A systematic review of potential long-term effects of sport-related concussion

A Clinicopathological Report of a 93-Year-Old Former Street Boxer With Coexistence of Chronic Traumatic Encephalopathy, Alzheimer's Disease, Dementia With Lewy Bodies, and Hippocampal Sclerosis With TDP-43 Pathology

Chronic traumatic encephalopathy (CTE) was recently recognized as a new tauopathy in which multifocal perivascular phosphorylated tau aggregates accumulate in neurons, astrocytes, and neurites at the depths of the cortical sulci. Traumatic brain injury (TBI) in early or mid-life is known to be associated with an increased risk of dementia in late life. This case report describes a 93-year-old former street boxer with a premortem diagnosis of severe dementia, who showed pathological evidence of the coexistence of Alzheimer's disease, CTE, dementia with Lewy bodies, and hippocampal sclerosis with TDP-43 pathology. These findings suggest that TBI may trigger a variety of misfolded proteins leading to dementia. Currently, clear clinical diagnostic criteria for CTE have not been established. Therefore, clinicians should be aware that TBI is a risk factor for dementia and that CTE can overlap with other neurodegenerative diseases.

Integrated Stress Response Inhibitor Reverses Sex-Dependent Behavioral and Cell-Specific Deficits after Mild Repetitive Head Trauma

Mild repetitive traumatic brain injury (rTBI) induces chronic behavioral and cognitive alterations and increases the risk for dementia. Currently, there are no therapeutic strategies to prevent or mitigate chronic deficits associated with rTBI. Previously we developed an animal model of rTBI that recapitulates the cognitive and behavioral deficits observed in humans. We now report that rTBI results in an increase in risk-taking behavior in male but not female mice. This behavioral phenotype is associated with chronic activation of the integrated stress response and cell-specific synaptic alterations in the type A subtype of layer V pyramidal neurons in the medial prefrontal cortex. Strikingly, by briefly treating animals weeks after injury with ISRIB, a selective inhibitor of the integrated stress response (ISR), we (1) relieve ISR activation, (2) reverse the increased risk-taking behavioral phenotype and maintain this reversal, and (3) restore cell-specific synaptic function in the affected mice. Our results indicate that targeting the ISR even at late time points after injury can permanently reverse behavioral changes. As such, pharmacological inhibition of the ISR emerges as a promising avenue to combat rTBI-induced behavioral dysfunction.

Sports career-related concussion and mental health symptoms in former elite athletes

BACKGROUND

In elite sports, concussion is common and recurrent, especially in high-speed contact or collision sports such as american and australian football, ice hockey and rugby. Mental health symptoms (e.g., anxiety, depression, sleep disturbance) are often reported by former elite athletes, with prevalence ranging from 16% for distress to 26% for anxiety/depression. This article focuses on the potential relationship between sports career-related concussion and mental health symptoms in former elite athletes.

METHOD

A narrative mini-review was based on the scientific literature.

RESULTS

Some literature based on cross-sectional data suggests that sports career-related concussion might lead in the long term to mental health symptoms in former elite athletes. Retired professional American football players reporting three or more previous concussions were found to be three times more likely to be diagnosed with depression than those with no history of concussion. Former professional athletes from football, ice hockey and rugby who reported a history of six or more concussions were approximately up to five times more likely to report mental health symptoms.

CONCLUSIONS

While longitudinal evidence about any causal relationship is lacking, the suggested relationship between sports career-related concussion and mental health symptoms in former elite athletes warrants the development of support measures for elite athletes transitioning out of sport, especially for those with a history of concussion.

History of Sport-Related Concussion and Long-Term Clinical Cognitive Health Outcomes in Retired Athletes: A Systematic Review

BACKGROUND

Sport-related concussions (SRCs) are known to have short-term effects on cognitive processes, which can result in diverse clinical presentations. The long-term effects of SRC and repeated exposure to head impacts that do not result in SRC on specific cognitive health outcomes remain unclear.

OBJECTIVES

To synthesize and appraise the evidence base regarding cognitive health in living retired athletes with a history of head-impact exposure or SRC.

DATA SOURCES

A systematic search of the EMBASE, PsycINFO, MEDLINE/PubMed, CINAHL, Cochrane Central Register of Controlled Trials, and Web of Science databases was conducted from inception to April 2018 using common key words and medical subject headings related to 3 components: (1) the participant (eg, retired athlete), (2) the primary outcome measure (eg, cognitive test used), and (3) the secondary outcome measure (eg, history of sport concussion).

STUDY SELECTION

Cross-sectional studies of living retired male or female athletes in which at least 1 cognitive test was used as an outcome measure were included. Two reviewers independently screened studies.

DATA EXTRACTION

Data extraction was performed using Strengthening the Reporting of Observational Studies in Epidemiology guidelines. Methodologic quality was assessed independently by 2 reviewers using the Downs and Black tool.

DATA SYNTHESIS

The search yielded 46 cross-sectional observational studies that were included in a qualitative synthesis. Most included studies (80%, n = 37) were published in the 5 years before our review. A large proportion of these studies (n = 20) included retired American National Football League players. The other research investigated professional, university, high school, and amateur retired athletes participating in sports such as American and Australian football, boxing, field and ice hockey, rugby, and soccer. The total sample consisted of 13 975 participants: 7387 collision-sport athletes, 662 contact-sport athletes, 3346 noncontact-sport athletes, and 2580 participants classified as controls. Compared with control participants or normative data, retired athletes displayed worse performance in 17 of 31 studies (55%) of memory, 6 of 11 studies (55%) of executive function, and 4 of 6 studies (67%) of psychomotor function and increased subjective concerns about cognitive function in 11 of 14 studies (79%). The authors of 13 of 46 investigations (28%) reported a frequency-response relationship, with poorer cognitive outcomes in athletes who had greater levels of exposure to head impacts or concussions. However, these results must be interpreted in light of the lack of methodologic rigor and moderate quality assessment of the included studies.

CONCLUSIONS

Evidence of poorer cognitive health among retired athletes with a history of concussion and head-impact exposure is evolving. Our results suggest that a history of SRC may more greatly affect the cognitive domains of memory, executive function, and psychomotor function. Retired athletes appeared to have increased self-reported cognitive difficulties, but the paucity of high-quality, prospective studies limited the conclusions that could be drawn regarding a cause-and-effect relationship between concussion and long-term health outcomes. Future researchers should consider a range of cognitive health outcomes, as well as premorbid ability, in diverse samples of athletes with or without a history of concussion or head-impact exposure to delineate the long-term effects of sport participation on cognitive functioning.

Cerebral white matter lacerations in children caused by repetitive head trauma

It has been known that infants less than 1 year develop cerebral white matter (WM) lacerations associated with head trauma, however, there has been no report of similar WM lesions over 1 year. We report three teenage boys (11, 12, and 18 years at final MRI studies) with acquired WM lacerations associated with recurrent head trauma who developed neurologic symptoms such as spastic paralysis, afebrile convulsions, and cognitive impairment. Two of them (patients 1 and 2) were given a diagnosis of autism spectrum disorder and had a history of repeated severe self-inflicted head trauma from preschool age. Patient 3, who practiced karate and boxing from preschool age, showed gradual declining intellectual ability. Brain MRI of the three patients revealed severe lacerations in the bilateral cerebral WM. Previous neuroimaging showed no WM lacerations at 4 and 5 years in patients 1 and 2, or mild WM lacerations at 17 years in patient 3, indicating the WM lacerations could have been acquired in childhood. It is suggested that repetition of head trauma in children can cause cerebral WM lacerations and brain dysfunction.

Characterizing the Link Between Glial Activation and Changed Functional Connectivity in National Football League Players Using Multimodal Neuroimaging

OBJECTIVE

The primary objective of this preliminary study was to examine the impact of NFL play on interregional functional connectivity between two brain regions, the supramarginal gyrus (SMG) and the thalamus, identified as having higher binding of [¹¹C]DPA-713 in NFL players. The authors' secondary objective was to examine the effect of years since play on the interregional connectivity.

