Magnetic resonance imaging and computerized tomography in relation to the neurobehavioral sequelae of mild and moderate head injuries

Thyroid hormone T4 mitigates traumatic brain injury in mice by dynamically remodeling cell type specific genes, pathways, and networks in hippocampus and frontal cortex

The complex pathology of mild traumatic brain injury (mTBI) is a main contributor to the difficulties in achieving a successful therapeutic regimen. Thyroxine (T4) administration has been shown to prevent the cognitive impairments induced by mTBI in mice but the mechanism is poorly understood. To understand the underlying mechanism, we carried out a single cell transcriptomic study to investigate the spatiotemporal effects of T4 on individual cell types in the hippocampus and frontal cortex at three post-injury stages in a mouse model of mTBI. We found that T4 treatment altered the proportions and transcriptomes of numerous cell types across tissues and timepoints, particularly oligodendrocytes, astrocytes, and microglia, which are crucial for injury repair. T4 also reversed the expression of mTBI-affected genes such as Ttr, mt-Rnr2, Ggn12, Malat1, Gnaq, and Myo3a, as well as numerous pathways such as cell/energy/iron metabolism, immune response, nervous system, and cytoskeleton-related pathways. Cell-type specific network modeling revealed that T4 mitigated select mTBI-perturbed dynamic shifts in subnetworks related to cell cycle, stress response, and RNA processing in oligodendrocytes. Cross cell-type ligand-receptor networks revealed the roles of App, Hmgb1, Fn1, and Tnf in mTBI, with the latter two ligands having been previously identified as TBI network hubs. mTBI and/or T4 signature genes were enriched for human genome-wide association study (GWAS) candidate genes for cognitive, psychiatric and neurodegenerative disorders related to mTBI. Our systems-level single cell analysis elucidated the temporal and spatial dynamic reprogramming of cell-type specific genes, pathways, and networks, as well as cell-cell communications as the mechanisms through which T4 mitigates cognitive dysfunction induced by mTBI.

Headache management in traumatic brain injury

Traumatic brain injury (TBI) is estimated to rank as the third most important disease burden worldwide. About 60% of the survivors develop chronic headaches and visual symptoms, and the long-term management of headaches in these patients is controversial. Importantly, the care pathway of most patients is fragmented, complicating conclusive headache management. Here we review the epidemiology and aetiology of post traumatic headaches (PTH), discuss the diagnostic work up and summarise the acute and long-term management.

Attention Training After Moderate-to-Severe Traumatic Brain Injury in Adults: A Systematic Review

OBJECTIVE

To determine the extent and efficacy of attentional training as a form of neuropsychological rehabilitation to ameliorate attention deficits in adults with moderate-to-severe traumatic brain injury.

DATA SOURCES

Articles published in Cumulative Index to Nursing and Allied Health Literature, Cochrane Library, PubMed, PsycINFO, Scopus, and Web of Science were searched between January 17, and February 27, 2021.

STUDY SELECTION

Two reviewers blindly assessed studies for eligibility according to the following criteria: any article evaluating the efficacy of any type of behavioral intervention that targeted attention (by means of cognitive rehabilitative, psychoeducational, or neuropsychological strategies, at either an individual or group level) in adults who had sustained a formally documented moderate-to-severe traumatic brain injury.

DATA EXTRACTION

Methodological quality of each article was blindly assessed by 2 reviewers. Data were extracted from each study, including study type, sample size, sample characteristics, summary of intervention, measures used to assess attention, statistical outcomes and results, effect size, conclusion, and limitations.

DATA SYNTHESIS

7314 articles were retrieved from databases, 4325 articles remained after duplicate removal, and finally 21 articles met eligibility criteria and were included in this review. Articles represented varied methodological quality in group or single subject design. Irrespective of the heterogeneity regarding intervention types and attentional outcome measures used across the studies, overall findings suggest that attentional gains can be made in this sample, irrespective of time since injury, age, and injury severity. Further, a growing interest in technology-based interventions is frequently used and holds promise to bettering rehabilitation efforts. However, there is still limited evidence supporting the ecological validity of attentional training interventions (eg, the transfer of treatment effects to daily activities).

CONCLUSIONS

This article plays a crucial role in informing ongoing rehabilitation practices, guiding clinicians with evidence-based strategies and shaping future research directions for more effective attentional training guidelines.

The potential role and mechanism of circRNAs in Ferroptosis: A comprehensive review

Cell death encompasses various mechanisms, including necrosis and apoptosis. Ferroptosis, a unique form of regulated cell death, emerged as a non-apoptotic process reliant on iron and reactive oxygen species (ROS). Distinguishing itself from other forms of cell death, ferroptosis exhibits distinct morphological, biochemical, and genetic features. Circular RNAs (circRNAs), a novel class of RNA molecules, play crucial regulatory roles in ferroptosis-mediated pathways and cellular processes. With their circular structure and stability, circRNAs function as microRNA sponges and participate in protein regulation, offering diverse mechanisms for cellular control. Accumulating evidence indicates that circRNAs are key players in diseases associated with ferroptosis, presenting opportunities for diagnostic and therapeutic applications. This study explores the regulatory roles of circRNAs in ferroptosis and their potential in diseases such as cancer, neurological disorders, and cardiovascular diseases. By investigating the relationship between circRNAs and ferroptosis, this research provides new insights into the diagnosis, treatment, and prognosis of ferroptosis-related diseases. Furthermore, the therapeutic implications of targeting circRNAs in cancer treatment and the modulation of ferroptosis pathways demonstrate the potential of circRNAs as diagnostic markers and therapeutic targets. Overall, understanding the involvement of circRNAs in regulating ferroptosis opens up new avenues for advancements in disease management.

Diffusion MRI approaches for investigating microstructural complexity in a rat model of traumatic brain injury

Our study explores the potential of conventional and advanced diffusion MRI techniques including diffusion tensor imaging (DTI), and single-shell 3-tissue constrained spherical deconvolution (SS3T-CSD) to investigate complex microstructural changes following severe traumatic brain injury in rats at a chronic phase. Rat brains after sham-operation or lateral fluid percussion (LFP) injury were scanned ex vivo in a 9.4 T scanner. Our region-of-interest-based approach of tensor-, and SS3T-CSD derived fixel-, 3-tissue signal fraction maps were sensitive to changes in both white matter (WM) and grey matter (GM) areas. Tensor-based measures, such as fractional anisotropy (FA) and radial diffusivity (RD), detected more changes in WM and GM areas as compared to fixel-based measures including apparent fiber density (AFD), peak FOD amplitude and primary fiber bundle density, while 3-tissue signal fraction maps revealed distinct changes in WM, GM, and phosphate-buffered saline (PBS) fractions highlighting the complex tissue microstructural alterations post-trauma. Track-weighted imaging demonstrated changes in track morphology including reduced curvature and average pathlength distal from the primary lesion in severe TBI rats. In histological analysis, changes in the diffusion MRI measures could be associated to decreased myelin density, loss of myelinated axons, and increased cellularity, revealing progressive microstructural alterations in these brain areas five months after injury. Overall, this study highlights the use of combined conventional and advanced diffusion MRI measures to obtain more precise insights into the complex tissue microstructural alterations in chronic phase of severe brain injury.

