Current concepts. Concussion in sports

Analysis of bicycle helmet damage visibility for concussion-threshold impacts

Any helmet involved in an accident should be replaced, regardless of appearance after impact. However, consumer compliance and interpretation of this recommendation is unclear, for which there is additional ambiguity for lesser impacts. This study aims to investigate the relation between helmet damage visibility and lesser impacts in line with concussion. As a preliminary model, a commercially available road-style helmet was chosen. Twelve helmets underwent impact attenuation testing; four were dropped from the standard testing height of 2 m, and eight from lower drop heights (0.34 and 0.42 m) associated with the production of linear accelerations (90 and 100 g, respectively) consistent with the production of concussion. Expanded polystyrene damage was assessed via flat punch penetration testing. American adults were then polled on helmet damage visibility based upon before and after photos. All helmets demonstrated damage to the expanded polystyrene liner in the form of altered material properties. Helmets dropped from 2 m displayed significant changes in elastic buckling (p < .01) and densification behavior (p < .01) as compared with lower drop height results. Adverse change in elastic buckling behavior was found to increase linearly with drop height (p < .001). Damage visibility was significant for helmets dropped from a 2-meter height, however, such a relation among the helmets impacted at the threshold for concussion was lacking. These findings suggest that for the chosen helmet model, consumers may be unable to distinguish between new helmets and helmets with diminished protective abilities.

Two Sports, Two Systems, One Goal: A Comparative Study of Concussion Policies and Practices of the Australian Football League and Hockey Canada

Concussion in sport is today regarded as both a public health issue and high profile injury concern in many contact and collision sports. This paper undertakes a comparative review of the current policies and practices of two high profile national sporting organisations of such sports—the Australian Football League (AFL) and Hockey Canada (HC)—in governing the issue as a regulatory concern. By examining the policies and practices of the AFL and HC, this study aims to identify common themes, divergent practices, and nuanced sport-specific approaches to develop understandings on the regulation and governance of this high profile sports injury. The paper aims to contribute to understanding concussion as a regulatory concern, while at the same time recognising the heterogeneity of sport and reinforcing nuanced understandings that align to specific social and cultural settings. We make recommendations based on regulatory and cultural legitimacy. The paper concludes that these NSOs are institutional actors with historical and cultural roots who assert regulatory legitimacy by steering and influencing behaviour and directing the regulatory agenda to manage and mitigate the harm associated with concussion.

Effect of Diagnosed Sleep Disorders on Baseline Concussion Symptom, Cognitive, and Balance Assessments in Collegiate Athletes

BACKGROUND

Symptoms, cognition, balance, and other domains are commonly assessed at baseline testing as part of comprehensive preseason evaluations among collegiate student-athletes. Although approximately 27% of college students have at least 1 sleep disorder, researchers have yet to examine the role of a preexisting sleep disorder on preinjury baseline performance.

PURPOSE

To compare athletes with and without a reported history of diagnosed sleep disorders on commonly used baseline concussion assessments.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 666 National Collegiate Athletic Association student-athletes completed baseline measures including the Balance Error Scoring System (BESS), Brief Symptom Inventory-18 (BSI-18), Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Post-Concussion Symptom Scale (PCSS), Sport Concussion Assessment Tool-5th Edition (SCAT5), and Standardized Assessment of Concussion (SAC). There were 333 athletes with a history of diagnosed sleep disorders who were matched on age, sex, sport, and concussion history to 333 athletes with no history of diagnosed sleep disorders. Participants in both groups had a mean age of 19.89 ± 1.36 years and included 182 (54.7%) male athletes, and 126 (37.8%) reported a history of ≥1 concussions.

