Clinical Outcomes after Traumatic Brain Injury

Impaired oligodendrogenesis in the white matter of aged mice following diffuse traumatic brain injury

Senescence is a negative prognostic factor for outcome and recovery following traumatic brain injury (TBI). TBI-induced white matter injury may be partially due to oligodendrocyte demise. We hypothesized that the regenerative capacity of oligodendrocyte precursor cells (OPCs) declines with age. To test this hypothesis, the regenerative capability of OPCs in young [(10 weeks ±2 (SD)] and aged [(62 weeks ±10 (SD)] mice was studied in mice subjected to central fluid percussion injury (cFPI), a TBI model causing widespread white matter injury. Proliferating OPCs were assessed by immunohistochemistry for the proliferating cell nuclear antigen (PCNA) marker and labeled by 5-ethynyl-2'-deoxyuridine (EdU) administered daily through intraperitoneal injections (50 mg/kg) from day 2 to day 6 after cFPI. Proliferating OPCs were quantified in the corpus callosum and external capsule on day 2 and 7 post-injury (dpi). The number of PCNA/Olig2-positive and EdU/Olig2-positive cells were increased at 2dpi (p < .01) and 7dpi (p < .01), respectively, in young mice subjected to cFPI, changes not observed in aged mice. Proliferating Olig2+/Nestin+ cells were less common (p < .05) in the white matter of brain-injured aged mice, without difference in proliferating Olig2+/PDGFRα+ cells, indicating a diminished proliferation of progenitors with different spatial origin. Following TBI, co-staining for EdU/CC1/Olig2 revealed a reduced number of newly generated mature oligodendrocytes in the white matter of aged mice when compared to the young, brain-injured mice (p < .05). We observed an age-related decline of oligodendrogenesis following experimental TBI that may contribute to the worse outcome of elderly patients following TBI.

Severe traumatic brain injury and acute kidney injury patients: factors associated with in-hospital mortality and unfavorable outcomes

OBJECTIVE

The purpose of this study was to identify the occurrence of AKI, and factors associated with in-hospital mortality and unfavorable outcomes in patients with severe traumatic brain injury (TBI) and acute kidney injury (AKI) severity.

METHOD

A retrospective cohort study which analyzed data with severe TBI between 2013 and 2017. We examined demographic and clinical information, and outcome by in-hospital mortality, and the Glasgow Outcome Scale six months after TBI. We associated factors to in-hospital mortality and unfavorable outcome in severe TBI and AKI with an association test.

RESULTS

A total of 219 patients were selected, 39.3% had an AKI, and several factors associated with AKI occurrence after severe TBI. Stage 2 or 3 of AKI (OR 12.489; 95% CI = 4.45-37.94) were independent risk for both outcomes in multivariable models, severity injury by the New Trauma Injury Severity Score (OR 0.97; 95% CI = 0.96-0.99) for mortality, and the New Injury Severity Score (OR1.07; 95% CI = 1.04-1.10) and Trauma and Injury Severity Score (OR = 0.98; 95% CI = 0.965-0.997) for unfavorable outcome.

CONCLUSION

The findings of our study confirmed that AKI severity and severity of injury was also related to increased mortality and unfavorable outcome after severe TBI.

Poor nutritional status is associated with incomplete functional recovery in elderly patients with mild traumatic brain injury

Background

The geriatric nutritional risk index (GNRI) is a simple index for evaluating the nutrition status of elderly patients. Many investigations have demonstrated that this index is associated with the prognosis of several diseases. This study aims to identify the relationship between the GNRI and recovery in elderly mild traumatic brain injury (mTBI) patients.

Methods

A total of 228 mTBI patients older than 65 years were included in this study. mTBI was defined as an injury to the brain with a loss of consciousness of 30 min or less, a duration of posttraumatic amnesia of &lt;24 h, and an admission Glasgow Coma Scale (GCS) score of 13–15. The Glasgow Outcome Scale Extended (GOSE), an outcome scale assessing functional independence, work, social activities, and personal relationships, was applied to assess the recovery of the patients. The clinical outcome was divided into complete recovery (GOSE = 8) and incomplete recovery (GOSE ≤ 7) at 6 months after the injury. Multivariate logistic regression was applied to evaluate the association between the GNRI and recovery of elderly mTBI patients, with adjustment for age, sex, hypertension, diabetes, and other important factors.