Milnacipran Ameliorates Executive Function Impairments following Frontal Lobe Traumatic Brain Injury in Male Rats: A Multimodal Behavioral Assessment

Traumatic brain injuries (TBIs) affect more than 10 million patients annually worldwide, causing long-term cognitive and psychosocial impairments. Frontal lobe TBIs commonly impair executive function, but laboratory models typically focus primarily on spatial learning and declarative memory. We implemented a multi-modal approach for clinically relevant cognitive-behavioral assessments of frontal lobe function in rats with TBI and assessed treatment benefits of the serotonin-norepinephrine reuptake inhibitor, milnacipran (MLN). Two attentional set-shifting tasks (AST) evaluated cognitive flexibility via the rats' ability to locate food-based rewards by learning, unlearning, and relearning sequential rule sets with shifting salient cues. Adult male rats reached stable pre-injury operant AST (oAST) performance in 3-4 weeks, then were isoflurane-anesthetized, subjected to a unilateral frontal lobe controlled cortical impact (2.4 mm depth, 4 m/sec velocity) or Sham injury, and randomized to treatment conditions. Milnacipran (30 mg/kg/day) or vehicle (VEH; 10% ethanol in saline) was administered intraperitoneally via implanted osmotic minipumps (continuous infusions post-surgery, 60 μL/h). Rats had a 10-day recovery post-TBI/Sham before performing light/location-based oAST for 10 days and, subsequently, odor/media-based digging AST (dAST) on the last test day (26-27 days post-injury) before sacrifice. Both AST tests revealed significant deficits in TBI+VEH rats, seen as elevated total trials and errors (p < 0.05), which generally normalized in MLN-treated rats (p < 0.05). This first simultaneous dual AST assessment demonstrates oAST and dAST are sufficiently sensitive and robust to detect subtle attentional and cognitive flexibility executive impairments after frontal lobe TBI in rats. Chronic MLN administration shows promise for attenuation of post-TBI executive function deficits, thus meriting further investigation.

Temporary or Permanent? A Clinical Challenge in the Evaluation of Traumatic Brain Injury Patients with Unconsciousness and Normal Initial Head CT

BACKGROUND

Traumatic brain injury (TBI) patients with unconsciousness and normal initial head computed tomography (CT) present a clinical dilemma for physicians and neurosurgeons in the emergency department (ED). We recorded how long it took for patients to regain consciousness and evaluated the patients' characteristics.

METHODS

From 2018 to 2020, TBI patients with unconsciousness and normal initial head CT [Glasgow coma scale (GCS) score < 13, negative CT scan and normal laboratory test results] were evaluated. Patients who regained consciousness were analyzed. Multivariate logistic regression (MLR) analyses were used to evaluate independent factors for regaining consciousness.

RESULTS

A total of 77 patients were included in this study. Fifty-eight (75.3%) patients regained consciousness, most within one day (43.1%). Nineteen (24.7%) patients never regained consciousness. MLR analysis showed that initial GCS score (odds 1.85, p = 0.017), early airway protection in ED (odds 25.02, p = 0.018) and 72-h GCS score improvement by two points (odds 0.02, p = 0.001) were independent factors for regaining consciousness. Overall, 94.1% of patients who received early airway protection and improved 2 points in 72-h GCS score regained consciousness. The association between days to M5 status and days to M6 status (consciousness) was highly significant. Fewer days to M5 status were highly associated with needing fewer days to regain consciousness.

CONCLUSIONS

For TBI patients with unconsciousness and normal initial head CT, a higher probability of regaining consciousness was observed in those who underwent early airway protection and who improved 2 points in 72-h GCS score. Regaining consciousness within a short period could be expected in patients with M5 status.

The influence of methylphenidate on sustained attention in paediatric acquired brain injury: a meta-analytical review

Impairment in sustained attention is a common consequence of childhood Acquired Brain Injury (ABI). Whilst methylphenidate provides promise in enhancing "attention" as a unitary construct, little work has explored its effectiveness upon individual attentional domains. The current systematic review and meta-analysis evaluates the utility of methylphenidate on sustained attentional performance across childhood ABI groups. Five databases (PsycINFO, MEDLINE, Embase, Scopus & Cochrane Library) were searched for relevant articles from their inception to March 2022. A purpose-developed evaluation tool was used to assess each study's research quality (QuEST:MAP). Nine of the 1600 identified articles were included within this review (n = 259). Meta-analytical findings reported an overall significant benefit of methylphenidate on sustained attention in childhood ABI (g = -0.33, 95% CI: -0.62 to -0.04). Associated summary effect sizes were relatively small, particularly when adjusting for outlier cases. Subgroup analyses identified a significantly greater benefit of methylphenidate in clinical subgroups with comorbid ADHD diagnoses (p < .01). The current evidence base is characterized by small-scale clinical trials with variable research quality and low generalizability. Further robust research is needed to quantify methylphenidate utility upon individual attentional domains in larger and more representative ABI samples.

Psychometric Properties of the Revised Dysexecutive Questionnaire in a Non-clinical Population

Aims

The aim of this study was to assess the psychometric properties of the revised self-rated version of the Dysexecutive Questionnaire (DEX-R) within a non-clinical sample.

Methods

The study was hosted online, with 140 participants completing the DEX-R, GAD-2 and PHQ-2. Sixty participants also completed the FrSBe, with 99 additionally completing the DEX-R again 3 weeks later. Correlations with demographic factors and symptoms of anxiety and depression were conducted. Rasch and factor analysis were also used to explore underlying subconstructs.

Results

The DEX-R correlated highly with the FrSBe, indicating sound concurrent validity. Internal consistency, split-half reliability and test-retest reliability were excellent. Age and symptoms of depression and anxiety correlated with DEX-R scores, with older age associated with less dysexecutive problems. The Rasch analysis confirmed the multidimensionality of the rating scale, and a three-factor structure was found relating to activation-self-regulatory, cognitive and social-emotional processes. Frequencies of responses on DEX-R items varied, many were not fully endorsed indicating specific relevance of most but not all items to patients.

