prehospital assessment and management of the brain-injured patient. The initial evaluation and physical examination are discussed with a focus on interpretation of specific physical examination findings and interpretation of vital signs. We evaluate patient management strategies including indications for advanced airway management, oxygenation, ventilation, and fluid resuscitation, as well as prehospital strategies for the management of suspected or impending cerebral herniation including hyperventilation and brain-directed hyperosmolar therapy. Transport decisions including the role of triage models and trauma centers are discussed. Finally, future directions in the prehospital management of traumatic brain injury are explored.

Extracellular ezrin: a novel biomarker for traumatic brain injury

Traumatic brain injury (TBI) is a heterogeneous disease, and the discovery of diagnostic and prognostic TBI biomarkers is highly desirable in order to individualize patient care. We have previously published a study in which we identified possible TBI biomarkers by mass spectrometry 24 h after injury in a cell culture model. Ezrin-radixin-moesin (ERM) proteins were found abundantly in the medium after trauma, and in the present study we have identified extracellular ezrin as a possible biomarker for brain trauma by analyzing cell culture medium from injured primary neurons and glia and by measuring ezrin in cerebrospinal fluid (CSF) from both rats and humans. Our results show that extracellular ezrin concentration was substantially increased in cell culture medium after injury, but that the intracellular expression of the protein remained stable over time. Controlled cortical impact injured rats showed an increased amount of ezrin in CSF at both day 3 and day 7 after trauma. Moreover, ezrin was present in all ventricular CSF samples from seven humans with severe TBI. In contrast to intracellular ezrin, which is distinctly activated following TBI, extracellular ezrin is nonphosphorylated. This is the first report of extracellular ERM proteins in human and experimental models of TBI, providing a scientific foundation for further assessment of ezrin as a potential biomarker.

Neuroglobin expression and oxidant/antioxidant balance after graded traumatic brain injury in the rat

Neuroglobin is a neuron-specific hexacoordinated globin capable of binding various ligands, including O2, NO, and CO, the biological function of which is still uncertain. Various studies seem to indicate that neuroglobin is a neuroprotective agent when overexpressed, acting as a potent inhibitor of oxidative and nitrosative stress. In this study, we evaluated the pathophysiological response of the neuroglobin gene and protein expression in the cerebral tissue of rats sustaining traumatic brain injury of differing severity, while simultaneously measuring the oxidant/antioxidant balance. Two levels of trauma (mild and severe) were induced in anesthetized animals using the weight-drop model of diffuse axonal injury. Rats were then sacrificed at 6, 12, 24, 48, and 120 h after traumatic brain injury, and the gene and protein expression of neuroglobin and the concentrations of malondialdehyde (as a parameter representative of reactive oxygen species-mediated damage), nitrite + nitrate (indicative of NO metabolism), ascorbate, and glutathione (GSH) were determined in the brain tissue. Results indicated that mild traumatic brain injury, although causing a reversible increase in oxidative/nitrosative stress (increase in malondialdehyde and nitrite + nitrate) and an imbalance in antioxidants (decrease in ascorbate and GSH), did not induce any change in neuroglobin. Conversely, severe traumatic brain injury caused an over nine- and a fivefold increase in neuroglobin gene and protein expression, respectively, as well as a remarkable increase in oxidative/nitrosative stress and depletion of antioxidants. The results of this study, showing a lack of effect in mild traumatic brain injury as well as asynchronous time course changes in neuroglobin expression, oxidative/nitrosative stress, and antioxidants in severe traumatic brain injury, do not seem to support the role of neuroglobin as an endogenous neuroprotective antioxidant agent, at least under pathophysiological conditions.

Perspectives on molecular biomarkers of oxidative stress and antioxidant strategies in traumatic brain injury

Traumatic brain injury (TBI) is frequently associated with abnormal blood-brain barrier function, resulting in the release of factors that can be used as molecular biomarkers of TBI, among them GFAP, UCH-L1, S100B, and NSE. Although many experimental studies have been conducted, clinical consolidation of these biomarkers is still needed to increase the predictive power and reduce the poor outcome of TBI. Interestingly, several of these TBI biomarkers are oxidatively modified to carbonyl groups, indicating that markers of oxidative stress could be of predictive value for the selection of therapeutic strategies. Some drugs such as corticosteroids and progesterone have already been investigated in TBI neuroprotection but failed to demonstrate clinical applicability in advanced phases of the studies. Dietary antioxidants, such as curcumin, resveratrol, and sulforaphane, have been shown to attenuate TBI-induced damage in preclinical studies. These dietary antioxidants can increase antioxidant defenses via transcriptional activation of NRF2 and are also known as carbonyl scavengers, two potential mechanisms for neuroprotection. This paper reviews the relevance of redox biology in TBI, highlighting perspectives for future studies.

Hereditary vulnerabilities to post-operative cognitive dysfunction and dementia

In view of multiple prospective investigations reporting an incidence of 10% or greater in elderly patients after cardiac and non-cardiac procedures, it is surprising that no families, twins or even individual cases have been reported with persistent post-operative cognitive dysfunction (POCD) or post-operative dementia (POD) that is otherwise unexplained. As POCD and POD research has shifted in recent years from surgical and anesthetic variables to predictors of intrinsic, patient-specific susceptibility, a number of markers based on DNA sequence variation have been investigated. Nevertheless, no heritable, genomic indices of persistent POCD or post-operative dementia lasting 3 months or longer after surgery have been identified to date. The present manuscript surveys challenges confronting the search for markers of heritable vulnerability to POCD and POD, and proposes steps forward to be taken now, including the addition of surgical and anesthetic descriptors to ongoing longitudinal dementia protocols and randomized clinical trials (RCTs) comprising serial psychometric testing, and a fresh focus on phenotypes and genotypes shared between outliers with "extreme" POCD and POD traits.

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

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

Meta-analytic methods and the importance of non-TBI factors related to outcome in mild traumatic brain injury: response to Bigler et al. (2013)

Bigler et al. (2013, The Clinical Neuropsychologist) contend that weak methodology and poor quality of the studies comprising our recent meta-analysis led us to miss detecting a subgroup of mild traumatic brain injury (mTBI) characterized by persisting symptomatic complaint and positive biomarkers for neurological damage. Our computation of non-significant Q, tau(2), and I(2) statistics contradicts the existence of a subgroup of mTBI with poor outcome, or variation in effect size as a function of quality of research design. Consistent with this conclusion, the largest single contributor to our meta-analysis, Dikmen, Machamer, Winn, and Temkin (1995, Neuropsychology, 9, 80) yielded an effect size, -0.02, that was smaller than our overall effect size of -0.07 despite using the most liberal definition of mTBI: loss of consciousness less than 1 hour, with no exclusion of subjects who had positive CT scans. The evidence is weak for biomarkers of mTBI, such as diffusion tensor imaging and for demonstrable neuropathology in uncomplicated mTBI. Postconcussive symptoms, and reduced neuropsychological test scores are not specific to mTBI but can result from pre-existing psychosocial and psychiatric problems, expectancy effects and diagnosis threat. Moreover, neuropsychological impairment is seen in a variety of primary psychiatric disorders, which themselves are predictive of persistent complaints following mTBI. We urge use of prospective studies with orthopedic trauma controls in future investigations of mTBI to control for these confounding factors.