METHODS

Resting-state functional MRI was used to examine functional brain changes between regions with evidence of past injury in active or recently retired NFL players (defined as ≤12 years since NFL play) and distantly retired players (defined as >12 years since NFL play). Age-comparable individuals without a history of concussion or participation in collegiate or professional collision sports were included as a control group.

RESULTS

Compared with healthy control subjects, NFL players showed a loss of anticorrelation between the left SMG and bilateral thalami (mean z score=-2.434, p=0.015). No difference was observed when examining right SMG connectivity. The pattern of connectivity in active and recently retired players mimicked the pattern observed in distantly retired players and older control subjects.

CONCLUSIONS

Further study of the clinical significance of this altered pattern of interregional connectivity in active and recently retired NFL players is needed.

Exploring Traumatic Brain Injuries and Aggressive Antisocial Behaviors in Young Male Violent Offenders

Background: Traumatic brain injury (TBI) is a major cause of disabilities and mortality worldwide, with higher prevalence in offender populations than in the general population. Previous research has strongly advocated increased awareness of TBI in offender populations. The aim of this study was to explore the prevalence and characteristics of TBI, and to investigate associations and interactions between TBI, aggressive antisocial behaviors, general intellectual functioning, and substance use disorders (SUD) in a well-characterized group of young violent offenders. Methods: The study investigated a cohort (n = 269) of 18 to 25-year-old male violent offenders in Sweden. Data on TBI (files + self-report), aggressive antisocial behaviors (Life History of Aggression), SUD (clinical interviews), and general intellectual functioning (General Ability Index, Wechsler Adult Intelligence Scales Third Edition) were collected between 2010 and 2012. Parametric (Student's t-test) and non-parametric (Mann-Whitney U-test, Spearman's rho, χ², Kruskal Wallis test) inferential statistics were applied and effect sizes reported. Results: TBI, both with and without loss of consciousness, was common, with 77.5% of the offenders reporting having suffered at least one TBI during their lifetime. TBI was associated with an increased occurrence of aggressive antisocial behaviors and SUD, and offenders with both TBI and SUD evidenced the largest amount of aggressive antisocial behaviors. No clinically meaningful associations were found between TBI and general intelligence. Effect sizes were in the small to medium range. Conclusions: Our study confirms an increased prevalence of TBI among young violent offenders compared to the general population, as well as associations between TBI, aggressive antisocial behaviors, and SUD. However, it provides no information on the severity of the TBI, nor on the causality of the demonstrated associations. Nevertheless, TBI, and possible related deficits, need to be considered in the assessment and treatment of young violent offenders.

The Effect of Sport-Related Concussion Injuries on Concussion Symptoms and Health-Related Quality of Life in Male and Female Adolescent Athletes: A Prospective Study

BACKGROUND

Sport-related concussions (SRCs) are associated with short-term disablement, characterized as increased concussion symptoms and lower health-related quality of life (HRQoL). However, there are limited longitudinal data detailing how an SRC affects disablement beyond short-term injury recovery.

PURPOSE

To longitudinally assess the effect of SRCs on symptoms and HRQoL in high school athletes through the 12 months after injury.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The 125 participants included high school athletes who sustained an SRC (female patients, 36%; mean ± SD age, 15.9 ± 1.1 years). The Post-concussion Symptom Scale (PCSS) from the Sport Concussion Assessment Tool-3 and the Pediatric Quality of Life Inventory 4.0 (PedsQL) were completed at enrollment and repeated at 24 to 72 hours (onset) and at 7 days (D7) after the SRC; on the date of return to play (RTP); and at 3, 6, and 12 months (M12) after the SRC. Scores at each time point were compared with the athletes' own baseline via linear mixed models for repeated measures, controlling for age, sex, and history of previous SRC and with patient as a random effect.

RESULTS

Relative to baseline, female patients reported higher PCSS symptom and severity scores at onset (P < .001) and D7 (P < .001), while scores were not higher (P > .05) for RTP through M12. As compared with baseline, male patients reported higher PCSS scores at onset (P < .001) and D7 (P = .003) and severity scores at onset (P < .001) and D7 (P = .016), while the symptom and severity scores were not higher (P > .05) at RTP through M12. Female participants reported lower PedsQL physical scores at onset (P = .006), while scores were not lower (P > .05) from D7 through M12. Female psychosocial scores were not lower (P > .05) at any time after the SRC, while the total PedsQL score was lower at onset (P = .05) but not from D7 through M12. Male physical scores were lower at onset (P < .001) and D7 (P = .001) but not lower (P > .05) from RTP through M12. Male psychosocial and PedsQL scores were unchanged (P > .05) from baseline at onset through M12.

CONCLUSION

After an SRC, high school athletes reported initial disablement (increased symptoms and lower HRQoL) through their RTP. However, after RTP, no similar disablement was detected through 12 months after injury.

Surfing-related head injuries presenting to United States emergency departments

This study examined the incidence and trends of surfing-related and mild traumatic brain injuries that presented to United States emergency departments between 2001 and 2016. Subjects with surging-related head injuries were retrieved from the National Electronic Injury Surveillance System. A weighted total of 34,337 surfing-related head injuries were identified. The annual incidence of surfing-related head injuries insignificantly decreased from 2001 to 2016 (R² = .119; p = .19). Most common injuries included lacerations (50.4%), blunt head injuries (25.7%), and mild traumatic brain injuries (16.1%). Mild traumatic brain injury incidence and annual percentage increased significantly during the study period (R² = .251; p = .05 and R² = .346; p = .02, respectively).

Sports Medicine Update: Concussion

A systematic approach is required for patients with a suspected concussion. Although standardized tools can aid in assessment, the diagnosis of concussion remains a clinical one. At the time of diagnosis, patients should be given both verbal and written review of the common symptoms of concussion, expected course of recovery, as well as strategies to manage symptoms. Most patients benefit from a brief period of rest, followed by a gradual reintroduction of activities, and a graduated return-to-sport protocol. Patients with prolonged recovery from a concussion may benefit from exercise, vestibular, and cognitive rehabilitation programs.

Multiple Concussions Increase Odds and Rate of Lower Extremity Injury in National Collegiate Athletic Association Athletes After Return to Play

BACKGROUND

Concussion in collegiate athletics is one of the most prevalent sport-related injuries in the United States, with recent studies suggesting persistent deficits in neuromuscular control after a concussion and an associated increase in risk of lower extremity injury.

PURPOSE

To expand on the relationship between concussion and lower extremity injury by examining the effect of multiple concussions (MC) on rate and odds of future lower extremity injury in collegiate athletes after return to play (RTP) compared with matched controls.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

From 2001 to 2016, 48 National Collegiate Athletic Association Division I athletes sustaining multiple concussions at a single institution were identified. Athletes with multiple concussions (MC) were matched directly to athletes with a single concussion (SC) and to athletes with no concussion history (NC) by sex, sport, position, and games played. Incidence of, time to, and location of lower extremity injury were recorded for each group after RTP from their first reported concussion until completion of their collegiate career. Logistic regression was used to analyze odds ratios (ORs) for sustaining lower extremity injury, whereas time to injury was summarized by use of Kaplan-Meier curves and log rank test analysis.

RESULTS

The incidence of lower extremity injury after RTP was significantly greater (P = .049) in the MC cohort (36/48, 75%) than in SC athletes (25/48 = 52%) and NC athletes (27/48 = 56%). Similarly, odds of lower extremity injury were significantly greater in the MC cohort than in SC athletes (OR, 3.00; 95% CI, 1.26-7.12; P = .01) and NC athletes (OR, 1.66; 95% CI, 1.07-2.56; P = .02). Time to lower extremity injury was significantly shorter in the MC group compared with matched controls (P = .01). No difference was found in odds of lower extremity injury or time to lower extremity injury between SC and NC athletes.

CONCLUSION

Collegiate athletes with MC were more likely to sustain a lower extremity injury after RTP in a shorter time frame than were the matched SC and NC athletes. This may suggest the presence of a cohort more susceptible to neuromuscular deficits after concussion or more injury prone due to player behavior, and it may imply the need for more stringent RTP protocols for athletes experiencing MC.

