Sports concussion and the risk of chronic neurological impairment

Information seeking behaviors and attitudes of wives of former football players regarding chronic traumatic encephalopathy

This study examines CTE-related knowledge and information-seeking behaviors of caregivers of persons who are at high risk of CTE. Online survey responses were collected from 64 females, ages 18-74, who were married to former college, semiprofessional, or professional football players and were fluent in English. Ranging from 0 to 18, a score was calculated to represent level of CTE knowledge. Participants were classified into groups based on their spouse's reported symptoms and diagnosis. Approximately 87% of participants reported that their spouses have been diagnosed with a football-related concussion and were significantly more likely to seek out information from a healthcare provider, a scientific journal or article, and post/comment on social media compared to spouses of symptomatic/undiagnosed and non-symptomatic groups. Participants reported 77% of available information as probably true, with social media thought to be highly credible. Highest levels of dissatisfaction were reported for league-sponsored websites and physicians/healthcare providers. Although the majority of participants sought CTE related information on regular or social media, and the internet, information sources differed amongst the groups. These findings may help healthcare providers and organizations develop more effective health-related educational programs that will help the wives make informed decisions regarding care for their spouses with respect to CTE.

A non-invasive biomechanical model of mild TBI in larval zebrafish

A mild traumatic brain injury is a neurological dysfunction caused by biomechanical forces transmitted to the brain in physical impacts. The current understanding of the neuropathological cascade resulting in the manifested clinical signs and symptoms is limited due to the absence of sensitive brain imaging methods. Zebrafish are established models for the reproduction and study of neurobiological pathologies. However, all available models mostly recreate moderate-to-severe focal injuries in adult zebrafish. The present work has induced a mild brain trauma in larval zebrafish through a non-invasive biomechanical approach. A custom-made apparatus with a commercially available motor was employed to expose larvae to rapidly decelerating linear movements. The neurophysiological changes following concussion were assessed through behavioural quantifications of startle reflex locomotor distance and habituation metrics. Here we show that the injury was followed, within five minutes, by a transient anxiety state and CNS dysfunction manifested by increased startle responsivity with impaired startle habituation, putatively mirroring the human clinical sign of hypersensitivity to noise. Within a day after the injury, chronic effects arose, as evidenced by an overall reduced responsivity to sensory stimulation (lower amplitude and distance travelled along successive stimuli), reflecting the human post-concussive symptomatology. This study represents a step forward towards the establishment of a parsimonious (simple, less ethically concerning, yet sensitive) animal model of mild TBI. Our behavioural findings mimic aspects of acute and chronic effects of human concussion, which warrant further study at molecular, cellular and circuit levels. While our model opens wide avenues for studying the underlying cellular and molecular pathomechanisms, it also enables high-throughput testing of therapeutic interventions to accelerate post-concussive recovery.

Review of wearable technologies and machine learning methodologies for systematic detection of mild traumatic brain injuries

Mild traumatic brain injuries (mTBIs) are the most common type of brain injury. Timely diagnosis of mTBI is crucial in making 'go/no-go' decision in order to prevent repeated injury, avoid strenuous activities which may prolong recovery, and assure capabilities of high-level performance of the subject. If undiagnosed, mTBI may lead to various short- and long-term abnormalities, which include, but are not limited to impaired cognitive function, fatigue, depression, irritability, and headaches. Existing screening and diagnostic tools to detect acute andearly-stagemTBIs have insufficient sensitivity and specificity. This results in uncertainty in clinical decision-making regarding diagnosis and returning to activity or requiring further medical treatment. Therefore, it is important to identify relevant physiological biomarkers that can be integrated into a mutually complementary set and provide a combination of data modalities for improved on-site diagnostic sensitivity of mTBI. In recent years, the processing power, signal fidelity, and the number of recording channels and modalities of wearable healthcare devices have improved tremendously and generated an enormous amount of data. During the same period, there have been incredible advances in machine learning tools and data processing methodologies. These achievements are enabling clinicians and engineers to develop and implement multiparametric high-precision diagnostic tools for mTBI. In this review, we first assess clinical challenges in the diagnosis of acute mTBI, and then consider recording modalities and hardware implementation of various sensing technologies used to assess physiological biomarkers that may be related to mTBI. Finally, we discuss the state of the art in machine learning-based detection of mTBI and consider how a more diverse list of quantitative physiological biomarker features may improve current data-driven approaches in providing mTBI patients timely diagnosis and treatment.