Conclusion

Interpretations of DEX-R ratings of dysexecutive problems should consider mood and individual variation. Systematic comparison of DEX-R responses between healthy and clinical groups could help identify a suitable cut off for dysexecutive symptoms.

The relationship between plasma free fatty acids, cognitive function and structural integrity of the brain in middle-aged healthy humans

Background: The cerebral composition of ω-3 and ω-6 polyunsaturated fatty acids (PUFAs) is believed to influence cognitive function and structural damage of the aging brain. However, existing data is inconsistent.

Materials and Methods: This retrospective study explored the association between free plasma PUFA concentrations, cognitive function and brain structure atrophy in a well-characterized community-dwelling cohort of elderly individuals without stroke and dementia. Ten different fatty acids were analyzed in stored plasma samples from 391 non-demented elderly individuals by gas chromatography mass spectrometry. Neuropsychiatric tests capturing memory, executive function and visuopractical skills were performed in all participants. Brain atrophy was assessed by MRI in a subset of 167 individuals.

Results: Higher plasma concentrations of free ω-6 PUFAs (p = 0.042), and, in particular, linoleic acid (p = 0.01), were significantly associated with lower executive function. No significant association existed between ω-3 PUFA concentrations and cognitive functioning. The volume of the frontal lobes was inversely associated with ω-6 PUFAs, whereas ω-3 PUFAs were positively related with temporal lobe volumes. All associations did not withstand correction for multiple comparisons.

Conclusions: Our study suggests subtle effects of PUFA imbalances on cognition and brain structure. Yet the observed associations are weak and unlikely to be of clinical relevance. The brain regions that seem to be most sensitive to imbalances of ω-3 and ω-6 PUFAs are the frontal and temporal lobes.

Visuospatial Attention Allocation as an Indicator of Cognitive Deficit in Traumatic Brain Injury: A Systematic Review and Meta-Analysis

Traumatic Brain Injury (TBI) is defined by changes in brain function resulting from external forces acting on the brain and is typically characterized by a host of physiological and functional changes such as cognitive deficits including attention problems. In the present study, we focused on the effect of TBI on the ability to allocate attention in vision (i.e., the use of endogenous and exogenous visual cues) by systematically reviewing previous literature on the topic. We conducted quantitative synthesis of 16 selected studies of visual attention following TBI, calculating 80 effect size estimates. The combined effect size was large (g = 0.79, p < 0.0001) with medium heterogeneity (I² = 68.39%). Subgroup analyses revealed an increase in deficit with moderate-to-severe and severe TBI as compared to mild TBI [F_{(2, 76)} = 24.14, p < 0.0001]. Task type was another key source of variability and subgroup analyses indicated that higher order attention processes were severely affected by TBI [F_{(2, 77)} = 5.66, p = 0.0051). Meta-regression analyses revealed significant improvement in visual attention deficit with time [p(mild) = 0.031, p(moderate-to-severe) = 0.002, p(severe) < 0.0001]. Taken together, these results demonstrate that visual attention is affected by TBI and that regular assessment of visual attention, using a systematic attention allocation task, may provide a useful clinical measure of cognitive impairment and change after TBI.

Quantitative susceptibility mapping of the rat brain after traumatic brain injury

The primary lesion arising from the initial insult after traumatic brain injury (TBI) triggers a cascade of secondary tissue damage, which may also progress to connected brain areas in the chronic phase. The aim of this study was, therefore, to investigate variations in the susceptibility distribution related to these secondary tissue changes in a rat model after severe lateral fluid percussion injury. We compared quantitative susceptibility mapping (QSM) and R₂ * measurements with histological analyses in white and grey matter areas outside the primary lesion but connected to the lesion site. We demonstrate that susceptibility variations in white and grey matter areas could be attributed to reduction in myelin, accumulation of iron and calcium, and gliosis. QSM showed quantitative changes attributed to secondary damage in areas located rostral to the lesion site that appeared normal in R₂ * maps. However, combination of QSM and R₂ * was informative in disentangling the underlying tissue changes such as iron accumulation, demyelination, or calcifications. Therefore, combining QSM with R₂ * measurement can provide a more detailed assessment of tissue changes and may pave the way for improved diagnosis of TBI, and several other complex neurodegenerative diseases.

Behavioral responses following repeated bilateral frontal region closed head impacts and fear conditioning in male and female mice

The frontal lobes are among the most vulnerable sites in traumatic brain injuries. In the current study, a balanced 2 × 2 × 2 design (n = 18 mice/group), female and male C57Bl/6J mice received repeated bilateral frontal concussive brain injury (frCBI) and underwent fear conditioning (FC) to assess how injured mice respond to adverse conditions. Shocks received during FC impacted behavior on all subsequent tests except the tail suspension test. FC resulted in more freezing behavior in all mice that received foot shocks when evaluated in subsequent context and cue tests and induced hypoactivity in the open field (OF) and elevated zero maze (EZM). Mice that sustained frCBI learned the FC association between tone and shock. Injured mice froze less than sham controls during context and cue tests, which could indicate memory impairment, but could also suggest that frCBI resulted in hyperactivity that overrode the rodent's natural freezing response to threat, as injured mice were also more active in the OF and EZM. There were notable sex differences, where female mice exhibited more freezing behavior than male mice during FC context and cue tests. The findings suggest frCBI impaired, but did not eliminate, FC retention and resulted in an overall increase in general activity. The injury was characterized pathologically by increased inflammation (CD11b staining) in cortical regions underlying the injury site and in the optic tracts. The performance of male and female mice after injury suggested the complexity of possible sex differences for neuropsychiatric symptoms.

Modulation of posttraumatic epileptogenesis in aquaporin-4 knockout mice

OBJECTIVE

To determine the role of aquaporin-4 (AQP4) in posttraumatic epileptogenesis using long-term video-electroencephalographic (vEEG) recordings. Here, differences in EEG were analyzed between wild-type (WT) and AQP4 knockout (KO) mice and between mice with and without posttraumatic epilepsy (PTE).

METHODS

WT and AQP4 KO mice were subjected to a single controlled cortical impact traumatic brain injury (TBI) in the frontal cortex, and vEEG was recorded in the ipsilateral hippocampus at 14, 30, 60, and 90 days postinjury (dpi). Intrahippocampal electrical stimulation was also used to assess electrographic seizure threshold and electrographic seizure duration (ESD).