Considerations for Diagnosis and Management of Concussion

Concussion is an ongoing concern for health care providers. The incidence rates continue to be high and the rate of recovery is variable due to potential risk factors. With no valid biomarkers, diagnosis and assessment of concussion remain a clinical challenge. The heterogeneity in presentation following injury provides an additional level of complexity, requiring the screening and evaluation of diverse body systems, including oculomotor, vestibular, autonomic, psychiatric, cervical, and cognitive symptoms. While a few tools, such as the Vestibular/Ocular Motor Screening and Balance Error Scoring System, have been developed specifically for concussion, the vast majority of tests are adapted from other conditions. Further complicating the process is the overlapping and interactive nature of the multiple domains of postconcussion presentation. This commentary illustrates how clinicians can conceptualize the multiple profiles that present following concussion and describes tools that are available to assist with screening and evaluation of each area. The multifaceted nature of concussion warrants broad clinical screening skills and an interdisciplinary approach to management. J Orthop Sports Phys Ther 2019;49(11):787-798. doi:10.2519/jospt.2019.8855.

Football Increases Future Risk of Symptomatic Radiographic Knee Osteoarthritis

INTRODUCTION

Male youth in the United States commonly participate in gridiron (American) football. There are little data substantiating current popular opinion that it is associated with knee pain or osteoarthritis (OA) later in life. We aimed to evaluate the relationship of football with these outcomes in the Osteoarthritis Initiative (OAI).

METHODS

This is a study of male OAI participants with knee x-ray readings, symptom assessments, and completed surveys on lifetime physical activity. The OAI is a multicenter, observational cohort recruited from the community not based on football participation status. A history of exposure to American football was ascertained via self-report. Knee radiographs were scored for Kellgren-Lawrence grade (0-4). Radiographic OA (ROA) was defined as Kellgren-Lawrence ≥ 2 in at least one knee. Frequent knee pain meant at least one knee with frequent knee pain. Symptomatic ROA required at least one knee with both ROA and frequent knee pain.

RESULTS

A total of 1166 men had a mean age of 63.7 (SD, 9.2) yr and body mass index of 28.6 (SD, 4.2) kg·m. Thirty-one percent (365/1166) played football at some point in their lives, 95% of whom participated from ages 12 to 18 yr. The ORs for symptomatic ROA from the lowest to highest football participation were 1.2, 1.5, and 2.2, respectively (P for trend = 0.004). Findings were similar for football from ages 12 to 18 yr and for outcomes of knee pain and ROA.

CONCLUSION

This is the first large epidemiologic study to suggest that football participation, including in the teen years, may be detrimental toward knee health. Prospective studies evaluating football players are warranted.

Mapping brain recovery after concussion: From acute injury to 1 year after medical clearance

OBJECTIVE

To test the hypothesis that concussion-related brain alterations seen at symptomatic injury and medical clearance to return to play (RTP) will have dissipated by 1 year after RTP.

METHODS

For this observational study, 24 athletes with concussion were scanned longitudinally within 1 week after injury, at RTP, and 1 year after RTP. A large control cohort of 122 athletes were also scanned before the season. Each imaging session assessed global functional connectivity (Gconn) and cerebral blood flow (CBF), along with white matter fractional anisotropy (FA) and mean diffusivity (MD). The main effects of concussion on MRI parameters were evaluated at each postinjury time point. In addition, covariation was assessed between MRI parameters and clinical measures of acute symptom severity and time to RTP.

RESULTS

Different aspects of brain physiology showed different patterns of recovery over time. Both Gconn and FA displayed no significant effects at 1 year after RTP, whereas CBF and MD exhibited persistent long-term effects. The effects of concussion on MRI parameters were also dependent on acute symptom severity and time to RTP for all postinjury time points.

CONCLUSION

This study provides the first longitudinal evaluation of concussion focused on time of RTP and 1 year after medical clearance, using multiple different MRI measures to assess brain structure and function. These findings significantly enhance our understanding of the natural course of brain recovery after a concussion.

Preventive potential of low intensity pulsed ultrasound for chronic traumatic encephalopathy after repetitive head collisions in contact sports

Chronic traumatic encephalopathy (CTE), a disease process well-recognized in boxers, American football players and military personnel, is a progressive neurodegenerative disease caused by repetitive blows to the head. Subjects with CTE can have a wide range of emotional, cognitive and physical symptoms. The cognitive group patients had a significantly higher probability of developing dementia in later years. Currently, there are no disease modifying regimen for CTE. Timely intervention of head blow could diminish the development of CTE. Low-intensity pulsed ultrasound (LIPUS) is a common adjunct used to promote bone healing for fresh fracture. Recent reports suggest that LIPUS can noninvasively modulate the cortical function and have neuroprotective effect in various animal models of traumatic brain injury, stroke, Alzheimer's disease and major depressive disorder. The multifunctional mechanisms of LIPUS neuroprotective effect include several trophic factor stimulations, anti-inflammatory properties and reduction of brain edema. From the above evidence, LIPUS intervention could be a strategy for the prevention of the clinical CTE sequelae of repetitive head blows. We hypothesized that due to its neuroprotective effects, the non-invasive and easy-to-use method of LIPUS brain stimulation could have a preventive effect on players who have head blows during the match. The development of a time sensitive protocol, resembling the therapeutic algorithm for traumatic brain injury, would potentially prevent the development of subsequent CTE adverse outcome. Further long-term longitudinal studies of LIPUS stimulation are warranted to verify the prevention efficacy of this intervention for CTE.

Association of Adolescent Sport Participation With Cognition and Depressive Symptoms in Early Adulthood

Background:

Recent studies have associated sport-related concussion with depression and impaired cognitive ability later in life in former professional football players. However, population studies with two 1950s-era cohorts did not find an association between high school football participation and impaired cognition or depressive symptoms in late adulthood.

Purpose/Hypothesis:

This study assessed whether actual/intended participation in contact sports during adolescence had an adverse effect on participants’ cognition or depressive symptoms in early adulthood. We hypothesized that there would not be an association.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

This study used a subsample (n = 10,951) from the National Longitudinal Study of Adolescent to Adult Health (Add Health), a nationally (United States) representative prospective cohort study following participants through 4 waves of data collection from 1994 through 2008. Participants were categorized as actual/intended participation in no sports, noncontact sports only, and contact sports. We constructed 6 multivariate and logistic regression models predicting word recall, number recall, modified Center for Epidemiologic Studies Depression Scale, depression diagnosis, suicide ideation, and suicide attempts at wave IV as a function of sport participation during wave I. Sport participation was treated as a factor with the referent category noncontact sports. This analysis was repeated on a males-only sample (n = 5008). In the males-only analysis, participants were classified as actual/intended participation in no sports, noncontact sports, contact sports other than American football, and American football. The referent category remained noncontact sports.

Results:

Intention to participate in contact sports was not significantly associated with any of the outcomes in the full-sample analysis. Intention to participate in football was significantly associated with a reduced odds of depression diagnosis in adulthood (odds ratio, 0.70; P = .02) when compared with noncontact sports participation in the males-only sample. Football was not significantly associated with impaired cognitive ability, increased depressive symptoms, or increased suicide ideation.

Conclusion:

Actual/intended participation in contact sports during adolescence did not adversely affect Add Health participants’ cognition or depressive symptoms in young adulthood.

Estimated Age of First Exposure to Contact Sports Is Not Associated with Greater Symptoms or Worse Cognitive Functioning in Male U.S. Service Academy Athletes

This study examined the association between estimated age of first exposure (eAFE) to contact sport participation and neurocognitive performance and symptom ratings in U.S. service academy National Collegiate Athletic Association (NCAA) athletes. Male cadets (N = 891), who participate in lacrosse (n = 211), wrestling (n = 170), ice hockey (n = 81), soccer (n = 119), rugby (n = 10), or non-contact sports (n = 298), completed the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test before the season. Generalized linear modeling was used to predict each neurocognitive domain score and total symptom severity score. Predictor variables were entered in the following order: group (contact vs. non-contact); eAFE (eAFE <12 years vs. eAFE ≥12 years); group-by-eAFE; and covariates for learning accommodation status, concussion history, and age. The group-by-eAFE interaction was not significant for any of the ImPACT composite scores (Verbal Memory, Wald χ² = 0.073, p = 0.788; Visual Memory, Wald χ² = 2.71, p = 0.100; Visual Motor Speed, Wald χ² = 0.078, p = 0.780; Reaction Time, Wald χ² = 0.003, p = 0.955; Symptom Severity, Wald χ² = 2.87, p = 0.090). Learning accommodation history was associated with lower scores on Visual Motor Speed (χ² = 6.19, p = 0.013, B = -2.97). Older age was associated with faster reaction time (χ² = 4.40, p = 0.036, B = -0.006) and lesser symptom severity (χ² = 5.55, p = 0.019, B = -0.068). No other parameters were significant. We observed no association between eAFE, contact sport participation, neurocognitive functioning, or subjectively experienced symptoms in this cohort. Earlier eAFE to contact sport participation is not related to worse neurocognitive performance or greater subjectively experienced symptoms in male U.S. service academy NCAA athletes.