The possible role of hydration in concussions and long-term symptoms of concussion for athletes. A review of the evidence

The purpose of this review is to address what is known, speculated, and hypothesized regarding the issue of hydration and concussions. Based on the question, “What impact does hydration have on the relative risk for suffering concussive injuries along with long-term ramifications that have been associated with concussive (and repeated subconcussive) traumas to the cerebral cortex?,” a search of available literature was performed through June 2019. Deducing from the available literature, we can stipulate that changes in hydration within the cerebral cortex increase the likelihood for disruption of neurofilament proteins, dysregulation of membrane dynamics of the neurons and exacerbate inflammation responses following head trauma. As such, it can be speculated that differences in incidence rates may be attributed to difference in tissue fluid based on athlete demographics, level of whole-body water balance, and degree of tissue dehydration more than selection of sport. Moreover, tissue hydration in combination with other inflammation factors provides the scaffolding for the development of long-term issues (e.g. chronic traumatic encephalopathy) associated with repetitive head trauma in athletes.

Comparison of Neurocognitive Performance in Contact and Noncontact Nonconcussed High School Athletes Across a Two-Year Interval

Investigating short-term effects of subconcussive impacts on neurocognitive functioning, we employed a repeated measures multivariate model and regression-based measure to examine neurocognitive changes in 771 contact and noncontact high school athletes over a two-year period. Results reveal significant changes in Visual Motor Speed for both groups over a two-year period, with small effect sizes. According to regression-based measures, differences in contact sport athletes' expected Time 2 performances were significant for Visual Motor Speed, also with minimal effects. Results do not conclusively implicate subconcussive hits as the offending factor in differences observed, with gender and sport-type possibly contributing to the small effects.

Head-Eye Vestibular Motion Therapy Affects the Mental and Physical Health of Severe Chronic Postconcussion Patients

Context

Approximately 1.8–3.6 million annual traumatic brain injuries occur in the United States. An evidence-based treatment for concussions that is reliable and effective has not been available.

Objective

The objective of this study is to test whether head–eye vestibular motion (HEVM) therapy is associated with decreased symptoms and increased function in postconcussive syndrome (PCS) patients that have been severely impaired for greater than 6 months after a mild traumatic brain injury.

Design

Retrospective clinical chart review.

Setting and participants

Tertiary Specialist Brain Rehabilitation Center.

Interventions

All subjects underwent comprehensive neurological examinations including measurement of eye and head movement. The seven modules of the C3 Logix Comprehensive Concussion Management System were used for pre- and postmeasurements of outcome of HEVM therapy.

Materials and methods

We utilized an objective validated measurement of physical and mental health characteristics of our patients before and after a 1-week HEVM rehabilitation program. We included only PCS patients that were disabled from work or school for a period of time exceeding 6 months after suffering a sports concussion. These subjects all were enrolled in a 5-day HEVM rehabilitation program at our Institutional Brain Center with pre- and post-C3 Logix testing outcomes.

Results

There were statistical and substantive significant decreases in PCS symptom severity after treatment and statistical and substantive significant increases in standardized assessment of concussion scores. The outcomes were associated with positive changes in mental and physical health issues. This is a retrospective review and no control group has been included in this study. These are major limitations with retrospective reviews and further investigations with prospective designs including a randomized controlled study are necessary to further our understanding.

Conclusion

Head–eye vestibular motion therapy of 5 days duration is associated with statistical and substantive significant decreases of symptom severity associated with chronic PCS.

The Influence of Head Impact Threshold for Reporting Data in Contact and Collision Sports: Systematic Review and Original Data Analysis

BACKGROUND

Head impacts and resulting head accelerations cause concussive injuries. There is no standard for reporting head impact data in sports to enable comparison between studies.

OBJECTIVE

The aim was to outline methods for reporting head impact acceleration data in sport and the effect of the acceleration thresholds on the number of impacts reported.

METHODS

A systematic review of accelerometer systems utilised to report head impact data in sport was conducted. The effect of using different thresholds on a set of impact data from 38 amateur senior rugby players in New Zealand over a competition season was calculated.

RESULTS

Of the 52 studies identified, 42% reported impacts using a >10-g threshold, where g is the acceleration of gravity. Studies reported descriptive statistics as mean ± standard deviation, median, 25th to 75th interquartile range, and 95th percentile. Application of the varied impact thresholds to the New Zealand data set resulted in 20,687 impacts of >10 g, 11,459 (45% less) impacts of >15 g, and 4024 (81% less) impacts of >30 g.

DISCUSSION

Linear and angular raw data were most frequently reported. Metrics combining raw data may be more useful; however, validity of the metrics has not been adequately addressed for sport. Differing data collection methods and descriptive statistics for reporting head impacts in sports limit inter-study comparisons. Consensus on data analysis methods for sports impact assessment is needed, including thresholds. Based on the available data, the 10-g threshold is the most commonly reported impact threshold and should be reported as the median with 25th and 75th interquartile ranges as the data are non-normally distributed. Validation studies are required to determine the best threshold and metrics for impact acceleration data collection in sport.