RESULTS

A series of 1-way analyses of covariance with Bonferroni corrections revealed significant group differences on the BESS (F_1,559 = 8.88; P < .01); BSI-18 somatization (F_1,640 = 18.48; P < .01), depression (F_1,640 = 18.78; P < .01), anxiety (F_1,640 = 19.42; P < .01), and global severity index (F_1,640 = 27.18; P < .01); PCSS (F_1,424 = 29.42; P < .01); SCAT5 symptom number (F_1,634 = 28.79; P < .01) and symptom severity (F_1,634 = 31.74; P < .01); and SAC (F_1,578 = 4.36; P = .037). Specifically, while the sleep disorder group did perform better on the BESS, they also reported higher symptoms on the BSI-18, PCSS, and SCAT5 and performed worse on the SAC. There were no group differences on ImPACT performance.

CONCLUSION

Collegiate student-athletes with diagnosed sleep disorders reported elevated affective and concussion symptoms at baseline that could affect the interpretation of postinjury impairments and symptoms. Based on the small effect sizes of our findings, however, the magnitude of these differences is of questionable clinical significance. Still, clinicians should consider diagnosed sleep disorders as reported during preparticipation sports physical examinations when interpreting baseline and postinjury concussion assessments.

On-Field Signs Predict Future Acute Symptoms After Sport-Related Concussion: A Structural Equation Modeling Study

OBJECTIVES

This study investigated the relationship between on-field, objective signs immediately following sport-related concussion and self-reported symptom endorsement within 1 day post injury.

METHODS

A retrospective case series of 237 concussed high school athletes was performed. On-field signs were evaluated immediately post injury. Self-reported symptoms (2 clusters) were collected within 1 day post injury. A two-step structural equation model and follow-up bivariate regression analyses of significant on-field signs and symptom clusters were performed.

RESULTS

Signs of immediate memory, β=0.20, p=.04, and postural instability, β=0.19, p < .01, significantly predicted a greater likelihood of endorsing the cognitive-migraine-fatigue symptom cluster within 1 day post injury. Regarding signs correlated with specific symptoms, immediate memory was associated with symptoms of trouble remembering, χ 2 =37.92, p < .001, odds ratio (OR)=3.89 (95% confidence interval (CI) [2.47, 6.13]), and concentration difficulties, χ 2 =10.84, p=.001, OR=2.13 (95% CI [1.37, 3.30]). Postural instability was associated with symptom endorsement of trouble remembering, χ 2 =12.08, p < .001, OR=1.76 (95% CI [1.29, 2.40]).

CONCLUSIONS

Certain post-concussion on-field signs exhibited after injury were associated with specific symptom endorsement within 1 day post injury. Based on these associations, individualized education-based interventions and academic accommodations may help reduce unanticipated worry from parents, students, and teachers following a student-athlete's sport-related concussion, especially in cases of delayed onset symptoms. (JINS, 2018, 24, 476-485).

Genetic polymorphisms associated with the risk of concussion in 1056 college athletes: a multicentre prospective cohort study

BACKGROUND/AIM

To evaluate the association of genetic polymorphisms APOE, APOE G-219T promoter, microtubule associated protein(MAPT)/tau exon 6 Ser⁵³Pro, MAPT/tau Hist⁴⁷Tyr, IL-6572 G/C and IL-6R^Asp358^Ala with the risk of concussion in college athletes.

METHODS

A 23-centre prospective cohort study of 1056 college athletes with genotyping was completed between August 2003 and December 2012. All athletes completed baseline medical and concussion questionnaires, and post-concussion data were collected for athletes with a documented concussion.

RESULTS

The study cohort consisted of 1056 athletes of mean±SD age 19.7±1.5 years, 89.3% male, 59.4% Caucasian, 35.0% African-American, 5.6% other race. The athletes participated in American football, soccer, basketball, softball, men's wrestling and club rugby. A total of 133 (12.1% prevalence) concussions occurred during an average surveillance of 3 years per athlete. We observed a significant positive association between IL-6R CC (p=0.001) and a negative association between APOE4 (p=0.03) and the risk of concussion. Unadjusted and adjusted logistic regression analysis showed a significant association between IL-6R CC and concussion (OR 3.48; 95% CI 1.58 to 7.65; p=0.002) and between the APOE4 allele and concussion (OR 0.61; 95% CI 0.38 to 0.96; p=0.04), which persisted after adjustment for confounders.

