The Pathophysiology of Concussion

An Assessment of Existing Sport-Related Concussion Guidelines in Ireland: The Need for a United Approach

In 2014, an Irish parliament white paper called for greater addressing of sport-related concussions (SRCs) in Ireland, requesting the adoption of the Concussion in Sport Group's (CISGs) guidelines and greater consistency in SRC return to play (RTP) management. Ten years later, it is unclear how these requests have been addressed. Recently, the United Kingdom's government centralised guidelines to one SRC document for all grassroots sports. This study aimed to investigate all publicly available SRC guidance in Irish sports and national governing bodies (NGBs) to determine if centralised guidelines are warranted. Sport Ireland and the Irish Federation of Sports were searched for all recognised NGBs and sports in Ireland. Websites were searched for any information pertaining to SRCs and data were extracted and collated in Microsoft Excel. In total, 15 of 83 sports and/or NGBs included SRC guidance, nine of which provided RTP protocols. Various iterations of the CISGs guidance and tools were implemented. Several sports with a documented SRC risk had no guidelines present. The findings indicate disjointed and outdated guidance across Irish sport. Additionally, there are sports with a documented concussion risk that have no SRC guidance available. This study provides support for centralised guidelines to be adopted in Irish grassroots sports.

The Convergent Validity of the SWAY Balance Application to Assess Postural Stability in Military Cadets Recovering from Concussion

Background

Concussions are often accompanied by balance disturbances. Clinically accurate evaluation systems are often expensive, large, and inaccessible to most clinicians. The Sway Balance Mobile Application (SWAY) is an accessible method to quantify balance changes.

Purpose

To determine the known groups and convergent validity of the SWAY to assess balance after a concussion.

Study Design

Case-Control Study.

Methods

Twenty participants with acute concussion and twenty controls were recruited. At initial, one-week, and final return to activity (RTA) evaluations, all participants completed the Sports Concussion Assessment Tool (SCAT-5), and balance control measured by SWAY mBESS and NeuroCom Balance Master Sensory Organization Test (SOT). Mixed model ANOVAs were used to detect differences in SWAY mBESS and NeuroCom SOT scores with time (initial, one-week, final RTA) as the within-subjects factor and group (concussed, healthy) as the between-subjects factor. Spearman's Rho correlations explored the associations between NeuroCom SOT scores, SWAY scores, SCAT-5 symptom scores, and time in days to final RTA.

Results

The sampled population was predominantly male and age (20 ± 1), and BMI differences were insignificant between groups. The SWAY did not detect differences between healthy and concussed participants and did not detect change over time [F(2,40) = .114, p = 0.89; F(2,40)= .276, p =0.60]. When assessing the relationship between the SWAY and the SOT, no correlation was found at any time point (r = -0.317 to -0.062, p > 0.05). Time to RTA demonstrated a moderate correlation with both SCAT-5 symptom severity score (r = .693, p < 0.01) and SCAT-5 total symptom score (r = .611, p < 0.01) at the one-week follow-up.

Conclusion

The SWAY mBESS does not appear to be a valid balance assessment for the concussed patient. The SWAY mBESS in patients with concussion failed to demonstrate convergent validity and did not demonstrate an ability to validate known groups. When assessing the time to final RTA, the one-week post-initial assessment SCAT-5 symptom severity and total scores may help determine the length of recovery in this population.

Level of Evidence

Level 3.

Molecular mechanisms involved in the destabilization of two types of R3-R4 tau fibrils associated with chronic traumatic encephalopathy by Fisetin

Chronic traumatic encephalopathy is a neurodegenerative tauopathy pathologically characterized by fibrillary tau aggregates in the depth of sulci. Clearing fibrous tau aggregates is considered a promising strategy in the treatment of CTE. Fisetin (FS), a natural polyphenolic small molecule, was confirmed to disassociate the tau filaments in vitro. However, the molecular mechanisms of FS in destabilizing the CTE-related R3-R4 tau fibrils remain largely unknown. In this study, we compared the atomic-level structural differences of the two types of CTE-related R3-R4 tau fibrils and explored the influence and molecular mechanisms of FS on the two types of fibrils by conducting multiple molecular dynamics (MD) simulations. The results reveal that the type 1 fibril displays higher structural stability than the type 2 fibril, with a lower root-mean-square-fluctuation value and higher β-sheet structure probability. FS can destabilize both types of fibrils by decreasing the β-sheet structure content, interrupting the mainchain H-bond network, and increasing the solvent accessible surface area and β7-β8 angle of the fibrils. H-bonding, π-π stacking and cation-π are the common interactions driving FS molecules binding on the two types of fibrils, while the hydrophobic interaction occurs only in the type 2 fibril. Due to the relatively short simulation time, our study captures the early molecular mechanisms. However, it does provide beneficial information for the design of drugs to prevent or treat CTE.

Molecular biomarkers of diffuse axonal injury: recent advances and future perspectives

INTRODUCTION

Diffuse axonal injury (DAI), with high mortality and morbidity both in children and adults, is one of the most severe pathological consequences of traumatic brain injury. Currently, clinical diagnosis, disease assessment, disability identification, and postmortem diagnosis of DAI is mainly limited by the absent of specific molecular biomarkers.

AREAS COVERED

In this review, we first introduce the pathophysiology of DAI, summarized the reported biomarkers in previous animal and human studies, and then the molecular biomarkers such as β-Amyloid precursor protein, neurofilaments, S-100β, myelin basic protein, tau protein, neuron-specific enolase, Peripherin and Hemopexin for DAI diagnosis is summarized. Finally, we put forward valuable views on the future research direction of diagnostic biomarkers of DAI.

EXPERT OPINION

In recent years, the advanced technology has ultimately changed the research of DAI, and the numbers of potential molecular biomarkers was introduced in related studies. We summarized the latest updated information in such studies to provide references for future research and explore the potential pathophysiological mechanism on diffuse axonal injury.

Trends in Pediatric Mild Traumatic Brain Injury During COVID-19-Related Lockdown-A Single-Center Study

BACKGROUND

A relevant number of visits to pediatric emergency departments (pED) are associated with mild traumatic brain injury (mTBI). On March 16, 2020, the Bavarian government declared a first full lockdown (LD) related to the coronavirus (COVID-19) pandemic.

AIM

The aim of the study was to investigate the impact of LD on pediatric mTBI.

METHODS

Retrospective chart review of presentations to a pED due to mTBI. Study periods covered LD (03/17/2020 through 05/05/2020) and the same time in 2017, 2018, and 2019 as reference period (RP). Comparative analyses were performed by Chi-square or Fisher's exact test.

RESULTS

Numbers of mTBI cases decreased by half. Age distribution did not differ. A significantly higher proportion of mTBI were related to falls at home (p = 0.001). Further, a higher rate of hospital admissions (p = 0.03), a higher proportion of intensive care unit admissions (p = 0.001), a longer duration of hospital stay (p = 0.02), and a higher rate of intracranial pathologies on neuroimaging were observed during LD (p = 0.007).

CONCLUSION

The decrease in mTBI presentations is likely due to an absolute decrease in numbers related to the LD measures, combined with a hesitation to present very minor mTBI to the hospital, because of fear of being infected or not to put additional strain on the healthcare system during this healthcare crisis. On the other hand, data of those that presented with mTBI tend to reflect the more severe spectrum of mTBI.

Parental Factors Associated With Recovery After Mild Traumatic Brain Injury: A Systematic Review

While parental factors have been shown to potentially influence recovery after mild traumatic brain injury (mTBI) in children, both the strength and direction of the relationships remain unclear. We performed a systematic review regarding the association between parental factors and recovery after mTBI. PubMed, CINHL, Embase, PsychINFO, Web of Science, ProQuest, Cochrane Central, and Cochrane databases were queried for articles published between September 1, 1970, and September 10, 2022, reporting any parental factor and its association with recovery after mTBI in children younger than 18 years old. The review included both quantitative and qualitative studies published in English. Regarding the directionality of the association, only studies that assessed the effects of parental factors on recovery after mTBI were included. Study quality was assessed using a five-domain scale created by the Cochrane Handbook and the Agency for Healthcare Research and Quality. The study was prospectively registered with PROSPERO (CRD42022361609). Of 2050 studies queried, 40 met inclusion criteria, and 38 of 40 studies used quantitative outcome measures. Across 38 studies, 24 unique parental factors and 20 different measures of recovery were identified. The most common parental factors studied were socioeconomic status/income (SES; n = 16 studies), parental stress/distress (n = 11), parental level of education (n = 9), pre-injury family functioning (n = 8), and parental anxiety (n = 6). Among all associations between parental factors and recovery reported, having a family history of a neurologic disease (i.e., migraine, epilepsy, neurodegenerative disease; 5/6 significant associations reported, 83%), parental stress/distress (9/11, 82%), parental anxiety (4/6, 67%), parental level of education (5/9, 56%), and SES/income (11/19, 57.9%) were shown to have the strongest evidence reporting significant associations with recovery, while a family history of psychiatric disease (3/6, 50%) and pre-injury family functioning (4/9, 44%) showed mixed results. Evidence regarding other parental factors including parental sex, race/ethnicity, insurance status, parental history of concussion, family litigation status, family adjustment levels, and family psychosocial adversity were limited, as studies investigating such factors were few. The current review highlights literature describing several parental factors that significantly influence recovery from mTBI. It will likely be useful for future studies to incorporate parental SES, education, stress/distress, anxiety, quality of parent-child relationships, and parenting style when examining modifying factors in recovery after mTBI. Future studies should also consider how parental factors may serve as potential interventions or policy levers to optimize sport concussion-related policy and return-to-play guidelines.