CONCLUSION

Until in-field validation studies are completed, it is recommended that head impact data should be reported as median and interquartile ranges using the 10-g impact threshold.

The accumulation of brain injury leads to severe neuropathological and neurobehavioral changes after repetitive mild traumatic brain injury

Traumatic brain injury (TBI) is a major public health problem with long-term neurobehavioral sequela. The evidences have revealed that TBI is a risk factor for later development of neurodegenerative disease and both the single and repetitive brain injury can lead to the neurodegeneration. But whether the effects of accumulation play an important role in the neurodegenerative disease is still unknown. We utilized the Sprague Dawley (SD) rats to develop the animal models of repetitive mild TBI and single mild TBI in order to detect the neurobehavioral changes. The results of neurobehavioral test revealed that the repetitive mild TBI led to more severe behavioral injuries than the single TBI. There were more activated microglia cells and astrocytes in the repetitive mild TBI group than the single TBI group. In consistent with this, the levels of TNF-α and IL-6 were higher and the expression of IL-10 was lower in the repetitive mild TBI group compared with the single TBI group. The expression of amyloid precursor protein (APP) increased in the repetitive TBI group detected by ELISA and western blot. But the levels of total tau (Tau-5) and P-tau (ser202) seem no different between the two groups in most time point. In conclusion, repetitive mild TBI could lead to more severe neurobehavioral impairments and the effects of accumulation may be associated with the increased inflammation in the brain.

Follow-up issues in children with mild traumatic brain injuries

OBJECTIVE Concerns about mild traumatic brain injury (mTBI) have increased in recent years, and neurosurgical consultation is often requested for patients with radiographic abnormalities or clinical findings suspicious for mTBI. However, to the authors' knowledge, no study has used the Acute Concussion Evaluation (ACE) tool to systematically evaluate the evolution of symptoms in patients with mTBI during neurosurgical follow-up. The goal in this study was to evaluate symptom progression in pediatric patients referred for neurosurgical consultation by using the ACE, as endorsed by the Centers for Disease Control and Prevention. METHODS The authors performed a retrospective review of records of consecutive pediatric patients who had presented to the emergency department, were diagnosed with possible mTBI, and were referred for neurosurgical consultation. Outpatient follow-up for these patients included serial assessment using the ACE. Data collected included the mechanisms of the patients' injuries, symptoms, follow-up duration, and premorbid conditions that might potentially contribute to protracted recovery. RESULTS Of 91 patients identified with mTBI, 58 met the inclusion criteria, and 33 of these had sufficient follow-up data to be included in the study. Mechanisms of injury included sports injury (15 patients), isolated falls (10), and motor vehicle collisions (8). Ages ranged from 5 to 17 years (mean age 11.6 years), and 29 of the 33 patients were male. Six patients had preinjury developmental and/or psychiatric diagnoses such as attention deficit hyperactivity disorder. Seventeen had negative findings on head CT scans. The first follow-up evaluation occurred at a mean of 30 days after injury. The mean number of symptoms reported on the ACE inventory at first follow-up were 3.2; 12 patients were symptom free. Patients with positive head CT findings required longer follow-up: these patients needed 14.59 weeks, versus 7.87 weeks of follow-up in patients with negative findings on head CT scans (p < 0.05). CONCLUSIONS The data suggest that patients with mTBI, particularly those with developmental and/or psychiatric comorbidities and concurrent cerebral or extracranial injury, often report symptoms for several weeks after their initial injury. Serial ACE assessment permits systematic identification of patients who are experiencing continued symptoms, leading to appropriate patient management and referral.

Theta burst stimulation to characterize changes in brain plasticity following mild traumatic brain injury: A proof-of-principle study

PURPOSE

Recent studies investigating the effects of mild traumatic brain injury (mTBI) suggest the presence of unbalanced excitatory and inhibitory mechanisms within primary motor cortex (M1). Whether these abnormalities are associated with impaired synaptic plasticity remains unknown.

METHODS

The effects of continuous theta burst stimulation (cTBS) on transcranial magnetic stimulation-induced motor evoked potentials (MEPs) were assessed on average two weeks and six weeks following mTBI in five individuals.

RESULTS

The procedure was well-tolerated by all participants. Continuous TBS failed to induce a significant reduction of MEP amplitudes two weeks after the injury, but response to cTBS normalized six weeks following injury, as a majority of patients became asymptomatic.

CONCLUSIONS

These preliminary results suggest that cTBS can be used to assess M1 synaptic plasticity in subacute phase following mTBI and may provide insights into neurobiological substrates of symptoms and consequences of mTBI.

