Temporal Profile of Serum Neurofilament Light (NF-L) and Heavy (pNF-H) Level Associations With 6-Month Cognitive Performance in Patients With Moderate-Severe Traumatic Brain Injury.

OBJECTIVE: Identification of biomarkers of cognitive recovery after traumatic brain injury (TBI) will inform care and improve outcomes. This study assessed the utility of neurofilament (NF-L and pNF-H), a marker of neuronal injury, informing cognitive performance following moderate-to-severe TBI (msTBI). SETTING: Level 1 trauma center and outpatient via postdischarge follow-up. PARTICIPANTS: N = 94. Inclusion criteria: Glasgow Coma Scale score less than 13 or 13-15 with clinical evidence of moderate-to-severe injury traumatic brain injury on clinical imaging. Exclusion criteria: neurodegenerative condition, brain death within 3 days after injury. DESIGN: Prospective observational study. Blood samples were collected at several time points post-injury. Cognitive testing was completed at 6 months post-injury. MAIN MEASURES: Serum NF-L (Human Neurology 4-Plex B) pNF-H (SR-X) as measured by SIMOA Quanterix assay. Divided into 3 categorical time points at days post-injury (DPI): 0-15 DPI, 16-90 DPI, and >90 DPI. Cognitive composite comprised executive functioning measures derived from 3 standardized neuropsychological tests (eg, Delis-Kaplan Executive Function System: Verbal Fluency, California Verbal Learning Test, Second Edition, Wechsler Adult Intelligence Scale, Third Edition). RESULTS: pNF-H at 16-90 DPI was associated with cognitive outcomes including a cognitive-executive composite score at 6 months (ß = -.430, t34 = -3.190, P = .003). CONCLUSIONS: Results suggest that "subacute" elevation of serum pNF-H levels may be associated with protracted/poor cognitive recovery from msTBI and may be a target for intervention. Interpretation is limited by small sample size and including only those who were able to complete cognitive testing.

Parallel Cerebrospinal Fluid and Serum Temporal Profile Assessment of Axonal Injury Biomarkers Neurofilament-Light Chain and Phosphorylated Neurofilament-Heavy Chain: Associations With Patient Outcome in Moderate-Severe Traumatic Brain Injury.

Neurofilament-light chain (NF-L) and phosphorylated neurofilament-heavy chain (pNF-H) are axonal proteins that have been reported as potential diagnostic and prognostic biomarkers in traumatic brain injury (TBI). However, detailed temporal profiles for these proteins in blood, and interrelationships in the acute and chronic time periods post-TBI have not been established. Our objectives were: 1) to characterize acute-to-chronic serum NF-L and pNF-H profiles after moderate-severe TBI, as well as acute cerebrospinal fluid (CSF) levels; 2) to evaluate CSF and serum NF-L and pNF-H associations with each other; and 3) to assess biomarker associations with global patient outcome using both the Glasgow Outcome Scale-Extended (GOS-E) and Disability Rating Scale (DRS). In this multi-cohort study, we measured serum and CSF NF-L and pNF-H levels in samples collected from two clinical cohorts (University of Pittsburgh [UPITT] and Baylor College of Medicine [BCM]) of individuals with moderate-severe TBI. The UPITT cohort includes 279 subjects from an observational cohort study; we obtained serum (n = 277 unique subjects) and CSF (n = 95 unique subjects) daily for 1 week, and serum every 2 weeks for 6 months. The BCM cohort included 103 subjects from a previous randomized clinical trial of erythropoietin and blood transfusion threshold after severe TBI, which showed no effect on neurological outcome between treatment arms; serum (n = 99 unique subjects) and CSF (n = 54 unique subjects) NF-L and pNF-H levels were measured at least daily during Days (D) 0-10 post-injury. GOS-E and DRS were assessed at 6 months (both cohorts) and 12 months (UPITT cohort only). Results show serum NF-L and pNF-H gradually rise during the first 10 days and peak at D20-30 post-injury. In the UPITT cohort, acute (D0-6) NF-L and pNF-H levels correlate within CSF and serum (Spearman r = 0.44-0.48; p < 0.05). In the UPITT cohort, acute NF-L CSF and serum levels, as well as chronic (Months [M]2-6) serum NF-L levels, were higher among individuals with unfavorable GOS-E and worse DRS at 12 months (p < 0.05, all comparisons). In the BCM cohort, higher acute serum NF-L levels were also associated with unfavorable GOS-E. Higher pNF-H serum concentrations (D0-6 and M2-6), but not CSF pNF-H, were associated with unfavorable GOS-E and worse DRS (p < 0.05, all comparisons) in the UPITT cohort. Relationships between biomarker levels and favorable outcome persisted after controlling for age, sex, and Glasgow Coma Scale. This study shows for the first time that serum levels of NF-L and pNF-H peak at D20-30 post-TBI. Serum NF-L levels, and to a lesser extent pNF-H levels, are robustly associated with global patient outcomes and disability after moderate-severe TBI. Further studies on clinical utility as prognosis and treatment-response indicators are needed.

Transcriptomic Signatures of Neuronally Derived Extracellular Vesicles Reveal the Presence of Olfactory Receptors in Clinical Samples from Traumatic Brain Injury Patients.

