Two-year prospective study of relative risk of a second cerebral concussion

Individual behavioral and sporting risk factors affecting injuries in recreational skiers and snowboarders: a case-control study

This case-control study aimed to analysis of the relationship between individual behaviours and sports risk factors and injuries among skiers and snowboarders. During the 2021-2022 winter season, 1132 injured and 1069 non-injured skiers and snowboarders were surveyed regarding demographic, self-reported individual behavioural and sporting characteristics. Multivariate regression analysis revealed previous snow-sports injury (OR: 26.39, 95% CI: 13.32-52.31, P < 0.001), nervousness (OR: 3.78, 95% CI: 2.91-4.90, P < 0.001), calm (OR: 1.90, 95% CI: 1.46-2.48, P < 0.001) and fearful (OR: 20.60, 95% CI: 11.45-37.04, P < 0.001) emotional states, and higher risk-taking behaviours (OR: 3.72, 95% CI: 2.87-4.83, P < 0.001) were important risk factors associated with injuries to all skiers and snowboarders. Compared to snowboarders, the risk of injury to skiers was more likely to increase as the length of their skiing experience increases. Emotional and cognitive levels appear to be important conditions that influence injuries to skiers and snowboarders, a proper understanding of the potential interactions between cognition and behaviour appears to be important for public ski safety management.

Assessing Brain Processing Deficits Using Neuropsychological and Vision-Specific Tests for Concussion

INTRODUCTION

Since verbal memory and visual processing transpire within analogous cerebral regions, this study assessed (i) if a visual function can predict verbal memory performance. It also hypothesized whether neurocognitive (e.g., ImPACT) tests focusing on the Visual Memory and Cognitive Efficacy Index will predict Verbal Memory scores and (ii) if vision metrics and age can identify individuals with a history of concussion. Finally, it also hypothesized that King-Devick and near point of convergence scores alongside age considerations will identify candidates with a prior reported history of concussion.

MATERIALS AND METHODS

This observational cohort assessed 25 collegiate ice hockey players prior to the competitive season considering age (19.76 ± 1.42 years) and BMI (25.9 ± 3.0 kg/cm2). Hypothesis 1 was assessed using a hierarchical (sequential) multiple regression analysis, assessing the predictive capacity of Visual Memory and Cognitive Efficacy Index scores in relation to Verbal Memory scores. Hypothesis 2 utilized a binomial logistic regression to determine if King-Devick and near point of convergence scores predict those with a prior history of concussion.

RESULTS

Hypothesis 1 developed two models, where Model 1 included Visual Memory as the predictor, while Model 2 added the Cognitive Efficacy Index as a predictor for verbal memory scores. Model 1 significantly explained 41% of the variance. Results from Model 2 suggest that the Cognitive Efficacy Index explained an additional 24.4%. Thus, Model 2 was interpreted where only the Cognitive Efficacy Index was a significant predictor (p = 0.001). For every 1 unit increase in the Cognitive Efficacy Index, Verbal Memory increased by 41.16. Hypothesis 2's model was significant, accounting for 37.9% of the variance in those with a history of concussion. However, there were no significant unique predictors within the model as age (Wald = 1.26, p = 0.261), King-Devick (Wald = 2.31, p = 0.128), and near point of convergence (Wald = 2.43, p = 0.119) were not significant predictors individually.

CONCLUSIONS

The conflicting findings of this study indicate that baseline data for those with a history of concussion greater than one year may not be comparable to the same metrics during acute concussion episodes. Young athletes who sustain a concussion may be able to overcompensate via the visual system. Future prospective studies with larger sample sizes are required using the proposed model's objective metrics.

The current state of concussion knowledge and attitudes in British American Football

OBJECTIVES

To examine concussion knowledge and concussion attitudes of players, coaches, and support staff in British American Football (BAF).

METHODS

Data from players, coaches and support staff (n = 236) were collected from across all leagues in BAF. An online survey tool was used which included the Rosenbaum Concussion Knowledge and Attitudes Survey (RoCKAS), and questions examining concussion education and perceived risk of participating in football.

RESULTS

The mean score on the RoCKAS concussion knowledge was 21.0 ± 2.1 of a possible score of 25 reflecting good knowledge. Of a possible score of 65, the mean concussion attitude score was 55.6 ± 6.1 showing safe attitude. Whilst an overall safe attitude was seen, almost half of participants (45.3%) noted they would continue to play with a concussion. No relationship was found between CAI and prior concussion history. Fifty seven percent of participants agreed the benefits of playing football outweighed the risks. Forty eight percent reported that they had received no concussion-related education in the past 12 months.

CONCLUSION

BAF participants have good concussion knowledge and safe attitudes. However, risky behavior is demonstrated through unsafe likelihood to report and attitude to long-term health risks. Access to the British American Football Association (BAFA) concussion policy and education was poor raising questions over what sources of information stakeholders are drawing their knowledge from. These findings can help form the foundation of educational interventions (e.g. coaching workshops) to challenge current misconceptions and improve likelihood to report concussion in BAF.

Cranial Bone Changes Induced by Mild Traumatic Brain Injuries: A Neglected Player in Concussion Outcomes?

Mild traumatic brain injuries (TBIs), particularly when repetitive in nature, are increasingly recognized to have a range of significant negative implications for brain health. Much of the ongoing research in the field is focused on the neurological consequences of these injuries and the relationship between TBIs and long-term neurodegenerative conditions such as chronic traumatic encephalopathy and Alzheimer's disease. However, our understanding of the complex relationship between applied mechanical force at impact, brain pathophysiology, and neurological function remains incomplete. Past research has shown that mild TBIs, even below the threshold that results in cranial fracture, induce changes in cranial bone structure and morphology. These structural and physiological changes likely have implications for the transmission of mechanical force into the underlying brain parenchyma. Here, we review this evidence in the context of the current understanding of bone mechanosensitivity and the consequences of TBIs or concussions. We postulate that heterogeneity of the calvarium, including differing bone thickness attributable to past impacts, age, or individual variability, may be a modulator of outcomes after subsequent TBIs. We advocate for greater consideration of cranial responses to TBI in both experimental and computer modeling of impact biomechanics, and raise the hypothesis that calvarial bone thickness represents a novel biomarker of brain injury vulnerability post-TBI.

Sport-Related Concussion: A Cognitive Perspective

Purpose of Review

The incidence of sport-related concussion (SRC) has been increasing in different sports and its impact on long-term cognitive function is increasingly recognized. In this study, we review the epidemiology, neuropathophysiology, clinical symptoms, and long-term consequences of SRC with a specific focus on cognition.

Recent Findings

Repeated concussions are associated with an increased risk of several neurologic diseases and long-term cognitive deficits. To improve cognitive outcomes in athletes with SRC, standardized guidelines for the assessment and management of SRC are vital. However, current concussion management guidelines lack procedures for rehabilitating acute and long-term cognitive symptoms.

Summary

Increased awareness for the management and rehabilitation of cognitive symptoms in SRC is needed in all clinical neurologists treating professional and amateur athletes. We propose cognitive training as a prehabilitation tool to alleviate the severity of cognitive symptoms and as a rehabilitative tool to improve cognitive recovery postinjury.

The Relationship Between Measures of Postural Control in Concussion Assessment

OBJECTIVE

To determine the relationship between postural sway performance during commonly utilized postural control assessments following a concussion, including the modified Balance Error Scoring System (mBESS), concussion balance test (COBALT), and sensory organization test (SOT) in healthy young adults.

APPROACH

Twenty participants completed all balance testing. The mBESS conditions included double limb stance, single limb stance, and tandem stance. The COBALT was comprised of yaw plane head shake (HS) and vestibular ocular reflex cancellation conditions performed on firm and foam surfaces. Subjects performed 6 conditions of the SOT (C1-C6), which systematically perturbed sensory inputs. Postural sway performance was measured using a single force plate and quantified as a sway score for the mBESS and COBALT, and an equilibrium score for the SOT. Spearman rank correlations were used to examine the relationship between postural sway performance for each test.