Precision Concussion Management: Approaches to Quantifying Head Injury Severity and Recovery

Mitigating the substantial public health impact of concussion is a particularly difficult challenge. This is partly because concussion is a highly prevalent condition, and diagnosis is predominantly symptom-based. Much of contemporary concussion management relies on symptom interpretation and accurate reporting by patients. These types of reports may be influenced by a variety of factors for each individual, such as preexisting mental health conditions, headache disorders, and sleep conditions, among other factors. This can all be contributory to non-specific and potentially misleading clinical manifestations in the aftermath of a concussion. This review aimed to conduct an examination of the existing literature on emerging approaches for objectively evaluating potential concussion, as well as to highlight current gaps in understanding where further research is necessary. Objective assessments of visual and ocular motor concussion symptoms, specialized imaging techniques, and tissue-based concentrations of specific biomarkers have all shown promise for specifically characterizing diffuse brain injuries, and will be important to the future of concussion diagnosis and management. The consolidation of these approaches into a comprehensive examination progression will be the next horizon for increased precision in concussion diagnosis and treatment.

'If in Doubt, Sit Them Out': How Long to Return to Elite Cycling Competition following a Sports-Related Concussion (SRC)?

INTRODUCTION

A concussion or sports-related concussion (SRC) is a traumatic brain injury induced by biomechanical forces. After a SRC diagnosis is made, a concussed individual must undergo a period away from competition while they return to their baseline level of functioning. The Union Cycliste Internationale (UCI) currently recommend a minimum of 6 days restriction from competitive cycling following a SRC but there is a growing feeling amongst those involved in brain injury research that this period is too short. Therefore, how much time should cyclists be removed from competitive sporting action following a SRC?

AIMS

To review the time out of competition following the diagnosis of a SRC for elite cyclists within British Cycling (BC).

METHODS

All medical records for elite cyclists within BC were audited for diagnoses of "concussion" or "sports-related concussions" from January 2017 until September 2022. The days out of competition following the concussion until ready to compete again (that is, returned to full training) was then calculated. All diagnoses and management of SRC were undertaken by the medical team at BC and in-keeping with current international guidelines.

RESULTS

Between January 2017 and September 2022, there were 88 concussions diagnosed, 54 being males and 8 in para-athletes. The median duration for time out of competition for all concussions was 16 days. There was no statistical difference between males (median 15.5 days) and females (median 17.5 days) for time out of competition (p-value 0.25). The median duration out of competition following a concussion for able-bodied athletes was 16 (80 athletes) compared to 51 days (8 athletes) in para-cyclists, which was not statistically different (p-value 0.39).

CONCLUSIONS

This is the first study to report SRC concussion recovery times in elite cycling, including para-athletes. Between January 2017 and September 2022, there were 88 concussions diagnosed at BC and the median duration for time out of competition for all concussions was 16 days. There was no statistically significant difference in recovery times between male and females and para- and able-bodied athletes. This data should be used to help establish minimum withdrawal times post-SRC for elite cycling participation and we call on the UCI to review this data when establishing SRC protocols for cycling, with further research required in para-cyclists.

Salivary microRNA as a prospective tool for concussion diagnosis and management: A scoping review

BACKGROUND

Despite increased efforts directed toward research, concussions are a growing concern and can be a complex injury for healthcare professionals to manage. Current practices are largely dependent on patients self-reporting symptoms and a clinical assessment, which uses objective tools that lack effectiveness. With the demonstrated effects of concussions, it is imperative that a more valid or reliable objective tool, like a clinical biomarker, be identified to improve outcomes. One potential biomarker that has shown promise is salivary microRNA. However, there is no objective consensus as to which microRNA offers the most clinical value regarding concussions, hence this review. Therefore, the purpose of this scoping review was to identify salivary miRNAs associated with concussions.

METHODS

Two independent reviewers performed a literature search to identify research articles. Studies using human subjects, collected salivary miRNA, and were published in English were included. Data of interest were salivary miRNA, collection timing, and relation to concussion diagnosis or management.

RESULTS

This paper reviews nine studies that analyzed salivary miRNA for concussion diagnosis and management.

CONCLUSIONS

In total, the studies have identified 49 salivary miRNA that show promise in assisting with concussion practices. With continued research, the use of salivary miRNA may enhance clinicians' abilities to diagnose and manage concussions.

Molecular Mechanism in the Disruption of Chronic Traumatic Encephalopathy-Related R3-R4 Tau Protofibril by Quercetin and Gallic Acid: Similarities and Differences

Chronic traumatic encephalopathy (CTE) is a unique progressive neurodegenerative tauopathy pathologically related to the aggregation of the tau protein to neurofibrillary tangles. Disrupting tau oligomers (protofibril) is a promising strategy to prevent CTE. Quercetin (QE) and gallic acid (GA), two polyphenol small molecules abundant in natural crops, were proved to inhibit recombinant tau and the R3 fragment of human full-length tau in vitro. However, their disruptive effect on CTE-related protofibril and the underlying molecular mechanism remain elusive. Cryo-electron microscopy resolution reveals that the R3-R4 fragment of tau forms the core of the CTE-related tau protofibril. In this study, we conducted extensive all-atom molecular dynamics simulations on CTE-related R3-R4 tau protofibril with and without QE/GA molecules. The results disclose that both QE and GA can disrupt the global structure of the protofibril, while GA shows a relatively strong effect. The binding sites, exact binding patterns, and disruptive modes for the two molecules show similarities and differences. Strikingly, both QE and GA can insert into the hydrophobic cavity of the protofibril, indicating they have the potential to compete for the space in the cavity with aggregation cofactors unique to CTE-related protofibril and thus impede the further aggregation of the tau protein. Due to relatively short time scale, our study captures the early disruptive mechanism of CTE-related R3-R4 tau protofibril by QE/GA. However, our research does provide valuable knowledge for the design of supplements or drugs to prevent or delay the development of CTE.

Co-administration of Nanowired Oxiracetam and Neprilysin with Monoclonal Antibodies to Amyloid Beta Peptide and p-Tau Thwarted Exacerbation of Brain Pathology in Concussive Head Injury at Hot Environment

Environmental temperature adversely affects the outcome of concussive head injury (CHI)-induced brain pathology. Studies from our laboratory showed that animals reared at either cold environment or at hot environment exacerbate brain pathology following CHI. Our previous experiments showed that nanowired delivery of oxiracetam significantly attenuated CHI-induced brain pathology and associated neurovascular changes. Military personnel are the most susceptible to CHI caused by explosion, blasts, missile or blunt head trauma leading to lifetime functional and cognitive impairments affecting the quality of life. Severe CHI leads to instant death and/or lifetime paralysis. Military personnel engaged in combat operations are often subjected to extreme high or low environmental temperature zones across the globe. Thus, further exploration of novel therapeutic agents at cold or hot ambient temperatures following CHI are the need of the hour. CHI is also a major risk factor for developing Alzheimer's disease by enhancing amyloid beta peptide deposits in the brain. In this review, effect of hot environment on CHI-induced brain pathology is discussed. In addition, whether nanodelivery of oxiracetam together with neprilysin and monoclonal antibodies (mAb) to amyloid beta peptide and p-tau could lead to superior neuroprotection in CHI is explored. Our results show that co-administration of oxiracetam with neprilysin and mAb to AβP and p-tau significantly induced superior neuroprotection following CHI in hot environment, not reported earlier.