Traumatic brain injury (TBI) is defined as an injury to the brain by external forces which can lead to cellular damage and the disruption of normal central nervous system functions. The recently approved blood-based biomarkers GFAP and UCH-L1 can only detect injuries which are detectable on CT, and are not sensitive enough to diagnose milder injuries or concussion. Exosomes are small microvesicles which are released from the cell as a part of extracellular communication in normal as well as diseased states. The objective of this study was to identify the messenger RNA content of the exosomes released by injured neurons to identify new potential blood-based biomarkers for TBI. Human severe traumatic brain injury samples were used for this study. RNA was isolated from neuronal exosomes and total transcriptomic sequencing was performed. RNA sequencing data from neuronal exosomes isolated from serum showed mRNA transcripts of several neuronal genes. In particular, mRNAs of several olfactory receptor genes were present at elevated concentrations in the neuronal exosomes. Some of these genes were OR10A6, OR14A2, OR6F1, OR1B1, and OR1L1. RNA sequencing data from exosomes isolated from CSF showed a similar elevation of these olfactory receptors. We further validated the expression of these samples in serum samples of mild TBI patients, and a similar up-regulation of these olfactory receptors was observed. The data from these experiments suggest that damage to the neurons in the olfactory neuroepithelium as well as in the brain following a TBI may cause the release of mRNA from these receptors in the exosomes. Hence, olfactory receptors can be further explored as biomarkers for the diagnosis of TBI.

Isolated Traumatic Subarachnoid Hemorrhage on Head Computed Tomography Scan May Not Be Isolated: A Transforming Research and Clinical Knowledge in Traumatic Brain Injury Study (TRACK-TBI) Study.

Isolated traumatic subarachnoid hemorrhage (tSAH) after traumatic brain injury (TBI) on head computed tomography (CT) scan is often regarded as a "mild" injury, with reduced need for additional workup. However, tSAH is also a predictor of incomplete recovery and unfavorable outcome. This study aimed to evaluate the characteristics of CT-occult intracranial injuries on brain magnetic resonance imaging (MRI) scan in TBI patients with emergency department (ED) arrival Glasgow Coma Scale (GCS) score 13-15 and isolated tSAH on CT. The prospective, 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury Study (TRACK-TBI; enrollment years 2014-2019) enrolled participants who presented to the ED and received a clinically-indicated head CT within 24 h of TBI. A subset of TRACK-TBI participants underwent venipuncture within 24 h for plasma glial fibrillary acidic protein (GFAP) analysis, and research MRI at 2-weeks post-injury. In the current study, TRACK-TBI participants age ≥17 years with ED arrival GCS 13-15, isolated tSAH on initial head CT, plasma GFAP level, and 2-week MRI data were analyzed. In 57 participants, median age was 46.0 years [quartile 1 to 3 (Q1-Q3): 34-57] and 52.6% were male. At ED disposition, 12.3% were discharged home, 61.4% were admitted to hospital ward, and 26.3% to intensive care unit. MRI identified CT-occult traumatic intracranial lesions in 45.6% (26 of 57 participants; one additional lesion type: 31.6%; 2 additional lesion types: 14.0%); of these 26 participants with CT-occult intracranial lesions, 65.4% had axonal injury, 42.3% had subdural hematoma, and 23.1% had intracerebral contusion. GFAP levels were higher in participants with CT-occult MRI lesions compared with without (median: 630.6 pg/mL, Q1-Q3: [172.4-941.2] vs. 226.4 [105.8-436.1], p = 0.049), and were associated with axonal injury (no: median 226.7 pg/mL [109.6-435.1], yes: 828.6 pg/mL [204.0-1194.3], p = 0.009). Our results indicate that isolated tSAH on head CT is often not the sole intracranial traumatic injury in GCS 13-15 TBI. Forty-six percent of patients in our cohort (26 of 57 participants) had additional CT-occult traumatic lesions on MRI. Plasma GFAP may be an important biomarker for the identification of additional CT-occult injuries, including axonal injury. These findings should be interpreted cautiously given our small sample size and await validation from larger studies.

Serial Measurements of Serum Glial Fibrillary Acidic Protein in Moderate-Severe Traumatic Brain Injury: Potential Utility in Providing Insights into Secondary Insults and Long-Term Outcome.