Results

The receiver operating curve (ROC) analysis demonstrated that the cutoff value of GNRI was 97.85, and the area under the curve (AUC) was 0.860. Compared to the patients with a high GNRI, the patients with a low GNRI were older, had a higher prevalence of anemia, acute subdural hematoma, and subarachnoid hemorrhage, had a higher age-adjusted Charlson Comorbidity Index value, and had lower levels of albumin, lymphocytes, and hemoglobin. Multivariable analysis showed that high GNRI was associated with a lower risk of 6-month incomplete recovery (OR, 0.770, 95% CI: 0.709–0.837, p &lt; 0.001).

Conclusion

The GNRI has utility as part of the objective risk assessment of incomplete 6-month functional recovery in elderly patients with mTBI.

Spindle wave in intracranial pressure signal analysis for patients with traumatic brain injury: A single-center prospective observational cohort study

Objective: Intracranial pressure (ICP) monitoring is an integral part of the multimodality monitoring system in the neural intensive care unit. The present study aimed to describe the morphology of the spindle wave (a shuttle shape with wide middle and narrow ends) during ICP signal monitoring in TBI patients and to investigate its clinical significance. Methods: Sixty patients who received ICP sensor placement and admitted to the neurosurgical intensive care unit between January 2021 and September 2021 were prospectively enrolled. The patient's Glasgow Coma Scale (GCS) score on admission and at discharge and length of stay in hospital were recorded. ICP monitoring data were monitored continuously. The primary endpoint was 6-month Glasgow Outcome Scale-Extended (GOSE) score. Patients with ICP spindle waves were assigned to the spindle wave group and those without were assigned to the control group. The correlation between the spindle wave and 6-month GOSE was analyzed. Meanwhile, the mean ICP and two ICP waveform-derived indices, ICP pulse amplitude (AMP) and correlation coefficient between AMP and ICP (RAP) were comparatively analyzed. Results: There were no statistically significant differences between groups in terms of age (p = 0.89), gender composition (p = 0.62), and GCS score on admission (p = 0.73). Patients with spindle waves tended to have a higher GCS score at discharge (12.75 vs. 10.90, p = 0.01), a higher increment in GCS score during hospitalization (ΔGCS, the difference between discharge GCS score and admission GCS score) (4.95 vs. 2.80, p = 0.01), and a better 6-month GOSE score (4.90 vs. 3.68, p = 0.04) compared with the control group. And the total duration of the spindle wave was positively correlated with 6-month GOSE (r = 0.62, p = 0.004). Furthermore, the parameters evaluated during spindle waves, including mean ICP, AMP, and RAP, demonstrated significant decreases compared with the parameters before the occurrence of the spindle wave (all p < 0.025). Conclusion: The ICP spindle wave was associated with a better prognosis in TBI patients. Physiological parameters such as ICP, AMP, and RAP were significantly improved when spindle waves occurred, which may explain the enhancement of clinical outcomes. Further studies are needed to investigate the pathophysiological mechanisms behind this wave.

Clinical Value of TCCD for Evaluating the Prognosis of Patients with Severe Traumatic Brain Injury After Large Decompressive Craniectomy: A Retrospective Study

INTRODUCTION

It is challenging to assess the prognosis of patients with severe traumatic brain injury (sTBI) after large decompressive craniectomy (DC). The aim of this study was to evaluate the clinical value of transcranial color-coded duplex sonography (TCCD) for assessing the prognosis of sTBI patients 6 months after large DC.

METHODS

This was a retrospective observational study that consecutively enrolled 84 patients with sTBI who were followed up for prognosis until 6 months after large DC. The primary endpoint was the Glasgow Outcome Score (GOS). According to the GOS, patients were divided into an unfavorable prognosis group (GOS 1-3, n = 47) and a favorable prognosis group (GOS 4-5, n = 37).

RESULTS

Significant between-group differences were found in age and hemodynamic parameters (systolic peak blood flow velocity, end-diastolic blood flow velocity, mean blood flow velocity, pulsatility index and resistance index) of the middle cerebral artery detected by TCCD (P < 0.05 for all). Subsequently, ridge regression was used to build a prognostic model for patients with large DC. Based on the cerebral hemodynamic parameters measured by TCCD and age, the mean (± standard deviation) area under the curve of the prognostic model in patients with sTBI after large DC was 0.76 ± 0.22. The sensitivity and specificity were 82.08% and 74.17%, respectively.