RESULTS

The mean seizure frequency per day for WT mice was 0.07 ± 0.07, 0.11 ± 0.07, 0.26 ± 0.13, and 0.12 ± 0.10 at 14, 30, 60, and 90 dpi, respectively. The mean seizure frequency per day for AQP4 KO mice was 0.45 ± 0.27, 0.29 ± 0.12, and 0.26 ± 0.19 at 14, 30, and 60 dpi, respectively. The mean seizure duration was 15 ± 2 seconds and 24 ± 3 seconds for WT and AQP4 KO mice, respectively. The percentage of mice that developed PTE were 28% and 37% for WT and AQP4 KO mice, respectively. Power spectral density (PSD) analysis revealed alterations in EEG frequency bands between sham and TBI in both genotypes. Additionally, PSD analysis of spontaneous recurrent seizures revealed alterations in delta power between genotypes. Morlet wavelet analysis detected heterogeneity in EEG seizure subtypes and dynamic EEG power patterns after TBI. Compared with AQP4 KO mice, a significant increase in ESD was observed in WT mice at 14 dpi.

SIGNIFICANCE

Posttraumatic seizures (PTSs) may be modulated by the astrocyte water channel AQP4. Absence of AQP4 increases the number of spontaneous seizures, increases seizure duration, and alters EEG power patterns of PTSs.

Mild, moderate and severe: terminology implications for clinical and experimental traumatic brain injury

PURPOSE OF REVIEW

When describing clinical or experimental traumatic brain injury (TBI), the adjectives 'mild,' 'moderate' and 'severe' are misleading. 'Mild' clinical TBI frequently results in long-term disability. 'Severe' rodent TBI actually resembles mild or complicated mild clinical TBI.

RECENT FINDINGS

Many mild TBI patients appear to have recovered completely but have postconcussive symptoms, deficits in cognitive and executive function and reduced cerebral blood flow. After moderate TBI, 31.8% of patients died or were discharged to skilled nursing or hospice. Among survivors of moderate and severe TBI, 44% were unable to return to work. On MRI, 88% of mild TBI patients have evidence of white matter damage, based on measurements of fractional anisotropy and mean diffusivity/apparent diffusion coefficient. After sports concussion, clinically recovered patients have abnormalities in functional connectivity on functional MRI. Methylphenidate improved fatigue and cognitive impairment and, combined with cognitive rehabilitation, improved memory and executive functioning. In comparison to clinical TB, because the entire spectrum of experimental rodent TBI, although defined as moderate or severe, more closely resembles mild or complicated mild clinical TBI.

SUMMARY

Many patients after mild or moderate TBI suffer long-term sequelae and should be considered a major target for translational research. Treatments that improve outcome in rodent TBI, even when the experimental injuries are defined as severe, might be most applicable to mild or moderate TBI.

Preprocessing of Medical Image Data for Three-Dimensional Bioprinted Customized-Neural-Scaffolds

IMPACT STATEMENT

Nerve damage, which can be devastating, triggers several biological cascades, which result in the insufficiencies of the human nervous system to provide complete nerve repair and regain of function. Since no therapeutic strategy exists to provide immediate attention and intervention to patients with newly acquired nerve damage, we propose a strategy in which accelerated medical image processing through graphical processing unit implementation and three-dimensional printing are combined to produce a time-efficient, patient-specific (custom-neural-scaffold) solution to nerve damage. This work aims to beneficially shorten the time required for medical decision-making so that improved patient outcomes are achieved.

Traumatic brain injury and frontal lobe plasticity

Over 1.4 million people in the United States experience traumatic brain injury (TBI) each year and approximately 52,000 people die annually due to complications related to TBI. Traditionally, TBI has been viewed as a static injury with significant consequences for frontal lobe functioning that plateaus after some window of recovery, remaining relatively stable thereafter. However, over the past decade there has been growing consensus that the consequences of TBI are dynamic, with unique characteristics expressed at the individual level and over the life span. This chapter first discusses the pathophysiology of TBI in order to understand its dynamic process and then describes the behavioral changes that are the result of injury with focus on frontal lobe functions. It integrates a historical perspective on structural and functional brain-imaging approaches used to understand how TBI impacts the frontal lobes, as well as more recent approaches to examine large-scale network changes after TBI. The factors most useful for outcome prediction are surveyed, along with how the theoretical frameworks used to predict recovery have developed over time. In this chapter, the authors argue for the need to understand outcome after TBI as a dynamic process with individual trajectories, taking a network theory perspective to understand the consequences of disrupting frontal systems in TBI. Within this framework, understanding frontal lobe dysfunction within a larger coordinated neural network to study TBI may provide a novel perspective in outcome prediction and in developing individualized treatments.

Undertriage of major trauma patients at a university hospital: a retrospective cohort study

Background

Studies show increased mortality among severely injured patients not met by trauma team. Proper triage is important to ensure that all severely injured patients receive vital trauma care. In 2017 a new national trauma plan was implemented in Norway, which recommended the use of a modified version of “Guidelines for Field Triage of Injured Patients” to identify severely injured patients.

Methods

A retrospective study of 30,444 patients admitted to Haukeland University Hospital in 2013, with ICD-10 injury codes upon discharge. The exclusion criteria were department affiliation considered irrelevant when identifying trauma, patients with injuries that resulted in Injury Severity Score < 15, patients that did receive trauma team, and patients admitted > 24 h after time of injury. Information from patient records of every severely injured patient admitted in 2013 was obtained in order to investigate the sensitivity of the new guidelines.

Results

Trauma team activation was performed in 369 admissions and 85 patients were identified as major trauma. Ten severely injured patients did not receive trauma team resuscitation, resulting in an undertriage of 10.5%. Nine out of ten patients were men, median age 54 years. Five patients were 60 years or older. All of the undertriaged patients experienced fall from low height (< 4 m). Traumatic brain injury was seen in six patients. Six patients had a Glasgow Coma Scale score ≤ 13. The new trauma activation guidelines had a sensitivity of 95.0% in our 2013 trauma population. The degree of undertriage could have been reduced to 4.0% had the guidelines been implemented and correctly applied.

Conclusions

The rate of undertriage at Haukeland University Hospital in 2013 was above the recommendations of less than 5%. Use of the new trauma guidelines showed increased triage precision in the present trauma population.

Systematic review on the characterization of chronic traumatic encephalopathy by MRI and MRS

BACKGROUND

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease that is found in people who have suffered from chronic traumatic brain injury (TBI). Up to now, diagnosis of CTE could only be made based on postmortem histopathological examinations. The application of MR techniques might offer a promising possibility for in vivo diagnoses.