Brain vital signs detect concussion-related neurophysiological impairments in ice hockey

There is a growing demand for objective evaluations of concussion. We developed a portable evoked potential framework to extract ‘brain vital signs’ using electroencephalography. Brain vital signs were derived from well established evoked responses representing auditory sensation (N100), basic attention (P300), and cognitive processing (N400) amplitudes and latencies, converted to normative metrics (six total). The study evaluated whether concussion-related neurophysiological impairments were detected over the duration of ice hockey seasons using brain vital signs. Forty-seven Tier III, Junior A, male ice hockey players were monitored over two seasons. Twelve sustained concussions after baseline testing then completed post-injury and return-to-play assessments. Twenty-three were not diagnosed with a concussion during the season and completed both baseline and post-season testing. Scores were evaluated using a repeated-measures analysis of variance with post hoc two-tailed paired t-tests. Concussion resulted in significantly increased amplitude and delayed latency scores for all six brain vital signs (P < 0.0001). Importantly, significant changes at return-to-play were also detected in basic attention (P300) amplitude, indicating persistent subclinical impairment. In the non-concussed group, there was also a significant change between baseline and post-season (P = 0.0047), with specific decreases in cognitive processing (N400) speed (P = 0.011) and overall total score (P = 0.002).

Chronic Traumatic Encephalopathy and Neurodegeneration in Contact Sports and American Football

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease characterized by the presence of abnormally phosphorylated tau protein in the depths of one or more cortical sulci. Controversy over the risk of CTE and neurologic disorders later in life among contact sport athletes has taken hold in the public spotlight, most notably in American football. Players, parents, coaches, and legislators have taken action based on the commonly held notion that contact sports invariably lead to neurodegenerative disorders. However, to fully understand the science behind this assumed association, a critical appraisal of the evidence is warranted. With regards to CTE in sports, the objectives of the current report are to: 1) describe the history of CTE, 2) review current CTE definitions, 3) critically evaluate the empiric data, divided into all contact sports and exclusively American football, and 4) summarize notable themes for future research.

Long-Term Cognitive Performance of Retired Athletes with Sport-Related Concussion: A Systematic Review and Meta-Analysis

Objective: The purpose of this systematic review is to quantitatively estimate (or invest) the impacts of sports-related concussions (SRCs) on cognitive performance among retired athletes more than 10 years after retirement. Methods: Six databases including (MEDLINE, Scopus, Web of Science, SPORTDiscus, CINAHL, and PsycArtilces) were employed to retrieve the related studies. Studies that evaluate the association between cognitive function and the SRC of retired athletes sustaining more than 10 years were included. Results: A total of 11 studies that included 792 participants (534 retired athletes with SRC) were identified. The results indicated that the retired athletes with SRCs, compared to the non-concussion group, had significant cognitive deficits in verbal memory (SMD = -0.29, 95% CI -0.59 to -0.02, I² = 52.8%), delayed recall (SMD = -0.30, 95% CI -0.46 to 0.07, I² = 27.9%), and attention (SMD = -0.33, 95% CI -0.59 to -0.06, I² = 0%). Additionally, meta-regression demonstrated that the period of time between testing and the last concussion is significantly associated with reduced verbal memory (β = -0.03681, p = 0.03), and increasing age is significantly associated with the verbal memory (β = -0.03767, p = 0.01), immediate recall (β = -0.08684, p = 0.02), and delay recall (β = -0.07432, p = 0.02). Conclusion: The retired athletes who suffered from SRCs during their playing career had declined cognitive performance in partial domains (immediate recall, visuospatial ability, and reaction time) later in life.

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.

Modeling the Risk of Team Sport Injuries: A Narrative Review of Different Statistical Approaches

Injuries are a common occurrence in team sports and can have significant financial, physical and psychological consequences for athletes and their sporting organizations. As such, an abundance of research has attempted to identify factors associated with the risk of injury, which is important when developing injury prevention and risk mitigation strategies. There are a number of methods that can be used to identify injury risk factors. However, difficulty in understanding the nuances between different statistical approaches can lead to incorrect inferences and decisions being made from data. Accordingly, this narrative review aims to (1) outline commonly implemented methods for determining injury risk, (2) highlight the differences between association and prediction as it relates to injury and (3) describe advances in statistical modeling and the current evidence relating to predicting injuries in sport. Based on the points that are discussed throughout this narrative review, both researchers and practitioners alike need to carefully consider the different types of variables that are examined in relation to injury risk and how the analyses pertaining to these different variables are interpreted. There are a number of other important considerations when modeling the risk of injury, such as the method of data transformation, model validation and performance assessment. With these technical considerations in mind, researchers and practitioners should consider shifting their perspective of injury etiology from one of reductionism to one of complexity. Concurrently, research implementing reductionist approaches should be used to inform and implement complex approaches to identifying injury risk. However, the ability to capture large injury numbers is a current limitation of sports injury research and there has been a call to make data available to researchers, so that analyses and results can be replicated and verified. Collaborative efforts such as this will help prevent incorrect inferences being made from spurious data and will assist in developing interventions that are underpinned by sound scientific rationale. Such efforts will be a step in the right direction of improving the ability to identify injury risk, which in turn will help improve risk mitigation and ultimately the prevention of injuries.

Functional brain effects of acute concussion in Australian rules football players

Aim

To determine whether acute sport-related concussion is associated with functional brain changes in Australian rules footballers.

Methods

Twenty acutely concussed professional Australian footballers were studied with 3 T magnetic resonance imaging and compared to 20 age-matched control subjects. We statistically compared whole-brain local functional magnetic resonance imaging connectivity between acutely concussed footballers and controls using voxel-wise permutation testing.

Results

The acutely concussed football players had significantly decreased local functional magnetic resonance imaging connectivity in the right dorsolateral prefrontal cortex, right inferior parietal lobe, and right anterior insula, compared to controls. No functional brain changes between groups within the default mode network were observed.

Discussion

Acutely concussed footballers had in common decreased functional connectivity within the right lateralized “cognitive control network” of the brain that is involved in executive functions, and the “salience network” involved in switching between tasks. Dysfunction of these brain regions is a plausible explanation for typical clinical features of concussion.

Risk of Repeat Concussion Among Patients Diagnosed at a Pediatric Care Network

OBJECTIVE

To quantify the risk of repeat concussions for children and identify demographic and clinical aspects of the index concussion associated with repeat injury.

STUDY DESIGN

For this retrospective cohort study, we queried the Children's Hospital of Philadelphia healthcare network's unified electronic health record to identify all 5- to 15-year-old patients who had their first clinical visit for an index concussion at a Children's Hospital of Philadelphia location from July 2012 through June 2013. A 25% random sample (n = 536) were selected. Clinical data were abstracted for their index concussion and all concussion-related visits for 2 years following the index concussion.

RESULTS

Overall, 16.2% (n = 87) of patients experienced at least 1 repeat concussion within 2 years of their index concussion. The risk of repeat concussion increased with patient age (9.5% for ages 5-8 years; 10.7% for ages 9-11 years; and 19.8% for ages 12-15 years). After we adjusted for other factors, risk was particularly heightened among patients whose index concussion had a longer clinical course (>30 vs 0-7 days, adjusted risk ratio 1.65 [1.01-2.69]) and greater symptom burden (>11 vs 0-2 symptoms, adjusted risk ratio 2.12 [1.12-3.72]).