CONCLUSIONS

IL-6R CC was associated with a three times greater concussion risk and APOE4 with a 40% lower risk.

Systematic Review of Genetic Risk Factors for Sustaining a Mild Traumatic Brain Injury

This systematic review examined the association between genetics and risk for sustaining a traumatic brain injury. We retrieved articles published in English from 1980 to July 2016 obtained from the online databases PubMed, PsycINFO®, MEDLINE®, Embase, and Web of Science. In total 5903 articles were identified, 77 underwent full-text screening, and 6 were included in this review. Five studies examined the risk of concussion associated with apolipoprotein E alleles (APOE-ɛ2, ɛ3,ɛ4), and polymorphisms of the APOE promoter (rs405509), brain derived neurotrophic factor (BDNF, rs6265), and dopamine receptor D2 (DRD2, rs1800497) were each considered in two studies. Microtubule associated protein tau (TAU exon 6 polymorphisms His47Tyr [rs2258689] and Ser53Pro [rs10445337]), and neurofilament heavy (NEHF, rs165602) genotypic variants, were the focus of single studies. No study showed an increased risk associated solely with the presence of the APOE-ɛ4 allele, nor were there any significant findings for the NEFH, TAU, or DRD2 genotypic variants. Two studies examined the APOE promoter -219G/T polymorphism in athletes, and both found an association with concussion. Both BDNF studies also found a significant association with concussion incidence; United States soldiers with the Met/Met genotype were more likely to report a history of concussion prior to deployment and to sustain a concussion during deployment. We conclude that the APOE promoter -219G/T polymorphism and the BDNF Met/Met genotype might confer risk for sustaining a TBI. Based on research to date, the APOE-ɛ4 allele does not appear to influence risk. More research is needed to determine if these findings replicate.

Assessment of motor cortex excitability and inhibition during a cognitive task in individuals with concussion

PRIMARY OBJECTIVE

To examine the function of the motor cortex during executive function tasks in individuals with concussion, relative to healthy controls.

METHODS AND PROCEDURES

Transcranial magnetic stimulation (TMS) was used to assess motor cortex excitability and inhibition acutely, within 72 hours, and over two months, post-concussion in 23 participants, nine individuals with concussion and 14 controls. Participants performed a cognitive task during TMS to determine the impact of cognitive task on the motor cortex.

MAIN OUTCOMES AND RESULTS

Resting motor threshold (p = 0.02) and motor-evoked potential (MEP_Rest) amplitude (p = 0.03) were different between groups, both suggesting greater corticospinal excitability in individuals with concussion. Cortical silent period (CSP) duration was greater at 72 hours (p = 0.03), one month (p = 0.003) and two months (p = 0.05) in individuals with concussion, suggesting increased intracortical inhibition. The performance of a cognitive task caused an increase in MEP_Rest (p = 0.006) and CSP (p = 0.04), compared to baseline in both groups, but no interaction of condition by group (p ≥ 0.91) for either measure.

CONCLUSION

Simultaneously performing a cognitive task during motor cortex assessments increased corticospinal excitability and intracortical inhibition; however, the increase was not different between groups.

Using a dual-task protocol to investigate motor and cognitive performance in healthy children and youth

OBJECTIVES

Mild traumatic brain injury (or concussion) is a prevalent yet understudied health concern in children and youth. This injury can cause dysfunction in both motor and cognitive domains; however, most literature focuses on single-task neuropsychological tests which only assess cognition. Although dual-task research on concussed children and youth is needed as many daily activities require both motor and cognitive domains, we must first investigate whether performing simultaneous motor and cognitive tasks of varied complexity impact these domains in healthy children and youth.