PURPOSE/HYPOTHESIS

To provide a critical systematic review of the characterization of chronic TBI and CTE by considering the range of MR techniques.

STUDY TYPE

This was a systematic review for which the electronic databases PubMed and Embase were searched using the terms ("chronic traumatic encephalopathy" OR "punch drunk syndrome" OR "chronic traumatic brain injury" OR "dementia pugilistica" OR "chronic head trauma") AND ("magnetic resonance imaging" OR mri OR imaging OR mrs OR "magnetic resonance spectroscopy" OR spectroscopy).

POPULATION/SUBJECTS/PHANTOM/SPECIMEN/ANIMAL MODEL

Of the 432 studies identified by the database search, 25 were included in this review.

FIELD STRENGTH/SEQUENCE

Diffusion, structural, and functional MRI sequences and MR spectroscopy were evaluated at 1.5T or 3T and at 11.74T for the ex vivo studies.

ASSESSMENT

Data were extracted by two reviewers independently. Specific inclusion and exclusion criteria like the study design, publication type, and applied MR techniques were used to select studies for review.

STATISTICAL TESTS

Results of the original research articles were stated in this review as significant if P ≤ 0.05.

RESULTS

Of the included articles, two were ex vivo studies focusing on the coregistration of histology and MRI. All other studies were based on in vivo data.

DATA CONCLUSION

The included studies varied considerably regarding study setup, MR techniques, and results. Nevertheless, this work aims to establish links between the studies and discusses the results and limitations associated with the characterization of chronic TBI and CTE based on MR.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:212-228.

Supplements, nutrition, and alternative therapies for the treatment of traumatic brain injury

Studies using traditional treatment strategies for mild traumatic brain injury (TBI) have produced limited clinical success. Interest in treatment for mild TBI is at an all time high due to its association with the development of chronic traumatic encephalopathy and other neurodegenerative diseases, yet therapeutic options remain limited. Traditional pharmaceutical interventions have failed to transition to the clinic for the treatment of mild TBI. As such, many pre-clinical studies are now implementing non-pharmaceutical therapies for TBI. These studies have demonstrated promise, particularly those that modulate secondary injury cascades activated after injury. Because no TBI therapy has been discovered for mild injury, researchers now look to pharmaceutical supplementation in an attempt to foster success in human clinical trials. Non-traditional therapies, such as acupuncture and even music therapy are being considered to combat the neuropsychiatric symptoms of TBI. In this review, we highlight alternative approaches that have been studied in clinical and pre-clinical studies of TBI, and other related forms of neural injury. The purpose of this review is to stimulate further investigation into novel and innovative approaches that can be used to treat the mechanisms and symptoms of mild TBI.

Neuro-ophthalmologic disorders following concussion

Visual symptoms, such as photophobia and blurred vision, are common in patients with concussion. Such symptoms may be accompanied by abnormalities of specific eye movements, such as saccades and convergence, or accommodation deficits. The high frequency of visual involvement in concussion is not surprising, since more than half of the brain's pathways are dedicated to vision and eye movement control. These areas include many that are most vulnerable to head trauma, including the frontal and temporal lobes. Vision and eye movement testing is important at the bedside and on the sidelines of athletic events, where brief performance measures that require eye movements, such as rapid number naming, are reliable and sensitive measures for concussion detection. Tests of vision and eye movements are also being explored clinically to identify and monitor patients with symptoms of both sport- and nonsport-related concussion. Evaluation of vision and eye movements can assist in making important decisions after concussion, including the prognosis for symptom recovery, and to direct further visual rehabilitation as necessary.

Decreased leftward 'aiming' motor-intentional spatial cuing in traumatic brain injury

OBJECTIVE

To characterize the mediation of attention and action in space following traumatic brain injury (TBI).

METHOD

Two exploratory analyses were performed to determine the influence of spatial 'Aiming' motor versus spatial 'Where' bias on line bisection in TBI participants. The first experiment compared performance according to severity and location of injury in TBI. The second experiment examined bisection performance in a larger TBI sample against a matched control group. In both experiments, participants bisected lines in near and far space using an apparatus that allowed for the fractionation of spatial Aiming versus Where error components.

RESULTS

In the first experiment, participants with severe injuries tended to incur rightward error when starting from the right in far space, compared with participants with mild injuries. In the second experiment, when performance was examined at the individual level, more participants with TBI tended to incur rightward motor error compared to controls.

CONCLUSIONS

TBI may cause frontal-subcortical cognitive dysfunction and asymmetric motor perseveration, affecting spatial Aiming bias on line bisection. Potential effects on real-world function need further investigation. (PsycINFO Database Record

Both hemorrhagic and non-hemorrhagic traumatic MRI lesions are associated with the microstructural damage of the normal appearing white matter

Traumatic microbleeds (TMBs) and non-hemorrhagic lesions (NHLs) on MRI are regarded as surrogate markers of diffuse axonal injury. However, the actual relation between lesional and diffuse pathology remained unclear, since lesions were related to clinical parameters, largely influenced by extracranial factors. The aim of this study is to directly compare TMBs, NHLs and their regional features with the co-existing diffuse injury of the normal appearing white matter (NAWM) as measured by diffusion tensor imaging (DTI). Thirty-eight adults with a closed traumatic brain injury (12 mild, 4 moderate and 22 severe) who underwent susceptibility weighted imaging (SWI), T1-, T2 weighted and FLAIR MRI and routine CT were included in the study. TMB (on SWI) and NHL (on T1-, T2 weighted and FLAIR images) features and Rotterdam scores were evaluated. DTI metrics such as fractional anisotropy (FA) and mean diffusivity (MD) were measured over different NAWM regions. Clinical parameters including age; Glasgow Coma Scale; Rotterdam score; TMB and NHL features were correlated to regional NAWM diffusivity using multiple regression. Overall NHL presence and basal ganglia area TMB load were significantly, negatively correlated with the subcortical NAWM FA values (partial r=-0.37 and -0.36; p=0.006 and 0.025, respectively). The presence of any NHL, or TMBs located in the basal ganglia area indicates diffuse NAWM damage even after adjusting for clinical and CT parameters. To estimate DAI, a conventional lesional MRI pathology evaluation might at least in part substitute the use of quantitative DTI, which is yet not widely feasible in a clinical setting.

Improving Traumatic Brain Injury Outcomes: The Development of an Evaluation and Referral Tool at Groote Schuur Hospital

BACKGROUND

The Western Cape Province of South Africa has a great shortage of diagnostic expertise, rehabilitative infrastructure, and support services for patients with traumatic brain injury (TBI). The neurosurgical outpatient setting is busy and often chaotic, and patients are frequently lost to follow-up. This study sought to continue with the design and development of a comprehensive, yet brief tool to aid patient referrals and ensure that no consequence of TBI is left unidentified and unaddressed.