CONCLUSIONS

The cerebral hemodynamic parameters detected by TCCD, combined with age, may be used to predict the outcomes of patients with sTBI at 6 months after large DC. As a noninvasive method, TCCD has the potential to assess the prognosis of these patients.

TRIAL REGISTRATION

ChiCTR: ChiCTR1800019758. Registered 27 November 2018-retrospectively registered ( http://www.chictr.org.cn/index.aspx ).

Prognostic Models in Severe Traumatic Brain Injury: A Systematic Review and Meta-analysis

This review aimed to analyze the results of investigations that performed external validation or that compared prognostic models to identify the models and their variations that showed the best performance in predicting mortality, survival, and unfavorable outcome after severe traumatic brain injury. Pubmed, Embase, Scopus, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Google Scholar, TROVE, and Open Grey databases were searched. A total of 1616 studies were identified and screened, and 15 studies were subsequently included for analysis after applying the selection criteria. The Corticosteroid Randomization After Significant Head Injury (CRASH) and International Mission for Prognosis and Analysis of Clinical Trials in Traumatic Brain Injury (IMPACT) models were the most externally validated among studies of severe traumatic brain injury. The results of the review showed that most publications encountered an area under the curve ≥ 0.70. The area under the curve meta-analysis showed similarity between the CRASH and IMPACT models and their variations for predicting mortality and unfavorable outcomes. Calibration results showed that the variations of CRASH and IMPACT models demonstrated adequate calibration in most studies for both outcomes, but without a clear indication of uncertainties in the evaluations of these models. Based on the results of this meta-analysis, the choice of prognostic models for clinical application may depend on the availability of predictors, characteristics of the population, and trauma care services.

Evaluation of post-traumatic stress disorder (PTSD) and related comorbidities in clinical studies

Patients with traumatic brain injury (TBI) of varying severities are experiencing adverse outcomes during and after rehabilitation. Besides depression and anxiety, post-traumatic stress disorder (PTSD) is highly encountered in civilian and military populations. As more prospective and retrospective studies - focused on evaluating new or old psychological therapies in inpatient, outpatient, or controlled environments, targeting patients with PTSD with or without a history of TBI - are carried out, researchers are employing various scales to measure PTSD as well as other psychiatric diagnoses or cognitive impairments that might appear following TBI. We aimed to explore the literature published between January 2010 and October 2021 by querying three databases. Our preliminary results showed that several scales - such as the Clinician-Administered PTSD Scale (CAPS), the Posttraumatic Stress Disorder Checklist Military Version (PCL-M) as well as Specific Version (PCL-S), and Civilian Version (PCL-C) - have been frequently used for PTSD diagnosis and symptom severity. However, heterogeneity in the scales used when assessing and evaluating additional psychiatric comorbidities and cognitive impairments are due to the study aim and therapeutic approaches. Therefore, conducting an intervention focusing on post-TBI PTSD patients requires increased attention to patients' medical history in capturing multiple cognitive impairments and affected neuropsychological processes when designing the study and including validated instruments for measuring primary and secondary neuropsychological outcomes.

Neurochemical Markers of Traumatic Brain Injury: Relevance to Acute Diagnostics, Disease Monitoring, and Neuropsychiatric Outcome Prediction

Considerable advancements have been made in the quantification of biofluid-based biomarkers for traumatic brain injury (TBI), which provide a clinically accessible window to investigate disease mechanisms and progression. Methods with improved analytical sensitivity compared with standard immunoassays are increasingly used, and blood tests are being used in the diagnosis, monitoring, and outcome prediction of TBI. Most work to date has focused on acute TBI diagnostics, while the literature on biomarkers for long-term sequelae is relatively scarce. In this review, we give an update on the latest developments in biofluid-based biomarker research in TBI and discuss how acute and prolonged biomarker changes can be used to detect and quantify brain injury and predict clinical outcome and neuropsychiatric sequelae.