In patients with traumatic brain injury (TBI), serum biomarkers may have utility in assessing the evolution of secondary brain injury. A panel of nine brain-injury- associated biomarkers was measured in archived serum samples over 10 days post-injury from 100 patients with moderate-severe TBI. Among the biomarkers evaluated, serum glial fibrillary acidic protein (GFAP) had the strongest associations with summary measures of acute pathophysiology, including intracranial pressure (ICP), cerebral perfusion pressure (CPP), and brain tissue pO2 (PbtO2). Group based trajectory (TRAJ) analysis was used to identify three distinct GFAP subgroups. The low TRAJ group (n = 23) had peak levels of 9.4 + 1.2 ng/mL that declined rapidly. The middle TRAJ group (n = 48) had higher peak values (31.5 + 5.0 ng/mL) and a slower decline over time. The high TRAJ group (n = 26) had very high, sustained peak values (59.6 + 12.5 ng/mL) that even rose among some patients over 10 days. Patients in the high TRAJ group had significantly higher mortality rate than patients in low and middle TRAJ groups (26.9% vs. 7.0%, p = 0.028). The frequency of poor neurological outcome (Glasgow Outcome Score Extended [GOS-E] 1-4) was 88.5% in the high TRAJ group, 54.2% in the middle TRAJ group, and 30.4% in the low TRAJ group (p < 0.001). ICP was highest in the high TRAJ group (median 17.6 mm Hg), compared with 14.4 mmHg in the low and 15.9 mm Hg in middle TRAJ groups (p = 0.002). High TRAJ patients spent the longest time with ICP >25 mm Hg, median 23 h, compared with 2 and 6 h in the low and middle TRAJ groups (p = 0.006), and the longest time with ICP >30 mm Hg, median 5 h, compared with 0 and 1 h in the low and middle TRAJ groups, respectively (p = 0.013). High TRAJ group patients more commonly required tier 2 or 3 treatment to control ICP. The high TRAJ group had the longest duration when CPP was <50 mm Hg (p = 0.007), and PbtO2 was <10 mm Hg (p = 0.002). Logistical regression was used to study the relationship between temporal serum GFAP patterns and 6-month GOS-E. Here, the low and middle TRAJ groups were combined to form a low-risk group, and the high TRAJ group was designated the high-risk group. High TRAJ group patients had a greater chance of a poor 6-month GOS-E (p < 0.0001). When adjusting for baseline injury characteristics, GFAP TRAJ group membership remained associated with GOS-E (p = 0.003). When an intensive care unit (ICU) injury burden score, developed to quantify physiological derangements, was added to the model, GFAP TRAJ group membership remained associated with GOS-E (p = 0.014). Mediation analysis suggested that ICU burden scores were in the causal pathway between TRAJ group and 6-month mortality or GOS-E. Our results suggest that GFAP may be useful to monitor serially in moderate-severe TBI patients. Future studies in larger cohorts are needed to confirm these results.

Clinical Outcomes After Traumatic Brain Injury and Exposure to Extracranial Surgery: A TRACK-TBI Study.

Importance: Traumatic brain injury (TBI) is associated with persistent functional and cognitive deficits, which may be susceptible to secondary insults. The implications of exposure to surgery and anesthesia after TBI warrant investigation, given that surgery has been associated with neurocognitive disorders. Objective: To examine whether exposure to extracranial (EC) surgery and anesthesia is related to worse functional and cognitive outcomes after TBI. Design, Setting, and Participants: This study was a retrospective, secondary analysis of data from the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study, a prospective cohort study that assessed longitudinal outcomes of participants enrolled at 18 level I US trauma centers between February 1, 2014, and August 31, 2018. Participants were 17 years or older, presented within 24 hours of trauma, were admitted to an inpatient unit from the emergency department, had known Glasgow Coma Scale (GCS) and head computed tomography (CT) status, and did not undergo cranial surgery. This analysis was conducted between January 2, 2020, and August 8, 2023. Exposure: Participants who underwent EC surgery during the index admission were compared with participants with no surgery in groups with a peripheral orthopedic injury or a TBI and were classified as having uncomplicated mild TBI (GCS score of 13-15 and negative CT results [CT- mTBI]), complicated mild TBI (GCS score of 13-15 and positive CT results [CT+ mTBI]), or moderate to severe TBI (GCS score of 3-12 [m/sTBI]). Main Outcomes and Measures: The primary outcomes were functional limitations quantified by the Glasgow Outcome Scale-Extended for all injuries (GOSE-ALL) and brain injury (GOSE-TBI) and neurocognitive outcomes at 2 weeks and 6 months after injury. Results: A total of 1835 participants (mean [SD] age, 42.2 [17.8] years; 1279 [70%] male; 299 Black, 1412 White, and 96 other) were analyzed, including 1349 nonsurgical participants and 486 participants undergoing EC surgery. The participants undergoing EC surgery across all TBI severities had significantly worse GOSE-ALL scores at 2 weeks and 6 months compared with their nonsurgical counterparts. At 6 months after injury, m/sTBI and CT+ mTBI participants who underwent EC surgery had significantly worse GOSE-TBI scores (B = -1.11 [95% CI, -1.53 to -0.68] in participants with m/sTBI and -0.39 [95% CI, -0.77 to -0.01] in participants with CT+ mTBI) and performed worse on the Trail Making Test Part B (B = 30.1 [95% CI, 11.9-48.2] in participants with m/sTBI and 26.3 [95% CI, 11.3-41.2] in participants with CT+ mTBI). Conclusions and Relevance: This study found that exposure to EC surgery and anesthesia was associated with adverse functional outcomes and impaired executive function after TBI. This unfavorable association warrants further investigation of the potential mechanisms and clinical implications that could inform decisions regarding the timing of surgical interventions in patients after TBI.

Temporal Profiles of P-Tau, T-Tau, and P-Tau:Tau Ratios in Cerebrospinal Fluid and Blood from Moderate-Severe Traumatic Brain Injury Patients and Relationship to 6-12 Month Global Outcomes.