Traumatic axonal injury: neuropathological features, postmortem diagnostic methods, and strategies

Traumatic brain injury (TBI) has high morbidity and poor prognosis and imposes a serious socioeconomic burden. Traumatic axonal injury (TAI), which is one of the common pathological changes in the primary injury of TBI, is often caused by the external force to the head that causes the white matter bundles to generate shear stress and tension; resulting in tissue damage and leading to the cytoskeletal disorder. At present, the forensic pathological diagnosis of TAI-caused death is still a difficult problem. Most of the TAI biomarkers studied are used for the prediction, evaluation, and prognosis of TAI in the living state. The research subjects are mainly humans in the living state or model animals, which are not suitable for the postmortem diagnosis of TAI. In addition, there is still a lack of recognized indicators for the autopsy pathological diagnosis of TAI. Different diagnostic methods and markers have their limitations, and there is a lack of systematic research and summary of autopsy diagnostic markers of TAI. Therefore, this study mainly summarizes the pathological mechanism, common methods, techniques of postmortem diagnosis, and corresponding biomarkers of TAI, and puts forward the strategies for postmortem diagnosis of TAI for forensic cases with different survival times, which is of great significance to forensic pathological diagnosis.

The University of Kansas Health System Outpatient Clinical Concussion Comprehensive Protocol: An Interdisciplinary Approach

Objective:

The concussion team at The University of Kansas Health System outpatient rehabilitation spine center is comprised of experienced multi-disciplinary experts including physical therapists and a speech language pathologist. The team set forth with a purpose of creating and organizing an internal physical therapy clinical recommendation protocol for initial evaluations and subsequent treatments for the concussed patient. The aim of this paper is to share these recommendation protocols with other therapy teams and provide a foundational layout for treating the patient with post-concussion symptoms in an outpatient physical therapy clinical setting.

Study design:

Clinical recommendation protocol provides guidance for patients ages 10+ from initial evaluation through discharge with emphasis on evidence-based research in the areas of: oculomotor, cervical, vestibular, post-concussion migraine influence, mood disorders(such as anxiety and depression), exertion, and cognitive communicative dysfunction.

Results:

Finding a written, comprehensive clinical resource protocol for post-concussion outpatient evaluation(s) and treatment strategies can be difficult. This document serves as a resource for other outpatient concussion rehabilitation clinics, providing rationale, and objective measurement tools, for assessing and treating concussion patients. To the authors’ knowledge, no other research has produced a practical, efficient evaluation tool to be utilized at bed side, condensing evidence-based research into an easy-to-use form.

Conclusion:

The University of Kansas Health System outpatient concussion rehabilitation center developed clinical recommendation protocols for concussion care. The intent was to standardize assessment and treatment for concussion patients and to share these objective measurement tools and procedures, focused on a team approach of concussion providers, as a clinical outline for both the novice and seasoned clinician specializing in the field of concussion work in an outpatient rehabilitation setting.

Corticospinal Excitability and Inhibition Are Not Different between Concussed Males and Females

It has been consistently demonstrated that females report greater numbers of concussions in sex-comparable sports and take longer to recover from concussive symptoms than males. However, it is unknown if the neurophysiological consequences of concussion may contribute to these sex differences in concussion symptoms and recovery. The purpose of this study was to examine potential sex-related differences in neurophysiology in healthy and concussed individuals. Twenty-one (nine F) concussed individuals (20.9 ± 4.1 years; CONC) and twenty-one age-, sex-, height-, weight-, and activity-matched controls (21.2 ± 4.2 years; CONT) participated in the study. The CONC group reported to the lab within 72 h, 1-week, and 2-weeks post-injury and the CONT group followed a similar measurement schedule. Using transcranial magnetic stimulation, motor evoked potential (MEP) amplitude and cortical silent period (CSP) duration were measured from the first dorsal interosseous muscle to assess corticospinal excitability and inhibition, respectively. There were no significant differences across time (p ≥ 0.13) or between the CONC and CONT group in MEP amplitude (p = 0.72) or CSP duration (p = 0.54). Overall, males (119.08 ± 29.91 ms) had significantly longer CSP durations compared with females (101.24 ± 33.43 ms), indicating greater corticospinal inhibition in males, regardless of injury status (p = 0.04). An important and novel finding of this study was the lack of differences in these neurophysiological measures between males and females following concussion. To our knowledge, this is the first study to document greater corticospinal inhibition in males compared with females.

Post-traumatic headache: Pathophysiology and management - A review

Background

Post-traumatic headache (PTH) is a common secondary headache due to traumatic brain injury. In the past, significant research has been conducted to understand the pathophysiology and treatment options for PTH. However, PTH still lacks evidence-based treatment, and most of the management depends on the primary phenotype observed in the patient.

Objective

The main objective of this review is to provide a single reference that covers the current understanding of the pathophysiology and the treatment options available for PTH.

Methods

A detailed literature search on PubMed was performed, and a narrative review was prepared.

Results

The pathophysiology of PTH is multifactorial. Acute PTH may be attributed to increased peripheral pain sensitization with impaired pain inhibiting pathways. Chronic or persistent PTH may be due to a chronic inflammatory response and peripheral as well as central sensitization. The mechanism responsible for the transition of acute to persistent PTH is unknown. The migraine-like phenotype is reported to be the most prevalent headache type seen in PTH. New targets for preventive treatment have been identified in recent years, such as neuropeptides like calcitonin-gene-related peptide (CGRP), nitric oxide, and glutamate. The preventive pharmacological and non-pharmacological strategies employed for migraine (e.g. anti-CGRP monoclonal antibodies, onabotulinumtoxinA, physical therapy, cognitive and behavioral treatment, and neurostimulation techniques) have shown in preliminary studies that they are potentially efficacious, but large, randomized, double blind, placebo controlled trials are needed to further establish these as treatment options for PTH.

Conclusions

The lack of evidence-based treatment for PTH has created a need for future large trials to confirm the safety and efficacy of the currently employed treatments.

Nano-PSO Administration Attenuates Cognitive and Neuronal Deficits Resulting from Traumatic Brain Injury

Traumatic Brain Injury (TBI), is one of the most common causes of neurological damage in young populations. It is widely considered as a risk factor for neurodegenerative diseases, such as Alzheimer’s disease (AD) and Parkinson’s (PD) disease. These diseases are characterized in part by the accumulation of disease-specific misfolded proteins and share common pathological features, such as neuronal death, as well as inflammatory and oxidative damage. Nano formulation of Pomegranate seed oil [Nano-PSO (Granagard ^TM)] has been shown to target its active ingredient to the brain and thereafter inhibit memory decline and neuronal death in mice models of AD and genetic Creutzfeldt Jacob disease. In this study, we show that administration of Nano-PSO to mice before or after TBI application prevents cognitive and behavioral decline. In addition, immuno-histochemical staining of the brain indicates that preventive Nano-PSO treatment significantly decreased neuronal death, reduced gliosis and prevented mitochondrial damage in the affected cells. Finally, we examined levels of Sirtuin1 (SIRT1) and Synaptophysin (SYP) in the cortex using Western blotting. Nano-PSO consumption led to higher levels of SIRT1 and SYP protein postinjury. Taken together, our results indicate that Nano-PSO, as a natural brain-targeted antioxidant, can prevent part of TBI-induced damage.

Sex-related differences in visuomotor skill recovery following concussion in working-aged adults

BACKGROUND

The ability to perform visually-guided motor tasks requires the transformation of visual information into programmed motor outputs. When the guiding visual information does not align spatially with the motor output, the brain processes rules to integrate somatosensory information into an appropriate motor response. Performance on such rule-based, "cognitive-motor integration" tasks is affected in concussion. Here, we investigate the relationship between visuomotor skill performance, concussion history, and sex during the course of a post-concussion management program.

METHODS

Fifteen acutely concussed working-aged adults, 11 adults with a history of concussion, and 17 healthy controls all completed a recovery program over the course of 4 weeks. Prior to, mid-way, and following the program, all participants were tested on their visuomotor skills.

RESULTS

We observed an overall change in visuomotor behaviour in all groups, as participants completed the tasks faster and more accurately. Specifically, we observed significant visuomotor skill improvement between the first and final sessions in participants with a concussion history compared to no-concussion-history controls. Notably, we observed a stronger recovery of these skills in females.

CONCLUSIONS

Our findings indicate that (1) concussion impairs visuomotor skill performance, (2) the performance of complex, rule-based tasks showed improvement over the course of a recovery program, and (3) stronger recovery in females suggests sex-related differences in the brain networks controlling skilled performance, and the effect of injury on these networks.

