The new neurometabolic cascade of concussion

Endophenotype presentation of athletes with concussion contingent on sex and time since injury

INTRODUCTION

Athletes with concussions experience heterogeneous symptoms and clinical trajectories. Subclassification provides diagnostic clarity that may improve prognostication and individualized treatments.

METHODS

We hypothesized that endophenotypes of adolescent athletes with concussions differ based on sex and time since injury. Post-concussive testing was performed for athletes (n = 1385) in the North Texas Concussion Registry (ConTex) at four timepoints: acute [0-3 days post-injury (DPI)], subacute-early (4-7DPI), subacute-late (8-28DPI), and persistent (29+DPI). Six endophenotypes (cognitive, headache, ocular-motor, vestibular, affective, sleep) were constructed by allocating post-concussion testing data elements described by the Concussion Subtype Workgroup.

RESULTS

Endophenotypes were defined using correlations between data elements and compared based on sex or time since injury. Correlograms revealed endophenotypes differed based on sex and time since injury. The affective endophenotype was dependent on the interaction between sex and time since injury and was more prevalent at the subacute-late and persistent timepoints. The sleep endophenotype became more prevalent at the persistent timepoint. Affective and sleep endophenotypes were interrelated with cognitive, vestibular, and headache endophenotypes at the persistent timepoint suggesting that dysregulated mood and sleep influence lingering symptoms.

CONCLUSIONS

Adolescent symptom-based concussion endophenotypes differ based on sex and time since injury. Clinical consideration may improve identification of separate trajectories following sport-related concussion and provide targeted care.

Traumatic brain injury persistently increases the incidence of both ischemic and hemorrhagic strokes: Potential mechanisms

Traumatic brain injuries (TBI) significantly increase the risk of both ischemic and hemorrhagic strokes, with effects persisting for years after the initial injury. The mechanisms underlying this increased stroke risk are complex, multifactorial, and incompletely understood but likely include chronic cerebrovascular dysfunction, blood-brain barrier disruption, and inflammatory responses. Epidemiological studies consistently show that TBI is an independent risk factor for stroke, with more severe injuries associated with greater risk, especially for hemorrhagic strokes. Traditional risk factors for stroke, such as hypertension, poor diet, and sedentary lifestyle, further elevate the risk in TBI survivors. Modifiable lifestyle factors, such as improving sleep, increasing physical activity, and adopting heart-healthy diets, offer potential intervention points to mitigate stroke risk. Pharmacological considerations, including the use of antidepressants, anticoagulants, and statins, also influence stroke risk, particularly with regard to hemorrhagic complications. This review explores the pathophysiological mechanisms linking TBI and stroke, emphasizing the need for future research to identify specific biomarkers and imaging techniques to predict stroke vulnerability in TBI patients. Addressing the gaps in understanding, particularly regarding small vessel pathology, will be essential to developing targeted therapies for reducing stroke incidence in TBI survivors.

Sport-Related Concussions in High School Athletes: A Comprehensive Update

PURPOSE OF REVIEW

Sport-related concussions (SRC) in high school athletes are a growing public health concern, with recent advancements in epidemiology, pathophysiology, diagnosis, management, and prevention. We concisely summarize SRC in high school athletes, emphasizing current research and clinical implications.

RECENT FINDINGS

Athletes are at significant risk of SRCs, with incidence varying by sport, sex, and competitive setting. Advances in pathophysiology highlight the role of metabolic disruption, inflammation, and axonal injury. Updated diagnostic tools, such as SCAT6, aid clinical evaluation, while advanced neuroimaging and biomarkers remain investigational. Return-to-sport/learn protocols emphasize a gradual, stepwise return. Preventative measures, including policy changes, neuromuscular training, and protective equipment, have reduced SRC incidence. Comprehensive SRC management includes recognition and removal from play followed by a structured return to sport/learning. Future research directions include biomarker validation, optimized prevention strategies, and long-term outcome assessment to reduce the burden of SRC in adolescent athletes.

TRANSCENDENT (Transforming Research by Assessing Neuroinformatics across the Spectrum of Concussion by Embedding iNterdisciplinary Data-collection to Enable Novel Treatments): protocol for a prospective observational cohort study of concussion patients with embedded comparative effectiveness research within a network of learning health system concussion clinics in Canada

INTRODUCTION

Concussion affects over 400 000 Canadians annually, with a range of causes and impacts on health-related quality of life. Research to date has disproportionately focused on athletes, military personnel and level I trauma centre patients, and may not be applicable to the broader community. The TRANSCENDENT Concussion Research Program aims to address patient- and clinician-identified research priorities, through the integration of clinical data from patients of all ages and injury mechanisms, patient-reported outcomes and objective biomarkers across factors of intersectionality. Seeking guidance from our Community Advisory Committee will ensure meaningful patient partnership and research findings that are relevant to the wider concussion community.

METHODS AND ANALYSIS

This prospective observational cohort study will recruit 5500 participants over 5 years from three 360 Concussion Care clinic locations across Ontario, Canada, with a subset of participants enrolling in specific objective assessments including testing of autonomic function, exercise tolerance, vision, advanced neuroimaging and fluid biomarkers. Analysis will be predicated on pre-specified research questions, and data shared with the Ontario Brain Institute's Brain-CODE database. This work will represent one of the largest concussion databases to date, and by sharing it, we will advance the field of concussion and prevent siloing within brain health research.

ETHICS AND DISSEMINATION

This study was approved by the Children's Hospital of Eastern Ontario Research Ethics Board and preregistered on OSF (25 June 2024); https://doi.org/10.17605/OSF.IO/HYDZC. Dissemination of findings will be multifaceted, including conference presentations, peer-reviewed publications and sharing of adapted materials (eg, videos, infographics, plain language summaries) with community groups and key knowledge users.

Post-Concussion Brain Changes Relative to Pre-Injury White Matter and Cerebral Blood Flow: A Prospective Observational Study

BACKGROUND AND OBJECTIVES

Medical clearance for return to play (RTP) after sports-related concussion is based on clinical assessment. It is unknown whether brain physiology has entirely returned to preinjury baseline at the time of clearance. In this longitudinal study, we assessed whether concussed individuals show functional and structural MRI brain changes relative to preinjury levels that persist beyond medical clearance. Secondary objectives were to test whether postconcussion changes exceed uninjured brain variability and to correlate MRI findings with clinical recovery time.

METHODS

For this prospective observational study, healthy athletes without a history of psychiatric, neurologic, or sensory-motor conditions were recruited from a single university sport medicine clinic. Clinical and MRI data were collected at preseason baseline, and those who were later concussed were reassessed at 1-7 days after injury, RTP, 1-3 months after RTP, and 1 year after RTP. A demographically matched control cohort of uninjured athletes was also reassessed at their subsequent preseason baseline. Primary outcomes were postconcussion changes in MRI measures of cerebral blood flow (CBF), white matter mean diffusivity (MD), and fractional anisotropy (FA), evaluated using mixed models. Secondary outcomes were group differences in MRI change scores and correlations of change scores with days to RTP.

RESULTS

Of the 187 athletes enrolled in the study, 25 had concussion with follow-up imaging (20.3 ± 1.5 years, 56% male, 44% female) and were compared with 27 controls (19.7 ± 1.8 years, 44% male, 56% female). Concussed athletes showed statistically significant changes from baseline, including decreased frontoinsular CBF (mean and 95% CI -8.97 [-12.80, -5.01] mL/100 g/minute, z = -4.53), along with increased MD (1.94 × 10-5 [1.26, 2.69] × 10-5, z = 5.48) and reduced FA (-7.30 × 10-3 [-9.80, -5.05] × 10-3, z = -6.07) in the corona radiata and internal capsule. Effects persisted beyond RTP, although only CBF changes exceeded longitudinal variability in controls. For participants with longer recovery periods, significantly greater changes in medial temporal CBF were also seen (ρ = 0.64 [0.44, 0.81], z = 6.80).

DISCUSSION

This study provides direct evidence of persistent postconcussion changes in CBF and white matter at RTP and up to 1 year later. These results support incomplete recovery of brain physiology at medical clearance, with secondary analyses emphasizing the sensitivity of CBF to clinical recovery.

Using neuroimaging to identify sex differences in adults with sports-related concussion: a systematic review

Concussion is a common injury in sports that causes neurological damage, leading to memory loss and difficulty concentrating. Insufficient recovery time may result in significant long-term harm to individuals. Several neuroimaging techniques have been used to understand the pathophysiological changes following concussion, and how long individuals need to recover before returning to play. Despite the progress in neuroimaging concussion research, few studies have considered whether females sustain different effects on the brain and how recovery from concussion might differ from males. Thus, we conducted a systematic review of the existing literature to highlight sex differences in concussion with neuroimaging techniques. By searching four different databases, studies were selected if they used a neuroimaging technique to examine sex differences following concussion in athletes over the age of 18. After screening 2295 studies from an initial search, 15 were found to match the selection criteria. Nine papers established some difference between males and females, however many of these studies were not designed to specifically examine sex differences, and hence conclusions in this regard are somewhat limited. A further common limitation among these papers was a lack of whole brain scans, instead relying on regions of interest analyses, which reduces the ability to compare studies effectively. The current systematic review has highlighted the need for future studies to specifically consider whether, and how sex influences the impact and trajectory of brain recovery from concussion. This can then help to inform suitable amendments to current concussion return-to-play protocols for male and female athletes.