MAIN RESULTS

There was a moderate positive correlation between mBESS-tandem stance and the HS on foam COBALT condition (r = .643, P = .002). There was a moderate negative correlation between mBESS-double limb stance and SOT-C6 (r = -.512, P = .021), and between mBESS-single limb stance and SOT-C6 (r = -.523, P = .018). The COBALT and SOT demonstrated numerous moderate to good negative correlations (r = -.448 to -.708, P ≤ .05), including a good negative correlation between HS on foam and SOT-C1 (r = -.725, P = .0003).

SIGNIFICANCE

Performance on the mBESS had minimal relationship to performance on the COBALT and SOT, suggesting that the clinical standard may not challenge sensory integration at the same capacity as other tests. All COBALT conditions had fair to good associations to at least 2 SOT conditions, suggesting both assessments are representative of sensory integration. Further investigation of the current clinical approach is warranted as the COBALT may be a clinically feasible test of sensory integration.

A Scoping Review of Concussion Guidelines in Amateur Sports in the United Kingdom

Objectives To investigate which United Kingdom (UK) amateur sporting organisations have published sports-related concussion (SRC) guidelines, their accessibility and the extent to which they follow the Berlin statement recommendations. This article is targeted at those involved with designing and implementing SRC guidelines in amateur sport. Design Scoping Review. Data Sources The SRC guidelines of 15 sporting organisations were accessed through public materials available from the official organisation website. Eligibility Criteria: To be included in this review, sports must enjoy broad participation by UK amateur athletes with a high risk of athletes sustaining an SRC. Results: 15 sporting organisations were included in this review with two, British Cycling and British Eventing, found not to have published SRC guidelines. There was found to be a large discrepancy between the extent to which the sport-specific guides followed the Berlin statement recommendations. Conclusions: The large discrepancy between the contents of the SRC guidelines may be putting the health of athletes at risk. We recommend the UK government publish standardised concussion guidelines based on the latest scientific research that must be used by all UK amateur sport groups.

The Intelligent Phenotypic Plasticity Platform (IP3) for Precision Medicine-Based Injury Prevention in Sport

The best predictor of future injury is previous injury and this has not changed in a quarter century despite the introduction of evidence-based medicine and associated revisions to post-injury treatment and care. Nearly nine million sports-related injuries occur annually, and the majority of these require medical intervention prior to clearance for the athlete to return to play (RTP). Regardless of formal care, these athletes remain two to four times more likely to suffer a second injury for several years after RTP. In the case of children and young adults, this sets them up for a lifetime of negative health outcomes. Thus, the initial injury is the tipping point for a post-injury cascade of negative sequelae exposing athletes to more physical and psychological pain, higher medical costs, and greater risk of severe long-term negative health throughout their life. This chapter details the technologies and method that make up the automated Intelligent Phenotypic Plasticity Platform (IP3)-a revolutionary new approach to the current standard of post-injury care that identifies and targets deficits that underly second injury risk in sport. IP3 capitalizes on the biological concept of phenotypic plasticity (PP) to quantify an athlete's functional adaptability across different performance environments, and it is implemented in two distinct steps: (1) phenomic profiling and (2) precision treatment. Phenomic profiling indexes the fitness and subsequent phenotypic plasticity of an individual athlete, which drives the personalization of the precision treatment step. IP3 leverages mixed-reality technologies to present true-to-life environments that test the athlete's ability to adapt to dynamic stressors. The athlete's phenotypic plasticity profile is then used to drive a precision treatment that systematically stresses the athlete, via a combination of behavioral-based and genetic fuzzy system models, to optimally enhance the athlete's functional adaptability. IP3 is computationally light-weight and, through the integration with mixed-reality technologies, promotes real-time prediction, responsiveness, and adaptation. It is also the first ever phenotypic plasticity-based precision medicine platform, and the first precision sports medicine platform of any kind.

Concussion Among Children in the United States General Population: Incidence and Risk Factors

The objective of this study was to examine the incidence of concussion and risk factors for sustaining concussion among children from the United States general population. This prospective cohort study used data from the Adolescent Brain Cognitive Development (ABCD) Study^®. Children were recruited from schools across the US, sampled to reflect the sociodemographic variation of the US population. The current sample includes 11,013 children aged 9 to 10 years old (47.6% girls; 65.5% White) who were prospectively followed for an average of 1 year (mean = 367.9 days, SD = 40.8, range 249–601). The primary outcome was caregiver-reported concussion during a 1 year follow-up period. Logistic regression was used to determine which potential clinical, health history, and behavioral characteristics (assessed at baseline) were prospectively associated with concussion. In the 1 year follow-up period between ages 10 and 11, 1 in 100 children (n = 123, 1.1%) sustained a concussion. In univariate models, three baseline predictors (ADHD, prior concussion, and accident proneness) were significantly associated with sustaining a concussion. In a multivariate model, controlling for all other predictors, only prior concussion remained significantly associated with the occurrence of a concussion during the observation period (Odds Ratio = 5.49, 95% CI: 3.40–8.87). The most robust and only independent prospective predictor of sustaining a concussion was history of a prior concussion. History of concussion is associated with 5.5 times greater odds of sustaining concussion between ages 10 and 11 among children from the general US population.

A deep neural network approach for sentiment analysis of medically related texts: an analysis of tweets related to concussions in sports

Annually, over three million people in North America suffer concussions. Every age group is susceptible to concussion, but youth involved in sporting activities are particularly vulnerable, with about 6% of all youth suffering a concussion annually. Youth who suffer concussion have also been shown to have higher rates of suicidal ideation, substance and alcohol use, and violent behaviors. A significant body of research over the last decade has led to changes in policies and laws intended to reduce the incidence and burden of concussions. However, it is also clear that youth engaging in high-risk activities like sport often underreport concussion, while others may embellish reports for specific purposes. For such policies and laws to work, they must operate effectively within a facilitative social context so understanding the culture around concussion becomes essential to reducing concussion and its consequences. We present an automated deep neural network approach to analyze tweets with sport-related concussion context to identify the general public's sentiment towards concerns in sport-related concussion. A single-layer and multi-layer convolutional neural networks, Long Short-Term Memory (LSTM) networks, and Bidirectional LSTM were trained to classify the sentiments of the tweets. Afterwards, we train an ensemble model to aggregate the predictions of our networks to provide a final decision of the tweet's sentiment. The system achieves an evaluation F1 score of 62.71% based on Precision and Recall. The trained system is then used to analyze the tweets in the FIFA World Cup 2018 to measure audience reaction to events involving concussion. The neural network system provides an understanding of the culture around concussion through sentiment analysis.

Injury Reduction Programs for Reducing the Incidence of Sport-Related Head and Neck Injuries Including Concussion: A Systematic Review

BACKGROUND

Sport-related head and neck injuries, including concussion, are a growing global public health concern with a need to explore injury risk reduction strategies such as neck exercises.

OBJECTIVES

To systematically review the literature to investigate: (1) the relationship between neck strength and sport-related head and neck injuries (including sport-related concussion (SRC); and (2) whether neck exercise programs can reduce the incidence of (a) sport-related head and neck injuries; and (b) SRC.

METHODS

Five databases (Ovid MEDLINE, CINAHL, EMBASE, SPORTDiscus, and Web of Science) and research lists of included studies were searched using a combination of medical subject headings and keywords to locate original studies which reported the association between incidence of head and/or neck injury and neck strength data, or included a neck exercise intervention either in isolation or as part of a more comprehensive exercise program.

RESULTS

From an initial search of 593 studies, six were included in this review. A narrative synthesis was performed due to the heterogeneity of the included studies. The results of two observational studies reported that higher neck strength, but not deep neck flexor endurance, is associated with a lower risk of sustaining a SRC. Four intervention studies demonstrated that injury reduction programs that included neck exercises can reduce the incidence of sport-related head and neck injuries including SRC.

CONCLUSION

Consideration should be given towards incorporating neck exercises into injury reduction exercise programs to reduce the incidence of sport-related head and neck injuries, including SRC.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO (registration number: 194217).