Effects of Competition Rule Changes on the Incidence of Head Kicks and Possible Concussions in Taekwondo

OBJECTIVE

Competition rules related to head kicks (HKs) in sparing-taekwondo (S-TKD) were changed in 2009, resulting in more points awarded to the head attacker. The objective of this research is to measure the incidence of HKs and to analyze the characteristics of situations leading up to and after HKs in a postrule change competition.

DESIGN

Descriptive epidemiology study using video analysis.

SETTING

The final matches of the World Taekwondo Championships (WTCs) in 2011 and 2013.

PARTICIPANTS

A total of 1760 athletes participated in both WTCs. Sixty-four athletes, who had won elimination-round matches and were 15 years or older, competed in final matches.

MAIN OUTCOME MEASURES

The final matches-a total of 64 matches including 95 rounds-were analyzed using an anatomical and outcome coding scheme for HKs.

RESULTS

Overall, a total of 30 athletes experienced receiving one or more HKs during 2 WTCs (469 HKs per 1000 athlete-exposures (A-E), 95% confidence interval = 296, 642). Female athletes showed higher incidences of HKs than male. A trend of increasing incidence of HKs was observed in the females. The HKs occurred more frequently among competitors in lightweight categories and those of similar height (49%).

CONCLUSIONS

Overall, the frequency of HKs seems to have increased compared with matches before 2009. A sharp increase in the numbers of HKs is evident among the elite female athletes. To prevent receiving an HK, updated game strategies such as training for blocking skills, and safety guidelines for HKs, or revisions to rules are needed.

CLINICAL RELEVANCE

The recent changes to competition rules promoting the use of HKs may have resulted in an increasing frequency of HKs compared with research findings before these changes. Multiple HKs occur frequently in S-TKD; care needs to be taken to avoid possible acute/chronic consequences.

Knowing What We Don't Know: Long-Term Psychiatric Outcomes following Adult Concussion in Sports

OBJECTIVE

Amidst a growing concern regarding concussion in sports, there is an emerging link between sport concussion and mental health outcomes. This review summarizes the current literature addressing long-term psychiatric sequelae associated with sport concussion in adults.

METHOD

Several databases were searched using a broad list of keywords for each of concussion, sports, and mental health, with a resultant 311 studies for initial review. After limiting studies based on duplication, appropriateness of data, and relevance, 21 studies remained pertaining to depression, anxiety, substance use, and behavioural changes, including those highlighting chronic traumatic encephalopathy (CTE).

RESULTS

Most studies identified suggested an increased prevalence of depressive symptoms related to concussion history. A conference abstract and qualitative study suggested increasing anxiety related to concussion history; however, a PhD dissertation found no relationship. In reviewing substance use, several studies mentioned use in athletes suspected of having concussion histories, although no link was established, while another noted undiagnosed concussion as leading to current substance misuse. Regarding behavioural changes, all studies identified occurrences of behaviour and/or cognitive changes in participants, with 2 studies suggesting a link with concussion history. With respect to CTE, concerns with mood, behaviour, cognition, and substance use were consistently highlighted, suggesting relations to previous sport concussion; however, the notion of different CTE subtypes and clear aetiology behind concussion severity or frequency was not consistently elucidated.

CONCLUSION

There appears to be a growing body of evidence supporting the presence of long-term psychiatric and psychological sequelae following sport concussion in adults.

The effect of selective head-neck cooling on physiological and cognitive functions in healthy volunteers

In general, brain temperatures are elevated during physical sporting activities; therefore, reducing brain temperature shortly after a sports-related concussion (SRC) could be a promising intervention technique. The main objective of this study was to examine the effects of head and neck cooling on physiological and cognitive function in normal healthy volunteers. Twelve healthy volunteers underwent two different sessions of combined head and neck cooling, one session with a cold pack and one session with a room temperature pack. Physiological measurements included: systolic/diastolic blood pressure, pulse oximetry, heart rate, and sublingual and tympanic temperature. Cognitive assessment included: processing speed, executive function, and working memory tasks. Physiological measurements were taken pre-, mid- and post-cooling, while cognitive assessments were done before and after cooling. The order of the sessions was randomized. There was a significant decrease in tympanic temperature across both sessions; however more cooling occurred when the cold pack was in the device. There was no significant decrease in sublingual temperature across either session. The observed heart rates, pulse oximetry, systolic and diastolic blood pressure during the sessions were all within range of a normal healthy adult. Cognitive assessment remained stable across each session for both pre- and post-cooling. We propose that optimizing brain temperature management after brain injury using head and neck cooling technology may represent a sensible, practical, and effective strategy to potentially enhance recovery and perhaps minimize the subsequent short and long term consequences from SRC.