Changes in Outcomes after Discharge from an Acute Hospital in Severe Traumatic Brain Injury

Neurological improvement occurs from the subacute to chronic phases in severe traumatic brain injury. We analyzed factors associated with improved neurological findings in the subacute phase, using data from the Japan Neurotrauma Data Bank (JNTDB). The subjects were 1345 patients registered in the JNTDB (Project 2015). Clinical improvement was evaluated by comparing the Glasgow Outcome Scale (GOS) at discharge and 6 months after injury. Of these patients, 157 with severe disability (SD) on the discharge GOS were examined to evaluate factors associated with neurological improvement in the subacute phase. Cases were defined as those with (group I) and without (group N) improvement: a change from SD at discharge to good recovery (GR) or moderate disability (MD) at 6 months after injury. Patient background, admission findings, treatment, and discharge destination were examined. In all patients, the favorable outcome (GR, MD) rate improved from 30.2% at discharge to 35.7% at 6 months after injury. Of SD cases at discharge, 44.6% had a favorable outcome at 6 months (group I). Patients in group I were significantly younger, and had a significantly lower D-dimer level in initial blood tests and a lower incidence of convulsions. In multivariate analysis, discharge to home was a significant factor associated with an improved outcome. Many SD cases at discharge ultimately showed neurological improvement, and the initial D-dimer level may be a predictor of such improvement. The environment after discharge from an acute care hospital may also contribute to an improved long-term prognosis.

Arterial Spin Labeling Reveals Elevated Cerebral Blood Flow with Distinct Clusters of Hypo- and Hyperperfusion after Traumatic Brain Injury

Imaging detection of brain perfusion alterations after traumatic brain injury (TBI) may provide prognostic insights. In this study, we used arterial spin labeling (ASL) to quantify cross-sectional and longitudinal changes in cerebral blood flow (CBF) after TBI and correlated changes with clinical outcome. We analyzed magnetic resonance imaging scans from adult participants with TBI requiring hospitalization in the acute (2 weeks post-injury, n = 33) and chronic (6 months post-injury, n = 16) phases, with 13 participants scanned longitudinally at both time points. We also analyzed 18 age- and sex-matched healthy controls. Whole-brain CBF maps were derived using a three-dimensional pseudo-continuous arterial spin label technique. Mean CBF across tissue-based regions (whole brain, gray matter, and white matter) was compared cross-sectionally and longitudinally. In addition, individual-level clusters of abnormal perfusion were identified using voxel-based z-score analysis of relative CBF maps, and number and volume of abnormally hypo- and hyperperfused clusters were assessed cross-sectionally and longitudinally. Finally, all CBF measures were correlated with clinical outcome measures. Mean global and gray matter CBF were significantly elevated in acute and chronic TBI participants compared to controls. Participants with better outcome at 6 months post-injury tended to have higher CBF in the acute phase compared to those with poorer outcome. Acute TBI participants had a significantly greater volume of hypo- and hyperperfused brain tissue compared to controls, with these regions partially normalizing by the chronic phase. Our findings demonstrate global elevation of CBF with focal hypo- and hyperperfusion in the early post-injury period and suggest a reparative role for acute elevation in CBF post-TBI.

High-Sensitivity C-Reactive Protein is a Prognostic Biomarker of Six-Month Disability after Traumatic Brain Injury: Results from the TRACK-TBI Study

Systemic inflammation impacts outcome after traumatic brain injury (TBI), but most TBI biomarker studies have focused on brain-specific proteins. C-reactive protein (CRP) is a widely used biomarker of inflammation with potential as a prognostic biomarker after TBI. The Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study prospectively enrolled TBI patients within 24 h of injury, as well as orthopedic injury and uninjured controls; biospecimens were collected at enrollment. A subset of hospitalized participants had blood collected on day 3, day 5, and 2 weeks. High-sensitivity CRP (hsCRP) and glial fibrillary acidic protein (GFAP) were measured. Receiver operating characteristic analysis was used to evaluate the prognostic ability of hsCRP for 6-month outcome, using the Glasgow Outcome Scale-Extended (GOSE). We included 1206 TBI subjects, 122 orthopedic trauma controls (OTCs), and 209 healthy controls (HCs). Longitudinal biomarker sampling was performed in 254 hospitalized TBI subjects and 19 OTCs. hsCRP rose between days 1 and 5 for TBI and OTC subjects, and fell by 2 weeks, but remained elevated compared with HCs (p < 0.001). Longitudinally, hsCRP was significantly higher in the first 2 weeks for subjects with death/severe disability (GOSE <5) compared with those with moderate disability/good recovery (GOSE ≥5); AUC was highest at 2 weeks (AUC = 0.892). Combining hsCRP and GFAP at 2 weeks produced AUC = 0.939 for prediction of disability. Serum hsCRP measured within 2 weeks of TBI is a prognostic biomarker for disability 6 months later. hsCRP may have utility as a biomarker of target engagement for anti-inflammatory therapies.