CONCLUSIONS

We estimate that 1 in 6 youth diagnosed with a concussion are diagnosed with a subsequent concussion within 2 years and that several clinical characteristics of the index concussion increase this risk. Identifying factors associated with a repeat injury is essential to inform the clinical management of concussion and direct injury prevention efforts.

The Role of TDP-43 in Military-Relevant TBI and Chronic Neurodegeneration

Due largely to the use of improvised explosive devices (IEDs) and other explosives in recent military conflicts, blast-related TBI has emerged as a prominent injury sustained by warfighters. In the recent wars in Iraq and Afghanistan, traumatic brain injury (TBI) has been one of the most common types of injury sustained by soldiers and military personnel; of the ~380,000 TBIs reported in service members from 2000 to 2017, 82.3% were classified as mild (mTBI). While mTBI is associated with normal structural imaging, brief or no loss of consciousness, and rapid recovery of mental state, mTBI can nevertheless lead to persistent behavioral and cognitive effects. As in other cases of mTBI, exposure to low-level blast often does not cause immediate overt neurological effects, but may similarly lead to persistent behavioral and cognitive deficits. These effects are likely to be compounded when multiple exposures to blast and/or impact are sustained, since there is increasing evidence that multiple mTBIs can lead to chronic neurodegeneration. One common form of this deleterious outcome is frontotemporal lobar degeneration (FTLD), which is a progressive neurodegenerative process marked by atrophy of the frontal and temporal lobes, leading to frontotemporal dementia, a common form of dementia affecting behavior, cognition and language. About half of all cases of FTLD are marked by TAR-DNA binding protein (TDP-43)-positive protein inclusions. TDP-43, a DNA/RNA binding protein, controls the expression of thousands of genes and is associated with several neurodegenerative diseases including amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease, and chronic traumatic encephalopathy. TDP-43 abnormalities have also been associated with traumatic brain injury in both pre-clinical and clinical studies. The role of TDP-43 in the manifestation of FTLD pathology in military TBI cases is currently unclear, and to date there has been only a limited number of pre-clinical studies addressing the effects of repeated blast-related mild TBI (rbTBI) in relation to FTLD and TDP-43. This review will summarize some of these findings and address the concerns and critical knowledge gaps associated with FTLD manifestation with military populations, as well as clinical findings on other forms of mTBI.

Pathological Assessment of Chronic Traumatic Encephalopathy: Review of Concepts and Methodology

Chronic traumatic encephalopathy (CTE) has become a topic of considerable interest in recent years, with wide-ranging implications for athletes, military members, and other groups exposed to frequent concussive or subconcussive head trauma. The condition has been subject to intensive neuropathological characterization by various groups, with assessment methodologies and staging criteria proposed. Clinical characterization of symptoms has also been performed, but has not yet been definitively formalized. While efforts are underway to develop in vivo markers of tauopathies including CTE, these remain experimental at this time, necessitating postmortem analysis for definitive diagnosis. The putative link between development of cognitive and behavioral dysfunction and neuropathological findings of CTE may prompt requests for postmortem assessment in the forensic setting. Here, we review current concepts in CTE research, describe histopathological findings in CTE, and describe methodologies for pathological assessment of CTE which may be useful to the forensic pathologist.

Session Availability as a Result of Prior Injury Impacts the Risk of Subsequent Non-contact Lower Limb Injury in Elite Male Australian Footballers

Prior injury is a commonly identified risk factor for subsequent injury. However, a binary approach to classifying prior injury (i.e., yes/no) is commonly implemented and may constrain scientific findings, as it is possible that variations in the amount of time lost due to an injury will impact subsequent injury risk to differing degrees. Accordingly, this study investigated whether session availability, a surrogate marker of prior injury, influenced the risk of subsequent non-contact lower limb injury in Australian footballers. Data were collected from 62 male elite Australian footballers throughout the 2015, 2016, and 2017 Australian Football League seasons. Each athlete's participation status (i.e., full or missed/modified) and any injuries that occurred during training sessions/matches were recorded. As the focus of the current study was prior injury, any training sessions/matches that were missed due to reasons other than an injury (e.g., load management, illness and personal reasons) were removed from the data prior to all analyses. For every Monday during the in-season periods, session availability (%) in the prior 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, and 84 days was determined as the number of training sessions/matches fully completed (injury free) relative to the number of training sessions/matches possible in each window. Each variable was modeled using logistic regression to determine its impact on subsequent injury risk. Throughout the study period, 173 non-contact lower limb injuries that resulted in at least one missed/modified training session or match during the in-season periods occurred. Greater availability in the prior 7 days increased injury probabilities by up to 4.4%. The impact of session availability on subsequent injury risk diminished with expanding windows (i.e., availability in the prior 14 days through to the prior 84 days). Lesser availability in the prior 84 days increased injury probabilities by up to 14.1%, only when coupled with greater availability in the prior 7 days. Session availability may provide an informative marker of the impact of prior injury on subsequent injury risk and can be used by coaches and clinicians to guide the progression of training, particularly for athletes that are returning from long periods of injury.

Age of First Exposure to American Football and Behavioral, Cognitive, Psychological, and Physical Outcomes in High School and Collegiate Football Players

BACKGROUND

Although some studies have observed a relationship between age of first exposure (AFE) to American football and long-term outcomes, recent findings in collegiate athletes did not observe a relationship between AFE and more intermediate outcomes at early adulthood. This, however, requires independent replication.

HYPOTHESIS

There will be no association between AFE to football and behavioral, cognitive, emotional/psychological, and physical functioning in high school and collegiate athletes.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Active high school and collegiate football players (N = 1802) underwent a comprehensive preseason evaluation on several clinical outcome measures. Demographic and health variables that significantly differed across AFE groups were identified as potential covariates. General linear models (GLMs) with AFE as the independent variable were performed for each clinical outcome variable. Similar GLMs that included identified covariates, with AFE as the predictor, were subsequently performed for each clinical outcome variable.

RESULTS

After controlling for covariates of age, concussion history, race, and a diagnosis of ADHD, earlier AFE (<12 vs ≥12 years) did not significantly predict poorer performance on any clinical outcome measures (all P > 0.05). A single statistically significant association between AFE group and somatization score was recorded, with AFE <12 years exhibiting lower levels of somatization.

CONCLUSION

In a large cohort of active high school and collegiate football student-athletes, AFE before the age of 12 years was not associated with worse behavioral, cognitive, psychological, and physical (oculomotor functioning and postural stability) outcomes.

CLINICAL RELEVANCE

The current findings suggest that timing of onset of football exposure does not result in poorer functioning in adolescence and young adults and may contribute to resilience through decreased levels of physically related psychological distress.

Chronic traumatic encephalopathy is not a real disease

There was a long-lasting debate during the first half of the 1900s about whether boxers suffered from a condition called "dementia pugilistica". This included arguments as to whether there was such a distinct clinical condition, whether it was static or progressive, and whether boxers were actually at any increased risk of any neurological issues at all. The debate was never resolved, but was resuscitated in 2005 with the speculation that a similar condition, dubbed "chronic traumatic encephalopathy (CTE)" existed in retired National Football League (NFL) players. A specific pattern of p-tau deposition has been identified in the brains of NFL retirees, and also identifiable in the brains of at least a percentage of individuals exposed to contact sports in general. Advocates of CTE as a disease describe it as presenting with behavioral disturbance, increased suicidality and neurodegeneration leading to dementia. The evidence to date, however, does not rise to the level of a verifiable disease, and remains at the level of case report. To assume that CTE pathology represents a neurodegenerative disease flies in the face of a number of facts, including that traumatic brain injury does not cause neurodegeneration, protein deposits in the brain are a poor predictor of behavioral symptoms, p-tau is not necessarily toxic or self-propagating, and retired NFL players are actually much physically and mentally healthier than men of their demographic background. They have an all-cause mortality rate that is 50% of that expected, and a suicide rate that is 40% of that expected. The most parsimonious explanation of the evidence to date is that repetitive head trauma may result in p-tau deposition, but that this isoform of p-tau is inert and has no toxic or self-propagating effects.