PARTICIPANTS AND DESIGN

Data collected from 106 healthy children and youth (5-18 years) created a normative dataset. Participants performed motor (postural stability) and cognitive (visual attention) tasks under single- and dual-task conditions. The cognitive task difficulty remained constant while the motor task had four conditions of increasing difficulty. The relationship between the number of correct responses (cognitive performance) and sway index (motor performance) was determined using two repeated measures ANOVAs (p<0.05).

RESULTS

Dual-task conditions resulted in reduced postural stability, with greater differences on the foam surface (F_2,206=16.070, p<0.0005). No statistically significant differences were observed in attention (F_4,101=0.713, p=0.584).

CONCLUSIONS

Postural stability decreased under dual-task conditions, but attention was maintained or improved. Consequently, attention took precedence over postural control when performing tasks concurrently, demonstrating the ability for dual-task methodology to isolate specific processes. This study provides a normative dataset to be used during clinical management to identify functional deficits following concussion and acts as a starting point to explore dual-task protocols in children and youth following concussion.

Canadian Minor Hockey Participants’ Knowledge about Concussion

Background and Objectives:

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

Methods:

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

Results:

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

Conclusions:

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

Diagnostic accuracy studies in mild traumatic brain injury: a systematic review and descriptive analysis of published evidence

OBJECTIVES

To synthesize evidence and report findings from a systematic search and descriptive analysis of peer-reviewed published evidence of the accuracy of tests used for diagnosing mild traumatic brain injury (mTBI). The article also summarizes points of concurrence and divergence regarding case definitions of mTBI identified during the review. TYPE: Systematic review and descriptive analysis of published evidence.

LITERATURE SURVEY

A search of PubMed, PsychInfo, and the Cochrane Library for peer-reviewed publications between 1990 and July 6, 2011, identified 1218 abstracts; 277 articles were identified for full review, and 13 articles met the criteria for evaluation.

METHODOLOGY

Manuscript inclusion criteria were (1) reported sensitivity (Se) and specificity (Sp), or reported data were sufficient to compute Se and Sp; (2) >1 participant in the study; (3) at least 80% of the study cohort was ≥18 years of age; and (4) written in English. Articles describing clinical practice guidelines, opinions, theories, or clinical protocols were excluded. Seven investigators independently evaluated each article according to the Standards for Reporting of Diagnostic Accuracy (STARD) criteria.

SYNTHESIS

Findings indicate that all 13 studies involved civilian noncombat populations. In 7 studies, authors examined acute mTBI, and in 4 studies, historical remote mTBI was examined. In the 13 studies, Se ranged from 13%-92% and Sp ranged from 72%-99%, but confidence in these findings is problematic because the STARD review indicates opportunities for bias in each study.

CONCLUSIONS

Findings indicate that no well-defined definition or clinical diagnostic criteria exist for mTBI and that diagnostic accuracy is currently insufficient for discriminating between mTBI and co-occurring mental health conditions for acute and historic mTBI. Findings highlight the need for research examining the diagnostic accuracy for acute and historic mTBI.

Predicting mild traumatic brain injury patients at risk of persistent symptoms in the Emergency Department

OBJECTIVE

To identify factors that can predict which emergency department (ED) patients with mTBI are likely to develop persistent post-concussion symptoms (PPCS).

DESIGN

A matched case-control study was conducted at a Level 1 trauma centre between June 2006 and July 2009. Patients diagnosed with mTBI in the ED and diagnosed at a concussion management programme with at least one PPCS (85 cases) were compared to patients diagnosed with mTBI in the ED (340 controls) to determine if factors assessed at the time of ED presentation could predict patients likely to develop persistent symptoms.

RESULTS

Multivariable hierarchical logistic regression with variables indicating increased risk for PPCS (prior mTBI, history of depression, history of anxiety, multiple injury, forgetfulness/poor memory, noise sensitivity, or light sensitivity) resulted in a final predictive model including prior mTBI, history of anxiety, forgetfulness/poor memory and light sensitivity. The final model had a specificity of 87.9% and a sensitivity of 69.9%.