Traumatic brain injury (TBI) can initiate progressive injury responses, which are linked to increased risk of neurodegenerative diseases known as "tauopathies." Increased post-TBI tau hyperphosphorylation has been reported in brain tissue and biofluids. Acute-to-chronic TBI total (T)-tau and phosphorylated (P)-tau temporal profiles in the cerebrospinal fluid (CSF) and serum and their relationship to global outcome is unknown. Our multi-site longitudinal study examines these concurrent profiles acutely (CSF and serum) and also characterizes the acute- to-chronic serum patterns. Serial serum and CSF samples from individuals with moderate-to-severe TBI were obtained from two cohorts (acute, subacute, and chronic samples from University of Pittsburgh [UPitt] [n = 286 unique subjects] and acute samples from Baylor College of Medicine [BCM] [n = 114 unique subjects]) and assayed for T-tau and P-tau using the Rolling Circle Amplification-Surround Optical Fiber ImmunoAssay platform. Biokinetic analyses described serum T-tau and P-tau temporal patterns. T-tau and P-tau levels are compared with those in healthy controls (n = 89 for both CSF and serum), and univariate/multivariable associations are made with global outcome, including the Disability Rating Scale (DRS) and the Glasgow Outcome Scale-Extended (GOS-E) scores at 3 and 6 months post-TBI (BCM cohort) and at 6 and 12 months post-TBI (UPitt cohort). For both the UPitt and BCM cohorts, temporal increases in median serum and CSF T-tau and P-tau levels occurred over the first 5 days post-injury, while the initial increases of P-tau:T-tau ratio plateaued by day 4 post-injury (UPitt: n = 99, BCM: n = 48). Biokinetic analyses with UPitt data showed novel findings that T-tau (n = 74) and P-tau (n = 87) reached delayed maximum levels at 4.5 and 5.1 days, while exhibiting long serum half-lives (152 and 123 days), respectively. The post-TBI rise in acute (days 2-6) serum P-tau (up to 276-fold) far outpaced that of T-tau (7.3-fold), leading to a P-tau:T-tau increase of up to 267-fold, suggesting a shift toward tau hyperphosphorylation. BCM analyses showed that days 0-6 mean CSF T-tau and P-tau levels and P-tau:T-tau ratios were associated with greater disability (DRS) (n = 48) and worse global outcome (GOS-E) (n = 48) 6 months post-injury. Days 0-6 mean serum T-tau, P-tau, and P-tau:T-tau ratio were not associated with outcome in either cohort (UPitt: n = 145 [DRS], n = 154 [GOS-E], BCM: n = 99 [DRS and GOS-E]). UPitt multivariate models showed that higher chronic (months 1-6) mean P-tau levels and P-tau:T-tau ratio, but not T-tau levels, are associated with greater disability (DRS: n = 119) and worse global outcomes (GOS-E: n = 117) 12 months post-injury. This work shows the potential importance of monitoring post-TBI T-tau and P-tau levels over time. This multi-site longitudinal study features concurrent acute TBI T-tau and P-tau profiles in CSF and serum, and also characterizes acute-to-chronic serum profiles. Longitudinal profiles, along with no temporal concordance between trajectory groups over time, imply a sustained post-TBI shift in tau phosphorylation dynamics that may favor tauopathy development chronically.

Oxidized Activated Charcoal Nanozymes: Synthesis, and Optimization for In Vitro and In Vivo Bioactivity for Traumatic Brain Injury.

Carbon-based superoxide dismutase (SOD) mimetic nanozymes have recently been employed as promising antioxidant nanotherapeutics due to their distinct properties. The structural features responsible for the efficacy of these nanomaterials as antioxidants are, however, poorly understood. Here, the process-structure-property-performance properties of coconut-derived oxidized activated charcoal (cOAC) nano-SOD mimetics are studied by analyzing how modifications to the nanomaterial's synthesis impact the size, as well as the elemental and electrochemical properties of the particles. These properties are then correlated to the in vitro antioxidant bioactivity of poly(ethylene glycol)-functionalized cOACs (PEG-cOAC). Chemical oxidative treatment methods that afford smaller, more homogeneous cOAC nanoparticles with higher levels of quinone functionalization show enhanced protection against oxidative damage in bEnd.3 murine endothelioma cells. In an in vivo rat model of mild traumatic brain injury (mTBI) and oxidative vascular injury, PEG-cOACs restore cerebral perfusion rapidly to the same extent as the former nanotube-derived PEG-hydrophilic carbon clusters (PEG-HCCs) with a single intravenous injection. These findings provide a deeper understanding of how carbon nanozyme syntheses can be tailored for improved antioxidant bioactivity, and set the stage for translation of medical applications.

Profiles of Cognitive Functioning at 6 Months After Traumatic Brain Injury Among Patients in Level I Trauma Centers: A TRACK-TBI Study.