METHODS

There were 47 patients with TBI (mean age, 35 years; range, 18-75 years) assessed. The study was designed in 3 distinct phases, each representing a different stage in the tool's development.

RESULTS

The Groote Schuur Traumatic Brain Injury Evaluation was shortened and simplified. Overall, 81% of the participants indicated cognitive dysfunction. There was a high prevalence of psychological/psychiatric sequelae, with 85% of participants reporting at least 1 such problem.

CONCLUSIONS

The findings further highlight the prevalence of the cognitive, behavioral, and psychological consequences of TBI and shed additional light on the particular types of problems that patients with TBI face. Following the identified changes, the questionnaire and algorithm combination are now ready to be validated in the neurosurgical clinical setting.

Volumes of Chronic Traumatic Frontal Brain Lesions Measured by Mr Imaging and CBF Tomography

The volumes (ml) of chronic traumatic frontal brain lesions were compared measured “morphologically” with MR imaging (T1 and T2 weighted images) and “functionally” with a tomographic rCBF technique (SPECT with 133Xe i.v.). The T1 volumes varied between 11 and 220 ml. The correlation between T1 and T2 volumes was 0.95, the T2 volumes being 33% larger than T1 volumes (p < 0.001). The functional SPECT volumes were considerably larger (range 16–324 ml) than the MR volumes. The mean volume difference was 81% between T1 and SPECT images (p < 0.001), and 35% between T2 and SPECT images (p < 0.001). Correlations between the MR and SPECT volumes were also higher for T2 than T1 volumes. The volume difference is most likely explained by a functional decrease in regions around the lesion in which no morphologic change visible on MR images had taken place. MR and SPECT volume measurements were positively related to persistent lack of energy and personality changes, but only moderately related to duration of impaired consciousness and neuropsychologic outcome.

Systems Biology, Neuroimaging, Neuropsychology, Neuroconnectivity and Traumatic Brain Injury

The patient who sustains a traumatic brain injury (TBI) typically undergoes neuroimaging studies, usually in the form of computed tomography (CT) and magnetic resonance imaging (MRI). In most cases the neuroimaging findings are clinically assessed with descriptive statements that provide qualitative information about the presence/absence of visually identifiable abnormalities; though little if any of the potential information in a scan is analyzed in any quantitative manner, except in research settings. Fortunately, major advances have been made, especially during the last decade, in regards to image quantification techniques, especially those that involve automated image analysis methods. This review argues that a systems biology approach to understanding quantitative neuroimaging findings in TBI provides an appropriate framework for better utilizing the information derived from quantitative neuroimaging and its relation with neuropsychological outcome. Different image analysis methods are reviewed in an attempt to integrate quantitative neuroimaging methods with neuropsychological outcome measures and to illustrate how different neuroimaging techniques tap different aspects of TBI-related neuropathology. Likewise, how different neuropathologies may relate to neuropsychological outcome is explored by examining how damage influences brain connectivity and neural networks. Emphasis is placed on the dynamic changes that occur following TBI and how best to capture those pathologies via different neuroimaging methods. However, traditional clinical neuropsychological techniques are not well suited for interpretation based on contemporary and advanced neuroimaging methods and network analyses. Significant improvements need to be made in the cognitive and behavioral assessment of the brain injured individual to better interface with advances in neuroimaging-based network analyses. By viewing both neuroimaging and neuropsychological processes within a systems biology perspective could represent a significant advancement for the field.

Multi-echo susceptibility-weighted imaging and histology of open-field blast-induced traumatic brain injury in a rat model

Blast-induced traumatic brain injury is on the rise, predominantly as a result of the use of improvised explosive devices, resulting in undesirable neuropsychological dysfunctions, as demonstrated in both animals and humans. This study investigated the effect of open-field blast injury on the rat brain using multi-echo, susceptibility-weighted imaging (SWI). Multi-echo SWI provided phase maps with better signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), making it a sensitive technique for brain injury. Male Sprague-Dawley rats were subjected to a survivable blast of 180 kPa. The visibility of blood vessels of varying sizes improved with multi-echo SWI. Reduced signal intensity from major vessels post-blast indicates increased deoxyhaemoglobin. Relative cerebral blood flow was computed from filtered phase SWI images using inferred changes in oxygen saturation from major blood vessels. Cerebral blood flow decreased significantly at day 3 and day 5 post-blast compared with that pre-blast. This was substantiated by the upregulation of β-amyloid precursor protein (β-APP), a marker of ischaemia, in the neuronal perikaya of the cerebral cortex, as observed by immunofluorescence, and in the cortical tissue by western blot analysis. Our findings indicate the presence of brain ischaemia in post-blast acute phase of injury with possible recovery subsequently. Our results from cerebrovascular imaging, histology and staining provide an insight into the ischaemic state of the brain post-blast and may be useful for prognosis and outcome.

Effects of virtual reality-based bilateral upper-extremity training on brain activity in post-stroke patients

[Purpose] This study investigated the therapeutic effects of virtual reality-based bilateral upper-extremity training on brain activity in patients with stroke. [Subjects and Methods] Eighteen chronic stroke patients were divided into two groups: the virtual reality-based bilateral upper-extremity training group (n = 10) and the bilateral upper-limb training group (n = 8). The virtual reality-based bilateral upper-extremity training group performed bilateral upper-extremity exercises in a virtual reality environment, while the bilateral upper-limb training group performed only bilateral upper-extremity exercise. All training was conducted 30 minutes per day, three times per week for six weeks, followed by brain activity evaluation. [Results] Electroencephalography showed significant increases in concentration in the frontopolar 2 and frontal 4 areas, and significant increases in brain activity in the frontopolar 1 and frontal 3 areas in the virtual reality-based bilateral upper-extremity training group. [Conclusion] Virtual reality-based bilateral upper-extremity training can improve the brain activity of stroke patients. Thus, virtual reality-based bilateral upper-extremity training is feasible and beneficial for improving brain activation in stroke patients.