Talking with parents of high school football players about chronic traumatic encephalopathy: a concise summary

Over the past decade, athletic-related chronic traumatic encephalopathy (CTE) has garnered a great deal of attention in the popular press and, more recently, in the scientific press. With increasing frequency, sports medicine practitioners and providers are faced with questions from the parents of high school football players about CTE and the risk posed to children who participate in this or other contact or collision sports. The purpose of this review was to summarize the research on CTE in an attempt to provide some evidence-based answers to frequently asked questions in clinics from parents. Addressed are (1) the definitions of CTE and its symptoms, (2) the evidence for CTE in football, (3) abnormal tau protein, (4) the use of neuroimaging in CTE diagnosis, (5) risk for CTE, (6) CTE diagnosis in youth, (7) CTE and its relationship to suicide, and (8) contact and collision sports as a risk factor for permanent brain injury or death.

Neurological consequences of traumatic brain injuries in sports

Traumatic brain injury (TBI) is common in boxing and other contact sports. The long term irreversible and progressive aftermath of TBI in boxers depicted as punch drunk syndrome was described almost a century ago and is now widely referred as chronic traumatic encephalopathy (CTE). The short term sequelae of acute brain injury including subdural haematoma and catastrophic brain injury may lead to death, whereas mild TBI, or concussion, causes functional disturbance and axonal injury rather than gross structural brain damage. Following concussion, symptoms such as dizziness, nausea, reduced attention, amnesia and headache tend to develop acutely but usually resolve within a week or two. Severe concussion can also lead to loss of consciousness. Despite the transient nature of the clinical symptoms, functional neuroimaging, electrophysiological, neuropsychological and neurochemical assessments indicate that the disturbance of concussion takes over a month to return to baseline and neuropathological evaluation shows that concussion-induced axonopathy may persist for years. The developing brains in children and adolescents are more susceptible to concussion than adult brain. The mechanism by which acute TBI may lead to the neurodegenerative process of CTE associated with tau hyperphosphorylation and the development of neurofibrillary tangles (NFTs) remains speculative. Focal tau-positive NFTs and neurites in close proximity to focal axonal injury and foci of microhaemorrhage and the predilection of CTE-tau pathology for perivascular and subcortical regions suggest that acute TBI-related axonal injury, loss of microvascular integrity, breach of the blood brain barrier, resulting inflammatory cascade and microglia and astrocyte activation are likely to be the basis of the mechanistic link of TBI and CTE. This article provides an overview of the acute and long-term neurological consequences of TBI in sports. Clinical, neuropathological and the possible pathophysiological mechanisms are discussed. This article is part of a Special Issue entitled 'Traumatic Brain Injury'.

Chronic traumatic encephalopathy in professional sports: retrospective and prospective views

PRIMARY OBJECTIVE

The purposes of this paper are to review: (1) the history of chronic traumatic encephalopathy (CTE) in sports, (2) the similarities and differences between historic and current definitions of CTE, (3) recent epidemiology and cohort studies of CTE and (4) controversies regarding the current CTE positions.

RESEARCH DESIGN

Not applicable.

METHODS AND PROCEDURES

Selective review of published articles relevant to CTE.

MAIN OUTCOME AND RESULTS

The current definitions of CTE have evolved from its original definition and now rely heavily on the post-mortem detection of hyperphosphorylated tau for diagnosis. As of 2013, there is a blended cohort of 110 professional athletes diagnosed with CTE. It is being assumed that concussions and/or sub-concussive impacts in contact sports are the sole cause of CTE.

CONCLUSIONS

There are multiple causes of abnormal tau protein deposition in the human brain and the pathogenesis of CTE may not be related solely to concussion and/or sub-concussive injury. In all likelihood, the causes of CTE are a multivariate, as opposed to a univariate, phenomenon.

Counseling athletes on the risk of chronic traumatic encephalopathy

Context:

Chronic traumatic encephalopathy (CTE) is a rare progressive neurologic disorder that can manifest as a combination of cognitive, mood and behavioral, and neurologic symptoms. Despite clinically apparent symptoms, there is no imaging or other diagnostic test that can confirm diagnosis in living subjects. Diagnosis can only be confirmed postmortem by specific histopathologic features within the brain tissue identified on autopsy. CTE represents a unique tauopathy that is distinct from other neurodegenerative diseases.

Evidence Acquisition:

PubMed was searched from 1990 to 2013 for sport concussion and chronic traumatic encephalopathy. Articles were also identified from bibliographies of recent reviews and consensus statements.

Study Design:

Clinical review.

Level of Evidence:

Level 5.

Results:

Although CTE is postulated to occur as a result of repetitive mild traumatic brain injury, the specific etiology and risk factors have not yet been elucidated, and postmortem diagnosis makes causality difficult to determine.