ASSOCIATION BETWEEN ALTERED CORTISOL PROFILES AND NEUROBEHAVIORAL IMPAIRMENT FOLLOWING mTBI IN COLLEGE STUDENTS

Mild Traumatic Brain Injury (mTBI) is the most common form of TBI, accounting for over 2.5 million TBI cases in the United States annually. Identification of easily obtainable biomarkers that track strongly with mTBI symptoms may improve our understanding of biological factors that contribute to mTBI symptom profiles and long-term outcomes. Notably, some individuals with mTBI exhibit circadian disruptions and elevated stress sensitivity, which in other clinical groups often correlate with disrupted secretion of cortisol, a glucocorticoid hormone that coordinates circadian and stress physiology. Here, we sought to determine whether cortisol profiles could serve as a biomarker to complement the assessment of neurobehavioral sequelae following mTBI. We partnered with our on-campus health clinic to recruit college students seeking medical care following mTBI (n=46) and compared this population to a well-matched non-injured student control group (n=44). We collected data at an initial visit (shortly after injury in mTBI subjects) and one week later. At each visit, we evaluated neurobehavioral function using the Automated Neuropsychological Assessment Metric (ANAM). Our subjects then provided cortisol samples through at-home saliva collection. We observed strong coherence between ANAM subjective and objective measures, indicating significant multidimensional impairment in those with mTBI. Further, female mTBI subjects exhibited diminished neurobehavioral function compared to males. Regardless of sex, decreased amplitude of diurnal cortisol and a blunted cortisol awakening response predicted mTBI symptom severity and neurobehavioral impairment. Taken together, these findings suggest that salivary cortisol profiles may be a sensitive biomarker for studying underlying biological factors that impact mTBI outcomes.

The effect of transcranial direct current stimulation on cognitive performance in youth with persistent cognitive symptoms following concussion: a controlled pilot study

OBJECTIVE

Explore the feasibility, tolerability, and early efficacy of transcranial direct current stimulation (tDCS) as a therapeutic intervention for youth with cognitive persistent post-concussion symptoms (PPCS).

HYPOTHESIS

tDCS improves performance on a dual task working memory (WM) paradigm in youth with cognitive PPCS.

PARTICIPANTS

Twelve youth experiencing cognitive PPCS.

DESIGN

A quasi-randomized pilot trial was used to explore the tolerability of, and performance differences on, a dual N-Back WM task paired with active or sham tDCS over 3 sessions.

MEASURES

Accuracy and reaction time on WM task and self-report of tDCS tolerability.

RESULTS

Trends toward increases in accuracy from Day 1 to 3 seen in both groups. Active tDCS group performed better than sham on Day 2 in N-Back level N2 (p = .019), and marginally better than the sham group on Day 3 in level N3 (p = .26). Participants reported tDCS as tolerable; compared to the active tDCS group, the sham group reported more "considerable" (p = .078) and "strong" symptoms (p = .097).

CONCLUSION

tDCS is a promising tool for enhancing WM performance and is a feasible and tolerable adjunct to behavioral interventions in youth with cognitive PPCS. A clinical trial to demonstrate efficacy is warranted.

High altitude modulates concussion incidence, severity, and recovery in young athletes

BACKGROUND

High altitude may affect concussion, but prior studies are limited . We tested whether high altitude affects sport-related concussion (SRC) incidence, severity, and recovery.

METHODS

Twenty-five thousand eight hundred fifteen baseline and post-injury Immediate Post-Concussion Assessment and Cognitive Testing results were compiled from Florida and Colorado, low (27 m or 62 m) and high (1,640 m or 1,991 m) altitude locations, respectively. Incidence, severity, and recovery of injury were compared between altitudes.

RESULTS

High altitude was associated with increased suspected concussion incidence (adjusted OR, 2.04 [95% CI, 1.86 to 2.24];P < .0001). However, high altitude was associated with lower concussion severity measured by Severity Index (SI) (adjusted OR, 0.42 [95% CI, 0.37 to 0.49];P < .0001). High altitude was associated with decreased recovery from post-concussive symptoms in the migraine (β, -2.72 [95% CI, -3.31 to -2.13]; P < .0001), cognitive (β, -1.88 [95% CI, -2.40 to -1.36]; P < .0001), and sleep symptom clusters (β, -0.30 [95% CI, -0.52 to -0.08]; P = .007). Athletes with initial SI≥8 showed prolonged neurocognitive dysfunction at high altitude (HR, 1.38 [95% CI, 1.06 to 1.81]; P = .02).

CONCLUSIONS

High altitude was associated with increased suspected concussions and prolonged recovery but less severe initial injury.

Cerebrolysin restores balance between excitatory and inhibitory amino acids in brain following concussive head injury. Superior neuroprotective effects of TiO2 nanowired drug delivery

Concussive head injury (CHI) often associated with military personnel, soccer players and related sports personnel leads to serious clinical situation causing lifetime disabilities. About 3-4k head injury per 100k populations are recorded in the United States since 2000-2014. The annual incidence of concussion has now reached to 1.2% of population in recent years. Thus, CHI inflicts a huge financial burden on the society for rehabilitation. Thus, new efforts are needed to explore novel therapeutic strategies to treat CHI cases to enhance quality of life of the victims. CHI is well known to alter endogenous balance of excitatory and inhibitory amino acid neurotransmitters in the central nervous system (CNS) leading to brain pathology. Thus, a possibility exists that restoring the balance of amino acids in the CNS following CHI using therapeutic measures may benefit the victims in improving their quality of life. In this investigation, we used a multimodal drug Cerebrolysin (Ever NeuroPharma, Austria) that is a well-balanced composition of several neurotrophic factors and active peptide fragments in exploring its effects on CHI induced alterations in key excitatory (Glutamate, Aspartate) and inhibitory (GABA, Glycine) amino acids in the CNS in relation brain pathology in dose and time-dependent manner. CHI was produced in anesthetized rats by dropping a weight of 114.6g over the right exposed parietal skull from a distance of 20cm height (0.224N impact) and blood-brain barrier (BBB), brain edema, neuronal injuries and behavioral dysfunctions were measured 8, 24, 48 and 72h after injury. Cerebrolysin (CBL) was administered (2.5, 5 or 10mL/kg, i.v.) after 4-72h following injury. Our observations show that repeated CBL induced a dose-dependent neuroprotection in CHI (5-10mL/kg) and also improved behavioral functions. Interestingly when CBL is delivered through TiO₂ nanowires superior neuroprotective effects were observed in CHI even at a lower doses (2.5-5mL/kg). These observations are the first to demonstrate that CBL is effectively capable to attenuate CHI induced brain pathology and behavioral disturbances in a dose dependent manner, not reported earlier.

Pediatric concussion working memory outcomes: a scoping review

Objective: Characterize the working memory (WM) profile of children and youth who have experienced concussion by systematically synthesizing existing literature on the neuropsychological outcomes of these injuries.Methods: Implemented a peer-reviewed search strategy combining key concepts of concussion/mild traumatic brain injury (mTBI), WM, and pediatrics across MedLine, Embase, PsycINFO, and CINAHL. Included studies written in English with extractable results on a WM outcome measure in individuals aged 21 and under who experienced concussion. Applied narrative synthesis to identify trends in the literature. Assessed risk of bias and quality using the NHLBI's Quality Assessment of Observational Cohort and Cross-Sectional Studies.Results: 40 articles met inclusion criteria. 34/40 studies compared WM performance in children or youth with concussion to healthy controls, pre-injury performance, or normative values, of which 15 reported significantly lower WM performance in the concussion sample. Visual/spatial WM was more consistently impacted than verbal WM. Cognitive demanding dual-task conditions were also reliably impacted.Conclusion: Literature indicated that WM is vulnerable to negative outcomes following pediatric concussion, yet the nature of outcomes is variable. Clinicians and researchers should implement comprehensive and theoretically motivated WM assessments to better understand the WM components impacted by injury.

Teasing apart trauma: neural oscillations differentiate individual cases of mild traumatic brain injury from post-traumatic stress disorder even when symptoms overlap

Post-traumatic stress disorder (PTSD) and mild traumatic brain injury (mTBI) are highly prevalent and closely related disorders. Affected individuals often exhibit substantially overlapping symptomatology - a major challenge for differential diagnosis in both military and civilian contexts. According to our symptom assessment, the PTSD group exhibited comparable levels of concussion symptoms and severity to the mTBI group. An objective and reliable system to uncover the key neural signatures differentiating these disorders would be an important step towards translational and applied clinical use. Here we explore use of MEG (magnetoencephalography)-multivariate statistical learning analysis in identifying the neural features for differential PTSD/mTBI characterisation. Resting state MEG-derived regional neural activity and coherence (or functional connectivity) across seven canonical neural oscillation frequencies (delta to high gamma) were used. The selected features were consistent and largely confirmatory with previously established neurophysiological markers for the two disorders. For regional power from theta, alpha and high gamma bands, the amygdala, hippocampus and temporal areas were identified. In line with regional activity, additional connections within the occipital, parietal and temporal regions were selected across a number of frequency bands. This study is the first to employ MEG-derived neural features to reliably and differentially stratify the two disorders in a multi-group context. The features from alpha and beta bands exhibited the best classification performance, even in cases where distinction by concussion symptom profiles alone were extremely difficult. We demonstrate the potential of using 'invisible' neural indices of brain functioning to understand and differentiate these debilitating conditions.