Does Concussion Affect Perception-Action Coupling Behavior? Action Boundary Perception as a Biomarker for Concussion

BACKGROUND

After a concussion, athletes may be at increased risk of musculoskeletal injuries. Altered perception of action boundaries (ABP), or the limits of one's action capabilities, is one possible mechanism for this increase in injury risk after concussion.

OBJECTIVE

To evaluate differences in symptoms, neurocognitive, vestibular/oculomotor, and action boundary function between subjects with no concussion history (NoHx) and concussion history (ConcHX).

DESIGN

Cross-sectional study.

SETTING

Laboratory at the University of Pittsburgh.

PARTICIPANTS

ConcHx (n = 22; age: 21.8 ± 3.0 years, height: 174.0 ± 8.3 cm, and mass: 77.8 ± 14.8 kg) and NoHx athletes (n = 24; age: 21.6 ± 2.0 years, height: 176.0 ± 10.0 cm, and mass: 72.0 ± 15.3 kg).

INTERVENTION

Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) and Post-Concussion Symptom Scale (PCSS), Vestibular-Ocular Motor Screening (VOMS) tool, and the Perception-Action Coupling Task (PACT). The PACT measures the accuracy of ABP.

MAIN OUTCOME MEASURES

Neurocognitive domain scores, PCSS, VOMS subdomain symptom gain, ABP accuracy, and actualization.

RESULTS

ConcHx reported 2.7 ± 1.5 previous concussions occurring on average 263.8 ± 228.9 days prior. ConcHx was higher on several VOMS items including vertical/horizontal saccades (P = 0.001; P = 0.05), vertical/horizontal vestibular-ocular reflex (P < 0.001; P = 0.04), and visual motion sensitivity (P < 0.001). Average PACT movement time (P = 0.01) and reaction time (P = 0.01) were longer in ConcHx.

CONCLUSIONS

These findings provide preliminary support for impaired vestibular/oculomotor function and ABP in ConcHx compared with NoHx. The current results may enhance our understanding of the mechanisms for increased musculoskeletal injury risk after concussion.

The role of pre-season health characteristics as injury risk factors in female adolescent soccer players

[Purpose] Determine if female adolescent soccer players with a history of concussion, impaired K-D scores, and pre-season subjective complaints of neck pain, dizziness, and headache were predisposed to additional risk of musculoskeletal or concussive injury during 10-weeks of competitive play. [Participants and Methods] Twenty-three female high school soccer athletes provided concussion history and reported pre-season subjective complaints. K-D testing was performed pre and postseason. During the 10-week season, all injuries, preventing participation in practice or game, were recorded. [Results] Six reported a history of concussion. Of those six, three injuries were reported, including two concussions and a hamstring strain. Baseline K-D scores were worse in athletes that had two or more pre-season subjective factors compared to those that did not have any. Moderate positive correlations were found between a history of concussion and the number of injuries and a history of concussion and K-D post-test scores. [Conclusion] Findings indicate that pre-season subjective factors of neck pain, dizziness and headache, history of concussion, and K-D potentially increased injury risk. Combining pre-season metrics both at baseline and during the course of the season may assist in better injury risk screening in-season or indicate suboptimal function due to cumulative effects.

Gait Performance Is Associated with Subsequent Lower Extremity Injury following Concussion

PURPOSE

The purpose was to examine gait characteristics between collegiate athletes who did and did not sustain a lower-extremity musculoskeletal (LEMSK) injury in the year after concussion.

METHODS

Thirty-four NCAA collegiate athletes with diagnosed concussions were divided into two groups based on if they did (n = 16) or did not (n = 18) sustain a LEMSK in the year after concussion. Participants completed baseline testing before the start of the season and again at return to play postconcussion. Injuries were tracked using an electronic medical database. Participants were instrumented with three APDM Opal triaxial accelerometers and performed five single-task (ST) and five dual-task (DT) gait trials. Participants traversed a 10-meter walkway, turned around a specified endpoint, and returned to the original line. During DT, participants simultaneously walked and answered mini-mental style questions. A linear mixed-effects model assessed interactions and/or main effects between groups for gait speed, double support time, cadence, stride length, and cognitive accuracy.

RESULTS

The LEMSK group walked slower (ST, 1.15 ± 0.10 m·s; DT, 1.01 ± 0.10 m·s) than the uninjured group (ST, 1.23 ± 0.11 m·s; DT, 1.10 ± 0.11 m·s) during both ST (P = 0.04) and DT (P = 0.03). The injury group spent longer in double support (ST, 20.19% ± 2.34%; DT, 21.92% ± 2.13%) than the uninjured group (ST, 18.16% ± 2.60%; DT, 20.00% ± 2.32%) during both ST (P = 0.02) and DT (P = 0.02). The injury group had a significantly lower cognitive accuracy (89.56% ± 6.48%) than the uninjured group (95.40% ± 7.08%) across time points (P = 0.02).

CONCLUSIONS

There were significant differences in gait characteristics and cognitive accuracy between those who did and did not sustain a LEMSK injury after concussion. The LEMSK group demonstrated a conservative gait strategy both before and after their concussive injury.

Classification of Comprehensive Neuro-Ophthalmologic Measures of Postacute Concussion

IMPORTANCE

Symptom-based methods of concussion diagnosis in contact sports result in underdiagnosis and repeated head injury exposure, increasing the risk of long-term disability. Measures of neuro-ophthalmologic (NO) function have the potential to serve as objective aids, but their diagnostic utility is unknown.

OBJECTIVE

To identify NO measures that accurately differentiate athletes with and without concussion.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted among athletes with and without concussion who were aged 17 to 22 years between 2016 and 2017. Eye movements and cognitive function were measured a median of 19 days after injury among patients who had an injury meeting the study definition of concussion while playing a sport (retrospectively selected from a concussion clinic), then compared with a control group of participants without concussion (enrolled from 104 noncontact collegiate athlete volunteers without prior head injury). Data analysis was conducted from November 2019 through May 2020.

EXPOSURE

Concussion.

MAIN OUTCOMES AND MEASURES

Classification accuracy of clinically important discriminator eye-tracking (ET) metrics. Participants' eye movements were evaluated with a 12-minute ET procedure, yielding 42 metrics related to smooth pursuit eye movement (SPEM), saccades, dynamic visual acuity, and reaction time. Clinically important discriminator metrics were defined as those with significantly different group differences and area under the receiver operator characteristic curves (AUROCs) of at least 0.70.

RESULTS

A total of 34 participants with concussions (mean [SD] age, 19.7 [2.4] years; 20 [63%] men) and 54 participants without concussions (mean [SD] age, 20.8 [2.2] years; 31 [57%] men) completed the study. Six ET metrics (ie, simple reaction time, discriminate reaction time, discriminate visual reaction speed, choice visual reaction speed, and reaction time on 2 measures of dynamic visual acuity 2) were found to be clinically important; all were measures of reaction time, and none were related to SPEM. Combined, these 6 metrics had an AUROC of 0.90 (95% CI, 0.80-0.99), a sensitivity of 77.8%, and a specificity of 92.6%. The 6 metrics remained significant on sensitivity testing.

CONCLUSIONS AND RELEVANCE

In this study, ET measures of slowed visual reaction time had high classification accuracy for concussion. Accurate, objective measures of NO function have the potential to improve concussion recognition and reduce the disability associated with underdiagnosis.

Exposure to brain trauma in six age divisions of minor ice hockey

Acute and chronic neurological risks associated with brain trauma sustained in professional ice hockey has generated concern for youth participants. Minor hockey is a different game when compared to elite players presenting distinctive risk factors for each age division. Objective measures of brain trauma exposure were documented for six divisions in minor ice hockey; U7, U9, U11, U13, U15, U18. Game video analysis, physical reconstruction and computational modelling was employed to capture the event conditions, frequency of impacts, frequency of high strain magnitude (>0.17) impacts, and cumulative trauma. The results showed proportional differences in the event conditions; event type, closing velocity, and head impact location, informing the improvement of age appropriate protection, testing protocols, and safety standards. Frequency of events were highest for U7 when players were learning to skate, and again in U18 as game physicality increases. No significant difference was observed in frequency of high magnitude impacts across age divisions. A peak in high magnitude impacts was empirically observed at both U7 and U15 where skill development in skating and body checking, respectively, were most prominent. Finally, a cumulative trauma metric incorporating frequency and magnitude of impacts provided a detailed analysis of trauma exposure provides for a targeted approach to managing injury risk specific to age division. Objective measures of brain trauma exposure identified in the current study are important to inform strategy, guide legislation and initiate policy for safe play in minor ice hockey.