CONCLUSIONS

A strong prediction model to identify those ED patients with mTBI at risk for PPCS was developed and could be easily implemented in the ED; therefore, helping to target those patients who would potentially benefit from close follow-up.

Current sport-related concussion teaching and clinical practices of sports medicine professionals

CONTEXT

Various consensus and position statements recommend a multifaceted approach when diagnosing a possible concussion. The effectiveness of these materials depends largely on their content being disseminated to educators and to those in the clinical setting.

OBJECTIVE

To identify the concussion management methods and guidelines currently taught in the athletic training classroom and clinical settings and to track the dissemination of the Vienna guidelines throughout the educational curriculum.

DESIGN

A 17-question Internet survey.

SETTING

A Web link was e-mailed to the program directors and certified athletic trainers holding educational positions in athletic training at 300 accredited programs in the United States.

PATIENTS OR OTHER PARTICIPANTS

513 program directors and athletic trainers.

MAIN OUTCOME MEASURE(S)

Survey questions addressed education level, years of certification, employment setting, concussion assessment and return-to-play guidelines used in the clinical setting and the classroom, and clinical and teaching preferences for existing position statements and concussion grading systems. The Vienna guidelines' "simple" and "complex" definitions of concussions were provided with the return-to-play stepwise approach.

RESULTS

The National Athletic Trainers' Association position statement was the most widely used method of assessing, managing (61%), and making return-to-play decisions (47%) among participants. More than half of participants (66%) had never heard of the Vienna guidelines. After reading the Vienna guidelines' definitions and return-to-play criteria, nearly three-fourths of participants agreed with them. In addition, 68% said that they would use them, and 84% reported that they would teach them to students.

CONCLUSIONS

The majority of program directors and certified athletic trainers used a multidimensional approach to assess and manage a concussion. The National Athletic Trainers' Association position statement and Vienna guidelines were underused in both the classroom and clinical settings.

Emergency department visits for concussion in young child athletes

OBJECTIVES

The objective of this study was to characterize emergency department (ED) visits for pediatric sport-related concussion (SRC) in pre-high school- versus high school-aged athletes.

METHODS

A stratified probability sample of US hospitals that provide emergency services in the National Electronic Injury Surveillance System (1997-2007) and All Injury Program (2001-2005) was used. Concussion-related ED visits were analyzed for 8- to 13- and 14- to 19-year-old patients. Population data were obtained from the US Census Bureau; sport participation data were obtained from National Sporting Goods Association.

RESULTS

From 2001 to 2005, US children who were aged 8 to 19 years had an estimated 502 000 ED visits for concussion. The 8- to 13-year-old group accounted for approximately 35% of these visits. Approximately half of all ED visits for concussion were SRC. The 8- to 13-year-old group sustained 40% of these, which represents 58% of all concussions in this group. Approximately 25% of all SRC visits in the 8- to 13-year-old group occurred during organized team sport (OTS). During the study period, approximately 4 in 1000 children aged 8 to 13 years and 6 in 1000 children aged 14 to 19 years had an ED visit for SRC, and 1 in 1000 children aged 8 to 13 years and 3 in 1000 children aged 14 to 19 years had an ED visit for concussion sustained during OTS. From 1997 to 2007, although participation had declined, ED visits for concussions in OTS in 8- to 13-year-old children had doubled and had increased by >200% in the 14- to 19-year-old group.

CONCLUSIONS

The number of SRCs in young athletes is noteworthy. Additional research is required.

Sport-related concussion in adolescents

Sport-related concussion is a common problem encountered by pediatricians and other primary care physicians. Assessment of concussion is based on clinical evaluation. The Zurich consensus statement provides a basic framework to guide concussion management decisions and recommends an individualized approach and the exercising of clinical judgment in return-to-play decisions. This article reviews practice aspects of concussion for the adolescent athletes who present in the primary care office or clinic setting.