Emerging Applications for Quantitative Susceptibility Mapping in the Detection of Traumatic Brain Injury Pathology

Traumatic brain injury (TBI) is a common but heterogeneous injury underpinned by numerous complex and interrelated pathophysiological mechanisms. An essential trace element, iron is abundant within the brain and involved in many fundamental neurobiological processes, including oxygen transportation, oxidative phosphorylation, myelin production and maintenance, as well as neurotransmitter synthesis and metabolism. Excessive levels of iron are neurotoxic and thus iron homeostasis is tightly regulated in the brain, however, many details about the mechanisms by which this is achieved are yet to be elucidated. A key mediator of oxidative stress, mitochondrial dysfunction and neuroinflammatory response, iron dysregulation is an important contributor to secondary injury in TBI. Advances in neuroimaging that leverage magnetic susceptibility properties have enabled increasingly comprehensive investigations into the distribution and behaviour of iron in the brain amongst healthy individuals as well as disease states such as TBI. Quantitative Susceptibility Mapping (QSM) is an advanced neuroimaging technique that promises quantitative estimation of local magnetic susceptibility at the voxel level. In this review, we provide an overview of brain iron and its homeostasis, describe recent advances enabling applications of QSM within the context of TBI and summarise the current state of the literature. Although limited, the emergent research suggests that QSM is a promising neuroimaging technique that can be used to investigate a host of pathophysiological changes that are associated with TBI.

Neurofilament light chain in patients with a concussion or head impacts: a systematic review and meta-analysis

PURPOSE

Traumatic brain injury is one of the leading causes of disability worldwide. Mild traumatic brain injury (TBI) is the most common and benign form of TBI, usually referred to by the medical term "concussion". The purpose of our systematic review and meta-analysis was to explore the role of serum and CSF neurofilament light chain (NfL) as a potential biomarker in concussion.

METHODS

We systematically searched PubMed, Web of Science, and Cochrane databases using specific keywords. As the primary outcome, we assessed CSF or serum NfL levels in patients with concussion and head impacts versus controls. The role of NfL in patients with concussion and head impacts compared to healthy controls was also assessed, as well as in sports-related and military-related conditions.

RESULTS

From the initial 617 identified studies, we included 24 studies in our qualitative analysis and 14 studies in our meta-analysis. We found a statistically significant increase of serum NfL in patients suffering from a concussion or head impacts compared to controls (p = 0.0023), highlighting its potential role as a biomarker. From our sub-group analyses, sports-related concussion and mild TBI were mostly correlated with increased serum NfL values. Compared to controls, sports-related concussion was significantly associated with higher NfL levels (p = 0.0015), while no association was noted in patients suffering from head impacts or military-related TBI.

CONCLUSION

Serum NfL levels are higher in all patients suffering from concussion compared to healthy controls. The sports-related concussion was specifically associated with higher levels of NfL. Further studies exploring the use of NfL as a diagnostic and prognostic biomarker in mild TBI and head impacts are needed.

Potential Concussive Event Narratives of Post-9/11 Combat Veterans: Chronic Effects of Neurotrauma Consortium Study

INTRODUCTION

Deployment-related mild traumatic brain injury (mTBI) affects a significant proportion of those who served in Post-9/11 combat operations. The prevalence of head injuries, including those that lead to mTBI, is often reported quantitatively. However, service member (SM) and Veteran firsthand accounts of their potential concussive events (PCEs) and mTBIs can serve as a rich resource for better understanding the nuances and context of these exposures.

MATERIALS AND METHODS

Post-9/11 SMs and Veterans with a history of combat deployment were recruited through the Chronic Effects of Neurotrauma Consortium's observational study of deployment-related mTBI. During a comprehensive assessment, participants completed the Virginia Commonwealth University retrospective Concussion Diagnostic Interview, a specialized validated interview measure which obtains detailed narratives of deployment-incurred blast and non-blast-related PCEs. Qualitative thematic analysis was used to identify and code recurring themes within the narratives.

RESULTS

Among the sample of 106 SMs and Veterans, deployment-related mTBI was highly prevalent (67.0%). Over half (50.9%) of the participants identified a blast as the cause of their worst PCE, frequently with accompanying themes of self-reported acute neurological symptoms, intense physical blast forces, and tertiary head impact. Exposure to blast at close range, such as driving directly over an improvised explosive device, occurred in 24.7% of all blast-related narratives and in 59.3% of narratives where blast was identified as causing the worst PCE. Themes of potentially preventable head impacts experienced during noncombat circumstances were also frequent, accounting for 35% of all non-blast-related head injuries in the sample.

CONCLUSIONS

Prevalence of deployment-related close-range blast exposure, non-blast impact PCEs, and mTBIs among this Post-9/11 combatant sample was substantial, and in many cases potentially preventable. The use of detailed semi-structured interviews may help health care providers and policymakers to better understand the context and circumstances of deployment-related PCEs and mTBIs.

Rehabilitation of Concussion and Persistent Postconcussive Symptoms

Concussion and persistent postconcussive symptoms (PPCS) are encountered by clinicians in sports medicine, pediatrics, neurology, physiatry, emergency medicine, and primary care. Clinical management may require a multidisciplinary approach. This article presents a structured method for the diagnosis of concussion and PPCS in the outpatient setting, which includes a history, physical examination, and additional tests as clinically indicated to help identify underlying symptom generators. Treatment for concussion and PPCS should be individualized, based on predominant signs and symptoms, and can include subsymptom threshold aerobic exercise, cervical physical therapy, vestibulo-ocular rehabilitation, behavioral and cognitive psychotherapy, and some symptom-specific pharmacological therapies.

The management of concussion in sport is not standardized. A systematic review

INTRODUCTION

Concussion is traumatic brain injury with associated tissue damage commonly produced by an indirect or direct head or facial trauma that can negatively impact an athletes' career and personal life. In this context, the importance on how to deal with a concussion has received attention from worldwide literature and has become a topic of enormous interest in the sports medicine arena.

OBJECTIVE

This systematic review aimed to investigate how sports-related concussion is being managed regarding athletic injuries, athletes' age, clinical signs of concussion, adopted questionnaires, as well as decision making in sports medicine.

METHODS

A systematic review of the literature was performed searching 10 electronic databases with no limitations for year of publication up to December 2019. The search terms used were: Brain Concussion, Athletes, Sports Medicine, Athletic Injuries, Clinical Decision-Making, and Decision Making. The articles were considered eligible when the studies related to populations of regular sports practitioners, professional or recreational, of any age; sports injury; articles reporting concussion evaluation in at least 30 athletes; and articles published in English, French, Portuguese, Italian. We excluded systematic review articles, reviews, editorials, sport-unrelated concussion, no questionnaire application, approaching retired athletes, consensus statement letters, author's reply to editorials, synopsis, and abstracts.

RESULTS

The parameters adopted for decision-making and management were broadly variable and were based on a variety of clinical signs or scoring outcomes from a myriad of questionnaires with little consistency in protocol or management guidelines, which could guide the average clinician.

CONCLUSION

This systematic review provides current evidence that post-concussion management in sports medicine has yet to accomplish a standardized protocol that clinicians could use to optimally care for athletes. The extensive number of manuscripts and studies addressing the topic confirms that sports-related concussion in the pediatric and adolescent population has come to the forefront in the sports medicine field.