Conclusion:

When counseling athletes and families about the potential association of recurrent concussions and the development of CTE, discussion of proper management of concussion is cornerstone. Unfortunately, to date, there is no equipment that can prevent concussions; however, rule changes and legislation may decrease the risk. It is imperative that return to play is medically supervised by a provider trained in the management of concussion and begins only once symptoms have resolved. In addition, athletes with permanent symptoms should be retired from contact sport.

Chronic traumatic encephalopathy and the availability cascade

Chronic traumatic encephalopathy (CTE) in sports has been known for > 85 years, and has experienced a resurgence of interest over the past decade, both in the media and in the scientific community. However, there appears to be a disconnection between the public's perception of CTE and the currently available scientific data. The cognitive bias known as the "availability cascade" has been suggested as a reason to explain this rift in knowledge. This review summarizes and updates the history of CTE in sports, discusses recent epidemiological and autopsy studies, summarizes the evidence base related to CTE in sports, and offers recommendations for future directions.

FMRI and brain activation after sport concussion: a tale of two cases

Sport-related concussions are now recognized as a major public health concern: the number of participants in sport and recreation is growing, possibly playing their games faster, and there is heightened public awareness of injuries to some high-profile athletes. However, many clinicians still rely on subjective symptom reports for the clinical determination of recovery. Relying on subjective symptom reports can be problematic, as it has been shown that some concussed athletes may downplay their symptoms. The use of neuropsychological (NP) testing has enabled clinicians to measure the effects and extent of impairment following concussion more precisely, providing more objective metrics for determining recovery. Nevertheless, there is a remaining concern that brain abnormalities may exist beyond the point at which individuals achieve recovery in self-reported symptoms and cognition measured by NP testing. Our understanding of brain recovery after concussion is important, not only from a neuroscience perspective, but also from the perspective of clinical decision-making for safe return-to-play. A number of advanced neuroimaging tools, including blood oxygen level dependent functional magnetic resonance imaging (fMRI), have independently yielded early information on abnormal brain functioning. In the two cases presented in this article, we report contrasting brain activation patterns and recovery profiles using fMRI. Importantly, fMRI was conducted using adapted versions of the most sensitive computerized NP tests administered in our current clinical practice to determine impairments and recovery after sport-related concussion. One of the cases is consistent with the concept of lagging brain recovery.

Economic burden of time lost due to injury in NHL hockey players

OBJECTIVE

To determine the economic burden of salary costs lost due to injury in the National Hockey League (NHL).

METHODS

All NHL players who engaged in at least one regular season game during the 2009-2010 to 2011-2012 seasons comprised the study population. We performed a retrospective cross-sectional analysis of publically available media sources to collect injury and salary data. Outcome measurements were games missed during regular season play due to hockey-related injury and lost salary.

RESULTS

A total of 50.9% of all NHL players missed at least one game within a season of play, and injuries represented a total salary cost of approximately US$218 million per year. Concussions alone amounted to a salary loss of US$42.8 million a year. Head/neck injuries and leg/foot injuries were the most expensive in terms of overall cost, while head/neck and shoulder injuries had the highest mean cost.

CONCLUSIONS

NHL players commonly miss time due to injury, which creates a substantial burden in lost salary costs.

Instrumenting the balance error scoring system for use with patients reporting persistent balance problems after mild traumatic brain injury

OBJECTIVE

To determine whether alterations to the Balance Error Scoring System (BESS), such as modified conditions and/or instrumentation, would improve the ability to correctly classify traumatic brain injury (TBI) status in patients with mild TBI with persistent self-reported balance complaints.

DESIGN

Cross-sectional study.

SETTING

Outpatient clinic.

PARTICIPANTS

Subjects (n=13; age, 16.3±2y) with a recent history of concussion (mild TBI group) and demographically matched control subjects (n=13; age, 16.7±2y; control group).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Outcome measures included the BESS, modified BESS, instrumented BESS, and instrumented modified BESS. All subjects were tested on the noninstrumented BESS and modified BESS and were scored by visual observation of instability in 6 and 3 stance conditions, respectively. Instrumentation of these 2 tests used 1 inertial sensor with an accelerometer and gyroscope to quantify bidirectional body sway.

RESULTS

Scores from the BESS and the modified BESS tests were similar between groups. However, results from the instrumented measures using the inertial sensor were significantly different between groups. The instrumented modified BESS had superior diagnostic classification and the largest area under the curve when compared with the other balance measures.

CONCLUSIONS

A concussion may disrupt the sensory processing required for optimal postural control, which was measured by sway during quiet stance. These results suggest that the use of portable inertial sensors may be useful in the move toward more objective and sensitive measures of balance control postconcussion, but more work is needed to increase sensitivity.

Chronic traumatic encephalopathy in sport: a systematic review

OBJECTIVE

To provide a critical review of chronic traumatic encephalopathy (CTE) by considering the range of clinical presentations, neuropathology and the strength of evidence for CTE as a distinct syndrome.