Neurocognitive Performance of 425 Top-Level Football Players: Sport-specific Norm Values and Implications

OBJECTIVE

Concussion diagnosis and management in sports largely relies on neurocognitive testing. In the absence of baseline assessment, only norm values of the general population are available for comparison with scores of concussed athletes. To evaluate whether (elite) sport specific norm values are needed, cognitive performance was compared between top-level football players and the general population.

METHODS

Cognitive performance of 425 top-level football players was evaluated using the computerized test battery CNS Vital Signs. Players were split into two age groups (15-19 and 20-29 years) and test results were compared with a norm sample (n = 268) by means of age-standardized scores using Cohen's d effect size statistics.

RESULTS

The younger age group outperformed the norm sample in all domains, with small to moderate effects on tests of processing speed (d = 0.58, 95% CI = 0.31,0.85), cognitive flexibility (d = 0.27, 95% CI = 0.01,0.53) and psychomotor speed (d = 0.97, 95% CI = 0.69,1.24). In the older age group, no differences were found on four out of six domains; a moderate positive effect was found for psychomotor speed (d = 0.74, 95% CI = 0.54,0.93), a small negative effect for reaction time (d = -0.47, 95% CI = -0.66,-0.28). Relative to the norm, older football players scored lower than younger football players on all test domains.

CONCLUSION

Cognitive performance of elite football players may be different from the general population. It is recommended to use football-specific norm scores for comparison with test results of concussed players, and to choose an adequate control group when investigating effects of contact sport on cognition. Studies with older/retired football players are needed to further analyze potential sport-specific age effects.

Musculoskeletal Injury Risk After Sport-Related Concussion: A Systematic Review and Meta-analysis

BACKGROUND

Clinical management of sport-related concussion typically involves a symptom checklist, clinical examination of mental status, and neurocognitive testing. However, recent studies have identified unresolved, impaired sensorimotor function after athletes return to sport. A review and meta-analysis of all current literature regarding risk of subsequent musculoskeletal (MSK) injury after concussion has yet to be published in the medical literature.

PURPOSE/HYPOTHESIS

To determine the odds that athletes will sustain MSK injury after concussion. It was hypothesized a priori that concussion would increase the risk for MSK injury.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

PubMed and Google Scholar were searched from January 2000 to November 2017. Reference lists of the included studies were manually searched. Two reviewers independently searched the literature for studies published in English that reported MSK injury after athletes returned to play following a concussion. Two independent reviewers completed data extraction using PRISMA guidelines and assessed study quality using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies from the National Institutes of Health. Random effects meta-analyses were used to calculate odds ratio (OR) and incidence rate ratio (IRR) of MSK injury after concussion. The primary study outcome of interest was the number of athletes who sustained MSK injury after concussion.

RESULTS

Eight studies met inclusion criteria for meta-analysis. Meta-analysis results indicated that athletes who had a concussion had 2 times greater odds of sustaining a MSK injury than athletes without concussion (OR, 2.11; 95% CI, 1.46-3.06). In addition, athletes with concussion demonstrated a higher incidence of MSK injury after return to sport compared with nonconcussed athletes (IRR, 1.67; 95% CI, 1.42-1.96). Further analysis showed that both male and female athletes with concussion were at an increased risk of MSK injury compared with their respective same-sex, nonconcussed controls (OR > 1.56, P < .01).

CONCLUSION

Based on the evidence of higher risk of MSK injuries after concussion, standard clinical assessments for athletes with concussion should include not only physical symptoms and cognitive function before return to sport but also neuromuscular risk factors associated with increased risk for MSK injuries.

Concussions in the National Basketball Association: Analysis of Incidence, Return to Play, and Performance From 1999 to 2018

BACKGROUND

The effect of concussions on professional athletes has been investigated in many sports. However, few studies have evaluated concussions in National Basketball Association (NBA) players.

HYPOTHESIS

We hypothesized that concussion incidence has increased, yet the return-to-play (RTP) rate will remain high following the institution of the NBA concussion policy (NBACP). We also hypothesized that the incidence of repeat concussions will be similar to first occurrences and that player performance and game availability will not be significantly affected by sustaining a concussion.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Publicly available records were searched to identify all concussions from NBA seasons 1999-2000 to 2017-2018. Player demographics and information regarding career history were tabulated. Incidence of concussion and RTP timing were evaluated before and after institution of the NBACP (2011). Minutes per game and game score per minute were evaluated pre- versus postconcussion. Player availability and performance were also compared with an age-, body mass index-, position-, and experience-matched control group of players who did not sustain a concussion.

RESULTS

A total of 189 concussions were reported in the NBA from 1999 to 2018, with a mean ± SD incidence of 9.7 ± 7.3 concussions per season. Following implementation of the NBACP, incidence significantly increased from 5.7 ± 2.8 to 16.7 ± 7.5 concussions per season (P = .007). All players returned to play following first-time concussion after missing 7.7 ± 8.6 days and 3.5 ± 4.1 games. RTP time was not significantly different after implementation of the NBACP (games missed, P = .24; days missed, P = .27), and there was no difference in concussion-free time interval (P = .29). Game score per minute and minutes per game were not significantly affected by sustaining a concussion (both P > .05).

CONCLUSION

Concussion incidence in NBA players is approximately 17 instances per season since the 2011 institution of a league-wide concussion policy. The number of reported concussions significantly increased following the policy, in line with trends seen in other professional sports leagues. Players have retained a high rate of RTP after 3 to 4 missed games. Player performance and availability are not affected by sustaining a concussion following successful RTP.

Traumatic brain injury: neuropathological, neurocognitive and neurobehavioral sequelae

Traumatic brain injury (TBI) causes substantial neurological disabilities and mental distress. Annual TBI incidence is in magnitude of millions, making it a global health challenge. Categorization of TBI into severe, moderate and mild by scores on the Glasgow coma scale (GCS) is based on clinical grounds and standard brain imaging (CT). Recent research focused on repeated mild TBI (sport and non-sport concussions) suggests that a considerable number of patients have long-term disabling neurocognitive and neurobehavioral sequelae. These relate to subtle neuronal injury (diffuse axonal injury) visible only by using advanced neuroimaging distinguishing microstructural tissue damage. With advanced MRI protocols better characterization of TBI is achievable. Diffusion tensor imaging (DTI) visualizes white matter pathology, susceptibility weight imaging (SWI) detects microscopic bleeding while functional magnetic resonance imaging (fMRI) provides closer understanding of cognitive disorders etc. However, advanced imaging is still not integrated in the clinical care of patients with TBI. Patients with chronic TBI may experience many somatic disorders, cognitive disturbances and mental complaints. The underlying pathophysiological mechanisms occurring in TBI are complex, brain injuries are highly heterogeneous and include neuroendocrine dysfunctions. Post-traumatic neuroendocrine dysfunctions received attention since the year 2000. Occurrence of TBI-related hypopituitarism does not correlate to severity of the GCS scores. Complete or partial hypopituitarism (isolated growth hormone (GH) deficiency as most frequent) may occur after mild TBI equally as after moderate-to-severe TBI. Many symptoms of hypopituitarism overlap with symptoms occurring in patients with chronic TBI, i.e. they have lower scores on neuropsychological examinations (cognitive disability) and have more symptoms of mental distress (depression and fatigue). The great challenges for the endocrinologist are: (1) detection of hypopituitarism in patients with TBI prospectively (in the acute phase and months to years after TBI), (2) assessment of the extent of cognitive impairment at baseline, and (3) monitoring of treatment effects (alteration of cognitive functioning and mental distress with hormone replacement therapy). Only few studies recently suggest that with growth hormone (rhGH) replacement in patients with chronic TBI and with abnormal GH secretion, cognitive performance may not change while symptoms related to depression and fatigue improve. Stagnation in post-TBI rehabilitation progress is recommended as a signal for clinical suspicion of neuroendocrine dysfunction. This remains a challenging area for more research.

Does soccer headgear reduce the incidence of sport-related concussion? A cluster, randomised controlled trial of adolescent athletes

Background

There have been no large randomised controlled trials to determine whether soccer headgear reduces the incidence or severity of sport-related concussion (SRC) in US high school athletes.