Mild traumatic brain injury exacerbates Parkinson's disease induced hemeoxygenase-2 expression and brain pathology: Neuroprotective effects of co-administration of TiO2 nanowired mesenchymal stem cells and cerebrolysin

Mild traumatic brain injury (mTBI) is one of the leading predisposing factors in the development of Parkinson's disease (PD). Mild or moderate TBI induces rapid production of tau protein and alpha synuclein (ASNC) in the cerebrospinal fluid (CSF) and in several brain areas. Enhanced tau-phosphorylation and ASNC alters the molecular machinery of the brain leading to PD pathology. Recent evidences show upregulation of constitutive isoform of hemeoxygenase (HO-2) in PD patients that correlates well with the brain pathology. mTBI alone induces profound upregulation of HO-2 immunoreactivity. Thus, it would be interesting to explore whether mTBI exacerbates PD pathology in relation to tau, ASNC and HO-2 expression. In addition, whether neurotrophic factors and stem cells known to reduce brain pathology in TBI could induce neuroprotection in PD following mTBI. In this review role of mesenchymal stem cells (MSCs) and cerebrolysin (CBL), a well-balanced composition of several neurotrophic factors and active peptide fragments using nanowired delivery in PD following mTBI is discussed based on our own investigation. Our results show that mTBI induces concussion exacerbates PD pathology and nanowired delivery of MSCs and CBL induces superior neuroprotection. This could be due to reduction in tau, ASNC and HO-2 expression in PD following mTBI, not reported earlier. The functional significance of our findings in relation to clinical strategies is discussed.

Axonal Degeneration in AD: The Contribution of Aβ and Tau

Alzheimer's disease (AD) represents the most common age-related neurodegenerative disorder, affecting around 35 million people worldwide. Despite enormous efforts dedicated to AD research over decades, there is still no cure for the disease. Misfolding and accumulation of Aβ and tau proteins in the brain constitute a defining signature of AD neuropathology, and mounting evidence has documented a link between aggregation of these proteins and neuronal dysfunction. In this context, progressive axonal degeneration has been associated with early stages of AD and linked to Aβ and tau accumulation. As the axonal degeneration mechanism has been starting to be unveiled, it constitutes a promising target for neuroprotection in AD. A comprehensive understanding of the mechanism of axonal destruction in neurodegenerative conditions is therefore critical for the development of new therapies aimed to prevent axonal loss before irreversible neuronal death occurs in AD. Here, we review current evidence of the involvement of Aβ and tau pathologies in the activation of signaling cascades that can promote axonal demise.

Early Life Stress Exacerbates Outcome after Traumatic Brain Injury

The neurocognitive impairments associated with mild traumatic brain injury (TBI) often resolve within 1-2 weeks; however, a subset of people exhibit persistent cognitive dysfunction for weeks to months after injury. The factors that contribute to these persistent deficits are unknown. One potential risk factor for worsened outcome after TBI is a history of stress experienced by a person early in life. Early life stress (ELS) includes maltreatment such as neglect, and interferes with the normal construction of cortical and hippocampal circuits. We hypothesized that a history of ELS contributes to persistent learning and memory dysfunction following a TBI. To explore this interaction, we modeled ELS by separating Sprague Dawley pups from their nursing mothers from post-natal days 2-14 for 3 h daily. At 2 months of age, male rats received sham surgery or mild to moderate parasagittal fluid-percussion brain injury. We found that the combination of ELS with TBI in adulthood impaired hippocampal-dependent learning, as assessed with contextual fear conditioning, the water maze task, and spatial working memory. Cortical atrophy was significantly exacerbated in TBI animals exposed to ELS compared with normal-reared TBI animals. Changes in corticosterone in response to restraint stress were prolonged in TBI animals that received ELS compared with TBI animals that were normally reared or sham animals that received ELS. Our findings indicate that ELS is a risk factor for worsened outcome after TBI, and results in persistent learning and memory deficits, worsened cortical pathology, and an exacerbation of the hormonal stress response.

The Effects of Mild Traumatic Brain Injury on Cognitive-Motor Integration for Skilled Performance

Adults exposed to blast and blunt impact often experience mild traumatic brain injury, affecting neural functions related to sensory, cognitive, and motor function. In this perspective article, we will review the effects of impact and blast exposure on functional performance that requires the integration of these sensory, cognitive, and motor control systems. We describe cognitive-motor integration and how it relates to successfully navigating skilled activities crucial for work, duty, sport, and even daily life. We review our research on the behavioral effects of traumatic impact and blast exposure on cognitive-motor integration in both younger and older adults, and the neural networks that are involved in these types of skills. Overall, we have observed impairments in rule-based skilled performance as a function of both physical impact and blast exposure. The extent of these impairments depended on the age at injury and the sex of the individual. It appears, however, that cognitive-motor integration deficits can be mitigated by the level of skill expertise of the affected individual, suggesting that such experience imparts resiliency in the brain networks that underly the control of complex visuomotor performance. Finally, we discuss the next steps needed to comprehensively understand the impact of trauma and blast exposure on functional movement control.

Orally Administered Cinnamon Extract Attenuates Cognitive and Neuronal Deficits Following Traumatic Brain Injury

The present paper shows how cinnamon extract (CE) consumption mitigates neuronal loss and memory impairment following traumatic brain injury (TBI), one of the world's most common neurodegenerative diseases. TBI patients suffer short- and long-term behavioral, cognitive, and emotional impairments, including difficulties in concentration, memory loss, and depression. Research shows that CE application can mitigate cognitive and behavioral impairments in animal models for Alzheimer's and Parkinson's disease, whose pathophysiology is similar to that of TBI. This study builds on prior research by showing similar results in TBI mice models. After drinking CE for a week, mice were injured using our 70-g weight drop TBI device. For 2 weeks thereafter, the mice continued drinking CE alongside standard lab nutrition. Subsequently, the mice underwent behavioral tests to assess their memory, motor activity, and anxiety. The mice brains were harvested for immunohistochemistry staining to evaluate overall neuronal survival. Our results show that CE consumption almost completely mitigates memory impairment and decreases neuronal loss after TBI. Mice that did not consume CE demonstrated impaired memory. Our results also show that CE consumption attenuated neuronal loss in the temporal cortex and the dentate gyrus. Mice that did not consume CE suffered a significant neuronal loss. There were no significant differences in anxiety levels and motor activity between all groups. These findings show a new therapeutic approach to improve cognitive function and decrease memory loss after TBI.

Concussion History and Career Status Influence Performance on Baseline Assessments in Elite Football Players

OBJECTIVE

To determine if concussion history and career status is associated with neurocognitive performance in elite football players.

METHODS

The study design was a cross-sectional single assessment. Fifty-seven elite football players (age 29.39 ± 7.49 years) categorized as draft prospects, active professional players, and retired professional players were assessed on the Sport Concussion Assessment Tool - third edition (SCAT-3), in an outpatient therapy setting.

RESULTS

Common symptoms were the following: fatigue (45.6%), trouble falling asleep (35.1%), difficulty remembering (33.3%) and irritability (22.8%); 36.8% reported no symptoms. The low concussion (0-1) group reported fewer symptoms (U = 608.50, p < .001), less symptom severity (U = 598.00, p = -.001), and produced greater scores on the Standardized Assessment of Concussion (SAC) total scores compared to the multiple concussion (2+) group (U = 253.00, p = .024), but no differences were observed on modified Balance Error Scoring System (m-BESS) scores (U = 501.50, p = .066) on the Mann-Whitney U test. The Kruskal-Wallis test and post-hoc analysis indicated retired players were significantly different from draft prospects and current professional players for total symptom scores (p < .001), total symptom severity (p < .001), SAC total scores (p = .030), and m-BESS (p < .001).

CONCLUSIONS

Concussion history and career status appear associated with total symptoms, symptom severity, performance on the SAC, and the m-BESS in elite football players. With this in mind, future research is recommended to determine longitudinal impact for elite football players.

Influence of Sex and Previous Concussion History on Postconcussive Recovery in Young Athletes

OBJECTIVE

To determine whether concussed female athletes with a previous history of concussion have longer postconcussive recovery than that of male counterparts.

DESIGN

Retrospective cohort study.

SETTING

Outpatient sports medicine clinic in an academic practice.

PARTICIPANTS

Male and female youth, high school, and collegiate athletes (n = 431; ages = 10-21 years) who sustained a sport-related concussion (SRC).

INTERVENTIONS

The clinical courses of young athletes treated for concussion by 1 provider at an outpatient sports medicine clinic were retrospectively reviewed.

MAIN OUTCOME MEASURES

Recovery time was compared after an SRC with relationship to sex and previous concussion history.

RESULTS

When comparing male and female athletes with a previous history of concussion, there were no differences found (P = 0.820) in SRC recovery time. Regardless of previous concussion history, males recovered faster from an SRC compared with their female counterparts (P = 0.0002). Without regard to sex, those with no previous history of concussion recovered faster than those with a previous concussion history, although the difference was not statistically significant (P = 0.668). Athletes with a previous history of concussion were more likely to require neuropsychology referral than those with no previous concussion history (P = 0.021), and females, without regard to concussion history, were more likely to require neuropsychology referral than males (P = 0.001).