What is the risk of recurrent concussion in children and adolescents aged 5-18 years? A systematic review and meta-analysis

OBJECTIVE

We aimed to examine the risk of concussion in children with a previous history of concussion.

DESIGN

Systematic review and meta-analysis. The primary outcome was number of children with and without a previous lifetime history of concussion who sustained a diagnosed concussion within each study period. Risk of bias was assessed using the Newcastle-Ottawa Scale. A random effects model was used to estimate a pooled risk ratio (RR) with corresponding 95% CIs; results were summarised in forest plots.

DATA SOURCES

Four electronic databases (MEDLINE, Embase, CINAHL, SPORTDiscus) and selected reference lists were searched (PROSPERO registration No CRD42019135462).

ELIGIBILITY CRITERIA

Original English language peer-reviewed publications that compared concussion risk in children aged 5-18 years with and without a previous concussion history in which risk estimates were reported or able to be calculated.

RESULTS

Of 732 identified studies, 7 studies representing 23 411 children (risk of bias range, 7-9; maximum possible score=9) were included for meta-analysis. Pooled risk of sustaining a concussion was more than three times greater in children with a previous concussion compared with those with no previous concussion (RR=3.64; 95% CI: 2.68 to 4.96; p<0.0001; I ²=90.55%). Unreported sex-stratified data precluded direct comparison of concussion risk in male versus female athletes.

CONCLUSION

Previously concussed children have four times the risk of sustaining a concussion compared with those with no previous concussion history. This should be a consideration for clinicians in return to sport decision-making. Future studies examining subsequent recurrent concussion in youth sports must consider sex differences.

Head impacts in semiprofessional male Soccer players: a prospective video analysis over one season of competitive games

Soccer exposes players to head injuries and involves repeated intentional head impacts through heading the ball. Our objective was to investigate the rate of both intentional headers and involuntary head impacts in semiprofessional male soccer players during one season. In this prospective cohort study, we followed 54 men (16-35 years) playing in two soccer clubs participating in the same regional French championship throughout the 2017-2018 season. All head impacts that occurred in competitive games were analyzed using video recordings. Player position, game exposure, referee's decision were also reported. Head impact incidence rate (IR) per 1000 player-hours, with the 95% confidence intervals (CIs) were calculated. Results: Headers IR was 3584.7 per 1000 player-hours (95% CI = 3431.9, 3737.5). Forwards and center-backs performed a higher number of headers. Involuntary head impacts IR was 44.1/1000 player-hours (95% CI = 27.1, 60.9). Just under half led the referee to stop playing time for a caregiver examination. Three concussions with a loss of consciousness after a head-to-head impact in a heading duel were recorded. Conclusions: Intentional headers were relatively common, contrary to involuntary head impacts that were however mainly due to heading duels. Head-to-head impact should lead to a systematic exit from the game for suspicion of concussion.

Comparison of Laboratory and On-Field Performance of American Football Helmets

The relationship between laboratory and on-field performance of football helmets was assessed for 31 football helmet models selected from those worn by players in the 2015-2019 National Football League (NFL) seasons. Linear impactor tests were conducted with helmets placed on an instrumented Hybrid III head and neck assembly mounted on a sliding table. Based on impacts to each helmet at six impact locations and three velocities, a helmet performance score (HPS) was calculated using a linear combination of the head injury criterion (HIC) and the diffuse axonal multi-axis general evaluation (DAMAGE). To determine the on-field performance of helmets, helmet model usage, player participation, and incident concussion data were collected from the five NFL seasons and used to calculate helmet model-specific concussion rates. Comparison of laboratory HPS to the helmet model-specific concussion rates on a per play basis showed a positive correlation (r² = 0.61, p < 0.001) between laboratory and on-field performance of helmet models, indicating that helmets which exhibited reduced impact severity in the laboratory tests were also generally associated with lower concussion rates on-field. Further analysis showed that NFL-prohibited helmet models exhibited a significantly higher odds of concussion (OR 1.24; 95% CI 1.04-1.47; p = 0.017) relative to other helmet models.

Examining the Effects of Anabolic-Androgenic Steroids on Repetitive Mild Traumatic Brain Injury (RmTBI) Outcomes in Adolescent Rats

Background: Repetitive mild traumatic brain injury (RmTBI) is increasingly common in adolescents. Anabolic–androgenic steroid (AAS) consumption among younger professional athletes is a significant risk factor for impaired neurodevelopment. Given the increased rates and overlapping symptomology of RmTBI and AAS use, we sought to investigate the behavioural and neuropathological outcomes associated with the AAS Metandienone (Met) and RmTBI on rats. Methods: Rats received either Met or placebo and were then administered RmTBIs or sham injuries, followed by a behavioural test battery. Post-mortem MRI was conducted to examine markers of brain integrity and qRT-PCR assessed mRNA expression of markers for neurodevelopment, neuroinflammation, stress responses, and repair processes. Results: Although AAS and RmTBI did not produce cumulative deficits, AAS use was associated with detrimental outcomes including changes to depression, aggression, and memory; prefrontal cortex (PFC) atrophy and amygdala (AMYG) enlargement; damaged white matter integrity in the corpus callosum; and altered mRNA expression in the PFC and AMYG. RmTBI affected general activity and contributed to PFC atrophy. Conclusions: Findings corroborate previous results indicating that RmTBI negatively impacts neurodevelopment but also demonstrates that AAS results in significant neuropathological insult to the developing brain.

Recommendations for the Emergency Department Prevention of Sport-Related Concussion

Sport-related concussion refers to the subset of concussive injuries occurring during sport activities. Similar to concussion from nonsport mechanisms, sport-related concussion is associated with significant morbidity, including migrainous headaches, disruption in normal daily activities, and long-term depression and cognitive deficits. Unlike nonsport concussions, sport-related concussion may be uniquely amenable to prevention efforts to mitigate these problems. The emergency department (ED) visit for sport-related concussion represents an opportunity to reduce morbidity by timely diagnosis and management using best practices, and through education and counseling to prevent a subsequent sport-related concussion. This article provides recommendations to reduce sport-related concussion disability through primary, secondary, and tertiary preventive strategies enacted during the ED visit. Although many recommendations have a solid evidence base, several research gaps remain. The overarching goal of improving sport-related concussion outcome through enactment of ED-based prevention strategies needs to be explicitly studied.

History of concussion and risk of subsequent injury in athletes and service members: A systematic review and meta-analysis

Risk of secondary injury after a primary concussion in sports and military contexts is an emerging area of interest in research. The purpose of this review was to provide an evidence synthesis describing risk of injury in athletic and military populations with and without a history of concussion. Electronic database searches were completed through September 7, 2018 in PubMed, EMBASE, CINAHL and SCOPUS. Peer-reviewed observational studies of any design with participants who were athletes or service members; measured the outcome of any type of injury; and compared injury between those with and without a history of concussion were included. Risk of bias was assessed using the Q-Coh II. Twenty-seven articles were included. Seventeen meta-analyses were completed for risk of any injury, risk of concussion, and risk of extremity injury using odds, hazard, and rate ratios. The results indicate significantly increased odds of all injuries (OR = 2.55; 95%CI 1.85,3.52); concussion (OR = 3.73; 95%CI 2.41,5.78); and lower extremity injuries (OR = 1.60; 95%CI 1.32,1.94) in those with a history of concussion compared to those without. Additional analyses reveal this increased risk is apparent when looking at time to event data and rate of injury based on number of exposures. While the reasons for the increased incidence of secondary injury associated with a concussion are not yet understood, there are potentially behavioral attributes and motor control deficits that contribute. It is suggested that research is needed to determine if active therapeutic treatment for disturbances in sensorimotor and neuromotor control after concussion could attenuate the increased risk for injury.