Extracellular vesicle concentrations of glial fibrillary acidic protein and neurofilament light measured 1 year after traumatic brain injury

Traumatic brain injury (TBI) is linked to long-term symptoms in a sub-set of patients who sustain an injury, but this risk is not universal, leading us and others to question the nature of individual variability in recovery trajectories. Extracellular vesicles (EVs) are a promising, novel avenue to identify blood-based biomarkers for TBI. Here, our aim was to determine if glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) measured 1-year postinjury in EVs could distinguish patients from controls, and whether these biomarkers relate to TBI severity or recovery outcomes. EV GFAP and EV NfL were measured using an ultrasensitive assay in 72 TBI patients and 20 controls. EV GFAP concentrations were elevated in moderate and severe TBI compared to controls (p’s < 0.001) and could distinguish controls from moderate (AUC = 0.86) or severe TBI (AUC = 0.88). Increased EV GFAP and EV NfL levels were associated with lower 1-year Glasgow Outcome Scale–Extended (GOS-E) score (p’s < 0.05). These findings suggest that blood-derived EV concentrations of GFAP and NfL drawn even 1 year after injury are higher in TBI patients compared to controls, and are related to injury severity and poor recovery outcomes, suggesting that TBIs alter the activity of these biomarkers, likely contributing to individual variability in recovery.

Significance of ICP-related parameters for the treatment and outcome of severe traumatic brain injury

Objective

To analyze the significance of intracranial pressure (ICP)-related parameters on outcome in patients with severe traumatic brain injury. The ICP-related parameters included ICP, ICP dose (DICP), regression of the correlation coefficient between amplitude and pressure (RAP), pressure reactivity index (PRx), and cerebral perfusion pressure (CPP).

Methods

A retrospective analysis was performed using clinical information from 29 patients with severe traumatic brain injury who were admitted to the Department of Neurosurgery from January 2018 to January 2019. All patients underwent ICP probe implantation after admission. Patients were followed up for 6 months after discharge, and were categorized into either the favorable or unfavorable outcome group based on their Glasgow Outcome Scale score. The differences in ICP, DICP, RAP, PRx, and CPP between the two groups were analyzed for their effects on outcome.

Results

The average ICP, DICP, PRx, and RAP values in patients with favorable outcomes were significantly lower than in patients with unfavorable outcomes, while CPP values were significantly higher in the favorable outcome group.

Conclusion

Average ICP, DICP, PRx, RAP, and CPP values may indicate disease status and relate to patient outcomes. It is important to use multiple parameters to predict patients’ disease severity and prognosis.

Comparison of the CRASH Score-Predicted and Real Outcome of Traumatic Brain Injury in a Retrospective Analysis of 417 Patients

OBJECTIVE

The aim of this retrospective study was to externally validate the CRASH (Corticosteroid Randomisation After Significant Head Injury) clinical calculator as a prognostic tool. Mortality at 14 days and an unfavorable outcome (i.e., Glasgow Outcome Scale score <4) after 6 months were the primary endpoints.

METHODS

The study included adult patients admitted to the emergency department of Ghent University Hospital during 2010-2014 with traumatic brain injury. The CRASH score was calculated for every patient and compared with real-life outcome at 14 days and 6 months. Researchers were blinded for each other's results, and each observer either calculated the CRASH score or obtained clinical outcome. Receiver operating characteristic analysis was used to validate the CRASH calculator. The prognostic value of other variables was tested using logistic regression (P < 0.05 was significant).

RESULTS

Of 417 included patients with traumatic brain injury, 94.7% were still alive at 14 days, and 65% had a Glasgow Outcome Scale score ≥4 at 6 months. Receiver operating characteristic analysis showed an area under the curve of 92.1% at 14 days and 90.7% at 6 months (P < 0.05). Calculated cutoff value for the CRASH score at 14 days was 31.50% (sensitivity 0.823, specificity 0.895). At 6 months, calculated cutoff value was 55.75% (sensitivity 0.793, specificity 0.830).

CONCLUSIONS

The CRASH calculator is a good predictor of outcome in traumatic brain injury at 14 days and 6 months with high sensitivity and specificity. It does not replace clinical judgment of the physician treating the patient in the emergency department, but it constitutes a useful additional tool.