Investigating the Association of Concussion and Contact Sport Exposure History With Brain Microstructure Using Quantitative Susceptibility Mapping

A growing body of evidence suggests that repeated concussions and exposure to repetitive head impacts may be associated with subtle abnormalities in neurological health. Prior studies have demonstrated associations of prior concussion and repetitive head impacts with the brain's microstructure, typically using diffusion magnetic resonance imaging, though the direction of these relationships has varied across groups. Quantitative susceptibility mapping is a quantitative extension of susceptibility weighted imaging that is sensitive to pathophysiology associated with neurotrauma and thus represents an alternative method to characterize the effects of concussion and repetitive head impact exposure on brain microstructure. The goal of this work was to characterize the association of prior concussion and years of contact sport exposure (a proxy of repetitive head impacts) with magnetic susceptibility in a cohort of otherwise healthy male and female collegiate-aged athletes. We hypothesized that concussion and contact sport exposure would be independently associated with lower susceptibility in white matter regions. Higher general symptom severity and psychological symptoms were observed in athletes with a greater history of concussion, but not years of contact sport exposure. No associations between concussion or years of exposure with cognitive performance were observed. Voxel-wise analyses found that individuals with more prior concussions also had lower magnetic susceptibility in two predominantly white matter clusters including the superior longitudinal fasciculi and forceps major. No associations of susceptibility and contact sport exposure were observed. Finally, lower susceptibility in the identified regions was associated with worse psychological symptoms, worse general symptoms, and worse performance on a composite measure of fluid cognition tasks. Current results suggest that more prior concussions in otherwise healthy collegiate-aged athletes are associated with decreases in susceptibility that are in turn associated with elevated symptom reporting and poorer cognitive performance.

Is It All in Your Head? Placebo Effects in Concussion Prevention

Sports-related concussions (SRCs) are a major health issue in athletes of varying ages, ability levels, and sports. Concerns over the short- and long-term consequences of SRCs have incentivized a wealth of products and policies aimed at reducing SRC risk. Research suggesting the effectiveness of such interventions at reducing SRCs has facilitated their adoption by sports organizations and, in some cases, product commercialization. However, the body of SRC mitigation research is almost entirely devoid of placebo or sham groups, which raises important questions about the true clinical effectiveness of these interventions. This Current Opinion explores the plausibility of placebo effects within the scope of SRC prevention, describes why the lack of placebo/sham groups in the current body of literature is problematic, and provides recommendations for including placebo/sham groups in future SRC research.

Concussion injuries in sports and the role of instrumented mouthguards: a mini review

Contact sports such as American football, rugby, soccer, and ice hockey involve high-speed, high-impact interactions that frequently result in head acceleration events (HAEs), which can lead to concussions and other forms of traumatic brain injury. HAEs can lead to acute symptoms like dizziness and memory difficulties, as well as more severe, chronic conditions like cognitive decline and chronic traumatic encephalopathy. This mini-review focuses on concussion-related injuries in contact sports, examining their prevalence, impact, and the role of innovative prevention strategies. Particular attention is given to the development of instrumented mouthguards (iMGs), which incorporate real-time sensors to measure and analyze head impacts. Ultimately, this review aims to provide an overview of the role of iMGs on concussion prevention and its evolving landscape, with a focus on the potential of iMG technology.

Utility of pre-injury risk factors and the concussion clinical profiles screening (CP screen) tool for identifying concussion profiles in adolescents

This study determined the combined utility of pre-injury risk factors and Concussion Clinical Profile Screen (CP Screen) items to identify clinician-adjudicated concussion profiles in adolescents. This was a retrospective study of 236 adolescents aged 12-18 who presented to a concussion specialty clinic between 2019 and 2020 within 30 days of injury. Participants completed the CP Screen at their initial evaluation, and clinicians provided blindly adjudicated clinical profiles for each participant. Stepwise logistic regressions and receiver operating characteristic (ROC) curves were conducted. Participants (n = 236; 60.2% male) had a mean age of 14.79 ± 1.62 years, and most injuries were sport-related (n = 185, 78.4%). Combined pre-injury risk factor and CP Screen item predictors of anxiety/mood (AUC = 0.903) demonstrated outstanding utility; vestibular (AUC = 0.802) demonstrated excellent utility; and ocular (AUC = 0.766), PTM (AUC = 0.729), and cognitive (AUC = 0.723) demonstrated acceptable utility. Select pre-injury risk factors and CP Screen items provided acceptable to outstanding predictive utility for all clinical profiles in adolescents following concussion, highlighting their clinical utility for identifying concussion clinical profiles and subsequent targeted interventions. However, certain pre-injury risk factors and CP Screen items represented multiple profiles, highlighting the potential overlap and the need for clinicians to consider a multidomain evaluation to inform the best treatment approach.

Mild traumatic brain injury increases cortical iron: evidence from individual susceptibility mapping

Quantitative susceptibility mapping has been applied to map brain iron distribution after mild traumatic brain injury to understand properties of neural tissue which may be related to cellular dyshomeostasis. However, this is a heterogeneous injury associated with microstructural brain changes, and 'traditional' group-wise statistical approaches may lead to a loss of clinically relevant information, as subtle alterations at the individual level can be obscured by averages and confounded by within-group variability. More precise and individualized approaches are needed to characterize mild traumatic brain injury better and elucidate potential cellular mechanisms to improve intervention and rehabilitation. To address this issue, we use quantitative MRI to build individualized profiles of regional positive (iron-related) magnetic susceptibility across 34 bilateral cortical ROIs following mild traumatic brain injury. Healthy population templates were constructed for each cortical area using standardized Z-scores derived from 25 age-matched male controls aged between 16 and 32 years (M = 21.10, SD = 4.35), serving as a reference against which Z-scores of 35 males with acute (<14 days) sports-related mild traumatic brain injury were compared [M = 21.60 years (range: 16-33), SD = 4.98]. Secondary analyses sensitive to cortical depth and curvature were also generated to approximate the location of iron accumulation in the cortical laminae and the effect of gyrification. Primary analyses indicated that approximately one-third (11/35; 31%) of injured participants exhibited elevated positive susceptibility indicative of abnormal iron profiles relative to the healthy population, a finding that was mainly concentrated in regions within the temporal lobe. Injury severity was significantly higher (P = 0.02) for these participants than their iron-normal counterparts, suggesting a link between injury severity, symptom burden, and elevated cortical iron. Secondary exploratory analyses of cortical depth and curvature profiles revealed abnormal iron accumulation in 83% (29/35) of mild traumatic brain injury participants, enabling better localization of injury-related changes in iron content to specific loci within each region and identifying effects that may be more subtle and lost in region-wise averaging. Our findings suggest that individualized approaches can further elucidate the clinical relevance of iron in mild head injury. Differences in injury severity between iron-normal and iron-abnormal mild traumatic brain injury participants identified in our primary analysis highlight not only why precise investigation is required to understand the link between objective changes in the brain and subjective symptomatology, but also identify iron as a candidate biomarker for tissue pathology after mild traumatic brain injury.

Physiological outcomes of physical activity interventions in persistent postconcussive symptoms: a scoping review protocol

There are limited therapeutic options for patients with persistent postconcussive symptoms (PPCSs). Most PPCS assessments focus on subjective measures of progression and symptom monitoring. While early exercise interventions for rehabilitation are now considered best practice for acute concussion, no comprehensive review exists on how physical activity objectively and physiologically affects outcomes in PPCS. This scoping review protocol outlines the methods to identify the efficacy of therapeutic exercise interventions for PPCS, emphasising their impact on physiological parameters, including cardiovascular autonomic responses and cerebral autoregulation. Using the Patient, Intervention, Comparison and Outcome (PICO) framework, we will include all studies presenting original data. Narrative summaries will provide clinicians. An initial search in Medline/EMBASE/PubMed, Cochrane Library, PsycINFO, Web of Science and Scopus will be completed. Key parameters from each study will be extracted, tabulated and discussed in a narrative inquiry. The study references will be reviewed for additional studies meeting the inclusion criteria. Future research applications from the findings will be emphasised. After completion of the review, the results will be stratified by type of physical activity as the intervention, emphasising the physiological outcomes. Mapping these findings will allow us to identify the key research priorities for future studies. Findings will be shared with PPCS practitioners and local/national committees and submitted for conferences and publications.

Brain glucose metabolism in patients with traumatic brain injury undergoing rehabilitation: a longitudinal 18F-FDG PET study

Background

Measuring 18F-FDG PET-detected brain glucose uptake provides reliable information on metabolic tissue abnormalities, cells dysfunction, and neurovascular changes after traumatic brain injury (TBI).

Objectives

We aimed to study the relationship between post-traumatic brain glucose metabolism and functional outcomes in the so far unexplored field of longitudinally 18F-FDG PET-monitored patients undergoing rehabilitation after moderate-to-severe TBI.

Methods

Fourteen patients consecutively admitted to our unit in the post-acute phase after TBI underwent 18F-FDG-PET scans performed before and 6 months after inpatient rehabilitation program. The Glasgow Coma Scale (GCS) for neurological status, and the Functional Independence Measure (FIM) plus the Glasgow Outcome Scale-Extended (GOSE) scales for the rehabilitation outcome, were applied on admission and discharge. Voxel-wise analyses were performed, with the Statistical Parametric Mapping (SPM12) software, to investigate pre- vs. post-rehabilitation changes of brain metabolism, and their relationships with clinical indices.