Incidence and Risk of Concussions in Youth Athletes: Comparisons of Age, Sex, Concussion History, Sport, and Football Position

Objective

This study was designed to determine concussion incidence, risk, and relative risk among middle and high school athletes participating in various sports.

Method

Data were retrospectively obtained from 10,334 athletes of 12 different sports in Hawaii. In addition to determining the overall concussion incidence, comparisons of incidence, risk, and relative risk were made according to age, sex, concussion history, sport, and football position.

Results

The overall incidence of concussion among youth athletes was 1,250 (12.1%). The relative risk for a concussion was almost two times greater in 18-year olds than in 13-year-old athletes. In comparable sports, girls had a 1.5 times higher concussion risk than boys. Athletes with a prior concussion had 3-5 times greater risk to sustain a concussion than those with no history of a concussion. Among varied sports, wrestling and martial arts had the highest relative risk of a concussion, followed by cheerleading, football, and track and field. No differences in concussion risks were found among the football players in different positions.

Conclusions

Older youths, females, those with a history of concussion, and those participating in high contact sports were found to have higher risks of sustaining a concussion. The findings increase awareness of concussion patterns in young athletes and raise concerns regarding protective strategies and concussion management in youth sports.

Persistent impairment based symptoms post mild traumatic brain injury: Does a standard symptom scale detect them?

AIM

To further explore symptoms in patients beyond the expected recovery period post mild Traumatic Brain Injury (mTBI) that are potentially indicative of impairment.

METHODS

Ninety-four individuals (62 diagnosed with mTBI within the previous 4-24 weeks and 32 healthy controls) participated in the study. Participants in the mTBI group were further grouped as symptomatic (n = 33) or asymptomatic (n = 29) based on their spontaneous report of symptoms at the time of screening. Measures included a demographic questionnaire, 8 impairment specific self-report clinical tools, and a standard post-mTBI self-report symptom scale (Head Injury Scale (HIS)).

RESULTS

Compared to the control group, scores for all instruments (including the HIS) were higher in the symptomatic mTBI group (P < 0.05), and higher for the neck disability and hyperarousal measures in the asymptomatic mTBI group (p < 0.035), but not the HIS (p > 0.093). Overall 94% of the symptomatic and 62% of the asymptomatic participants post-mTBI, recorded scores considered to be clinically relevant on at least one impairment screening tool. In contrast, only 28% of the asymptomatic mTBI group recorded a clinically relevant score for the HIS.

CONCLUSION

Symptoms indicative of persisting impairments beyond the expected recovery period were apparent in a substantial proportion of individuals post mTBI. Furthermore, a high percentage of individuals initially reporting as symptom free demonstrated clinically relevant scores on at least one impairment screening tool. Findings also suggest that a standard post-mTBI self-report symptom scale may often not detect the presence of persisting symptoms.

The use of an intensive physical exertion test as a final return to play measure in concussed athletes: a prospective cohort

OBJECTIVES

To examine the utility of a novel physical exertion test developed by the Chicago Blackhawks medical staff as a final return to play (RTP) clearance test in youth and young adult athletes, and to determine the relationship between participant and test variables on RTP within asymptomatic athletes diagnosed with concussion.

METHODS

Once asymptomatic and following completion of all RTP steps, concussed athletes underwent the Gapski-Goodman Test (GGT) or modified GGT (mGGT) at partnered Complete Concussion Management Inc. (CCMI) clinics as part of RTP decision-making. Prospective data was collected electronically by trained CCMI clinicians utilizing the CCMI Concussion Database System. A review was conducted to examine data collected between January 2016 and February 2017. Participant and test variables were analyzed to determine relationships with pass/fail rate of the GGT/mGGT.

RESULTS

A total of 759 athletes performed the GGT/mGGT in the study period. Although all asymptomatic, 14.6% of concussed athletes failed the GGT/mGGT while attempting to achieve RTP clearance. Statistically significant relationships were found between failure of the test and symptom severity score on initial presentation and self-reported history of pre-morbid anxiety. When taken together, sex, age, and pre-morbid anxiety significantly predicted the length of time between injury and RTP clearance.

CONCLUSION

The GGT may identify individuals who are not ready to RTP despite a self-reported asymptomatic status and completion of all RTP steps. These results illustrate that RTP clearance decisions based on self-reported asymptomatic status at rest may be inadequate. Instead, monitored, intensive, sport-specific, physical exertion testing should be utilized to inform clinical RTP decisions.

Sensitivity of the Cogstate Test Battery for Detecting Prolonged Cognitive Alterations Stemming From Sport-Related Concussions

OBJECTIVE

To determine if the Cogstate test battery contains the requisite sensitivity to detect prolonged cognitive alterations.

METHODS

One hundred twenty collegiate athletes (71 with a history of concussion; 49 controls) completed the Cogstate test battery, to which we added a 2-back condition. In addition to the Cogstate clinical (transformed variables), we analyzed the raw data.

RESULTS

The clinical variables failed to reveal any group differences. Further, although the raw data failed to reveal group differences for tasks measuring lower-level cognition, group differences were observed for accuracy on the 1- and 2-back tasks, which require multiple aspects of higher cognition. The overall classification accuracy was higher using the raw data than the clinical variables. The combined sensitivity of the 1- and 2-back task was moderate and specificity was high.

CONCLUSIONS

These results suggest that using the raw scores over clinical variables increases the sensitivity of the test battery. Moreover, these results add another piece of evidence suggesting that concussive injuries are associated with subtle long-term alterations in aspects of higher cognition. Importantly, these deficits would have gone unobserved if we had relied solely on automated clinical variables. The current results further our scientific understanding of concussion and may be used to advance clinical practices.

Epidemiology of Head Injuries Focusing on Concussions in Team Contact Sports: A Systematic Review

BACKGROUND

Although injuries to the head represent a small proportion of all sport injuries, they are of great concern due to their potential long-term consequences, which are even suspected in mild traumatic brain injuries.

OBJECTIVE

The aim of this review was to compare the incidence of concussions and other head injuries in elite level football, rugby, ice hockey and American Football.

METHODS

Four electronic databases (CINAHL, PsycINFO, Web of Science, PubMed) were searched. Prospective cohort studies on the incidence of concussion in elite athletes aged 17 years or older that were published in an English-language peer-reviewed journal since 2000 were included. Two authors independently evaluated study eligibility and quality. The extracted data on concussions were pooled in a meta-analysis using an inverse-variance fixed-effects model. The extracted data on head injuries were reported in a narrative and tabular summary.

RESULTS

The search yielded 7673 results of which 70 articles were included in the qualitative and 47 in the quantitative analysis. In our meta-analysis, we found the highest concussion incidences in rugby match play (3.89 and 3.00 concussions per 1000 h and athletic exposures (AEs), respectively), and the lowest in men's football training (0.01 and 0.08 per 1000 h and AEs, respectively). Overall, concussions and all head injuries were rare in training when compared to match play. Female players had an increased concussion risk in football and ice hockey when compared to male players.

CONCLUSION

Future research should focus on concussion in women's contact sports, as there is little evidence available in this area. Methodological deficits are frequent in the current literature, especially regarding sample size and study power, and should be avoided.