Role of Thalamus in Recovery of Traumatic Brain Injury

Degree of recovery after traumatic brain injury is highly variable that lasts for many weeks to months. The evidence of brain structures involved in recovery mechanisms is limited. This review highlights evidence of the brain structure particularly thalamus in neuroplasticity mechanism. Thalamus with its complex global networking has potential role in refining the cortical and other brain structures. Thalamic nuclei activation both naturally or by neurorehabilitation in injured brain can enhance and facilitate the improvement of posttraumatic symptoms. This review provides evidence from literature that thalamus plays a key role in recovery mechanism after injury. The study also emphasize that thalamus should be specifically targeted in neurorehabilitation following brain injury.

Favorable Functional Recovery in Severe Traumatic Brain Injury Survivors beyond Six Months

Favorable long-term functional outcomes after severe traumatic brain injury (TBI) may be underestimated. We analyzed 24-month functional outcomes from a consecutive series of severe TBI survivors. A prospective, observational database of severe TBI survivors from a single institution was analyzed. Glasgow Outcome Scale-Extended (GOS-E) scores were obtained at 3, 6, 12, and 24 months post-injury. GOS-E scores were dichotomized into unfavorable and favorable outcomes, and the proportion of survivors changing from unfavorable to favorable outcomes was calculated using Wilcoxon signed-rank tests. Surviving adults (N = 304; mean age ± standard deviation = 35.06 ± 15.11; 80.92% male; mode of initial GCS = 7) were analyzed. A statistically significant mean increase in GOS-E was noted from 3 to 6, 6 to 12, 12 to 24, and 6 to 24 months after injury (0.65 [p < 0.0001], 0.42 [p < 0.0001], 0.23 [p = 0.020], and 0.61 [p < 0.0001], respectively). Moreover, 43% of survivors from 3 to 6 months, 36% from 6 to 12 months, 38% from 12 to 24 months, and 54% from 6 to 24 months progressed from an unfavorable to a favorable outcome. Two thirds of survivors in the unfavorable category at 3 months had favorable outcomes at 2 years. Overall, 74% of surviving adults with a documented GOS-E at 2 years after injury had a favorable outcome. Severe TBI survivors demonstrated significant improvement in functional outcomes from 3 to 24 months after injury. At 2 years, three fourths of survivors had a favorable outcome. Long-term prognosis in severe TBI is better than broadly appreciated.

High-sensitivity terahertz imaging of traumatic brain injury in a rat model

We demonstrated that different degrees of experimental traumatic brain injury (TBI) can be differentiated clearly in fresh slices of rat brain tissues using transmission-type terahertz (THz) imaging system. The high absorption region in THz images corresponded well with the injured area in visible images and magnetic resonance imaging results. The THz image and absorption characteristics of dehydrated paraffin-embedded brain slices and the hematoxylin and eosin (H&E)-stained microscopic images were investigated to account for the intrinsic differences in the THz images for the brain tissues suffered from different degrees of TBI and normal tissue aside from water. The THz absorption coefficients of rat brain tissues showed an increase in the aggravation of brain damage, particularly in the high-frequency range, whereas the cell density decreased as the order of mild, moderate, and severe TBI tissues compared with the normal tissue. Our results indicated that the different degrees of TBI were distinguishable owing to the different water contents and probable hematoma components distribution rather than intrinsic cell intensity. These promising results suggest that THz imaging has great potential as an alternative method for the fast diagnosis of TBI.

Current contribution of diffusion tensor imaging in the evaluation of diffuse axonal injury

ABSTRACT Traumatic brain injury (TBI) is the number one cause of death and morbidity among young adults. Moreover, survivors are frequently left with functional disabilities during the most productive years of their lives. One main aspect of TBI pathology is diffuse axonal injury, which is increasingly recognized due to its presence in 40% to 50% of all cases that require hospital admission. Diffuse axonal injury is defined as widespread axonal damage and is characterized by complete axotomy and secondary reactions due to overall axonopathy. These changes can be seen in neuroimaging studies as hemorrhagic focal areas and diffuse edema. However, the diffuse axonal injury findings are frequently under-recognized in conventional neuroimaging studies. In such scenarios, diffuse tensor imaging (DTI) plays an important role because it provides further information on white matter integrity that is not obtained with standard magnetic resonance imaging sequences. Extensive reviews concerning the physics of DTI and its use in the context of TBI patients have been published, but these issues are still hazy for many allied-health professionals. Herein, we aim to review the current contribution of diverse state-of-the-art DTI analytical methods to the understanding of diffuse axonal injury pathophysiology and prognosis, to serve as a quick reference for those interested in planning new studies and who are involved in the care of TBI victims. For this purpose, a comprehensive search in Pubmed was performed using the following keywords: “traumatic brain injury”, “diffuse axonal injury”, and “diffusion tensor imaging”.