Results

In the whole sample, 18F-FDG uptake significantly increased in the following five regions that were hypometabolic before rehabilitation: inferior frontal gyrus bilaterally, alongside right precentral gyrus, inferior parietal lobule, and cerebellum. However, only for the right precentral gyrus the median voxel peak-value at baseline resulted a significant predictor of both cognitive (FIM cognitive subscale, p = 0.012), and functional (GOS-E, p = 0.02; post- vs. pre-treatment GOS-E difference, p = 0.009) improvements. ROC curve analysis showed that a peak voxel-value of 1.7998 was the optimal cut-off for favorable rehabilitation outcome. Unfavorable functional outcomes were predicted by increased 18F-FDG uptake in the inferior frontal gyrus (GOS-E, p = 0.032) and precentral gyrus (FIM cognitive subscale, p = 0.017; GOS-E, p = 0.015).

Conclusion

This proof-of-principle study enlightens the metabolic changes occurring in moderate-to-severe TBI course. Notably, such changes preferentially involve definite frontal brain areas regardless of TBI localization and entity. These findings pave the way for further studies with translational purposes.

Characterizing positive and negative quantitative susceptibility values in the cortex following mild traumatic brain injury: a depth- and curvature-based study

Evidence has linked head trauma to increased risk factors for neuropathology, including mechanical deformation of the sulcal fundus and, later, perivascular accumulation of hyperphosphorylated tau adjacent to these spaces related to chronic traumatic encephalopathy. However, little is known about microstructural abnormalities and cellular dyshomeostasis in acute mild traumatic brain injury in humans, particularly in the cortex. To address this gap, we designed the first architectonically motivated quantitative susceptibility mapping study to assess regional patterns of net positive (iron-related) and net negative (myelin-, calcium-, and protein-related) magnetic susceptibility across 34 cortical regions of interest following mild traumatic brain injury. Bilateral, between-group analyses sensitive to cortical depth and curvature were conducted between 25 males with acute (<14 d) sports-related mild traumatic brain injury and 25 age-matched male controls. Results suggest a trauma-induced increase in net positive susceptibility focal to superficial, perivascular-adjacent spaces in the parahippocampal sulcus. Decreases in net negative susceptibility values in distinct voxel populations within the same region indicate a potential dual pathology of neural substrates. These mild traumatic brain injury-related patterns were distinct from age-related processes revealed by correlation analyses. Our findings suggest depth- and curvature-specific deposition of biological substrates in cortical tissue convergent with features of misfolded proteins in trauma-related neurodegeneration.

Acute diffuse axonal injury following repeated mild traumatic brain injury in juvenile rats

Mild traumatic brain injuries (mTBIs) are caused by biomechanical forces being transmitted to the brain, causing neuronal connections to be subjected to sheering forces. The injury severity can be affected by a number of factors that include age and sex, however, there remains a paucity of data on how repeated mTBI (r-mTBI) impacts the female brain. In these studies, male and female juvenile rats [postnatal day (PND) 25-26] were administered a total of eight mTBIs over a 2-day period. Following each mTBI, rats were immediately assessed for acute neurological impairment. After eight mTBIs were completed, the Barnes maze was used to assess spatial learning and memory. Axonal injury was assessed using silver stain histological analyses. We found that injured females exhibited less acute neurological impairment than males. Three days after the final r-mTBI, no significant differences were observed in spatial learning and memory, with all animals showing similar times to locate the escape platform on the reversal trial, additionally there was no main effect of sex in the Barnes maze. Silver stain uptake was significantly increased in the optic tract, corpus callosum, and cortex compared with sham animals at seven days postinjury in a sex-specific manner. Females showed significant increase in all three regions following r-mTBI, whereas males only showed a significant increase in staining in the optic tract. Overall, these findings show that females may be more susceptible to axonal damage than males, and that cognitive deficits were not evident in this population following r-mTBI. These results indicate that there may be benefits in examining biomarkers that reflect axonal injury and the therapies that target reducing axonal degradation.NEW & NOTEWORTHY Diffuse axonal injury is a hallmark feature of all severities of traumatic brain injury (TBI) yet, in preclinical mild (m)TBI research no studies have yet investigated axonal damage with silver stain immunohistochemistry in female animals. This is a critical gap in the literature as recent studies suggest that females experience mTBI more frequently than males. We found that repeated mTBI (r-mTBI) caused significant diffuse axonal injury that was more pronounced in females compared with males.

Differing clinical characteristics among individuals with concussions sustained at work, in motor vehicle collisions, and sport

PURPOSE

To compare clinical characteristics in patients with concussions sustained by prevalent, but understudied, mechanisms (work-related concussion [WRC] and motor vehicle collision [MVC]-related concussion) to sport-related concussion (SRC).

METHODS

Retrospective review of 281 electronic medical records from an outpatient concussion clinic. Time since injury (days), duration of care (days), amount of care (number of visits), and perceived health (Short-Form 12) were collected.

RESULTS

The time between injury and clinic presentation was significantly greater in WRC and MVC-related concussion compared to SRC. These groups were also older, had a longer duration of care, required more referrals for outside clinical services, and reported worse perceived mental and physical health versus SRC.

CONCLUSION

These results suggest that clinical courses may be significantly different for individuals with SRC, WRC and MVC-related concussion, and that different management approaches and expectations may be necessary for these groups. Further research is indicated.

Differences in Network Functional Connectivity in Response to Sub-Symptomatic Exercise Between Elite Adult Athletes after Sport-Related Concussion and Healthy Matched Controls: A Pilot Study

Resting-state electroencephalography (rsEEG) has developed as a method to explore functional network alterations related to sport-related concussion (SRC). Although exercise is an integral part of an athlete's return to sport (RTS) protocol, our understanding of the effects of exercise on (impaired) brain network activity in elite adult athletes is limited. However, this information may be beneficial to inform recovery and RTS progressions. Recording (128-channel) rsEEG datasets before and after a standardized moderate aerobic bike exercise test, this study aimed to explore functional connectivity patterns in whole brain and relevant functional networks in a group of elite adult athletes post-injury compared with healthy matched controls. The following networks were selected a priori: whole brain (68 regions of interest [ROIs]), default mode network (14 ROIs), central autonomic network (CAN, 24 ROIs), and visual network (8 ROIs). Twenty-one SRC athletes and 21 age-, sex-, sport type-, and skill level-matched healthy controls participated in this study. The SRC athletes were recruited during their RTS protocol (days since injury: 2-140 days). All athletes were able to achieve the exercise goal of reaching a moderate intensity (70% of their age-calculated maximum heart rate) while staying sub-symptomatic. Before and after exercise, functional connectivity was calculated by the phase locking value, in the alpha band (7-13 Hz). Mann-Whitney U and Wilcoxon signed rank tests were used to explore neurophysiological differences between and within groups, respectively. Whole-brain connectivity increased significantly from pre- to post-exercise within both groups (SRC: 0.264-0.284; p = 0.011 vs. controls: 0.253-0.257; p = 0.011). While CAN connectivity significantly increased only within the SRC group from pre-(0.298) to post-exercise (0.317; p = 0.003). Although all athletes reached their exercise goal without exacerbation of symptoms, the impact of exercise on the CAN appears to be greater for the SRC athletes, than matched healthy controls. The potential clinical significance of this finding is that it may have revealed an underlying mechanism for the cardiac autonomic alterations post-injury. This study merits further investigation into the CAN, as a network of interest more closely aligned with the clinical features (e.g., autonomic dysfunction) during athletes' RTS.

Trajectories of intrinsic connectivity one year post pediatric mild traumatic brain injury: Neural injury superimposed on neurodevelopment

The developing brain undergoes rapid changes throughout middle childhood and adolescence. The disambiguation of long-term changes in intrinsic activity following pediatric mild traumatic brain injury (pmTBI) from typical development can therefore only be ascertained in longitudinal studies with large sample size and at least three serial assessments. A comprehensive clinical battery and resting-state fMRI data were collected approximately 1-week (N = 263; 8-18 years old), 4-months (N = 192) and 1-year (N = 153) post-injury, with identical visits in a large cohort (N = 228) of age- and sex-matched healthy controls (HC). Results indicated persistent frontocerebellar and thalamic connectivity changes up to 1-year post-injury in pmTBI relative to controls (P's < .001), with similar longitudinal connectivity trajectories (i.e., typical neurodevelopment). Alterations in precuneal midline connectivity (p's < .05) and occupancy of a default mode/limbic dynamic brain state were present only up to 4-months (p's < .001) rather than 1-year (p's > .44) post-injury. However, absent group differences at 1-year post-injury may be explained as pseudo-normalization due to altered longitudinal connectivity trajectories in pmTBI associated with neurodevelopment. Persistent alterations of precuneal connectivity were also associated with lower executive function and long-term memory scores. In conclusion, pmTBI may result in chronic changes to both static and dynamic intrinsic connectivity which further interact with typical neurodevelopment. Longer follow-up studies may be needed to unravel this interaction.