Importance: Cognitive dysfunction is common after traumatic brain injury (TBI), with a well-established dose-response relationship between TBI severity and likelihood or magnitude of persistent cognitive impairment. However, patterns of cognitive dysfunction in the long-term (eg, 6-month) recovery period are less well known. Objective: To characterize the prevalence of cognitive dysfunction within and across cognitive domains (processing speed, memory, and executive functioning) 6 months after injury in patients with TBI seen at level I trauma centers. Design, Setting, and Participants: This prospective longitudinal cohort study used data from Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) and included patients aged 17 years or older presenting at 18 US level I trauma center emergency departments or inpatient units within 24 hours of head injury, control individuals with orthopedic injury recruited from the same centers, and uninjured friend and family controls. Participants were enrolled between March 2, 2014, and July 27, 2018. Data were analyzed from March 5, 2020, through October 3, 2023. Exposures: Traumatic brain injury (Glasgow Coma Scale score of 3-15) or orthopedic injury. Main Outcomes and Measures: Performance on standard neuropsychological tests, including premorbid cognitive ability (National Institutes of Health Toolbox Picture Vocabulary Test), verbal memory (Rey Auditory Verbal Learning Test), processing speed (Wechsler Adult Intelligence Scale [4th edition] Processing Speed Index), and executive functioning (Trail Making Test). Results: The sample included 1057 persons with TBI (mean [SD] age, 39.3 [16.4] years; 705 [67%] male) and 327 controls without TBI (mean [SD] age, 38.4 [15.1] years; 222 [68%] male). Most persons with TBI demonstrated performance within 1.5 SDs or better of the control group (49.3% [95% CI, 39.5%-59.2%] to 67.5% [95% CI, 63.7%-71.2%] showed no evidence of impairment). Similarly, 64.4% (95% CI, 54.5%-73.4%) to 78.8% (95% CI, 75.4%-81.9%) of participants demonstrated no evidence of cognitive decline (defined as performance within 1.5 SDs of estimated premorbid ability). For individuals with evidence of either cognitive impairment or decline, diverse profiles of impairment across memory, speed, and executive functioning domains were observed (ie, the prevalence was >0 in each of the 7 combinations of impairment across these 3 cognitive domains for most TBI subgroups). Conclusions and Relevance: In this cohort study of patients seen at level I trauma centers 6 months after TBI, many patients with TBI demonstrated no cognitive impairment. Impairment was more prevalent in persons with more severe TBI and manifested in variable ways across individuals. The findings may guide future research and treatment recommendations.

Longitudinal Recovery Following Repetitive Traumatic Brain Injury.

Importance: One traumatic brain injury (TBI) increases the risk of subsequent TBIs. Research on longitudinal outcomes of civilian repetitive TBIs is limited. Objective: To investigate associations between sustaining 1 or more TBIs (ie, postindex TBIs) after study enrollment (ie, index TBIs) and multidimensional outcomes at 1 year and 3 to 7 years. Design, Setting, and Participants: This cohort study included participants presenting to emergency departments enrolled within 24 hours of TBI in the prospective, 18-center Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study (enrollment years, February 2014 to July 2020). Participants who completed outcome assessments at 1 year and 3 to 7 years were included. Data were analyzed from September 2022 to August 2023. Exposures: Postindex TBI(s). Main Outcomes and Measures: Demographic and clinical factors, prior TBI (ie, preindex TBI), and functional (Glasgow Outcome Scale-Extended [GOSE]), postconcussive (Rivermead Post-Concussion Symptoms Questionnaire [RPQ]), psychological distress (Brief Symptom Inventory-18 [BSI-18]), depressive (Patient Health Questionnaire-9 [PHQ-9]), posttraumatic stress disorder (PTSD; PTSD Checklist for DSM-5 [PCL-5]), and health-related quality-of-life (Quality of Life After Brain Injury-Overall Scale [QOLIBRI-OS]) outcomes were assessed. Adjusted mean differences (aMDs) and adjusted relative risks are reported with 95% CIs. Results: Of 2417 TRACK-TBI participants, 1572 completed the outcomes assessment at 1 year (1049 [66.7%] male; mean [SD] age, 41.6 [17.5] years) and 1084 completed the outcomes assessment at 3 to 7 years (714 [65.9%] male; mean [SD] age, 40.6 [17.0] years). At 1 year, a total of 60 participants (4%) were Asian, 255 (16%) were Black, 1213 (77%) were White, 39 (2%) were another race, and 5 (0.3%) had unknown race. At 3 to 7 years, 39 (4%) were Asian, 149 (14%) were Black, 868 (80%) were White, 26 (2%) had another race, and 2 (0.2%) had unknown race. A total of 50 (3.2%) and 132 (12.2%) reported 1 or more postindex TBIs at 1 year and 3 to 7 years, respectively. Risk factors for postindex TBI were psychiatric history, preindex TBI, and extracranial injury severity. At 1 year, compared with those without postindex TBI, participants with postindex TBI had worse functional recovery (GOSE score of 8: adjusted relative risk, 0.57; 95% CI, 0.34-0.96) and health-related quality of life (QOLIBRI-OS: aMD, -15.9; 95% CI, -22.6 to -9.1), and greater postconcussive symptoms (RPQ: aMD, 8.1; 95% CI, 4.2-11.9), psychological distress symptoms (BSI-18: aMD, 5.3; 95% CI, 2.1-8.6), depression symptoms (PHQ-9: aMD, 3.0; 95% CI, 1.5-4.4), and PTSD symptoms (PCL-5: aMD, 7.8; 95% CI, 3.2-12.4). At 3 to 7 years, these associations remained statistically significant. Multiple (2 or more) postindex TBIs were associated with poorer outcomes across all domains. Conclusions and Relevance: In this cohort study of patients with acute TBI, postindex TBI was associated with worse symptomatology across outcome domains at 1 year and 3 to 7 years postinjury, and there was a dose-dependent response with multiple postindex TBIs. These results underscore the critical need to provide TBI prevention, education, counseling, and follow-up care to at-risk patients.