Neuropsychological outcome and diffusion tensor imaging in complicated versus uncomplicated mild traumatic brain injury

This study examined whether intracranial neuroimaging abnormalities in those with mild traumatic brain injury (MTBI) (i.e., “complicated” MTBIs) are associated with worse subacute outcomes as measured by cognitive testing, symptom ratings, and/or diffusion tensor imaging (DTI). We hypothesized that (i) as a group, participants with complicated MTBIs would report greater symptoms and have worse neurocognitive outcomes than those with uncomplicated MTBI, and (ii) as a group, participants with complicated MTBIs would show more Diffusion Tensor Imaging (DTI) abnormalities. Participants were 62 adults with MTBIs (31 complicated and 31 uncomplicated) who completed neurocognitive testing, symptom ratings, and DTI on a 3T MRI scanner approximately 6-8 weeks post injury. There were no statistically significant differences between groups on symptom ratings or on a broad range of neuropsychological tests. When comparing the groups using tract-based spatial statistics for DTI, no significant difference was found for axial diffusivity or mean diffusivity. However, several brain regions demonstrated increased radial diffusivity (purported to measure myelin integrity), and decreased fractional anisotropy in the complicated group compared with the uncomplicated group. Finally, when we extended the DTI analysis, using a multivariate atlas based approach, to 32 orthopedic trauma controls (TC), the findings did not reveal significantly more areas of abnormal DTI signal in the complicated vs. uncomplicated groups, although both MTBI groups had a greater number of areas with increased radial diffusivity compared with the trauma controls. This study illustrates that macrostructural neuroimaging changes following MTBI are associated with measurable changes in DTI signal. Of note, however, the division of MTBI into complicated and uncomplicated subtypes did not predict worse clinical outcome at 6-8 weeks post injury.

Olfactory impairment and traumatic brain injury in blast-injured combat troops: a cohort study

OBJECTIVE

To determine whether a structured and quantitative assessment of differential olfactory performance-recognized between a blast-injured traumatic brain injury (TBI) group and a demographically comparable blast-injured control group-can serve as a reliable antecedent marker for preclinical detection of intracranial neurotrauma.

METHODS

We prospectively and consecutively enrolled 231 polytrauma inpatients, acutely injured from explosions during combat operations in either Afghanistan or Iraq and requiring immediate stateside evacuation and sequential admission to our tertiary care medical center over a 2½-year period. This study correlates olfactometric scores with both contemporaneous neuroimaging findings as well as the clinical diagnosis of TBI, tabulates population-specific incidence data, and investigates return of olfactory function.

RESULTS

Olfactometric score predicted abnormal neuroimaging significantly better than chance alone (area under the curve = 0.78, 95% confidence interval [CI] 0.70-0.87). Normosmia was present in all troops with mild TBI (i.e., concussion) and all control subjects. Troops with radiographic evidence of frontal lobe injuries were 3 times more likely to have olfactory impairment than troops with injuries to other brain regions (relative risk 3.0, 95% CI 0.98-9.14). Normalization of scores occurred in all anosmic troops available for follow-up testing.

CONCLUSION

Quantitative identification olfactometry has limited sensitivity but high specificity as a marker for detecting acute structural neuropathology from trauma. When considering whether to order advanced neuroimaging, a functional disturbance with central olfactory impairment should be regarded as an important tool to inform the decision process.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that central olfactory dysfunction identifies patients with TBI who have intracranial radiographic abnormalities with a sensitivity of 35% (95% CI 20.6%-51.7%) and specificity of 100% (95% CI 97.7%-100.0%).

Low-frequency connectivity is associated with mild traumatic brain injury

Mild traumatic brain injury (mTBI) occurs from a closed-head impact. Often referred to as concussion, about 20% of cases complain of secondary psychological sequelae, such as disorders of attention and memory. Known as post-concussive symptoms (PCS), these problems can severely disrupt the patient's quality of life. Changes in local spectral power, particularly low-frequency amplitude increases and/or peak alpha slowing have been reported in mTBI, but large-scale connectivity metrics based on inter-regional amplitude correlations relevant for integration and segregation in functional brain networks, and their association with disorders in cognition and behaviour, remain relatively unexplored. Here, we used non-invasive neuroimaging with magnetoencephalography to examine functional connectivity in a resting-state protocol in a group with mTBI (n = 20), and a control group (n = 21). We observed a trend for atypical slow-wave power changes in subcortical, temporal and parietal regions in mTBI, as well as significant long-range increases in amplitude envelope correlations among deep-source, temporal, and frontal regions in the delta, theta, and alpha bands. Subsequently, we conducted an exploratory analysis of patterns of connectivity most associated with variability in secondary symptoms of mTBI, including inattention, anxiety, and depression. Differential patterns of altered resting state neurophysiological network connectivity were found across frequency bands. This indicated that multiple network and frequency specific alterations in large scale brain connectivity may contribute to overlapping cognitive sequelae in mTBI. In conclusion, we show that local spectral power content can be supplemented with measures of correlations in amplitude to define general networks that are atypical in mTBI, and suggest that certain cognitive difficulties are mediated by disturbances in a variety of alterations in network interactions which are differentially expressed across canonical neurophysiological frequency ranges.

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Patients with mTBI display increased connectivity in low-frequency resting state.

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Elevated low-frequency power observed in temporal and deep-grey regions in mTBI

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Frontal, temporal and deep-grey regions show increased amplitude correlations in mTBI.

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Disorders of attention, anxiety and depression are associated with distinct, frequency-specific networks across the brain.

The Effects of Mild Traumatic Brain Injury, Post-Traumatic Stress Disorder, and Combined Mild Traumatic Brain Injury/Post-Traumatic Stress Disorder on Returning Veterans

United States veterans of the Iraqi (Operation Iraqi Freedom [OIF]) and Afghanistan (Operation Enduring Freedom [OEF]) conflicts have frequently returned from deployment after sustaining mild traumatic brain injury (mTBI) and enduring stressful events resulting in post-traumatic stress disorder (PTSD). A large number of returning service members have been diagnosed with both a history of mTBI and current PTSD. Substantial literature exists on the neuropsychological factors associated with mTBI and PTSD occurring separately; far less research has explored the combined effects of PTSD and mTBI. The current study employed neuropsychological and psychological measures in a sample of 251 OIF/OEF veterans to determine whether participants with a history of mTBI and current PTSD (mTBI+PTSD) have poorer cognitive and psychological outcomes than participants with mTBI only (mTBI-o), PTSD only (PTSD-o), or veteran controls (VC), when groups are comparable on intelligence quotient, education, and age. The mTBI+PTSD group performed more poorly than VC, mTBI-o, and PTSD-o groups on several neuropsychological measures. Effect size comparisons suggest small deleterious effects for mTBI-o on measures of processing speed and visual attention and small effects for PTSD-o on measures of verbal memory, with moderate effects for mTBI+PTSD on the same variables. Additionally, the mTBI+PTSD group was significantly more psychologically distressed than the PTSD-o group, and PTSD-o group was more distressed than VC and mTBI-o groups. These findings suggest that veterans with mTBI+PTSD perform significantly lower on neuropsychological and psychiatric measures than veterans with mTBI-o or PTSD-o. The results also raise the possibility of mild but persisting cognitive changes following mTBI sustained during deployment.