Does white matter and vascular injury from repetitive head impacts lead to a novel pattern on T2 FLAIR MRI? A hypothesis proposal and call for research

The goal of this paper is to introduce the hypothesis that white matter (WM) and vascular injury are long-term consequences of repetitive head impacts (RHI) that result in a novel T2 fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging pattern. A non-systematic literature review of autopsy and FLAIR studies of RHI-exposed adults was first conducted as a foundation for our hypothesis. A case series of RHI-exposed participants is presented to illustrate the unique FLAIR WM hyperintensities (WMH) pattern. Current literature shows a direct link between RHI and later-life WM/vascular neuropathologies, and that FLAIR WMH are associated with RHI, independent of modifiable vascular risk factors. Initial observations suggest a distinctive pattern of WMH in RHI-exposed participants, termed RHI-associated WMH (RHI-WMH). RHI-WMH defining features are as follows: (1) small, punctate, non-confluent, (2) spherical, and (3) proximal to the gray matter. Our hypothesis serves as a call for research to empirically validate RHI-WMH and clarify their biological and clinical correlates. HIGHLIGHTS: Repetitive head impacts (RHI) have been associated with later-life white matter (WM) and vascular neuropathologies. T2 FLAIR MRI of RHI-exposed participants reveals a potentially unique WM hyperintensity (WMH) pattern that is termed RHI-associated WMH (RHI-WMH). RHI-WMH are characterized as (1) small, punctate, and non-confluent, (2) spherical, and (3) proximal to the gray matter at an area anatomically susceptible to impact injury, such as the depths of the cortical sulci.

Challenges and Research Opportunities for Integrating Quantitative Electroencephalography Into Sports Concussion Rehabilitation

Although concussion management and return to play/learn decision making focuses on reducing symptoms, there is growing interest in objective physiological approaches to treatment. Clinical and technological advancements have aided concussion management; however, the scientific study of the neurophysiology of concussion has not translated into its standard of care. This expert commentary is motivated by novel clinical applications of electroencephalographic-based neurofeedback approaches (eg, quantitative electroencephalography [QEEG]) for treating traumatic brain injury and emerging research interest in its translation for treating concussion. QEEG's low-cost relative to other brain recording/imaging techniques and precedent in clinical and medical care makes it a potential tool for concussion rehabilitation. Although uncommon, licensed and certified clinicians and medical professionals are implementing QEEG neurofeedback for concussion management within their score of practice. These approaches are not widely adopted nor recommended by professional medical societies, likely because of a limited evidence base of well-designed studies with available standard protocols. Thus, the potential efficacy of QEEG neurofeedback for treating persistent symptoms or cognitive dysfunction after sports-related concussion is unknown. This commentary will update the concussion clinician-scientist on the emerging research, techniques, and disagreements pertaining to the translation of QEEG neurofeedback for concussion management, particularly in the treatment of persistent cognitive difficulties. This commentary will also introduce to readers the fundamentals of how the electroencephalogram may be acquired, measured, and implemented during QEEG neurofeedback. An evidence base of supportive findings from well-designed studies, including those that are retrospective, outcomes-based, and, ultimately, placebo/sham-controlled is recommended prior to considering more widespread adoption of QEEG neurofeedback approaches for treating persistent symptoms or cognitive deficits after sports-related concussion. We review the considerable barriers to this research and clinical implementation, and conclude with opportunities for future research, which will be necessary for establishing the quality and efficacy of QEEG neurofeedback for concussion care.

The Relationship Between Concussion and Combat History and Mental Health and Suicide Ideation Among United States Military Veterans-A Pilot Study

Background/Objectives: Suicides among U.S. military veterans are alarmingly high, driven by factors such as mental health issues, combat exposure, and history of mild traumatic brain injury (mTBI)/concussion. This study aims to examine the relationship between concussion history, combat experience, and their effects on mental health issues and suicide ideation among military veterans. Additionally, this study investigates the impact of post-traumatic stress disorder (PTSD) on these variables. Methods: A total of 78 veterans (62 males, 16 females) participated in this study. Participants completed a demographic survey and the Global Well-being Index (GWI) to assess concussion history and residual symptoms. A licensed social worker interviewed the veterans using the 9-Item Patient Health Questionnaire (PHQ-9) for depression, the Generalized Anxiety Disorder survey (7 Items) (GAD-7) for anxiety, and the Columbia-Suicide Severity Rating Scale (C-SSRS) for suicide ideation. A 2 × 2 cross-tabulation analysis examined the relationships between concussion history, combat experience, and outcomes of anxiety, depression, and suicide ideation. PTSD was also assessed as both a predictor and an outcome. Statistical analyses yielded odds ratios (OR) with 95% confidence intervals (CI), Chi-square, and Cramer's V (V) correlations along with associated p-values. Results: The combination of concussion history and combat experience strongly predicted either anxiety, depression, or suicide ideation (OR = 7.97, 95% CI: 1.70, 37.44; V = 0.334, (p = 0.003)), more than either factor alone. Combat experience was the strongest predictor of PTSD (OR = 11.12, 95% CI: 3.30, 37.47; V = 0.485, p ≤ 0.001), both individually and when combined with concussion history. PTSD strongly influenced mental health issues and suicide ideation (OR = 8.16, 95% CI: 1.74, 38.25; V = 0.339, p = 0.003). Stratification by PTSD status (positive or negative) affected the relationships between independent and dependent variables. Small cell counts resulted in a wide 95% CI for some ORs, though some statistically significant Fisher's Exact Test results were observed. Credibility analysis using the critical prior interval (CPI) metric confirmed the intrinsic credibility of the results. Conclusions: This study provides insights into the relationships between concussion history, combat experience, and their impacts on mental health issues and suicide ideation among military veterans.

A comprehensive literature review on the effects of saffron and its bioactive components on traumatic brain injury (TBI)

Traumatic brain injury (TBI) is a leading cause of death in accidents, sports, and warfare. Additionally, TBI imposes a significant financial burden on individuals and governments, necessitating substantial financial support. It also severely diminishes the quality of life for patients and their caregivers. TBI is consisted of two distinct phases: the primary and secondary phases. The primary phase consists of numerous events that occur immediately after the injury or concussion but the second phase takes times and include several of responsive cascades that human body express against TBI. After TBI incidence, several cellular and molecular pathways (inflammatory, apoptotic, anti-oxidant) will be dysregulated. Over the years, numerous therapeutic approaches have been implemented to treat this debilitating condition, aiming to alleviate its symptoms and complications, while enhancing patients' quality of life. Consequently, the search for more efficient with less adverse effects therapeutic methods remains a priority. One herbal medication that has recently garnered considerable attention is saffron. Data were collected from Scopus, Google Scholar, PubMed, and Cochrane Library for clinical, in vivo and in vitro studies published in English between 1992 and Jan 2025. Search terms included "TBI" OR "Traumatic brain injury" AND "Saffron" AND "Safranal" AND "Crocin" AND "Crocetin" AND "Kaempferol". The initial search yielded approximately 3,000 manuscripts. After screening and full-text evaluation, as detailed in the search methodology, ten experiments (in-vitro & in-vivo) were ultimately included. Saffron showed to modulate various signaling pathways and cytokines such as NF-kB, NLRP3, Nrf2, HO-1, Bcl2, and Bax, which will lead to the improvement of TBI sign and symptoms and increase the quality of life. It has been demonstrated that this compound could play a multifactorial role in TBI treatment such as reduction in inflammation, apoptosis, and oxidative stress, while modulating microglia activation. The findings suggest that saffron may play a pivotal role in treating TBI and mitigating its complications by regulating various pathophysiological pathways. However, more clinical trials are necessary to evaluate saffron's effectiveness in individuals diagnosed with TBI. Clinical trials should focus on various areas such as saffrons' safety profile, adverse effects, the exact mechanism of action, its' impact on acute and chronic TBI, rehabilitation, and long-term neuroprotection.

Performance of current tools used for on-the-day assessment and diagnosis of mild traumatic brain injury in sport: a systematic review

Objective

The monitoring and diagnosis of sports-related mild traumatic brain injury (SR-mTBI) remains a challenge. This systematic review summarises the current monitoring tools used for on-the-day assessment and diagnosis of SR-mTBI and their performance.

Design

Systematic review, using Quality Assessment of Diagnostic Accuracy Studies assessment.

Data sources

Embase via Ovid, IEEEXplore, Medline via Ovid, Scopus and Web of Science were searched up to June 2024.

Eligibility criteria

Peer-reviewed English-language journal articles which measured athletes using the index test within a day of injury and provided a performance measure for the method used. Studies of all designs were accepted, and no reference methods were required.

Results

2534 unique records were retrieved, with 52 reports included in the review. Participants were 76% male, when reported, and the mean injury-to-measurement time was reported in 10% of reports. 46 different methods were investigated. 38 different reference methods were used, highlighting the lack of gold standard within the field. Area under the curve (AUC), sensitivity and specificity were the most frequent outcome metrics provided. The most frequent index test was the King-Devick (KD) test. However, there were large variations in accuracy metrics between reports for the KD test, for instance, the range of AUC: 0.51-0.92.

Conclusion

Combinations of existing methods and the KD test were most accurate in assessing SR-mTBI, despite the inconsistent accuracy values related to the KD test. The absence of a gold-standard measurement hampers our ability to diagnose or monitor SR-mTBI. Further exploration of the mechanisms and time-dependent pathophysiology of SR-mTBI could result in more targeted diagnostic and monitoring techniques. The Podium Institute for Sports Medicine and Technology funded this work.

PROSPERO registration number

CRD42022376560.

Quantitative Susceptibility Mapping in Adults with Persistent Postconcussion Symptoms after Mild Traumatic Brain Injury: An Exploratory Study

BACKGROUND AND PURPOSE

It is estimated that 18%-30% of patients with concussion experience symptoms lasting more than 1 month, known as persistent post-concussion symptoms (PPCS). Symptoms can be debilitating, and include headache, dizziness, nausea, problems with memory and concentration, sleep and mood disruption, and exercise intolerance. Previous studies have used quantitative susceptibility mapping (QSM) to show altered tissue susceptibility levels in adults acutely following concussion, however this finding has yet to be investigated in participants with PPCS.