Long-term test-retest reliability of baseline cognitive assessments using ImPACT

BACKGROUND

Computer-based assessment programs are commonly used to document baseline cognitive performance for comparison with postconcussion testing. There are currently no guidelines for how often baseline assessments should be updated, and no data documenting the test-retest stability of baseline measures over relevant time periods.

PURPOSE

To establish long-term test-retest reliability of baseline assessments using ImPACT, and to compare various statistical methods for establishing test-retest reliability.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Participants were 95 collegiate varsity athletes completing baseline cognitive testing at 2 time periods, approximately 2 years apart. No participant sustained a concussion between assessments. All athletes completed the ImPACT test battery; dependent measures were the composite scores and total symptom scale score.

RESULTS

Intraclass correlation coefficient estimates for visual memory (.65), processing speed (.74), and reaction time (.68) composite scores reflected stability over the 2-year period, with greater variability in verbal memory (.46) and symptom scale (.43) scores. Using reliable change indices and regression-based methods, only a small percentage of participants' scores showed "reliable" or "significant" change on the composite scores (0%-6%), or symptom scale scores (5%-10%).

CONCLUSION

The current results suggest that college athletes' cognitive performance at baseline remains considerably stable over a 2-year period. These data help establish the effects of longer, clinically pragmatic testing intervals on test-retest reliability.

CLINICAL IMPLICATIONS

The current results suggest that stretching the time between baseline assessments from 1 to 2 years may have little effect on the clinical management of concussions in collegiate athletes. These results should not be generalized to collegiate football players, who were not included in this sample. Youth athletes (high school and younger) should continue to receive annually updated baseline assessments until prospective study of the stability of baseline assessments for this younger age group can be completed.

Is there a relationship between whiplash-associated disorders and concussion in hockey? A preliminary study

PRIMARY OBJECTIVE

To examine the relationship between the occurrence of whiplash-associated disorders and concussion symptoms in hockey players.

RESEARCH DESIGN

Prospective cohort observational study to examine the relationship between whiplash associated disorders and concussion in actual hockey play.

METHODS AND PROCEDURES

Twenty hockey teams were followed prospectively for one season. Team therapists completed acute and 7-10 day follow-up evaluation questionnaires for all of the players who received either a whiplash mechanism or a concussion.

MAIN OUTCOMES AND RESULTS

183 players were registered for this study; 13 received either a whiplash mechanistic injury or a concussion injury. Initial injuries ranged from WAD I to WAD III and all subjects reported concussion symptoms. Only three subjects reported full resolution of both WAD and concussion symptoms at the 7-10 day follow-up evaluation.

CONCLUSIONS

There is a strong association between whiplash induced neck injuries and the symptoms of concussion in hockey injuries. Both should be evaluated when dealing with athletes/patients suffering from either injury.

The neurophysiology and assessment of sports-related head injuries

This article provides a review of contemporary standards for the management of athletes who have sustained a sports-related head injury. Recent research regarding concussion management is reviewed with specific reference to clinical care. The use of neuropsychologic testing in sports also is reviewed, and a systematic protocol for the management of sports-related concussion is presented.

Adolescent sports concussion

Approximately 2 million sports and recreation concussive injuries occur per year in the United States, which may be an underestimate because of inconsistent data reporting. The field of concussion management has evolved rapidly over the last 10 years, and with these advances comes new understanding of the significant symptomatic and cognitive impairments of concussion. These sequelae are more fully realized and may last longer than previously thought. Data have emerged regarding pathophysiology of concussion, risk factors, outcome, effects of repetitive injury, subtypes of concussive injury, and treatment protocols. This evidence calls for more conservative management of concussion, particularly in younger athletes, and demonstrates the shortcomings of concussion guidelines.