Mild Traumatic Brain Injury in Adolescent Mice Alters Skull Bone Properties to Influence a Subsequent Brain Impact at Adulthood: A Pilot Study

Mild traumatic brain injuries (mTBI) are common during adolescence, and limited clinical evidence suggests that a younger age at first exposure to a mTBI may lead to worse long-term outcomes. In this study, we hypothesized that a mTBI during adolescence would predispose toward poorer neurobehavioral and neuropathological outcomes after a subsequent injury at adulthood. Mice received a mild weight drop injury (mTBI) at adolescence (postnatal day 35; P35) and/or at adulthood (P70). Mice were randomized to 6 groups: 'sham' (sham-surgery at P35 only); 'P35' (mTBI at P35 only); 'P35 + sham' (mTBI at P35 + sham at P70); 'sham + P70' (sham at P35 + mTBI at P70); 'sham + sham' (sham at both P35 and P70); or 'P35 + P70' (mTBI at both P35 and P70). Acute apnea and an extended righting reflex time confirmed a mTBI injury at P35 and/or P70. Cognitive, psychosocial, and sensorimotor function was assessed over 1-week post-injury. Injured groups performed similarly to sham controls across all tasks. Immunofluorescence staining at 1 week detected an increase in glial activation markers in Sham + P70 brains only. Strikingly, 63% of Sham + P70 mice exhibited a skull fracture at impact, compared to 13% of P35 + P70 mice. Micro computed tomography of parietal skull bones found that a mTBI at P35 resulted in increased bone volume and strength, which may account for the difference in fracture incidence. In summary, a single mTBI to the adolescent mouse brain did not exacerbate the cerebral effects of a subsequent mTBI in adulthood. However, the head impact at P35 induced significant changes in skull bone structure and integrity. These novel findings support future investigation into the consequences of mTBI on skull bone.

Repeated mild traumatic brain injury can cause acute neurologic impairment without overt structural damage in juvenile rats

Repeated concussion is becoming increasingly recognized as a serious public health concern around the world. Moreover, there is a greater awareness amongst health professionals of the potential for repeated pediatric concussions to detrimentally alter the structure and function of the developing brain. To better study this issue, we developed an awake closed head injury (ACHI) model that enabled repeated concussions to be performed reliably and reproducibly in juvenile rats. A neurological assessment protocol (NAP) score was generated immediately after each ACHI to help quantify the cumulative effects of repeated injury on level of consciousness, and basic motor and reflexive capacity. Here we show that we can produce a repeated ACHI (4 impacts in two days) in both male and female juvenile rats without significant mortality or pain. We show that both single and repeated injuries produce acute neurological deficits resembling clinical concussion symptoms that can be quantified using the NAP score. Behavioural analyses indicate repeated ACHI acutely impaired spatial memory in the Barnes maze, and an interesting sex effect was revealed as memory impairment correlated moderately with poorer NAP score performance in a subset of females. These cognitive impairments occurred in the absence of motor impairments on the Rotarod, or emotional changes in the open field and elevated plus mazes. Cresyl violet histology and structural magnetic resonance imaging (MRI) indicated that repeated ACHI did not produce significant structural damage. MRI also confirmed there was no volumetric loss in the cortex, hippocampus, or corpus callosum of animals at 1 or 7 days post-ACHI. Together these data indicate that the ACHI model can provide a reliable, high throughput means to study the effects of concussions in juvenile rats.

Epidemiological Patterns of Initial and Subsequent Injuries in Collegiate Football Athletes

BACKGROUND

A body of epidemiological studies has examined football injuries and associated risk factors among collegiate athletes. However, few existing studies specifically analyzed injury risk in terms of initial or subsequent injuries.

PURPOSE

To determine athlete-exposures (AEs) and rates of initial and subsequent injury among collegiate football athletes.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

Injury and exposure data collected from collegiate football players from two Division I universities (2007-2011) were analyzed. Rate of initial injury was calculated as the number of initial injuries divided by the total number of AEs for initial injuries, while the rate for subsequent injury was calculated as the number of subsequent injuries divided by the total number of AEs for subsequent injury. Poisson regression was used to determine injury rate ratio (subsequent vs initial injury), with adjustment for other covariates.

RESULTS

The total AEs during the study period were 67,564, resulting in an overall injury rate of 35.2 per 10,000 AEs. Rates for initial and subsequent injuries were 31.7 and 45.3 per 10,000 AEs, respectively, with a rate ratio (RR) of 1.4 for rate of subsequent injury vs rate of initial injury (95% CI, 1.1-1.9). Rate of injury appeared to increase with each successive injury. RR during games was 1.8 (95% CI, 1.1-3.0). The rate of subsequent injuries to the head, neck, and face was 10.9 per 10,000 AEs, nearly double the rate of initial injuries to the same sites (RR = 2.0; 95% CI, 1.1-3.5). For wide receivers, the rate of subsequent injuries was 2.2 times the rate of initial injuries (95% CI, 1.3-3.8), and for defensive linemen, the rate of subsequent injuries was 2.1 times the rate of initial injuries (95% CI, 1.1-3.9).

CONCLUSION

The method used in this study allows for a more accurate determination of injury risk among football players who have already been injured at least once. Further research is warranted to better identify which specific factors contribute to this increased risk for subsequent injury.

Repeat Concussion and Recovery Time in a Primary Care Pediatric Office

The authors enrolled 95 patients in a primary care office who presented with a concussion. Of these patients, 63% were sport concussions. The authors matched 90 of these patients to children in the authors' practice presenting for sports physicals or regular check-ups in the following demographics: age, participating in a particular sport, having attention-deficit disorder/attention-deficit hyperactivity disorder, gender, and grade. The authors found the odds of recurrent concussions, in a primary care pediatric office, to be a ratio of 2.909 (95% confidence interval 1.228-7.287). Recovery time for repeat concussion versus an initial concussion was analyzed. Patients with a recurrent concussion after a year recovered an average of 12.0 days after injury versus 13.4 days for those with no previous concussion (NS). Patients with a recurrent concussion within a year recovered a mean of 6.27 (SD 1.29) days sooner than patients with no previous concussion (P < .0001). This unexpected finding is preliminary, and the authors encourage further research.

English professional football players concussion knowledge and attitude

BACKGROUND

Concussions are a common pathology in football and multiple misconceptions exist amongst the players and managers. To address these misconceptions, and potentially reduce concussion associated sequela, effective educational interventions need to be developed. However, the current knowledge and attitude status must be ascertained to appropriately develop these interventions. The purpose of this study was to assess the concussion knowledge and attitude of English professional footballers.

METHODS

Twenty-six participants from one English Football League Championship club completed the study. A mixed methods approach included the Rosenbaum Concussion Knowledge and Attitudes Survey (RoCKAS) and a semi-structured interview. The RoCKAS contains separate knowledge (0-25) and attitude (15-75) scores and was followed by a semi-structured interview consisting of concussion knowledge, attitude, and behavior related questions.

RESULTS

The mean score on the RoCKAS knowledge was 16.4 ± 2.9 (range 11-22) and the attitude score was 59.6 ± 8.5 (range 41-71). The interview responses identified inconsistencies between the RoCKAS and the intended behaviors, endorsing multiple concussion misconceptions, and revealed barriers to concussion reporting.

CONCLUSION

The results of this study suggest that Championship Level English footballers have moderate concussion knowledge, safe attitudes, and good concussion symptom recognition when assessed with pen and paper questionnaires. However, within the semi-structured interview many respondents reported unsafe concussion behaviors despite accurately identifying the potential risks. Further, multiple barriers to concussion reporting were identified which included perceived severity of the injury, game situations, and the substitution rule. These findings can help form the foundation of educational interventions to potentially improve concussion reporting behaviors amongst professional footballers.

Postural control deficits identify lingering post-concussion neurological deficits

Concussion, or mild traumatic brain injury, incidence rates have reached epidemic levels and impaired postural control is a cardinal symptom. The purpose of this review is to provide an overview of the linear and non-linear assessments of post-concussion postural control. The current acute evaluation for concussion utilizes the subjective balance error scoring system (BESS) to assess postural control. While the sensitivity of the overall test battery is high, the sensitivity of the BESS is unacceptably low and, with repeat administration, is unable to accurately identify recovery. Sophisticated measures of postural control, utilizing traditional linear assessments, have identified impairments in postural control well beyond BESS recovery. Both assessments of quiet stance and gait have identified lingering impairments for at least 1 month post-concussion. Recently, the application of non-linear metrics to concussion recovery have begun to receive limited attention with the most commonly utilized metric being approximate entropy (ApEn). ApEn, most commonly in the medial-lateral plane, has successfully identified impaired postural control in the acute post-concussion timeframe even when linear assessments of instrumented measures are equivalent to healthy pre-injury values; unfortunately these studies have not gone beyond the acute phase of recovery. One study has identified lingering deficits in postural control, utilizing Shannon and Renyi entropy metrics, which persist at least through clinical recovery and return to participation. Finally, limited evidence from two studies suggest that individuals with a previous history of a single concussion, even months or years prior, may display altered ApEn metrics. Overall, non-linear metrics provide a fertile area for future study to further the understanding of postural control impairments acutely post-concussion and address the current challenge of sensitive identification of recovery.