MATERIALS AND METHODS

In this exploratory case-controlled study, we measured tissue susceptibility using QSM in 24 participants with PPCS after mild traumatic brain injury (mTBI) and 23 healthy controls with no history of concussion. We compute tissue susceptibility for 7 white matter tracts and 3 deep gray matter regions and compare tissue susceptibility between groups using ANCOVA models controlling for age and sex. We also assess the relationship between regional tissue susceptibility and symptoms.

RESULTS

There were no significant differences between tissue susceptibility in participants with PPCS compared with control subjects in any of the evaluated regions. However, we show lower tissue susceptibility across 4 white matter tracts was generally associated with worse symptoms in the PPCS group. Specifically, we saw relationships between white matter susceptibility and headache (p = .006), time since injury (p = .03), depressive symptoms (p = .021), and daytime fatigue (p = .01) in participants with PPCS.

CONCLUSIONS

These results provide evidence in support of persistent changes in the brain months to years after injury and highlight the need to further understand the pathophysiology of PPCS, to determine effective prevention and treatment options.

Sub-symptom threshold aerobic exercise improves executive function during the early stage of sport-related concussion recovery

We examined whether persons with a sport-related concussion (SRC) derive a postexercise executive function (EF) benefit, and whether a putative benefit is related to an exercise-mediated increase in cerebral blood flow (CBF). Participants with an SRC completed the Buffalo Concussion Bike Test to determine the heart rate threshold (HRt) associated with symptom exacerbation and/or voluntary exhaustion. On a separate day, SRC participants - and healthy controls (HC group) - completed 20-min of aerobic exercise at 80% HRt while middle cerebral artery velocity (MCAv) was measured to estimate CBF. The antisaccade task (i.e. saccade mirror-symmetrical to target) was completed pre- and postexercise to evaluate EF. SRC and HC groups showed a comparable exercise-mediated increase in CBF (ps < .001), and both groups elicited a postexercise EF benefit (ps < .001); however, the benefit was unrelated to the magnitude of the MCAv change. Moreover, SRC symptomology was not increased when assessed immediately postexercise and showed a 24 h follow-up benefit. Accordingly, persons with an SRC demonstrated an EF benefit following a single bout of sub-symptom threshold aerobic exercise. Moreover, the exercise intervention did not result in symptom exacerbation and thus demonstrates that a tailored aerobic exercise program may support cognitive and symptom recovery following an SRC.

Phenylephrine Usage During Anesthesia in Concussed Patients Undergoing Orthopedic Surgery: A Retrospective Cohort Study

Background and objective Concussion can lead to complex physiologic changes, including alterations to cerebral blow flow autoregulation. Based on this understanding, we aimed to analyze if concussed patients undergoing orthopedic surgery required a higher dosage or a more frequent administration of phenylephrine while under general anesthesia; we also sought to assess if a concussion with an associated loss of consciousness (LOC) influenced treatment. Methods We performed a retrospective review of the data of patients admitted in the past three years to the emergency room (ER) with a diagnosis of head concussion at our level-one trauma center. Patients were filtered by selecting those who underwent a single emergent orthopedic surgical procedure under general anesthesia: a total of 61 individuals. We further refined this group according to the presence/absence of LOC. The cohort with concussion coupled with LOC included 50 patients (82% of the treatment group), and the cohort with concussion without LOC had 11 patients (18% of the treatment group). Concussed patients were compared to a matched group of 118 patients without head trauma who also presented to the ER in the same period and required similar emergent orthopedic surgeries during their hospitalization. Phenylephrine was the most common vasopressor used in all surgeries. Statistical analyses involved chi-square tests for the frequency of phenylephrine usage. The Kruskal-Wallis and Dunn's tests were also used to examine differences in phenylephrine dosage across each cohort. Results In all concussed patients, regardless of LOC, there was no difference in phenylephrine usage during general anesthesia compared to controls without head trauma. However, concussed patients who experienced LOC required significantly higher doses of phenylephrine compared to controls.  Conclusions This is the first study to explore the relationship between concussion, LOC, and vasopressor usage during general anesthesia. Its findings demonstrated an increased requirement for phenylephrine in concussed patients with LOC compared to controls.

Minimally invasive serial collection of cerebrospinal fluid reveals sex-dependent differences in neuroinflammation in a rat model of mild traumatic brain injury

Traumatic brain injuries (TBI) are the seventh leading cause of disability globally with 48.99 million prevalent cases and 7.08 million years lived with diability. Approximately 80 % of TBI patients are diagnosed with mild TBI (mTBI), or concussion, caused by nonpenetrating mechanical trauma to the head or body along with sudden rotational motion of the head. Studies investigating the temporal dynamics of neuroinflammation after mTBI are greatly needed. Without longitudinal studies, translating preclinical studies to clinical studies remains challenging as the difference in timing remains poorly understood. In this study, we describe a method of minimally invasive serial cerebrospinal fluid (CSF) collection that enables longitudinal investigation of CSF inflammation. The method described in this study can easily be adapted by any laboratory prepared for animal studies. Multiplex immunoassay of serially collected and singly collected CSF samples show collection frequency does not alter protein expression in the CSF. Further, sex-dependent differences in TBI have been reported, but remain poorly understood. This study establishes a framework for assessing sex difference in neuroinflammation after a concussion. We showed that results vary based on the framing of the statistical test. However, it is evident that males experience a more robust inflammatory response to a single concussion than females.

Concussion characteristics in children and adolescents with ADHD: Exploring symptom burden and recovery trajectories

Concussions are a significant health concern for pediatric populations as children and adolescents engage in sports and recreational activities that increase their likelihood of sustaining brain injuries. Physical, cognitive, and emotional symptoms resulting from concussion overlap with other diagnoses, particularly mimicking many symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD). This study aimed to investigate and compare concussion characteristics, including symptom burden and recovery timeline, among pediatric patients with and without ADHD who have been diagnosed with a concussion. A retrospective chart review of 316 patients aged 6-18 years seen in a specialty concussion clinic in the Northwest United States was conducted. Patients with ADHD were selected, and patients without a positive developmental history were selected as an age-matched control group. Data from initial phone interviews and the Rivermead Post-Concussion Symptoms Questionnaire were recorded into Epic EHR. Variables included demographics, concussion details, and symptom severity. Younger patients with ADHD had a longer time to their first visit, but ADHD did not significantly impact overall recovery time. Adolescents with ADHD and concussion were more likely to have diagnoses of depression and anxiety than adolescents without ADHD who had a concussion. The findings highlight the complexity of outcomes following concussion in children and adolescents. Although ADHD was associated with delayed care-seeking and higher rates of depression and anxiety diagnoses, an ADHD diagnosis did not significantly affect concussion symptom burden, as measured by the Rivermead Post-Concussion Symptoms Questionnaire, or recovery timeline.

Parasympathetic Responses to Face Cooling in Adolescents with Sport-Related Concussion and After Clinical Recovery

Face cooling (FC) initiates the mammalian dive reflex, which elicits a parasympathetic autonomic response. In our pilot study, collegiate athletes had a blunted parasympathetic response to FC within 10 days of sport-related concussion (SRC). The objective of the current study was to assess the FC response in adolescent athletes with acute SRC and after clinical recovery. Symptomatic adolescents with SRC (n = 23, 15.48 ± 1.2 years, 52% male) had heart rate (HR) and blood pressure (BP) measured during the FC test (7.83 ± 2.5 days since injury) and again after clinical recovery (46.44 ± 36.4 days later). Controls (n = 24, 15.83 ± 1.6 years, 58% male) performed the same assessments twice (48.00 ± 18.9 days apart). The main outcome measures were the rate of change in HR and HR variability (HRV) during the first 2 min of FC. Throughout FC, we found no significant differences between groups at the initial visit in the rate of change for HR (mean difference = 2.58 [-0.33, 5.50] bpm/min, p = 0.082), mean arterial BP (-0.02 [-3.49, 3.45] mmHg/min, p = 0.990), root mean square of successive differences (-13.46 [-34.02, 7.10] ms/min, p = 0.197) or low to high-frequency ratio (0.24 [-0.77, 1.25], p = 0.637). We also found no differences in our main outcome measures among concussed adolescents with delayed recovery (n = 10) compared with those with normal recovery (n = 13). A history of prior concussion had a significant effect on the HR and HRV responses to FC, suggesting that SRC may have prolonged effects on the autonomic nervous system (ANS). We conclude that acutely concussed adolescents do not differ from controls in parasympathetic response to FC acutely or upon recovery but that a history of concussion affects this response. We recommend that future studies control for concussion history when investigating the ANS in concussed adolescents.

Concussion and the Autonomic, Immune, and Endocrine Systems: An Introduction to the Field and a Treatment Framework for Persisting Symptoms

A significant proportion of patients who sustain a concussion/mild traumatic brain injury endorse persisting, lingering symptoms. The symptoms associated with concussion are nonspecific, and many other medical conditions present with similar symptoms. Medical conditions that overlap symptomatically with concussion include anxiety, depression, insomnia, chronic pain, chronic fatigue, fibromyalgia, and cervical strain injuries. One of the factors that may account for these similarities is that these conditions all present with disturbances in the optimal functioning of the autonomic nervous system and its intricate interactions with the endocrine system and immune system-the three primary regulatory systems in the body. When clinicians are working with patients presenting with persisting symptoms after concussion, evidence-based treatment options drawn from the literature are limited. We present a framework for the assessment and treatment of persisting symptoms following concussion based on the available evidence (treatment trials), neuroanatomical principles (research into the physiology of concussion), and clinical judgment. We review the research supporting the premise that behavioral interventions designed to stabilize and optimize regulatory systems in the body following injury have the potential to reduce symptoms and improve functioning in patients. Foundational concussion rehabilitation strategies in the areas of sleep stabilization, fatigue management, physical exercise, nutrition, relaxation protocols, and behavioral activation are outlined along with practical strategies for implementing intervention modules with patients.