CONCLUSIONS

A previous concussion history does not appear to significantly influence postconcussive recovery time in young athletes, although it does increase the probability of neuropsychological referral. Without regard to a previous concussion history, young female athletes recover slower than males from concussion and are also more likely to require neuropsychological referral.

Neuroprotection Following Concussion: The Potential Role for Cannabidiol

Cannabidiol (CBD) has been generating increasing interest in medicine due to its therapeutic properties and an apparent lack of negative side effects. Research has suggested that high dosages of CBD can be taken acutely and chronically with little to no risk. This review focuses on the neuroprotective effects of a CBD, with an emphasis on its implications for recovering from a mild traumatic brain injury (TBI) or concussion. CBD has been shown to influence the endocannabinoid system, both by affecting cannabinoid receptors and other receptors involved in the endocannabinoid system such as vanilloid receptor 1, adenosine receptors, and 5-hydroxytryptamine via cannabinoid receptor-independent mechanisms. Concussions can result in many physiological consequences, potentially resulting in post-concussion syndrome. While impairments in cerebrovascular and cardiovascular physiology following concussion have been shown, there is unfortunately still no single treatment available to enhance recovery. CBD has been shown to influence the blood brain barrier, brain-derived neurotrophic factors, cognitive capacity, the cerebrovasculature, cardiovascular physiology, and neurogenesis, all of which have been shown to be altered by concussion. CBD can therefore potentially provide treatment to enhance neuroprotection by reducing inflammation, regulating cerebral blood flow, enhancing neurogenesis, and protecting the brain against reactive oxygen species. Double-blind randomized controlled trials are still required to validate the use of CBD as medication following mild TBIs, such as concussion.

A review of concussion diagnosis and management in Australian professional sporting codes

Objectives: The recognition and management of concussion has become a major health concern across all sports. Despite recent attention, concussion assessment and return-to-play protocols appear to be highly variable between leading professional sporting bodies across Australia. Without readily available guidelines, players at all levels may be at risk of suboptimal management following in-game trauma. The purpose of this study was to explore the publicly available concussion guidelines of the major Australian sporting codes with an aim to identify potential opportunities to develop a national sporting consensus.Methods: Internet sites of the major sporting organizations within Australia were accessed between June 2018 to July 2018. Sites were reviewed for information pertaining to an available concussion protocol or guidelines including; concussion definition, player education documentation, requirement of baseline testing, standard concussion diagnostic measures, use of sideline testing and removal from play guidelines, return-to-play, minimum return-to-play intervals and the implementation of external evaluation of potential concussion cases.Results: Twelve sites were visited. There was consensus between many of the sporting organizations in terms of concussion definition, removal of play and sideline testing protocols. A step-wise return-to-play protocol was prevalent across most sports. A number of sporting sites however did not have readily available information.Conclusions: There is notable room for the development of concussion guidelines in Australian sport. Researchers and sporting organizations need to continuously amend current protocols to ensure this reflects best evidence-based practice.

Neuroprotective Effects and Treatment Potential of Incretin Mimetics in a Murine Model of Mild Traumatic Brain Injury

Traumatic brain injury (TBI) is a commonly occurring injury in sports, victims of motor vehicle accidents, and falls. TBI has become a pressing public health concern with no specific therapeutic treatment. Mild TBI (mTBI), which accounts for approximately 90% of all TBI cases, may frequently lead to long-lasting cognitive, behavioral, and emotional impairments. The incretins glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are gastrointestinal hormones that induce glucose-dependent insulin secretion, promote β-cell proliferation, and enhance resistance to apoptosis. GLP-1 mimetics are marketed as treatments for type 2 diabetes mellitus (T2DM) and are well tolerated. Both GLP-1 and GIP mimetics have shown neuroprotective properties in animal models of Parkinson's and Alzheimer's disease. The aim of this study is to evaluate the potential neuroprotective effects of liraglutide, a GLP-1 analog, and twincretin, a dual GLP-1R/GIPR agonist, in a murine mTBI model. First, we subjected mice to mTBI using a weight-drop device and, thereafter, administered liraglutide or twincretin as a 7-day regimen of subcutaneous (s.c.) injections. We then investigated the effects of these drugs on mTBI-induced cognitive impairments, neurodegeneration, and neuroinflammation. Finally, we assessed their effects on neuroprotective proteins expression that are downstream to GLP-1R/GIPR activation; specifically, PI3K and PKA phosphorylation. Both drugs ameliorated mTBI-induced cognitive impairments evaluated by the novel object recognition (NOR) and the Y-maze paradigms in which neither anxiety nor locomotor activity were confounds, as the latter were unaffected by either mTBI or drugs. Additionally, both drugs significantly mitigated mTBI-induced neurodegeneration and neuroinflammation, as quantified by immunohistochemical staining with Fluoro-Jade/anti-NeuN and anti-Iba-1 antibodies, respectively. mTBI challenge significantly decreased PKA phosphorylation levels in ipsilateral cortex, which was mitigated by both drugs. However, PI3K phosphorylation was not affected by mTBI. These findings offer a new potential therapeutic approach to treat mTBI, and support further investigation of the neuroprotective effects and mechanism of action of incretin-based therapies for neurological disorders.

The Predictive Capacity of the Buffalo Concussion Treadmill Test After Sport-Related Concussion in Adolescents

The Buffalo Concussion Treadmill Test (BCTT) identifies the heart rate threshold (HRt) of exercise tolerance in concussed patients. A previous study found that an absolute HRt of < 135 bpm was associated with prolonged recovery (>30 days) from sport-related concussion (SRC). In this study, we assessed the relationship of ΔHR (difference between resting HR and HRt) and recovery from SRC. Using a retrospective cohort design, we compared acutely (<10 days since injury) concussed adolescents who were prescribed either (1) relative rest (RG, n = 27, 15.2 ± 1 years, 33% female, median 17 days to recovery, ΔHR = 69.6 ± 28 bpm), (2) a placebo-stretching program (PG, n = 51, 15.4 ± 2 years, 49% female, median 17 days to recovery, ΔHR = 60.9 ± 22 bpm), or (3) sub-threshold aerobic exercise (AG, n = 52, 15.3 ± 2 years, 46% female, median 13 days to recovery, ΔHR = 62.4 ± 26 bpm). Linear regression showed that ΔHR significantly correlated with duration of clinical recovery for RG (p = 0.012, R ² = 0.228) and PG (p = 0.011, R ² = 0.126) but not for AG (p = 0.084, R ² = 0.059). ΔHR values were significantly lower in participants with prolonged recovery (>30 days) in RG (p = 0.01) and PG (p = 0.04). A ΔHR of ≤50 bpm on the BCTT is 73% sensitive and 78% specific for predicting prolonged recovery in concussed adolescents who were prescribed the current standard of care (i.e., cognitive and physical rest).

Novel Mouse Tauopathy Model for Repetitive Mild Traumatic Brain Injury: Evaluation of Long-Term Effects on Cognition and Biomarker Levels After Therapeutic Inhibition of Tau Phosphorylation

Traumatic brain injury (TBI) is a risk factor for a group of neurodegenerative diseases termed tauopathies, which includes Alzheimer's disease and chronic traumatic encephalopathy (CTE). Although TBI is stratified by impact severity as either mild (m), moderate or severe, mTBI is the most common and the most difficult to diagnose. Tauopathies are pathologically related by the accumulation of hyperphosphorylated tau (P-tau) and increased total tau (T-tau). Here we describe: (i) a novel human tau-expressing transgenic mouse model, TghTau/PS1, to study repetitive mild closed head injury (rmCHI), (ii) quantitative comparison of T-tau and P-tau from brain and plasma in TghTau/PS1 mice over a 12 month period following rmCHI (and sham), (iii) the usefulness of P-tau as an early- and late-stage blood-based biochemical biomarker for rmCHI, (iii) the influence of kinase-targeted therapeutic intervention on rmCHI-associated cognitive deficits using a combination of lithium chloride (LiCl) and R-roscovitine (ros), and (iv) correlation of behavioral and cognitive changes with concentrations of the brain and blood-based T-tau and P-tau. Compared to sham-treated mice, behavior changes and cognitive deficits of rmCHI-treated TghTau/PS1 mice correlated with increases in both cortex and plasma T-tau and P-tau levels over 12 months. In addition, T-tau, but more predominantly P-tau, levels were significantly reduced in the cortex and plasma by LiCl + ros approaching the biomarker levels in sham and drug-treated sham mice (the drugs had only modest effects on the T-tau and P-tau levels in sham mice) throughout the 12 month study period. Furthermore, although we also observed a reversal of the abnormal behavior and cognitive deficits in the drug-treated rmCHI mice (compared to the untreated rmCHI mice) throughout the time course, these drug-treated effects were most pronounced up until 10 and 12 months where the abnormal behavior and cognition deficits began to gradually increase. These studies describe: (a) a translational relevant animal model for TBI-linked tauopathies, and (b) utilization of T-tau and P-tau as rmCHI biomarkers in plasma to monitor novel therapeutic strategies and treatment regimens for these neurodegenerative diseases.