Social norms theory and concussion education

Secondary prevention of harm from sport-related concussion is contingent on immediate removal from play post-injury. To-date, educational efforts to reduce the prevalent risk behavior of continued play while symptomatic have been largely ineffective. Social norms theory may hold promise as a foundation for more effective concussion education aimed at increasing concussion reporting. The primary objective of this study was to assess whether perceived team concussion reporting norms would be less supportive of an individual's safe concussion symptom reporting behavior than objective team norms. Participants were 328 male and female US collegiate athletes. Written surveys were completed in person during the spring of 2014. Among both male and female athletes, team concussion reporting norms were significantly misperceived, with athletes tending to think that they themselves have safer attitudes about concussion reporting than their teammates. Perceived norms were associated with symptom reporting intention, independent of the team's objective reporting norm. A social norms approach to concussion education, in which misperceived group norms are corrected and shifted in the direction of safety, is an important avenue for program development and evaluation research aimed at the secondary prevention of harm from concussion. Implications for the design of this type of educational programming are discussed.

Recognizing the Symptoms of Mental Illness following Concussions in the Sports Community: A Need for Improvement

OBJECTIVE

To evaluate the awareness of concussion-related symptoms amongst members of the sports community in Canada.

METHODS

A cross-sectional national electronic survey was conducted. Youth athletes, parents, coaches and medical professionals across Canada were recruited through mailing lists from sports-related opt-in marketing databases. Participants were asked to identify, from a list of options, the symptoms of a concussion. The proportion of identified symptoms (categorized as physical, cognitive, mental health-related and overall) as well as participant factors associated with symptom recognition were analyzed.

RESULTS

The survey elicited 6,937 responses. Most of the respondents (92.1%) completed the English language survey, were male (57.7%), 35-54 years of age (61.7%), with post-secondary education (58.2%), or high reported yearly household income (>$80,000; 53.0%). There were respondents from all provinces and territories with the majority of respondents from Ontario (35.2%) or British Columbia (19.1%). While participants identified most of the physical (mean = 84.2% of symptoms) and cognitive (mean = 91.2% of symptoms), they on average only identified 53.5% of the mental health-related symptoms of concussions. Respondents who were older, with higher education and household income, or resided in the Northwest Territories or Alberta identified significantly more of the mental health-related symptoms listed.

INTERPRETATION

While Canadian youth athletes, parents, coaches and medical professionals are able to identify most of the physical and cognitive symptoms associated with concussion, identification of mental health-related symptoms of concussion is still lagging.

Characteristics of Pediatric and Adolescent Concussion Clinic Patients With Postconcussion Amnesia

OBJECTIVE

The current study examines the demographics, injury characteristics, and outcomes associated with the presence of postconcussion amnesia in young concussion clinic patients.

DESIGN

Cross-sectional, retrospective clinical cohort.

SETTING

Concussion services clinic.

PATIENTS

Pediatric and adolescent concussion services program patients, presenting within 10 days postinjury, aged 10-18 years, with the goal of returning to sport (n = 245).

ASSESSMENT OF RISK FACTORS

Age, gender, race, head trauma history, injury mechanism, loss of consciousness (LOC), injury-related visit to an emergency department, cognitive and balance scores, symptoms, and management recommendations.

MAIN OUTCOME MEASURES

Univariate and multivariate analyses determined adjusted odds ratios for reported presence of any postconcussion amnesia (anterograde or retrograde).

RESULTS

Factors associated with amnesia (univariate, P < 0.10) and included in the multivariate model were race, head trauma history, mechanism of injury, LOC, injury-related visit to an emergency department, management recommendations and time of injury and initial visit symptom severity. Age and gender were also included in the model due to biological significance. Of the 245 patients, 181 had data for all model variables. Of the 181 patients, 58 reported amnesia. History of head trauma [odds ratio (OR), 2.7; 95% confidence interval (CI), 1.3-5.7]; time of injury (TOI) symptom severity >75th percentile (OR, 2.6; 95% CI, 1.2-5.3) and LOC (OR, 2.2; 95% CI, 1.1-4.6) were found to have significant and independent relationships with amnesia in the multivariate model.

CONCLUSIONS

This study illustrates that patients presenting with postconcussion amnesia are more likely to have a history of head trauma, LOC, and greater symptom severity. Future research is needed to better understand amnesia following concussion.

CLINICAL RELEVANCE

Amnesia presence, previous head trauma, LOC, and increased symptom severity may aid in identifying patients with a greater initial injury burden who warrant closer observation and more conservative management.

Engaging Teammates in the Promotion of Concussion Help Seeking

Concussion underreporting contributes to the substantial public health burden of concussions from sport. Teammates may be able to play an important role in encouraging injury identification and help seeking. This study assessed whether there was an association between beliefs about the consequences of continued play with a concussion and intentions to engage as a proactive bystander in facilitating or encouraging teammate help seeking for a possible concussion. Participants were 328 (male and female) members of 19 U.S. collegiate contact or collision sports teams. Athletes who believed that there were negative health or performance consequences of continued play with a concussion were significantly more likely than their peers to intend to encourage teammate help seeking, but not more likely to alert a coach or medical personnel. Additionally, athletes who believed that their teammates were more supportive of concussion safety were more likely to intend to engage as proactive bystanders in encouraging teammate help seeking. Exploring how to encourage bystander promotion of concussion safety is an important direction for future programming and evaluation research and may provide an opportunity to improve the effectiveness of concussion education.

Epidemiology of sports-related concussion in seven US high school and collegiate sports

BACKGROUND

The epidemiology of sports-related concussion is not well-described in the literature. This paper presents a descriptive epidemiology of concussion in seven high school and collegiate sports.

METHODS

We used the data from Concussion Prevention Initiative (CPI), which enrolled 8905 athletes at 210 high schools and 26 colleges in a prospective cohort study of 7 sports (football, men's and women's soccer, men's and women's lacrosse, and men's and women's ice hockey) between 1999 and 2001. Injury risks and injury rates were used to characterize the incidence of concussion, and changes in symptoms over time were described.

RESULTS

A total of 375 concussions were observed. The incidence of concussion was highest in football, followed by women's lacrosse, men's lacrosse, men's soccer, and women's soccer (only 10 ice hockey teams were included, too few to quantify incidence). The rate of incident concussion was strongly associated with history of concussion in the previous 24 months (rate ratio = 5.5; 95 %CI: 3.9, 7.8, for 2 or more concussions relative to no previous concussion). The most common symptoms at time of injury were headache (87 %), balance problems/dizziness (77 %), and feeling "in a fog" (62 %). Loss of consciousness and amnesia were present in relatively few cases (9 and 30 %). The most common mechanism of injury was collision with another player.

CONCLUSIONS

Sports-related concussions present with a diverse range of symptoms and are associated with previous concussion history.

Characterization of acute stress reaction following an IED blast-related mild traumatic brain injury

PRIMARY OBJECTIVE

To characterize an acute stress reaction (ASR) following an improvised explosive device (IED) blast-related mild traumatic brain injury (mTBI).

RESEARCH DESIGN

Participants were male, US military personnel treated in Afghanistan within 4 days following an IED-related mTBI event (n = 239).

METHODS AND PROCEDURES

Demographics, diagnosis of ASR, injury history and self-reported mTBIs, blast exposures and psychological health histories were recorded.

MAIN OUTCOMES AND RESULTS

In total, 12.5% of patients met ASR criteria. Patients with ASR were significantly younger and junior in rank (p < 0.05). Patients with ASR were more likely to experience the IED-blast while dismounted, report a loss of consciousness (LOC) and higher pain levels (p < 0.05). Adjusting for age and rank, multivariate logistic regression showed an association between mTBI history and ASR (AOR = 1.405; 95% CI = 1.105-1.786, p < 0.01). Adjusting for mechanism of injury (dismounted vs. mounted), LOC and pain, multivariate logistic regression showed an association between mTBI history and ASR (AOR = 1.453; 95% CI = 1.132-1.864, p < 0.01). Prior blast exposure and past psychological health issues were not associated with ASR.