Concussion acutely disrupts auditory processing in division I football student-athletes

INTRODUCTION

Diagnosis, assessment, and management of sports-related concussion require a multi-modal approach. Yet, currently, an objective assessment of auditory processing is not included. The auditory system is uniquely complex, relying on exquisite temporal precision to integrate signals across many synapses, connected by long axons. Given this complexity and precision, together with the fact that axons are highly susceptible to damage from mechanical force, we hypothesize that auditory processing is susceptible to concussive injury.

METHODS

We measured the frequency-following response (FFR), a scalp-recorded evoked potential that assesses processing of complex sound features, including pitch and phonetic identity. FFRs were obtained on male Division I Collegiate football players prior to contact practice to determine a pre-season baseline of auditory processing abilities, and again after sustaining a sports-related concussion. We predicted that concussion would decrease pitch and phonetic processing relative to the student-athlete's preseason baseline.

RESULTS

We found that pitch and phonetic encoding was smaller post-concussion. Student-athletes who sustained a second concussion showed similar declines after each injury.

CONCLUSIONS

Auditory processing should be included in the multimodal assessment of sports-related concussion. Future studies that extend this work to other sports, other injuries (e.g. blast exposure), and to female athletes are needed.

Pathophysiology, blood biomarkers, and functional deficits after intimate partner violence-related brain injury: Insights from emergency department patients and a new rat model

Intimate partner violence is a serious, but underappreciated, issue that predominantly affects women and often results in concussion (i.e., mild traumatic brain injury). However, concussion in intimate partner violence is unique because it often involves a concomitant strangulation which may exacerbate or alter the physiology and clinical presentation of the brain injury. Therefore, here we conducted human and rodent studies to provide insight into knowledge gaps related to the detection, pathophysiology, and functional consequences of intimate partner violence-related brain injury. We conducted the first study to analyze blood biomarkers and symptoms of brain injury in intimate partner violence patients presenting to an emergency department within 72 h of concussion. Intimate partner violence concussion patients, some of whom had also experienced a concomitant strangulation, had elevated serum neurofilament light and worse brain injury symptoms compared to healthy control, orthopedic trauma, and non-intimate partner violence concussion groups. We also developed the first rat model of non-fatal strangulation and examined the consequences of strangulation and concussion in isolation and in combination on pathophysiology, blood biomarkers, and behavior at 2 h and 1wk post-injury. Rats exposed to combined strangulation and concussion had exacerbated motor and cognitive deficits, neuroinflammation, and serum glial fibrillary acidic protein levels compared with either injury in isolation. Taken together, these rodent findings demonstrate that a concomitant strangulation modifies and exacerbates concussion pathophysiology, biomarkers, and functional consequences. Overall, these findings provide novel insights into intimate partner violence-related brain injury and provides a foundation for future translational studies.

Investigating the Impact of Turmeric on Neuroinflammation and Degenerative Changes in Repetitive Traumatic Brain Injuries: Insights from Murine Model

Objective

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. Preclinical and clinical studies investigating the effects of curcumin on TBI indicate that curcumin can modulate essential signaling pathways and molecules that mediate neuroinflammation in TBI. This study aimed to explore the effects of turmeric on neuroinflammation and neurodegenerative disorder following repetitive traumatic brain injuries (rTBIs) in a rat model.

Methods

Sixty male Rattus norvegicus were housed in a controlled environment. A modified Marmarou weight drop model was used. Turmeric extract was administered once daily in the morning. The avidin-biotin-peroxidase complex technique was used to evaluate the expression of all markers. Following incubation with normal rabbit serum, the slides were subsequently incubated with monoclonal antibodies targeting tau protein (AT-8), TAR DNA-binding protein 43 (TDP-43), glial fibrillary acidic protein (GFAP), and tumor necrosis factor (TNF)-α.

Results

rTBI significantly increased the levels of inflammatory markers, such as TNF-α and GFAP. A substantial decrease of TNF-α expression was observed in the treatment group. A distinct trend was observed for GFAP expression, which was markedly decreased after the rest period compared to that in the trauma group. Phosphorylated tau expression decreased in both the treatment and pretreatment groups relative to that in the trauma and rest groups. TDP-43 expression was also significantly decreased in the treatment and pretreatment groups.

Conclusion

In conclusion, Turmeric demonstrates significant potential as a neuroprotective and anti-inflammatory agent in rTBI, especially when used as a preventive measure. Our findings challenge the significance of rest in concussion management.

The effect of assessor expertise on reliability of analysis of video signs associated with concussion in Australian football

OBJECTIVES

To determine whether spotters with medical training and experience in managing concussion have higher inter-rater reliability and accuracy than non-medical personnel when identifying video signs associated with concussion in Australian football.

DESIGN

Retrospective cohort study.

METHODS

Video clips were collected of all impacts potentially resulting in concussion during 2012 and 2013 Australian Football League (AFL) seasons. Raters were divided into medical doctors and a non-medical group comprising allied health practitioners (physiotherapists) and non-medical/non-allied health personnel (performance analysts). Raters assessed 102 randomly selected videos for signs of concussion. The inter-rater reliability was calculated. Sensitivity, specificity, positive and negative predictive values were calculated by comparing the rater responses to the consensus opinion from two highly experienced clinicians with expertise in concussion.

RESULTS

No statistically significant difference in inter-rater reliability was observed between the medical doctors and the non-medical group. Both groups demonstrated good to excellent agreement for slow to get up, clutching at head/face and facial injury. Both groups displayed intra-class coefficient >0.55 for no protective action-floppy, loss of responsiveness, and motor incoordination, and displayed lowest agreement for no protective action-tonic posturing, impact seizure and blank/vacant look. No statistically significant difference was found between the groups for sensitivity, specificity, positive and negative predictive values for correctly classifying video signs compared to the expert consensus opinion.

CONCLUSIONS

After completing sufficient standardised training and testing, medical and non-medical personnel demonstrate comparable reliability in identifying video signs of concussion in professional Australian football and may be suitable for the role of video spotter.

Portable six-channel laser speckle system for simultaneous measurement of cerebral blood flow and volume with potential applications in characterization of brain injury

Significance

Cerebral blood flow (CBF) and cerebral blood volume (CBV) are key metrics for regional cerebrovascular monitoring. Simultaneous, non-invasive measurement of CBF and CBV at different brain locations would advance cerebrovascular monitoring and pave the way for brain injury detection as current brain injury diagnostic methods are often constrained by high costs, limited sensitivity, and reliance on subjective symptom reporting.

Aim

We aim to develop a multi-channel non-invasive optical system for measuring CBF and CBV at different regions of the brain simultaneously with a cost-effective, reliable, and scalable system capable of detecting potential differences in CBF and CBV across different regions of the brain.

Approach

The system is based on speckle contrast optical spectroscopy and consists of laser diodes and board cameras, which have been both tested and investigated for safe use on the human head. Apart from the universal serial bus connection for the camera, the entire system, including its battery power source, is integrated into a wearable headband and is powered by 9-V batteries.

Results

The temporal dynamics of both CBF and CBV in a cohort of five healthy subjects were synchronized and exhibited similar cardiac period waveforms across all six channels. The potential use of our six-channel system for detecting the physiological sequelae of brain injury was explored in two subjects, one with moderate and one with significant structural brain damage, where the six-point CBF and CBV measurements were referenced to structural magnetic resonance imaging (MRI) scans.

Conclusions

We pave the way for a viable multi-point optical instrument for measuring CBF and CBV. Its cost-effectiveness allows for baseline metrics to be established prior to injury in populations at risk for brain injury.

Unravelling Secondary Brain Injury: Insights from a Human-Sized Porcine Model of Acute Subdural Haematoma

Traumatic brain injury (TBI) remains one of the leading causes of death. Because of the individual nature of the trauma (brain, circumstances and forces), humans experience individual TBIs. This makes it difficult to generalise therapies. Clinical management issues such as whether intracranial pressure (ICP), cerebral perfusion pressure (CPP) or decompressive craniectomy improve patient outcome remain partly unanswered. Experimental drug approaches for the treatment of secondary brain injury (SBI) have not found clinical application. The complex, cellular and molecular pathways of SBI remain incompletely understood, and there are insufficient experimental (animal) models that reflect the pathophysiology of human TBI to develop translational therapeutic approaches. Therefore, we investigated different injury patterns after acute subdural hematoma (ASDH) as TBI in a post-hoc approach to assess the impact on SBI in a long-term, human-sized porcine TBI animal model. Post-mortem brain tissue analysis, after ASDH, bilateral ICP, CPP, cerebral oxygenation and temperature monitoring, and biomarker analysis were performed. Extracerebral, intraparenchymal-extraventricular and intraventricular blood, combined with brainstem and basal ganglia injury, influenced the experiment and its outcome. Basal ganglia injury affects the duration of the experiment. Recognition of these different injury patterns is important for translational interpretation of results in this animal model of SBI after TBI.