DATA SOURCES

Seven electronic databases were searched using a combination of MeSH terms and key words to identify relevant articles.

REVIEW METHODS

Specific inclusion and exclusion criteria were used to select studies for review. Data extracted where present included study population, exposure/outcome measures, clinical data, neurological examination findings, cognitive assessment, investigation results and neuropathology results.

RESULTS

The data from 158 published case studies were reviewed. Critical differences between the older descriptions of CTE (the 'classic' syndrome) and the recent descriptions (the 'modern' syndrome) exist in the age of onset, natural history, clinical features, pathological findings and diagnostic criteria, which suggests that modern CTE is a different syndrome. The methodology of the current studies does not allow determination of aetiology or risk factors.

CONCLUSIONS

The clinicopathological differences between the 'classic' CTE syndrome and the 'modern' syndrome suggest that the new syndrome needs a different nomenclature. Further research is required to clearly define the clinical phenotype of the modern CTE syndrome and establish the underlying aetiology. Future research needs to address these issues through large-scale, prospective clinicopathological studies.

Treatment of head injuries

Sports-related brain injuries are increasing in incidence and may affect athletes from many different sports. Concussion is the most common form of sports-related head injury and is a form of mild traumatic brain injury. Evaluations of concussed athletes should include careful history, focused neurologic examination, balance testing, and cognitive testing. Postinjury management consists of avoiding aggravating factors until symptoms resolve. Return to play should not begin until all symptoms resolve, and then this should be done in a graduated fashion that avoids recreating symptoms. Research is ongoing concerning the maximum safe number of concussive injuries and any possible long-term sequelae.

Repetitive traumatic brain injury and development of chronic traumatic encephalopathy: a potential role for biomarkers in diagnosis, prognosis, and treatment?

The diagnosis of chronic traumatic encephalopathy (CTE) upon autopsy in a growing number of athletes and soldiers alike has resulted in increased awareness, by both the scientific/medical and lay communities, of the potential for lasting effects of repetitive traumatic brain injury. While the scientific community has come to better understand the clinical presentation and underlying pathophysiology of CTE, the diagnosis of CTE remains autopsy-based, which prevents adequate monitoring and tracking of the disease. The lack of established biomarkers or imaging modalities for diagnostic and prognostic purposes also prevents the development and implementation of therapeutic protocols. In this work the clinical history and pathologic findings associated with CTE are reviewed, as well as imaging modalities that have demonstrated some promise for future use in the diagnosis and/or tracking of CTE or repetitive brain injury. Biomarkers under investigation are also discussed with particular attention to the timing of release and potential utility in situations of repetitive traumatic brain injury. Further investigation into imaging modalities and biomarker elucidation for the diagnosis of CTE is clearly both needed and warranted.

Tissue vulnerability is increased following repetitive mild traumatic brain injury in the rat

Repetitive mild traumatic brain injury (rmTBI) is an important medical concern for active sports and military personnel. Multiple mild injuries may exacerbate tissue damage resulting in cumulative brain injury and poor functional recovery. In the present study, we investigated the time course of brain vulnerability to rmTBI in a rat model of mild cortical controlled impact. An initial mild injury was followed by a second injury unilaterally at an interval of 1, 3, or 7 days. RmTBI animals were compared to single mTBI and sham treated animals. Neuropathology was assessed using multi-modal magnetic resonance imaging (MRI), followed by ex vivo tissue immunohistochemistry. Neurological and behavioral outcomes were evaluated in a subset of animals receiving rmTBI 3 days apart and shams. RmTBI 1 or 3 days apart but not 7 days apart revealed significantly exacerbated MRI-definable lesion volumes compared to single mTBI and shams. Increases in cortical tissue damage, extravascular iron and glial activation assessed by histology/immunohistochemistry correlated with in vivo MRI findings where shorter intervals (1 or 3 days apart) resulted in greater tissue pathology. There were no neurological deficits associated with rmTBI 3 day animals. At 1 mo post-injury, animals with rmTBI 3 days apart showed reduced exploratory behaviors and subtle spatial learning memory impairments were observed. Collectively, our findings suggest that the mildly-impacted brain is more vulnerable to repetitive injury when delivered within 3 days following initial mTBI.

Nine-year risk of depression diagnosis increases with increasing self-reported concussions in retired professional football players

BACKGROUND

Concussions may accelerate the progression to long-term mental health outcomes such as depression in athletes.