Cognitive Event-Related Potentials during the Sub-Acute Phase of Severe Traumatic Brain Injury and Their Relationship to Outcome

Predicting outcome in the early phase after severe traumatic brain injury (sTBI) is a major clinical challenge, particularly identifying patients with potential for good cognitive outcome. The current single-center prospective study aimed to explore presence and normalization of electroencephalography (EEG)-based event-related potentials (ERPs) in the early phase followings TBI, and their relationship to functional and cognitive outcome 6 months post-injury. Fourteen adult patients (eight males) with sTBI were recruited from the neurointensive care unit (mean age = 38.2 years [standard deviation (SD) = 14.7]; mean lowest Glasgow Coma Scale (GCS) score within first 24 h = 5.4, SD = 1.87). EEG recordings were conducted biweekly at three time-points applying an ERP paradigm encompassing a passive condition involving hearing their own name randomly interspersed between an unfamiliar name (UN), and an active condition with instruction to count their own name. Functional and cognitive outcome 6 months post-injury was measured with Glasgow Outcome Scale-Extended (GOSE) and neuropsychological tests of attention and memory. Ten patients demonstrated a significantly enhanced cognitive P3 in the active counting task compared with passive listening across recordings, and six presented with normalization of P3 in the counting task. Moreover, P3 amplitude to the counting task at the third time-point was positively correlated with both functional outcome (GOSE) and cognition (verbal learning, attentional set-shifting, and switching) 6 months post-injury. ERP can index cognitive capacities in the early phase following sTBI, and the cognitive P3 component in an active design is associated with functional and cognitive outcome, demonstrating that the cognitive P3 may yield valuable information of residual cognition and provide supplementary prognostic information.

Biomarkers Associated with the Outcome of Traumatic Brain Injury Patients

This review focuses on biomarkers associated with the outcome of traumatic brain injury (TBI) patients, such as caspase-3; total antioxidant capacity; melatonin; S100B protein; glial fibrillary acidic protein (GFAP); glutamate; lactate; brain-derived neurotrophic factor (BDNF); substance P; neuron-specific enolase (NSE); ubiquitin carboxy-terminal hydrolase L-1 (UCH-L1); tau; decanoic acid; and octanoic acid.

Alterations in the brain's connectome during recovery from severe traumatic brain injury: protocol for a longitudinal prospective study

INTRODUCTION

Traumatic brain injury (TBI) is considered one of the most pervasive causes of disability in people under the age of 45. TBI often results in disorders of consciousness, and clinical assessment of the state of consciousness in these patients is challenging due to the lack of behavioural responsiveness. Functional neuroimaging offers a means to assess these patients without the need for behavioural signs, indicating that brain connectivity plays a major role in consciousness emergence and maintenance. However, little is known regarding how changes in connectivity during recovery from TBI accompany changes in the level of consciousness. Here, we aim to combine cutting-edge neuroimaging techniques to follow changes in brain connectivity in patients recovering from severe TBI.

METHODS AND ANALYSIS

A multimodal, longitudinal assessment of 30 patients in the subacute stage after severe TBI will be made comprising an MRI session combined with electroencephalography (EEG), a positron emission tomography session and a transcranial magnetic stimulation (TMS) combined with EEG (TMS/EEG) session. A group of 20 healthy participants will be included for comparison. Four sessions for patients and two sessions for healthy participants will be planned. Data analysis techniques will focus on whole-brain, both data-driven and hypothesis-driven, connectivity measures that will be specific to the imaging modality.

ETHICS AND DISSEMINATION

The project has received ethical approval by the local ethics committee of the Capital Region of Denmark and by the Danish Data Protection. Results will be published as original research articles in peer-reviewed journals and disseminated in international conferences. None of the measurements will have any direct clinical impact on the patients included in the study but may benefit future patients through a better understanding of the mechanisms underlying the recovery process after TBI. TRIAL REGISTRATION NUMBER NCT02424656; PRE-RESULTS.