Regression-Based Classification of the Middle-Latency Auditory-Evoked Potentials in Vestibular Migraine and Concussion Patients with Dizziness

BACKGROUND/OBJECTIVES

The auditory middle-latency responses (AMLRs) assess central sensory processing beyond the brainstem and serve as a measure of sensory gating. They have clinical relevance in the diagnosis of neurological conditions. In this study, magnitude and habituation of the AMLRs were tested for sensitivity and specificity in classifying dizzy patients with vestibular migraine (VM) and post-concussive syndrome.

METHODS

Twenty-three healthy individuals, 12 concussion and 26 VM patients were recruited. AMLR were recorded performing five blocks of 200 binaural click-stimulations at 60 dB sensation level with a repetition rate of 6.1 Hz. Reduction in P0, Na and Pa magnitudes between blocks was measured. Group classifications were performed through logistic and multiple regression.

RESULTS

Among healthy subjects, a consistent P0 and Na habituation can be observed. Concussed subjects show control-like Na habituation, despite a lower magnitude, while P0 habituation was negligible. VM patients showed poor habituation for all waves. Regression analyses suggest that P0 and Na better distinguish healthy subjects from neurological patients, whereas Pa best distinguishes concussion from VM patients.

CONCLUSIONS

The results support that AMLR habituation can contribute to unraveling different mechanisms of dizziness due to concussion compared to VM, providing insights that can complement routine diagnostic assessments.

Long-term effects of concussion on attention, sensory gating and motor learning

The current work aimed to understand the behavioral manifestations that result from disruptions to the selective facilitation of task-relevant sensory information at early cortical processing stages in those with a history of concussion. A total of 40 participants were recruited to participate in this study, with 25 in the concussion history group (Hx) and 15 in the control group (No-Hx). Somatosensory-evoked potentials (SEPs) were elicited via median nerve stimulation while subjects performed a task that manipulated their focus of attention toward or away from proprioceptive cues. Participants also completed an implicit motor sequence learning task relying solely on proprioceptive cues, as well as a visual attentional blink (AB) task to understand the effect of concussion on rapid shifts in attention. The Hx SEP data replicated past work showing an absence of relevancy-based facilitation at early cortical processing stages (N20-P27) that emerged at later processing stages. Our Hx showed evidence of relevancy-based facilitation at either the P50-N70 or the N70-P100. Performance on the learning task was not significantly different between the Hx and No-Hx. Performance on the AB task revealed greater AB magnitude in the Hx compared to the No-Hx. Collectively, these results suggest a compensatory strategy in the Hx that enables them to learn to the same degree as controls. However, when the attentional system is taxed with high temporal demands there are decrements in performance. These results are of particular importance given that these individuals are at an increased risk of sustaining subsequent concussions, and musculoskeletal injuries.

Factors Affecting Sport-Related Concussion Non-Disclosure in Women's Rugby-A Multi-Country Qualitative Analysis

Background and Objectives: Collision-sport athletes, such as rugby players, are at risk of sport-related concussion (SRC). Women are known to be at higher risk of SRC and may experience more severe and chronic symptomology than men. Knowledge of the factors that affect a player's disclosure of their concussive symptoms could help to inform strategies to improve compliance with reporting and management of head injuries. The aim of this study was to investigate the factors that may impact women rugby players' disclosure of a concussion. Methods: Twenty-eight adult (≥18 years of age) elite and semi-elite women rugby players from the UK and Ireland (n = 17) and the United States (n = 11) were interviewed on their playing background and SRC experience in women's rugby via one-on-one interviews (UK and Ireland) or an online questionnaire (US). Results: SRC data were analysed inductively using a thematic analysis approach to determine the potential reasons for SRC non-disclosure in women's rugby. Four main themes were identified which may influence a player's SRC non-disclosure: 1. women rugby players are self-managing SRC; 2. work-related concerns impact on SRC disclosure; 3. players and support staff lack knowledge on SRC management; and 4. poor internal and external communication affect the support players receive when injured. Conclusions: The findings were consistent across players from different countries. This research highlighted several factors that may impact on women rugby players' disclosure of SRC regardless of country of origin (UK, Ireland, or US) and access to concussion care. Coaches and management teams should be aware of these reasons, which may enhance how they discuss and manage concussion. There is a clear need for further education on concussion for players and support staff and for strategies to create environments where women can openly discuss their concussion concerns.

The beneficial effects of modafinil administration on repeat mild traumatic brain injury (RmTBI) pathology in adolescent male rats are not dependent upon the orexinergic system

The sleep-wake cycle plays an influential role in the development and progression of repeat mild traumatic brain injury (RmTBI)-related pathology. Therefore, we first aimed to manipulate the sleep-wake cycle post-RmTBI using modafinil, a wake-promoting substance used for the treatment of narcolepsy. We hypothesized that modafinil would exacerbate RmTBI-induced deficits. Chronic behavioural analyses were completed along with a 27-plex serum cytokine array, metabolomic and proteomic analyses of cerebrospinal fluid (CSF), as well as immunohistochemical staining in structures important for sleep/wake cycles, to examine orexin, melanin-concentrating hormone, tyrosine hydroxylase, and choline acetyltransferase, in the lateral hypothalamus, locus coeruleus, and basal forebrain, respectively. Contrary to expectation, modafinil administration attenuated behavioural deficits, metabolomic changes, and neuropathological modifications. Therefore, the second aim was to determine if the beneficial effects of modafinil treatment were driven by the orexinergic system. The same experimental protocol was used; however, RmTBI rats received chronic orexin-A administration instead of modafinil. Orexin-A administration produced drastically different outcomes, exacerbating anxiety-related and motor deficits, while also significantly disrupting their metabolomic and neuropathological profiles. These results suggest that the beneficial effects of modafinil administration post-RmTBI, work independently of its wake-promoting properties, as activation of the orexinergic wake-promoting system with orexin-A was detrimental. Overall, these findings highlight the complexity of sleep-wake changes in the injured brain and showcase the potential of the arousal and sleep systems in its treatment.

SCAT Symptom Evolution in the Acute Concussion Phase: Findings from the NCAA-DoD CARE Consortium

The Sport Concussion Assessment Tool (SCAT) is the most widely used tool following sport-related concussion (SRC). Initial SCAT symptom burden is a strong predictor of recovery in collegiate athletes; however, it is unknown if symptom presentation varies within the acute (<48 h) post-SRC phase. The purpose of this cohort study was to examine acute SRC symptom presentation among the National Collegiate Athletic Association (NCAA) athletes. Concussed NCAA varsity athletes (n = 1,780) from 30 universities across the United States, which participated in the Concussion Assessment, Research, and Education (CARE) Consortium, were included. Time of injury occurrence and SCAT administration data were recorded, from which time-to-SCAT (hours, continuous) was calculated. The main outcome was SCAT total symptom severity [(TSS), 0-126]. Multivariable negative binomial regression was used to examine the association between time (hours) since injury and TSS. Covariates included sex, previous concussion, sport contact level, amnesia/loss of consciousness, immediate reporting of injury, and injury situation. A random effect (person level) accounted for multiple assessments. TSS score ratios (SR) with associated 95% confidence intervals (CI) were provided. The SCAT was administered an average of 14 (25th-75th percentile: 1.2-24) hours post-SRC, and average TSS was 27.35 ± 21.28 across all participants. Time-to-SCAT was associated with a 1% decrease in TSS after adjusting for covariate effects (SR: 0.99, 95% CI: 0.99-0.99, p < 0.001). Overall, we observed a small, but significant decrease in TSS with each hour post-SRC. Assessing a concussed athlete once in the acute phase will likely provide a sufficient sense of their symptomatic well-being, as measures did not fluctuate dramatically. Future research should aim to examine how acute symptom evolution influences recovery metrics.

Omega-3 Fatty Acids and Traumatic Injury in the Adult and Immature Brain

Background/Objectives: Traumatic brain injury (TBI) can lead to substantial disability and health loss. Despite its importance and impact worldwide, no treatment options are currently available to help protect or preserve brain structure and function following injury. In this review, we discuss the potential benefits of using omega-3 polyunsaturated fatty acids (O3 PUFAs) as therapeutic agents in the context of TBI in the paediatric and adult populations. Methods: Preclinical and clinical research reports investigating the effects of O3 PUFA-based interventions on the consequences of TBI were retrieved and reviewed, and the evidence presented and discussed. Results: A range of animal models of TBI, types of injury, and O3 PUFA dosing regimens and administration protocols have been used in different strategies to investigate the effects of O3 PUFAs in TBI. Most evidence comes from preclinical studies, with limited clinical data available thus far. Overall, research indicates that high O3 PUFA levels help lessen the harmful effects of TBI by reducing tissue damage and cell loss, decreasing associated neuroinflammation and the immune response, which in turn moderates the severity of the associated neurological dysfunction. Conclusions: Data from the studies reviewed here indicate that O3 PUFAs could substantially alleviate the impact of traumatic injuries in the central nervous system, protect structure and help restore function in both the immature and adult brains.