Objective

We aimed to determine whether headgear reduces the incidence or severity (days out from soccer) of SRCs in soccer players.

Methods

2766 participants (67% female, age 15.6±1.2) (who undertook 3050 participant years) participated in this cluster randomised trial. Athletes in the headgear (HG) group wore headgear during the season, while those in the no headgear (NoHG) group did not. Staff recorded SRC and non-SRC injuries and soccer exposures. Multivariate Cox proportional hazards models were used to examine time-to-SRC between groups, while severity was compared with a Wilcoxon rank-sum test.

Results

130 participants (5.3% female, 2.2% male) sustained an SRC. The incidence of SRC was not different between the HG and NoHG groups for males (HR: 2.00 (0.63–6.43) p=0.242) and females (HR: 0.86 (0.54–1.36) p=0.520). Days lost from SRC were not different (p=0.583) between the HG group (13.5 (11.0–018.8) days) and the NoHG group (13.0 (9.0–18.8) days).

Conclusions

Soccer headgear did not reduce the incidence or severity of SRC in high school soccer players.

Trial registration number

NCT02850926.

Head impacts sustained by male collegiate water polo athletes

Water polo is a contact sport that is gaining popularity in the United States and carries a risk of repeated head impacts and concussion. The frequency and magnitude of sport-related head impacts have not been described for water polo. We aimed to compare patterns of empirically measured head impact exposure of male collegiate water polo players to patterns previously reported by a survey of current and former water polo athletes. Participants wore water polo caps instrumented with head impact sensors during three seasons of collegiate water polo. Peak linear acceleration (PLA) and peak rotational acceleration (PRA) were recorded for head impacts. Athlete positions were recorded by research staff at the occurrence of each head impact. Head impacts were sustained by athletes in offensive positions more frequently than in defensive and transition positions (246, 59.9% vs. 93, 22.6% vs. 72, 17.5%). 37% of all head impacts during gameplay were sustained by athletes playing the offensive center position. Impact magnitude (means ± SD: PLA = 36.1±12.3g, PRA = 5.0±2.9 krads/sec²) did not differ between position or game scenario. Among goalies, impact frequency and magnitude were similar between games (means ± SD: 0.54±.51 hits/game, PLA = 36.9±14.2g, PRA = 4.3±4.2 krads/sec²) and practices (means ± SD: 0.96±1.11 hits/practice, PLA = 43.7±14.5g, PRA = 3.9±2.5 krads/sec²). We report that collegiate water polo athletes are at risk for sport-related head impacts and impact frequency is dependent on game scenario and player position. In contrast, magnitude does not differ between scenarios or across positions.

Elevated markers of brain injury as a result of clinically asymptomatic high-acceleration head impacts in high-school football athletes

OBJECTIVE

This prospective observational cohort study of high-school football athletes was performed to determine if high-acceleration head impacts (HHIs) that do not result in clinically diagnosed concussion still lead to increases in serum levels of biomarkers indicating traumatic brain injury (TBI) in asymptomatic athletes and to determine the longitudinal profile of these biomarkers over the course of the football season.

METHODS

Sixteen varsity high-school football athletes underwent baseline neurocognitive testing and blood sampling for the biomarkers tau, ubiquitin C-terminal hydrolase L1 (UCH-L1), neurofilament light protein (NF-L), glial fibrillary acidic protein (GFAP), and spectrin breakdown products (SBDPs). All athletes wore helmet-based accelerometers to measure and record head impact data during all practices and games. At various time points during the season, 6 of these athletes met the criteria for HHI (linear acceleration > 95g and rotational acceleration > 3760 rad/sec2); in these athletes a second blood sample was drawn at the end of the athletic event during which the HHI occurred. Five athletes who did not meet the criteria for HHI underwent repeat blood sampling following the final game of the season. In a separate analysis, all athletes who did not receive a diagnosis of concussion during the season (n = 12) underwent repeat neurocognitive testing and blood sampling after the end of the season.

RESULTS

Total tau levels increased 492.6% ± 109.8% from baseline to postsession values in athletes who received an HHI, compared with 164% ± 35% in athletes who did not receive an HHI (p = 0.03). Similarly, UCH-L1 levels increased 738.2% ± 163.3% in athletes following an HHI, compared with 237.7% ± 71.9% in athletes in whom there was no HHI (p = 0.03). At the end of the season, researchers found that tau levels had increased 0.6 ± 0.2 pg/ml (p = 0.003) and UCH-L1 levels had increased 144.3 ± 56 pg/ml (p = 0.002). No significant elevations in serum NF-L, GFAP, or SBDPs were seen between baseline and end-of-athletic event or end-of-season sampling (for all, p > 0.05).

CONCLUSIONS

In this pilot study on asymptomatic football athletes, an HHI was associated with increased markers of neuronal (UCH-L1) and axonal (tau) injury when compared with values in control athletes. These same markers were also increased in nonconcussed athletes following the football season.

Carnosic Acid Improves Outcome after Repetitive Mild Traumatic Brain Injury

In the majority of cases, the cognitive and behavioral impairments resulting from a mild traumatic brain injury (TBI) (also referred to as concussion) wane within days to weeks. In contrast, these impairments can persist for months to years after repetitive mild TBI (rmTBI). The cellular and molecular mechanisms underlying these impairments are not well understood. In the present study, we examined the consequences of rmTBI (three weight drops each separated by 72 h) on brain tissue respiration, pathology, and cognitive performance in mice. The transcription factor nuclear factor-erythroid 2-realted factor 2 (Nrf2) has been demonstrated to enhance the expression of numerous cytoprotective genes. Carnosic acid (CA) has been shown to activate Nrf2 and suppress the proinflammatory transcription factor nuclear factor kappa B (NF-κB). Because contemporaneous activation of cytoprotective genes and inhibition of proinflammatory genes can be beneficial, we questioned whether CA can be used to mitigate the pathobiology of rmTBI. The rmTBI increased hippocampal adenosine triphosphate-linked tissue respiration and proton leak that were unaffected by CA treatment. The rmTBI also caused significant motor and cognitive dysfunction, as tested using the foot fault, Barnes maze, and novel object recognition tasks. These impairments occurred in the absence of visible neuronal or dendritic loss. Post-rmTBI administration of CA significantly improved motor and cognitive function, and decreased Gfap and Iba1 immunoreactivities within white matter tracks. Taken together, these results show that rmTBI can cause cognitive impairments in the absence of overt neuronal pathologies, and post-injury treatment with CA can lessen some of these impairments.

Sport-Related Concussion: Evaluation, Treatment, and Future Directions

Sport-related concussion (SRC) is a highly prevalent injury predominantly affecting millions of youth through high school athletes every year. In recent years, SRC has received a significant amount of attention due to potential for long-term neurologic sequelae. However, the acute symptoms and possibility of prolonged recovery account for the vast majority of morbidity from SRC. Modifying factors have been identified and may allow for improved prediction of a protracted course. Potential novel modifying factors may include genetic determinants of recovery, as well as radiographic biomarkers, which represent burgeoning subfields in SRC research. Helmet design and understanding the biomechanical stressors on the brain that lead to concussion also represent active areas of research. This narrative review provides a general synopsis of SRC, including relevant definitions, current treatment paradigms, and modifying factors for recovery, in addition to novel areas of research and future directions for SRC research.

Management of concussion in soccer

BACKGROUND

When participating in contact sports, (mild) head trauma is a common incident-observed in both professional and amateur sports. When head trauma results in transient neurological impairment, a sports-related concussion has occurred. Acute concussion, repetitive concussions, as well as cumulative "sub-concussive" head impacts may increase the risk of developing cognitive and behavioral deficits for athletes, as well as accelerated cerebral degeneration. While this concept has been well established for classic contact sports like American Football, Rugby, or Boxing, there is still an awareness gap for the role of sports-related concussion in the context of the world's most popular sport-Soccer.

METHODS

Here, we review the relevance of sport-related concussion for Soccer as well as its diagnosis and management. Finally, we provide insight into future directions for research in this field.