PURPOSE

To prospectively determine the effects of recurrent concussions on the clinical diagnosis of depression in a group of retired football players.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Members of the National Football League Retired Players Association responded to a baseline General Health Survey (GHS) in 2001. They also completed a follow-up survey in 2010. Both surveys asked about demographic information, number of concussions sustained during their professional football career, physical/mental health, and prevalence of diagnosed medical conditions. A physical component summary (Short Form 36 Measurement Model for Functional Assessment of Health and Well-Being [SF-36 PCS]) was calculated from responses for physical health. The main exposure, the history of concussions during the professional playing career (self-report recalled in 2010), was stratified into 5 categories: 0 (referent), 1 to 2, 3 to 4, 5 to 9, and 10+ concussions. The main outcome was a clinical diagnosis of depression between the baseline and follow-up GHS. Classic tabular methods computed crude risk ratios. Binomial regression with a Poisson residual and robust variance estimation to stabilize the fitting algorithm estimated adjusted risk ratios. χ(2) analyses identified associations and trends between concussion history and the 9-year risk of a depression diagnosis.

RESULTS

Of the 1044 respondents with complete data from the baseline and follow-up GHS, 106 (10.2%) reported being clinically diagnosed as depressed between the baseline and follow-up GHS. Approximately 65% of all respondents self-reported sustaining at least 1 concussion during their professional careers. The 9-year risk of a depression diagnosis increased with an increasing number of self-reported concussions, ranging from 3.0% in the "no concussions" group to 26.8% in the "10+" group (linear trend: P < .001). A strong dose-response relationship was observed even after controlling for confounders (years retired from professional football and 2001 SF-36 PCS). Retired athletes with a depression diagnosis also had a lower SF-36 PCS before diagnosis. The association between concussions and depression was independent of the relationship between decreased physical health and depression.

CONCLUSION

Professional football players self-reporting concussions are at greater risk for having depressive episodes later in life compared with those retired players self-reporting no concussions.

The young brain and concussion: imaging as a biomarker for diagnosis and prognosis

Concussion (mild traumatic brain injury (mTBI)) is a significant pediatric public health concern. Despite increased awareness, a comprehensive understanding of the acute and chronic effects of concussion on central nervous system structure and function remains incomplete. Here we review the definition, epidemiology, and sequelae of concussion within the developing brain, during childhood and adolescence, with current data derived from studies of pathophysiology and neuroimaging. These findings may contribute to a better understanding of the neurological consequences of traumatic brain injuries, which in turn, may lead to the development of brain biomarkers to improve identification, management and prognosis of pediatric patients suffering from concussion.

Reliability of concussion history in former professional football players

PURPOSE

The reliability of athletes to recall and self-report a concussion history has never been quantified. This study examined the reliability of the self-report concussion history measure and explored determinants of recall in the number of self-reported concussions in a group of retired professional football players.

METHODS

In 2001, a short questionnaire was administered to a cohort of former professional football players to ascertain the number of self-reported concussions they sustained during their professional playing careers. In 2010, the same instrument was readministered to a subset (n = 899) of the original cohort to assess reliability.

RESULTS

Overall reliability was moderate (weighted Cohen κ = 0.48). The majority (62.1%) reported the same number of concussions in both administrations (2001 and 2010); 31.4% reported more concussions in the second administration. Compared with the "same number reported" group, the "greater number reported" group had more deficits in the second administration in their Short Form 36 physical health (composite score combining physical functioning, role physical, bodily pain, general health) and mental health (e.g., composite score combining vitality, social functioning, role emotional) scales.

CONCLUSIONS

The self-reported concussion history had moderate reliability in former professional football players, on the basis of two administrations of the same instrument, 9 yr apart. However, changes in health status may be differentially associated with recall of concussions.

Cognitive effects of one season of head impacts in a cohort of collegiate contact sport athletes

OBJECTIVE

To determine whether exposure to repetitive head impacts over a single season negatively affects cognitive performance in collegiate contact sport athletes.

METHODS

This is a prospective cohort study at 3 Division I National Collegiate Athletic Association athletic programs. Participants were 214 Division I college varsity football and ice hockey players who wore instrumented helmets that recorded the acceleration-time history of the head following impact, and 45 noncontact sport athletes. All athletes were assessed prior to and shortly after the season with a cognitive screening battery (ImPACT) and a subgroup of athletes also were assessed with 7 measures from a neuropsychological test battery.

RESULTS

Few cognitive differences were found between the athlete groups at the preseason or postseason assessments. However, a higher percentage of the contact sport athletes performed more poorly than predicted postseason on a measure of new learning (California Verbal Learning Test) compared to the noncontact athletes (24% vs 3.6%; p < 0.006). On 2 postseason cognitive measures (ImPACT Reaction Time and Trails 4/B), poorer performance was significantly associated with higher scores on several head impact exposure metrics.

CONCLUSION

Repetitive head impacts over the course of a single season may negatively impact learning in some collegiate athletes. Further work is needed to assess whether such effects are short term or persistent.