Long-Term Consequences of Traumatic Brain Injury: Current Status of Potential Mechanisms of Injury and Neurological Outcomes

Traumatic brain injury (TBI) is a significant clinical problem with few therapeutic interventions successfully translated to the clinic. Increased importance on the progressive, long-term consequences of TBI have been emphasized, both in the experimental and clinical literature. Thus, there is a need for a better understanding of the chronic consequences of TBI, with the ultimate goal of developing novel therapeutic interventions to treat the devastating consequences of brain injury. In models of mild, moderate, and severe TBI, histopathological and behavioral studies have emphasized the progressive nature of the initial traumatic insult and the involvement of multiple pathophysiological mechanisms, including sustained injury cascades leading to prolonged motor and cognitive deficits. Recently, the increased incidence in age-dependent neurodegenerative diseases in this patient population has also been emphasized. Pathomechanisms felt to be active in the acute and long-term consequences of TBI include excitotoxicity, apoptosis, inflammatory events, seizures, demyelination, white matter pathology, as well as decreased neurogenesis. The current article will review many of these pathophysiological mechanisms that may be important targets for limiting the chronic consequences of TBI.

Single-subject-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mild traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of sustained impairment in military and civilian populations. However, mild TBI (mTBI) can be difficult to detect using conventional MRI or CT. Injured brain tissues in mTBI patients generate abnormal slow-waves (1–4 Hz) that can be measured and localized by resting-state magnetoencephalography (MEG). In this study, we develop a voxel-based whole-brain MEG slow-wave imaging approach for detecting abnormality in patients with mTBI on a single-subject basis. A normative database of resting-state MEG source magnitude images (1–4 Hz) from 79 healthy control subjects was established for all brain voxels. The high-resolution MEG source magnitude images were obtained by our recent Fast-VESTAL method. In 84 mTBI patients with persistent post-concussive symptoms (36 from blasts, and 48 from non-blast causes), our method detected abnormalities at the positive detection rates of 84.5%, 86.1%, and 83.3% for the combined (blast-induced plus with non-blast causes), blast, and non-blast mTBI groups, respectively. We found that prefrontal, posterior parietal, inferior temporal, hippocampus, and cerebella areas were particularly vulnerable to head trauma. The result also showed that MEG slow-wave generation in prefrontal areas positively correlated with personality change, trouble concentrating, affective lability, and depression symptoms. Discussion is provided regarding the neuronal mechanisms of MEG slow-wave generation due to deafferentation caused by axonal injury and/or blockages/limitations of cholinergic transmission in TBI. This study provides an effective way for using MEG slow-wave source imaging to localize affected areas and supports MEG as a tool for assisting the diagnosis of mTBI.

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A voxel-based whole-brain MEG slow-wave source imaging method for mild TBI.

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The new approach showed 84.5% positive detection rate in 84 mild TBI patients.

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The new approach detected loci of injury in mild TBI patients on a single-subject basis.

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MEG slow-wave source imaging revealed brain areas vulnerable to mild TBI.

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MEG slow-wave generations correlated with mild TBI symptoms.

A neurovascular perspective for long-term changes after brain trauma

Traumatic brain injury (TBI) affects all age groups in a population and is an injury generating scientific interest not only as an acute event, but also as a complex brain disease with several underlying neurobehavioral and neuropathological characteristics. We review early and long-term alterations after juvenile and adult TBI with a focus on changes in the neurovascular unit (NVU), including neuronal interactions with glia and blood vessels at the blood-brain barrier (BBB). Post-traumatic changes in cerebral blood-flow, BBB structures and function, as well as mechanistic pathways associated with brain aging and neurodegeneration are presented from clinical and experimental reports. Based on the literature, increased attention on BBB changes should be integrated in studies characterizing TBI outcome and may provide a meaningful therapeutic target to resolve detrimental post-traumatic dysfunction.

Neuroimaging biomarkers in mild traumatic brain injury (mTBI)

Reviewed herein are contemporary neuroimaging methods that detect abnormalities associated with mild traumatic brain injury (mTBI). Despite advances in demonstrating underlying neuropathology in a subset of individuals who sustain mTBI, considerable disagreement persists in neuropsychology about mTBI outcome and metrics for evaluation. This review outlines a thesis for the select use of sensitive neuroimaging methods as potential biomarkers of brain injury recognizing that the majority of individuals who sustain an mTBI recover without neuroimaging signs or neuropsychological sequelae detected with methods currently applied. Magnetic resonance imaging (MRI) provides several measures that could serve as mTBI biomarkers including the detection of hemosiderin and white matter abnormalities, assessment of white matter integrity derived from diffusion tensor imaging (DTI), and quantitative measures that directly assess neuroanatomy. Improved prediction of neuropsychological outcomes in mTBI may be achieved with the use of targeted neuroimaging markers.

Traumatic brain injury in young rats leads to progressive behavioral deficits coincident with altered tissue properties in adulthood

Traumatic brain injury (TBI) affects many infants and children, and results in enduring motor and cognitive impairments with accompanying changes in white matter tracts, yet few experimental studies in rodent juvenile models of TBI (jTBI) have examined the timeline and nature of these deficits, histologically and functionally. We used a single controlled cortical impact (CCI) injury to the parietal cortex of rats at post-natal day (P) 17 to evaluate behavioral alterations, injury volume, and morphological and molecular changes in gray and white matter, with accompanying measures of electrophysiological function. At 60 days post-injury (dpi), we found that jTBI animals displayed behavioral deficits in foot-fault and rotarod tests, along with a left turn bias throughout their early developmental stages and into adulthood. In addition, anxiety-like behaviors on the zero maze emerged in jTBI animals at 60 dpi. The final lesion constituted only ∼3% of brain volume, and morphological tissue changes were evaluated using MRI, as well as immunohistochemistry for neuronal nuclei (NeuN), myelin basic protein (MBP), neurofilament-200 (NF200), and oligodendrocytes (CNPase). White matter morphological changes were associated with a global increase in MBP immunostaining and reduced compound action potential amplitudes at 60 dpi. These results suggest that brain injury early in life can induce long-term white matter dysfunction, occurring in parallel with the delayed development and persistence of behavioral deficits, thus modeling clinical and longitudinal TBI observations.