RESULTS

Soccer fulfills the criteria of a contact sport and is characterized by a high incidence of concussion. There is ample evidence that these events cause functional and structural cerebral disorders. Furthermore, heading, as a repeat sub-concussive impact, has been linked to structural brain changes and neurocognitive impairment. As a consequence, recommendations for the diagnosis and management of concussion in soccer have been formulated by consensus groups. In order to minimize the risk of repetitive concussion in soccer the rapid and reliable side-line diagnosis of concussion with adoption of a strict remove-from-play protocol is essential, followed by a supervised, graduated return-to-play protocol. Recent studies, however, demonstrate that adherence to these recommendations by players, coaches, clubs, and officials is insufficient, calling for stricter enforcement. In addition, future research to solidify the pathophysiological relevance of concussion for soccer athletes seems to be needed. Advanced neuroimaging and neurochemical biomarker analyses (e.g. S100β, tau and neurofilament light (NfL)) may assist in detecting concussion-related structural brain changes and selecting athletes at risk for irreversible damage.

CONCLUSION

Sports-related concussion represents a genuine neurosurgical field of interest. Given the high socioeconomic relevance, neurosurgeons should get involved in prevention and management of concussion in soccer.

American Medical Society for Sports Medicine Position Statement on Concussion in Sport

Sport-related concussion (SRC) is a common injury in recreational and organized sport. Over the past 30 years, there has been significant progress in our scientific understanding of SRC, which in turn has driven the development of clinical guidelines for diagnosis, assessment, and management of SRC. In addition to a growing need for knowledgeable health care professionals to provide evidence-based care for athletes with SRC, media attention and legislation have created awareness and, in some cases, fear about many issues and unknowns surrounding SRC. The American Medical Society for Sports Medicine formed a writing group to review the existing literature on SRC, update its previous position statement, and address current evidence and knowledge gaps regarding SRC. The absence of definitive outcomes-based data is challenging and requires relying on the best available evidence integrated with clinical experience and patient values. This statement reviews the definition, pathophysiology, and epidemiology of SRC, the diagnosis and management of both acute and persistent concussion symptoms, the short- and long-term risks of SRC and repetitive head impact exposure, SRC prevention strategies, and potential future directions for SRC research. The American Medical Society for Sports Medicine is committed to best clinical practices, evidence-based research, and educational initiatives that positively impact the health and safety of athletes.

Review of the Management of Pediatric Post-Concussion Syndrome-a Multi-Disciplinary, Individualized Approach

PURPOSE OF REVIEW

Post-concussion syndrome (PCS), when the patient's concussion symptoms last longer than 4-6 weeks, affects 10-30% of concussion patients. PCS presents a significant source of morbidity to patients and a management challenge to providers. In this review, we present the current evidence and best management approaches for pediatric PCS.

RECENT FINDINGS

There is limited high-quality evidence in pediatric PCS. There is some evidence supporting pharmaceutical management of post-traumatic headaches, cognitive symptoms, and emotional symptoms. Vestibular-ocular dysfunction should be evaluated and managed appropriately. Neuropsychological recovery is expected, but requires appropriate attention to Return to Learn. Emotional symptoms are common in PCS and the evidence supports treatment with cognitive behavioral therapy. PCS presents a unique therapeutic challenge affecting multiple domains for patients-physical, sleep, cognitive, and emotional. Successful management of PCS requires a multi-disciplinary and individualized approach. There remains a significant need for further research, specifically looking into the outcomes and effective interventions in pediatric PCS.

Head Trauma Exposure in Mixed Martial Arts Varies According to Sex and Weight Class

BACKGROUND

Brain injury arising from head trauma is a major concern in mixed martial arts (MMA) because knockout (KO) and technical knockout (TKO) are frequent fight outcomes. Previous studies have shown a high incidence of matches ending due to strikes to the head but did not consider weight categories and female fights. This study aimed at analyzing match stoppages in MMA and the exposure to head trauma distinguished by sex and weight categories.

HYPOTHESIS

The heavier the weight class, the greater the risk and incidence of head trauma will be, regardless of sex.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Publicly available data of 167 MMA events from 1903 fights between 2014 and 2017 were assessed, comprising 8 male and 2 female weight categories.

RESULTS

The combined KO/TKO rates per 100 athlete-exposures in the middleweight (19.53), light heavyweight (20.8), and heavyweight (26.09) divisions were greater than previously reported for MMA. While stoppage via KO/TKO occurred in 7.9% of combats in the female strawweight division, it occurred in 52.1% of the male heavyweight fights. The male middleweight ( P = 0.001), light heavyweight ( P < 0.001), and heavyweight divisions ( P < 0.001) had an increased risk of KO/TKO due to strikes to the head by 80%, 100%, and 206%, respectively. The risk in the flyweight division decreased 62% ( P = 0.001). All categories were compared with the lightweight division. The female bantamweight category presented a 221% increased risk in matches ending due to KO/TKO compared with the strawweight division ( P = 0.012). Punches to the head were the major technique used to end a combat via KO/TKO, regardless of sex and weight class.

CONCLUSION

Head injury risk and incidence varies considerably according to sex and weight category in MMA.

CLINICAL RELEVANCE

The analysis of head trauma exposure in MMA athletes should be distinguished according to sex and weight category.

Head Injury in Soccer: From Science to the Field; summary of the head injury summit held in April 2017 in New York City, New York

There has been an increased focus and awareness of head injury and sport-related concussion (SRC) across all sports from the medical and scientific communities, sports organisations, legislators, the media and the general population. Soccer, in particular, has been a focus of attention due to the popularity of the game, the frequency of SRC and the hypothesised effects of repetitive heading of the ball. Major League Soccer, US Soccer and the National Women’s Soccer League jointly hosted a conference entitled, ‘Head Injury in Soccer: From Science to the Field’, on 21–22 April 2017 in New York City, New York. The mission of this conference was to identify, discuss and disseminate evidence-based science related to the findings and conclusions of the fifth International Conference on Concussion in Sport held by the Concussion in Sport Group and apply them to the sport of soccer. In addition, we reviewed information regarding the epidemiology and mechanism of head injuries in soccer at all levels of play, data regarding the biomechanics and effects of repetitive head impacts and other soccer-specific considerations. We discussed how to release the information raised during the summit to key stakeholders including athletes, parents, coaches and healthcare providers. We identified future areas for research and collaboration to enhance the health and safety of soccer (football) players.

Traumatic brain injuries in New Zealand: National Insurance (Accident Compensation Corporation) claims from 2012 to 2016

AIM

To provide epidemiological data and related costs to the national health insurance scheme for traumatic brain injury (TBI) in New Zealand.

METHOD

A retrospective analytical review utilising detailed descriptive minor and moderate-to-severe epidemiological TBI data obtained from the Accident Compensation Corporation (ACC) for 2012-2016. Injuries were analysed by three levels of increasing severity: moderate, moderate-to-serious (MSC) and severe claims categories.

RESULTS

Over the January 2012 to December 2016 period there were 97,955 claims for TBI costing ACC $1,450,643,667 [equivalent to £$743,417,120]. Falls accounted for nearly half (41.7%, 8262), and over a quarter (39.9%; $67,626,000 [£34,662,176]) of the moderate claims for TBI. Motor vehicle accidents recorded the highest percentage (36.5%), total costs ($610,978,229 [£313,170,000]) and highest mean cost per-moderate claim per-year ($47,372 ± $2401 [£24,282 ± £1231]) for MSC TBI claims. This was similar for severe claims where motor vehicles accidents accounted for 56% of the total serious claims, 65.1% of the costs with a mean cost per-serious claim of $64,913 ± 4331 [£32,759 ± £2186] per-year.

CONCLUSION

There were 97,955 TBI injury claims lodged over the duration of the study with 36% (n = 35,304) classified as MSC. The incidence of total TBI in New Zealand was 432 per 100,000 population, and 155 per 100,000 for MSC TBI claims. Despite the growing number of studies reporting on the effects of sports-related TBI, there is a paucity of studies reporting on the longitudinal effects of TBI in falls, assaults and motor vehicle accidents. Further research is warranted into the assessment and management of intimate partner violence and child abuse victims for TBI's.