Integrating, Harmonizing, and Curating Studies With High-Frequency and Hourly Physiological Data: Proof of Concept from Seven Traumatic Brain Injury Data Sets.

Research in severe traumatic brain injury (TBI) has historically been limited by studies with relatively small sample sizes that result in low power to detect small, yet clinically meaningful outcomes. Data sharing and integration from existing sources hold promise to yield larger more robust sample sizes that improve the potential signal and generalizability of important research questions. However, curation and harmonization of data of different types and of disparate provenance is challenging. We report our approach and experience integrating multiple TBI data sets containing collected physiological data, including both expected and unexpected challenges encountered in the integration process. Our harmonized data set included data on 1536 patients from the Citicoline Brain Injury Treatment Trial (COBRIT), Effect of erythropoietin and transfusion threshold on neurological recovery after traumatic brain injury: a randomized clinical trial (EPO Severe TBI), BEST-TRIP, Progesterone for the Treatment of Traumatic Brain Injury III Clinical Trial (ProTECT III), Transforming Research and Clinical Knowledge in Traumatic brain Injury (TRACK-TBI), Brain Oxygen Optimization in Severe Traumatic Brain Injury Phase-II (BOOST-2), and Ben Taub General Hospital (BTGH) Research Database studies. We conclude with process recommendations for data acquisition for future prospective studies to aid integration of these data with existing studies. These recommendations include using common data elements whenever possible, a standardized recording system for labeling and timing of high-frequency physiological data, and secondary use of studies in systems such as Federal Interagency Traumatic Brain Injury Research Informatics System (FITBIR), to engage investigators who collected the original data.

HMG-CoA Reductase Inhibitors for Traumatic Brain Injury.

Traumatic brain injuries (TBIs) are associated with high morbidity and mortality due to both the original insult as well as the destructive biological response that follows. Medical management aims to slow or even halt secondary neurological injury while simultaneously laying the groundwork for recovery. Statins are one class of medications that is showing increased promise in the management of TBI. Used extensively in cardiovascular disease, these drugs were originally developed as competitive inhibitors within the cholesterol production pipeline. They are now used in diverse disease states due to their pleiotropic effects on other biological processes such as inflammation and angiogenesis. Preclinical studies, retrospective reviews, and randomized clinical trials have shown a variety of benefits in the management of TBI, but to date, no large-scale randomized clinical trial has been performed. Despite this limitation, statins' early promise and well-tolerated side effect profile make them a promising new tool in the management of TBIs. More bench and clinical studies are needed to delineate proper treatment regimens as well as understand their true potential.

Perceived Utility of Intracranial Pressure Monitoring in Traumatic Brain Injury: A Seattle International Brain Injury Consensus Conference Consensus-Based Analysis and Recommendations.

BACKGROUND: Intracranial pressure (ICP) monitoring is widely practiced, but the indications are incompletely developed, and guidelines are poorly followed. OBJECTIVE: To study the monitoring practices of an established expert panel (the clinical working group from the Seattle International Brain Injury Consensus Conference effort) to examine the match between monitoring guidelines and their clinical decision-making and offer guidance for clinicians considering monitor insertion. METHODS: We polled the 42 Seattle International Brain Injury Consensus Conference panel members' ICP monitoring decisions for virtual patients, using matrices of presenting signs (Glasgow Coma Scale [GCS] total or GCS motor, pupillary examination, and computed tomography diagnosis). Monitor insertion decisions were yes, no, or unsure (traffic light approach). We analyzed their responses for weighting of the presenting signs in decision-making using univariate regression. RESULTS: Heatmaps constructed from the choices of 41 panel members revealed wider ICP monitor use than predicted by guidelines. Clinical examination (GCS) was by far the most important characteristic and differed from guidelines in being nonlinear. The modified Marshall computed tomography classification was second and pupils third. We constructed a heatmap and listed the main clinical determinants representing 80% ICP monitor insertion consensus for our recommendations. CONCLUSION: Candidacy for ICP monitoring exceeds published indicators for monitor insertion, suggesting the clinical perception that the value of ICP data is greater than simply detecting and monitoring severe intracranial hypertension. Monitor insertion heatmaps are offered as potential guidance for ICP monitor insertion and to stimulate research into what actually drives monitor insertion in unconstrained, real-world conditions.

Prognostication and Goals of Care Decisions in Severe Traumatic Brain Injury: A Survey of The Seattle International Severe Traumatic Brain Injury Consensus Conference Working Group.