The neurobiological effects of repetitive head impacts in collision sports

It is now recognized that repetitive head impacts (RHI) in sport have the potential for long-term neurological impairments. In order to identify targets for intervention and/or pharmacological treatment, it is necessary to characterize the neurobiological mechanisms associated with RHI. This review aims to summarize animal and human studies that specifically address Blood Brain Barrier (BBB) dysfunction, abnormal neuro-metabolic and neuro-inflammatory processes as well as Tau aggregation associated with RHI in collision sports. Additionally, we examine the influence of physical activity and genetics on outcomes of RHI, discuss methodological considerations, and provide suggestions for future directions of this burgeoning area of research.

Pain with traumatic brain injury and psychological disorders

Traumatic brain injury (TBI) is the cause for long-term disability in more than 3 million patients in the US alone, with chronic pain being the most frequently reported complain. To date, predisposing mechanisms for chronic pain in TBI patients are largely unknown. Psychological disorders, including post-traumatic stress disorder, depression and anxiety following TBI are commonly reported comorbidities to post-traumatic pain. Long term consequences can be debilitating and affect quality of life even when the injury is mild. In this review, we present the most commonly reported chronic pain conditions across the spectrum of severity of TBI, mainly focusing on mild TBI. We discuss chronic post- traumatic headaches, widespread pain as well as post-traumatic central pain. We discuss pain in the context of injury severity and military versus civilian populations. We are only starting to understand the biological mechanisms behind post-traumatic pain and associated psychological distress following TBI, with genetic, biochemical and imaging studies pointing to the dopaminergic, neurotrophic factors and the role of Apolipoprotein. Physiological and neurological mechanisms are proposed to partially explain this interaction between post-traumatic pain and psychological distress. Nevertheless, the evidence for the role of structural brain damage remains incomplete and to a large extent debatable, as it is still difficult to establish clear causality between brain trauma and chronic pain. Finally, general aspects of management of chronic pain post-TBI are addressed.

Lifestyle modifications as therapy for medication refractory post-traumatic headache (PTHA) in the military population of Okinawa

Objective

Our aim was 1) to reduce disability, as characterized by headache frequency, duration and severity in patients with post-traumatic headache (PTHA), 2) to reduce the number of medical boards and work limitations in patients with post traumatic headache, and 3) to reduce use of medical resources and clinic visits related to headache or migraine.

Background

Modifiable risk factors for PTHA include stressful life event, sleep disturbances, and medication overuse. Cognitive-behavioral strategies, biofeedback, and relaxation therapy may have an important role in treatment and preventing progression to chronic post-traumatic headache (CPTHA). There is limited literature and a known practice gap for implementation of these techniques.

Design/methods

An IRB approved project focused on patients who were seen for PTHA and CPTHA. 1) Intervention consisted of lifestyle teaching, cognitive-behavioral therapy and biofeedback, supplemented by decreasing polypharmacy. 2) Patients were followed for 2 years and a retrospective review was conducted for 2 years prior to presentation. 3) Outcome measures included reduction in migraine intensity or frequency, improved quality of life, duty status, and decreased utilization of clinic visits.

Results

Over the course of one year, 221 patients were treated for migraines in the Naval Okinawa Neurology Clinic. Of these, 22 active duty service members and 3 Dependents suffered a mild TBI prior to onset. After intervention, there was a 36% decrease in PTHA frequency, 56% decrease in headache severity and 60% of patients had improved quality of life as compared to the 2 years prior to intervention. Twenty-four percent had reduction in polypharmacy. Appointment frequency for migraine decreased from an average of 6.8 to 2.6 per year.

Conclusions

An implemented program geared towards reducing polypharmacy was shown to improve safety, quality of life and reduce hospitalizations from the burden of migraines. Our systematic approach resulted in quality of life improvements and decreased use of medical resources.

Trial registration

Authors received the approval of NAVMED West, Okinawa Naval Hospital Institutional Review Board on January 13th, 2016. QI.2016.0021.

Heparan Sulfate Proteoglycans as Drivers of Neural Progenitors Derived From Human Mesenchymal Stem Cells

Background: Due to their relative ease of isolation and their high ex vivo and in vitro expansive potential, human mesenchymal stem cells (hMSCs) are an attractive candidate for therapeutic applications in the treatment of brain injury and neurological diseases. Heparan sulfate proteoglycans (HSPGs) are a family of ubiquitous proteins involved in a number of vital cellular processes including proliferation and stem cell lineage differentiation.

Methods: Following the determination that hMSCs maintain neural potential throughout extended in vitro expansion, we examined the role of HSPGs in mediating the neural potential of hMSCs. hMSCs cultured in basal conditions (undifferentiated monolayer cultures) were found to co-express neural markers and HSPGs throughout expansion with modulation of the in vitro niche through the addition of exogenous HS influencing cellular HSPG and neural marker expression.

Results: Conversion of hMSCs into hMSC Induced Neurospheres (hMSC IN) identified distinctly localized HSPG staining within the spheres along with altered gene expression of HSPG core protein and biosynthetic enzymes when compared to undifferentiated hMSCs.

Conclusion: Comparison of markers of pluripotency, neural self-renewal and neural lineage specification between hMSC IN, hMSC and human neural stem cell (hNSC H9) cultures suggest that in vitro generated hMSC IN may represent an intermediary neurogenic cell type, similar to a common neural progenitor cell. In addition, this data demonstrates HSPGs and their biosynthesis machinery, are associated with hMSC IN formation. The identification of specific HSPGs driving hMSC lineage-specification will likely provide new markers to allow better use of hMSCs in therapeutic applications and improve our understanding of human neurogenesis.

Heterotopic Ossification Formation Following a Simple Concussion: A Case Report

CASE

A 19-year-old woman presented with a 3-month history of an enlarging lesion on the proximal aspect of the femur. After imaging studies and a biopsy had been performed, the mass was determined to represent heterotopic ossification (HO). The only known risk factor was a history of concussion. The mass was resected and, as of the 12-month follow-up, had not recurred.

CONCLUSION

HO is a potentially serious complication of ossification in soft tissues that can develop secondary to several disease states; it commonly occurs following traumatic brain injury. To our knowledge, this is the only case report that describes HO associated with a concussion and no other risk factors.

Ca2+/calmodulin-dependent protein kinase II and Dimethyl Sulfoxide affect the sealing frequencies of transected hippocampal neurons

Traumatic injury often results in axonal severance, initiating obligatory Wallerian degeneration of distal segments, whereas proximal segments often survive. Calcium ion (Ca²⁺ ) influx at severed proximal axonal ends activates pathways that can induce apoptosis. However, this same Ca²⁺ -influx also activates multiple parallel pathways that seal the plasmalemma by inducing accumulation and fusion of vesicles at the lesion site that reduce Ca²⁺ -influx and enhance survival. We examined whether various inhibitors of Ca²⁺ /calmodulin-dependent protein kinases (CaMKs), and/or dimethyl sulfoxide (DMSO), a common solvent for biologically active substances, affected the ability of a hippocampal-derived neuronal cell line (B104 cells) to seal membrane damage following axotomy. Axolemmal sealing frequencies were assessed at different transection distances from the axon hillock and at various times after Ca²⁺ -influx (PC times) by observing whether transected cells took-up fluorescent dyes. Inhibition of CaMKII by tatCN21 and KN-93, but not inhibition of CaMKI and CaMKIV by STO-609, affected axonal sealing frequencies. That is, CaMKII is a component of previously reported parallel pathways that induce membrane sealing, whereas CaMKI and CaMKIV are not involved. The effects of these CaMKII inhibitors on plasmalemmal sealing depended on their mechanism of inhibition, transection distance, and PC time. DMSO at low concentrations (90 µM-28 mM or 0.00064%-0.2% v/v) significantly increased membrane-sealing frequencies at most PC times and transection distances, possibly by permeabilizing the plasmalemma to Ca²⁺ . Inhibition of CaMKII, DMSO, PC time, and the transection distance significantly affect plasmalemmal sealing that is critical to somal survival in traumatic lesions.