Drivers of resting-state fMRI heterogeneity in traumatic brain injury across injury characteristics and imaging methods: a systematic review and semiquantitative analysis

Traumatic brain injury (TBI) is common and costly. Although neuroimaging modalities such as resting-state functional MRI (rsfMRI) promise to differentiate injured from healthy brains and prognosticate long-term outcomes, the field suffers from heterogeneous findings. To assess whether this heterogeneity stems from variability in the TBI populations studied or the imaging methods used, and to determine whether a consensus exists in this literature, we performed the first systematic review of studies comparing rsfMRI functional connectivity (FC) in patients with TBI to matched controls for seven canonical brain networks across injury severity, age, chronicity, population type, and various imaging methods. Searching PubMed, Web of Science, Google Scholar, and ScienceDirect, 1,105 manuscripts were identified, 50 fulfilling our criteria. Across these manuscripts, 179 comparisons were reported between a total of 1,397 patients with TBI and 1,179 matched controls. Collapsing across injury characteristics, imaging methods, and networks, there were roughly equal significant to null findings and increased to decreased connectivity differences reported. Whereas most factors did not explain these mixed findings, stratifying across severity and chronicity, separately, showed a trend of increased connectivity at higher severities and greater chronicities of TBI. Among methodological factors, studies were more likely to find connectivity differences when scans were longer than 360 s, custom image processing pipelines were used, and when patients kept their eyes open versus closed during scans. We offer guidelines to address this variability, focusing on aspects of study design and rsfMRI acquisition to move the field toward reproducible results with greater potential for clinical translation.

The Relevance and Implications of Monoclonal Antibody Therapies on Traumatic Brain Injury Pathologies

Traumatic brain injury (TBI) is a global public health concern. It remains one of the leading causes of morbidity and mortality. TBI pathology involves complex secondary injury cascades that are associated with cellular and molecular dysfunction, including oxidative stress, coagulopathy, neuroinflammation, neurodegeneration, neurotoxicity, and blood-brain barrier (BBB) dysfunction, among others. These pathological processes manifest as a diverse array of clinical impairments. They serve as targets for potential therapeutic intervention not only in TBI but also in other diseases. Monoclonal antibodies (mAbs) have been used as key therapeutic agents targeting these mechanisms for the treatment of diverse diseases, including neurological diseases such as Alzheimer's disease (AD). MAb therapies provide a tool to block disease pathways with target specificity that may be capable of mitigating the secondary injury cascades following TBI. This article reviews the pathophysiology of TBI and the molecular mechanisms of action of mAbs that target these shared pathological pathways in a wide range of diseases. Publicly available databases for various applications of mAb therapy were searched and further classified to assess relevance to TBI pathology and evaluate current stages of development. The authors intend for this review to highlight the potential impact of current mAb technology within pathological TBI processes.

Weighted Coherence Analysis as a Window into the Neurophysiological Effects of Traumatic Brain Injury

Traumatic brain injury (TBI), resulting from external forces, is a leading cause of disability and death, often leading to cognitive deficits that affect attention, concentration, speech and language, learning and memory, reasoning, planning, and problem-solving. Given the diverse mechanisms underlying TBI symptoms, it is essential to characterize its neurophysiological and neuropsychological effects. To address this, we employed weighted coherence (WC) analysis in patients performing the Halstead-Reitan categorization task, alongside a control group of eight healthy individuals. Our findings indicate a significant decrease in WC within the theta and delta bands in the temporal regions during cognitive tasks in the TBI group compared to controls. Additionally, we observed a significant increase in WC in the beta and gamma bands in the parietal region during both rest and cognitive tasks in the TBI group, relative to the control group. Furthermore, there was a strong correlation between WC and task performance scores in the temporal regions.

Quantifying neurovascular coupling through a concurrent assessment of arterial, capillary, and neuronal activation in humans: A multimodal EEG-fNIRS-TCD investigation

BACKGROUND

This study explored a novel multimodal neuroimaging approach to assess neurovascular coupling (NVC) in humans using electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and transcranial Doppler ultrasound (TCD).

METHODS

Fifteen participants (nine females; age 19-32) completed concurrent EEG-fNIRS-TCD imaging during motor (finger tapping) and visual ("Where's Waldo?") tasks, with synchronized monitoring of blood pressure, capnography, and heart rate. fNIRS assessed microvascular oxygenation within the frontal, motor, parietal, and occipital cortices, while the middle and posterior cerebral arteries (MCA/PCA) were insonated using TCD. A 16-channel EEG set-up was placed according to the 10-20 system. Wilcoxon signed-rank tests were used to compare physiological responses between the active and resting phases of the tasks, while cross-correlations with zero legs compared cerebral and systemic hemodynamic responses across both tasks.

RESULTS

Time-frequency analysis demonstrated a reduction in alpha and low beta band power in electrodes C3/C4 during finger tapping (p<0.045) and all electrodes during the Waldo task (all p<0.001). During Waldo, cross-correlation analysis demonstrated the change in oxygenated hemoglobin and cerebral blood velocity had a moderate-to-strong negative correlation with systemic physiological influences, highlighting the measured change resulted from neuronal input. Deoxygenated hemoglobin displayed the greatest negative cross-correlation with the MCA/PCA within the motor cortices and visual during the motor and visual tasks, respectively (range:0.54, -0.82).

CONCLUSIONS

This investigation demonstrated the feasibility of the proposed EEG-fNIRS-TCD response to comprehensively assess the NVC response within human, specifically quantifying the real-time temporal synchrony between neuronal activation (EEG), microvascular oxygenation changes (fNIRS), and conduit artery velocity alterations (TCD).

Mild traumatic brain injury gives rise to chronic depression-like behavior and associated alterations in glutamatergic protein expression

Mild traumatic brain injury (mTBI) is known to result in chronic somatic, cognitive, and emotional symptoms. Depression is commonly reported among individuals suffering from persistent concussion symptoms; however, the underlying mechanisms are not understood. The glutamatergic system has recently been linked with mTBI and depression due to reports of similar changes in expression of glutamatergic proteins. Using a closed-head controlled cortical impact (cCCI) model in adult male rats (n = 8/group), this study investigated the emergence of self-care deficits and changes in social interaction behaviors at four, eight and twelve weeks post-injury. Western blotting was used to assess associated changes in expression of glutamate transporters and N-methyl-D-aspartate (NMDA) receptor subunits at twelve weeks. Splash test results revealed deficits in self-care behaviors beginning at eight weeks, which continued through twelve weeks in the injury group. Injured animals also exhibited decreased preference for social novelty at four weeks and loss of desire for social interaction as a whole by twelve weeks. GluN1 was increased in injured animals compared to shams in the frontal cortex and amygdala, while decreased GLT-1 was observed in the hippocampus. Linear regression was performed to evaluate relationships between behavioral and molecular variables; the results suggested that injury affects these relationships in a region-dependent manner. Together, these results suggest that the development of chronic depression-like behavior was associated with changes in glutamatergic protein expression. Deeper investigations into how injury influences glutamatergic synaptic protein expression are needed, as this has the potential to affect circuit-level neurotransmission that drives depression-like behavior following mTBI.

Changes in Resting-State Functional Connectivity and Cognitive-Affective Symptoms in Patients With Post-Concussion Syndrome Treated With N-Acetyl Cysteine

OBJECTIVE

Concussion accounts for more than 80% of people experiencing traumatic brain injury. Acute concussion is associated with characteristic cognitive and functional deficits that may persist for weeks to months. A subgroup of these patients (from 10% to 50%) have persistent symptoms referred to as chronic post-concussion syndrome (PCS). There are limited treatment options for these patients and the pathophysiology is poorly understood, though oxidative stress is thought to be a contributing factor. The purpose of this study was to evaluate whether an antioxidant, N-acetylcysteine (NAC), might be beneficial in patients with PCS.

SETTING

Outpatient medicine center.

PARTICIPANTS

Fifty patients with chronic PCS for at least 3 months post injury.

DESIGN

The patients with PCS were enrolled in this randomized unblinded clinical trial to receive the antioxidant NAC as a combination of daily oral and weekly intravenous infusions, or assigned to a waitlist control group where they would continue to receive standard of care.

MAIN MEASURES

Resting-state functional connectivity (FC) magnetic resonance imaging (rsFC-MRI) was performed pre and post either NAC or the waitlist period along with cognitive, emotional, and sensory symptom assessments.

RESULTS

The results demonstrated significant (P < .05) improvements in symptoms as determined by the Rivermead Post-Concussion Symptoms Questionnaire, Spielberger State-Trait Anxiety Inventory, and Profile of Mood Scale in the PCS group receiving NAC as compared to patients receiving ongoing standard care. Importantly, there were significant (P< .01) changes in FC in the NAC group, particularly in networks such as the default mode network, salience network, and executive control network. These changes in FC also correlated with improvements in symptoms.

CONCLUSIONS

In patients with chronic PCS, NAC treatment was associated with significant changes in resting state FC and improvement in a variety of symptoms, particularly cognitive and affective symptoms.

An Objective Assessment of Neuromotor Control Using a Smartphone App After Repeated Subconcussive Blast Exposure

Subconcussive blast exposure has been shown to alter neurological functioning. However, the extent to which neurological dysfunction persists after blast exposure is unknown. This longitudinal study examined the potential short- and long-term effects of repeated subconcussive blast exposure on neuromotor performance from heavy weapons training in military personnel. A total of 214 participants were assessed; 137 were exposed to repeated subconcussive blasts and 77 were not exposed to blasts (controls). Participants completed a short stepping-in-place task while an Android smartphone app placed on their thigh recorded movement kinematics. We showed acute suppression of neuromotor variability 6 h after subconcussive blast exposure, followed by a rebound to levels not different from baseline at the 72 h, 2-week, and 3-month post-tests. It is postulated that this suppression of neuromotor variability results from a reduction in the functional degrees of freedom from the subconcussive neurological insult. It is important to note that this change in behavior is short-lived, with a return to pre-blast exposure movement kinematics within 72 h.