Abstract Best practice guidelines have advanced severe traumatic brain injury (TBI) care; however, there is little that currently informs goals of care decisions and processes despite their importance and frequency. Panelists from the Seattle International severe traumatic Brain Injury Consensus Conference (SIBICC) participated in a survey consisting of 24 questions. Questions queried use of prognostic calculators, variability in and responsibility for goals of care decisions, and acceptability of neurological outcomes, as well as putative means of improving decisions that might limit care. A total of 97.6% of the 42 SIBICC panelists completed the survey. Responses to most questions were highly variable. Overall, panelists reported infrequent use of prognostic calculators, and observed variability in patient prognostication and goals of care decisions. They felt that it would be beneficial for physicians to improve consensus on what constitutes an acceptable neurological outcome as well as what chance of achieving that outcome is acceptable. Panelists felt that the public should help to define what constitutes a good outcome and expressed some support for a "nihilism guard." More than 50% of panelists felt that if it was certain to be permanent, a vegetative state or lower severe disability would justify a withdrawal of care decision, whereas 15% felt that upper severe disability justified such a decision. Whether conceptualizing an ideal or existing prognostic calculator to predict death or an unacceptable outcome, on average a 64-69% chance of a poor outcome was felt to justify treatment withdrawal. These results demonstrate important variability in goals of care decision making and a desire to reduce this variability. Our panel of recognized TBI experts opined on the neurological outcomes and chances of those outcomes that might prompt consideration of care withdrawal; however, imprecision of prognostication and existing prognostication tools is a significant impediment to standardizing the approach to care-limiting decisions.

Functional Recovery, Symptoms, and Quality of Life 1 to 5 Years After Traumatic Brain Injury.

Importance: Many level I trauma center patients experience clinical sequelae at 1 year following traumatic brain injury (TBI). Longer-term outcome data are needed to develop better monitoring and rehabilitation services. Objective: To examine functional recovery, TBI-related symptoms, and quality of life from 1 to 5 years postinjury. Design, Setting, and Participants: This cohort study enrolled trauma patients across 18 US level I trauma centers between 2014 and 2018. Eligible participants were enrolled within 24 hours of injury and followed up to 5 years postinjury. Data were analyzed January 2023. Exposures: Mild TBI (mTBI), moderate-severe TBI (msTBI), or orthopedic traumatic controls (OTC). Main Outcomes and Measures: Functional independence (Glasgow Outcome Scale-Extended [GOSE] score 5 or higher), complete functional recovery (GOSE score, 8), better (ie, lower) TBI-related symptom burden (Rivermead Post Concussion Symptoms Questionnaire score of 15 or lower), and better (ie, higher) health-related quality of life (Quality of Life After Brain Injury Scale-Overall Scale score 52 or higher); mortality was analyzed as a secondary outcome. Results: A total 1196 patients were included in analysis (mean [SD] age, 40.8 [16.9] years; 781 [65%] male; 158 [13%] Black, 965 [81%] White). mTBI and OTC groups demonstrated stable, high rates of functional independence (98% to 100% across time). While odds of independence were lower among msTBI survivors, the majority were independent at 1 year (72%), and this proportion increased over time (80% at 5 years; group × year, P = .005; independence per year: odds ratio [OR] for msTBI, 1.28; 95% CI, 1.03-1.58; OR for mTBI, 0.81; 95% CI, 0.64-1.03). For other outcomes, group differences at 1 year remained stable over time (group × year, P ≥ .44). Odds of complete functional recovery remained lower for persons with mTBI vs OTC (OR, 0.39; 95% CI, 0.28-0.56) and lower for msTBI vs mTBI (OR, 0.34; 95% CI, 0.24-0.48). Odds of better TBI-related symptom burden and quality of life were similar for both TBI subgroups and lower than OTCs. Mortality between 1 and 5 years was higher for msTBI (5.5%) than mTBI (1.5%) and OTC (0.7%; P = .02). Conclusions and Relevance: In this cohort study, patients with previous msTBI displayed increased independence over 5 years; msTBI was also associated with increased mortality. These findings, in combination with the persistently elevated rates of unfavorable outcomes in mTBI vs controls imply that more monitoring and rehabilitation are needed for TBI.

Cerebral microdialysis and glucopenia in traumatic brain injury: A review.

Traditionally, intracranial pressure (ICP) and partial brain tissue oxygenation (PbtO2) have been the primary invasive intracranial measurements used to guide management in patients with severe traumatic brain injury (TBI). After injury however, the brain develops an increased metabolic demand which may require an increment in the oxidative metabolism of glucose. Simultaneously, metabolic, and electrical dysfunction can lead to an inability to meet these demands, even in the absence of ischemia or increased intracranial pressure. Cerebral microdialysis provides the ability to accurately measure local concentrations of various solutes including lactate, pyruvate, glycerol and glucose. Experimental and clinical data demonstrate that such measurements of cellular metabolism can yield critical missing information about a patient's physiologic state and help limit secondary damage. Glucose management in traumatic brain injury is still an unresolved question. As cerebral glucose metabolism may be uncoupled from systemic glucose levels due to the metabolic dysfunction, measurement of cerebral extracellular glucose concentrations could provide more predictive information and prove to be a better biomarker to avoid secondary injury of at-risk brain tissue. Based on data obtained from cerebral microdialysis, specific interventions such as ICP-directed therapy, blood glucose increment, seizure control, and/or brain oxygen optimization can be instituted to minimize or prevent secondary insults. Thus, microdialysis measurements of parenchymal metabolic function provides clinically valuable information that cannot be obtained by other monitoring adjuncts in the standard ICU setting.

Polygenic risk for mental disorders as predictors of posttraumatic stress disorder after mild traumatic brain injury.