CONCLUSIONS

A history of multiple mTBIs is associated with increased risk of ASR. Future research is warranted.

Repetitive concussions in adolescent athletes - translating clinical and experimental research into perspectives on rehabilitation strategies

Sports-related concussions are particularly common during adolescence, a time when even mild brain injuries may disrupt ongoing brain maturation and result in long-term complications. A recent focus on the consequences of repetitive concussions among professional athletes has prompted the development of several new experimental models in rodents, as well as the revision of guidelines for best management of sports concussions. Here, we consider the utility of rodent models to understand the functional consequences and pathobiology of concussions in the developing brain, identifying the unique behavioral and pathological signatures of concussive brain injuries. The impact of repetitive concussions on behavioral consequences and injury progression is also addressed. In particular, we focus on the epidemiological, clinical, and experimental evidence underlying current recommendations for physical and cognitive rest after concussion, and highlight key areas in which further research is needed. Lastly, we consider how best to promote recovery after injury, recognizing that optimally timed, activity-based rehabilitative strategies may hold promise for the adolescent athlete who has sustained single or repetitive concussions. The purpose of this review is to inform the clinical research community as it strives to develop and optimize evidence-based guidelines for the concussed adolescent, in terms of both acute and long-term management.

Repetitive mild traumatic brain injury induces ventriculomegaly and cortical thinning in juvenile rats

Traumatic brain injury (TBI) most frequently occurs in pediatric patients and remains a leading cause of childhood death and disability. Mild TBI (mTBI) accounts for nearly 75% of all TBI cases, yet its neuropathophysiology is still poorly understood. While even a single mTBI injury can lead to persistent deficits, repeat injuries increase the severity and duration of both acute symptoms and long-term deficits. In this study, to model pediatric repetitive mTBI (rmTBI) we subjected unrestrained juvenile animals (postnatal day 20) to repeat weight-drop impacts. Animals were anesthetized and subjected to sham injury or rmTBI once per day for 5 days. Magnetic resonance imaging (MRI) performed 14 days after injury revealed marked cortical atrophy and ventriculomegaly in rmTBI animals. Specifically, beneath the impact zone the thickness of the cortex was reduced by up to 46% and the area of the ventricles increased by up to 970%. Immunostaining with the neuron-specific marker NeuN revealed an overall loss of neurons within the motor cortex but no change in neuronal density. Examination of intrinsic and synaptic properties of layer II/III pyramidal neurons revealed no significant difference between sham-injured and rmTBI animals at rest or under convulsant challenge with the potassium channel blocker 4-aminopyridine. Overall, our findings indicate that the neuropathological changes reported after pediatric rmTBI can be effectively modeled by repeat weight drop in juvenile animals. Developing a better understanding of how rmTBI alters the pediatric brain may help improve patient care and direct "return to game" decision making in adolescents.

Factors Influencing Risk and Recovery from Sport-Related Concussion: Reviewing the Evidence

Identifying factors that influence the risk and recovery from sport-related concussion (SRC) has become an important part of the clinical management of the injury. Consensus statements and clinical anecdotes have suggested several factors (i.e., history of migraine headaches) that may increase risk or lead to a protracted recovery from SRC. In the current paper, we will present evidence supporting primary and secondary risk factors listed in current consensus statements and relevant literature on emerging factors proposed to influence SRC risk and recovery.

Examining Neurocognitive Function in Previously Concussed Interscholastic Female Soccer Players

Awareness of sport-related concussions in soccer has gained recent attention in the medical community. Interestingly, purposeful heading-a unique yet strategic and inherent part of soccer-involves repeated subconcussive blows to the head. We divided 210 female interscholastic soccer players into control (CON [never concussed]) and experimental (EXP [previously concussed]) groups. We assessed neurocognitive performance using the Automated Neuropsychological Assessment Metrics computer program before and after the players' competitive season. Headers were recorded at all sanctioned matches. Data were analyzed using a series of one-way analyses of covariance and t tests. Both groups essentially played in the same number of games (EXP = 16.1 vs. CON = 16.1) and had an equal number of total headers (EXP = 24.9 vs. CON = 24.3). Additionally, headers per game were surprisingly low in both groups (1.4 in EXP vs. 1.3 in CON). Unexpectedly, there were no significant differences between the EXP and CON groups across all dependent variables measured (p > .05). This study suggests that although previously concussed players involve themselves in purposeful heading (i.e., subconcussive insults) throughout a competitive season, there appear to be no negative consequences on neuropsychological test performance or concussion-related symptoms. Additional research is needed to determine what may result during the course of a playing career.

Canadian Minor Hockey Participants’ Knowledge about Concussion

Background and Objectives:

In Canada and the USA, ice hockey is a cause of traumatic brain injury. Post-concussive symptoms are the most important feature of the diagnosis of concussion in sports and it is recommended that athletes not return to play while still symptomatic. Lack of knowledge of concussions could therefore be one of the main detriments to concussion prevention in hockey. The purpose of this research is to describe what minor league hockey players, coaches, parents and trainers know about concussion and its management.

Methods:

A questionnaire to assess concussion knowledge and return to play guidelines was developed and administered to players at different competitive levels (n = 267), coaches, trainers and parents (total adults n = 142) from the Greater Toronto Area.

Results:

Although a majority of adults and players could identify mechanisms responsible for concussion, about one-quarter of adults and about a quarter to a half of children could not recall any symptoms or recalled only one symptom of a concussion. A significant number of players and some adults did not know what a concussion was or how it occurred. Almost half of the players and a fifth of the adults incorrectly stated that concussion was treated with medication or physical therapy. Nearly one quarter of all players did not know if an athlete experiencing symptoms of concussion should continue playing.

Conclusions:

This study demonstrated that a significant number of people held misconceptions about concussion in hockey which could lead to serious health consequences and creates a need for better preventive and educational strategies.

Effects of Two Concussions on the Neuropsychological Functioning and Symptom Reporting of High School Athletes

To assess the effects of two sports-related concussions on neuropsychological functioning and symptom reporting, the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) was administered to 483 high school athletes. Three groups of athletes were determined based on the number of previous concussions: no concussion (n = 409), 1 concussion (n = 58), and 2 concussions (n = 16). The results showed that the three groups did not differ in terms of their ImPACT composite scores (Verbal Memory, Visual Memory, Reaction Time, and Processing Speed) and the Total Symptom Score. As there are only a few studies that have reported the sequelae of 2 concussions in high school athletes, it is premature to declare that a repeated concussion does not have persistent neurocognitive effects on high school athletes.

Adult cognitive ability and educational level in relation to concussions in childhood and adolescence: a population study of young men

OBJECTIVE

To investigate the relationship of concussion(s) suffered through childhood and adolescence with completed level of school education and cognitive ability in young adulthood.

METHODS

Educational level and scores on a test of cognitive ability were obtained for a cohort of 130,298 young men processed by the Danish draft board. Of these, 6146 had, at some age from birth onwards, been briefly admitted to hospital with a main discharge diagnosis of concussion. A further 402 had two such concussions and 48 had three or more.

RESULTS

Educational level and cognitive ability test scores were negatively associated with the number of concussions and the age at concussion(s). Most markedly, compared to the 123,684 non-concussed men, those with two or more concussions had lower educational levels (OR = 0.48; 95% CI = 0.26-0.89), as also did those sustaining one concussion between the age of 13 up to the time of testing (OR = 0.47: 0.42-0.52).

CONCLUSIONS

Since concussions do not generally have long-term effects, the results suggest that lower educational level is primarily a risk factor for sustaining a concussion at all ages, but in particular in adolescence more than in childhood and in the case of multiple concussions. It should, however, be recognized that, in some proportion of cases, the educational deficits have probably arisen as a consequence of the persistent symptoms of a lengthy post-concussional syndrome.