Many patients with mild traumatic brain injury (mTBI) are at risk for mental health problems such as posttraumatic stress disorder (PTSD). The objective of this study was to determine whether the polygenic risk for PTSD (or for related mental health disorders or traits including major depressive disorder [MDD] and neuroticism [NEU]) was associated with an increased likelihood of PTSD in the aftermath of mTBI. We used data from individuals of European ancestry with mTBI enrolled in TRACK-TBI (n = 714), a prospective longitudinal study of level 1 trauma center patients. One hundred and sixteen mTBI patients (16.3%) had probable PTSD (PCL-5 score ≥33) at 6 months post-injury. We used summary statistics from recent GWAS studies of PTSD, MDD, and NEU to generate polygenic risk scores (PRS) for individuals in our sample. A multivariable model that included age, sex, pre-injury history of mental disorder, and cause of injury explained 7% of the variance in the PTSD outcome; the addition of the PTSD-PRS (and five ancestral principal components) significantly increased the variance explained to 11%. The adjusted odds of PTSD in the uppermost PTSD-PRS quintile was nearly four times higher (aOR = 3.71, 95% CI 1.80-7.65) than in the lowest PTSD-PRS quintile. There was no evidence of a statistically significant interaction between PTSD-PRS and prior history of mental disorder, indicating that PTSD-PRS had similar predictive utility among those with and without pre-injury psychiatric illness. When added to the model, neither MDD-PRS nor NEU-PRS were significantly associated with the PTSD outcome. These findings show that the risk for PTSD in the context of mTBI is, in part, genetically influenced. They also raise the possibility that an individual's PRS could be clinically actionable if used-possibly with other non-genetic predictors-to signal the need for enhanced follow-up and early intervention; this precision medicine approach needs to be prospectively studied.

Emotional Resilience Predicts Preserved White Matter Microstructure Following Mild Traumatic Brain Injury.

BACKGROUND: Adult patients with mild traumatic brain injury (mTBI) exhibit distinct phenotypes of emotional and cognitive functioning identified by latent profile analysis of clinical neuropsychological assessments. When discerned early after injury, these latent clinical profiles have been found to improve prediction of long-term outcomes from mTBI. The present study hypothesized that white matter (WM) microstructure is better preserved in an emotionally resilient mTBI phenotype compared with a neuropsychiatrically distressed mTBI phenotype. METHODS: The present study used diffusion magnetic resonance imaging to investigate and compare WM microstructure in major association, projection, and commissural tracts between the two phenotypes and over time. Diffusion magnetic resonance images from 172 patients with mTBI were analyzed to compute individual diffusion tensor imaging maps at 2 weeks and 6 months after injury. RESULTS: By comparing the diffusion tensor imaging parameters between the two phenotypes at global, regional, and voxel levels, emotionally resilient patients were shown to have higher axial diffusivity compared with neuropsychiatrically distressed patients early after mTBI. Longitudinal analysis revealed greater compromise of WM microstructure in neuropsychiatrically distressed patients, with greater decrease of global axial diffusivity and more widespread decrease of regional axial diffusivity during the first 6 months after injury compared with emotionally resilient patients. CONCLUSIONS: These results provide neuroimaging evidence of WM microstructural differences underpinning mTBI phenotypes identified from neuropsychological assessments and show differing longitudinal trajectories of these biological effects. These findings suggest that diffusion magnetic resonance imaging can provide short- and long-term imaging biomarkers of resilience.

Characterization of Calpain and Caspase-6-Generated Glial Fibrillary Acidic Protein Breakdown Products Following Traumatic Brain Injury and Astroglial Cell Injury.

Glial fibrillary acidic protein (GFAP) is the major intermediate filament III protein of astroglia cells which is upregulated in traumatic brain injury (TBI). Here we reported that GFAP is truncated at both the C- and N-terminals by cytosolic protease calpain to GFAP breakdown products (GBDP) of 46-40K then 38K following pro-necrotic (A23187) and pro-apoptotic (staurosporine) challenges to primary cultured astroglia or neuron-glia mixed cells. In addition, with another pro-apoptotic challenge (EDTA) where caspases are activated but not calpain, GFAP was fragmented internally, generating a C-terminal GBDP of 20 kDa. Following controlled cortical impact in mice, GBDP of 46-40K and 38K were formed from day 3 to 28 post-injury. Purified GFAP protein treated with calpain-1 and -2 generates (i) major N-terminal cleavage sites at A-56*A-61 and (ii) major C-terminal cleavage sites at T-383*Q-388, producing a limit fragment of 38K. Caspase-6 treated GFAP was cleaved at D-78/R-79 and D-225/A-226, where GFAP was relatively resistant to caspase-3. We also derived a GBDP-38K N-terminal-specific antibody which only labels injured astroglia cell body in both cultured astroglia and mouse cortex and hippocampus after TBI. As a clinical translation, we observed that CSF samples collected from severe human TBI have elevated levels of GBDP-38K as well as two C-terminally released GFAP peptides (DGEVIKES and DGEVIKE). Thus, in addition to intact GFAP, both the GBDP-38K as well as unique GFAP released C-terminal proteolytic peptides species might have the potential in tracking brain injury progression.