Medical conditions affecting sports participation

Children and adolescents with medical conditions present special issues with respect to participation in athletic activities. The pediatrician can play an important role in determining whether a child with a health condition should participate in certain sports by assessing the child's health status, suggesting appropriate equipment or modifications of sports to decrease the risk of injury, and educating the athlete, parent(s) or guardian, and coach regarding the risks of injury as they relate to the child's condition. This report updates a previous policy statement and provides information for pediatricians on sports participation for children and adolescents with medical conditions.

APOE, APOE promoter, and Tau genotypes and risk for concussion in college athletes

OBJECTIVE

To investigate associations of APOE, APOE promoter (G-219T), and tau protein exon 6 polymorphisms (47 and 53) and a history of self-reported concussion in college athletes.

DESIGN

Multi-center cross-sectional study.

SETTING

Male football and male and female soccer programs at the University of South Carolina, Jacksonville University, Benedict College, and the College of Charleston.

PARTICIPANTS

Active 18- to 30-year-old (n = 195) intercollegiate male football players and male and female soccer players during 2001 and 2002.

ASSESSMENT OF RISK FACTORS

Written questionnaires and blood or mouthwash samples for DNA for genotyping by RFLP/PCR.

MAIN OUTCOME MEASUREMENT

Self-reported history of concussions over the previous 8 years.

RESULTS

A statistically significant, nearly 3-fold increase in risk of a history of concussion for those with the APOE promoter G-219T TT genotype relative to the GG genotype (OR, 2.8; 95% CI, 1.1 to 6.9) adjusted for age, sport, school, and years in their primary sport, a finding that was stronger for Cantu grade 2 and 3 concussions.

CONCLUSIONS

These results suggest that college athletes with an APOE promoter G-219T TT genotype may be at increased risk for having a history of concussions, especially more severe concussions. Although there was some support for the possibility that the tau 53 polymorphism may be associated with increased risk of prior concussion (OR, 2.1; 95% CI, 0.3 to 14.5), there was no support for an association with APOE genotypes. The results of this cross-sectional study support the need for a prospective study of genetic factors, such as APOE promoter polymorphisms, and the incidence of and sequelae from concussions in college athletes.

Alteration of postural responses to visual field motion in mild traumatic brain injury

OBJECTIVE

Balance deficits in individuals experiencing mild traumatic brain injury have been documented in numerous recent studies. However, long-lasting balance deficits and specific mechanisms causing these deficits have not been systematically examined. This article aimed to present empirical evidence showing destabilizing effects of visual field motion in concussed individuals up to 30 days postinjury.

METHODS

Sixty student athletes participated in the pilot (n = 12) and major experiments (n = 48) before injury. Eight of these 48 subjects who experienced mild traumatic brain injury in athletic events were tested again on Days 3, 10, and 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies.

RESULTS

The area of the center of pressure during upright stance did not change from Day 3 to 30 postinjury with respect to pre-injury status (P > .05). However, balance deficits induced by visual field motion were present up to 30 days postinjury. Destabilizing effect of visual field motion was observed via significant increase of the center of pressure data (P < .05) and reduced coherence value.

CONCLUSION

Our data suggest the presence of residual sensory integration dysfunction in concussed individuals at least 30 days postinjury and may indicate a lower threshold for brain reinjury.

Field-side and prehospital management of the spine-injured athlete

Rapid on-field diagnosis and early stabilization can help to optimize the outcomes of spinal injury, which can have devastating consequences. Several basic principles will guide the rescuer through this process. Preinjury planning should include appointing a team leader, assessing the athletes' equipment, acquiring appropriate equipment to facilitate stabilization, and establishing lines of communication to emergency medical services (EMS). When an athlete is down, the team leader should proceed to quickly assess airway, breathing, circulation, level of consciousness, and activation of EMS. This should be followed by stabilization of the head and neck, a coordinated log roll, and ultimately complete spinal immobilization for transport. Specific techniques for stabilizing the cervical spine, removing the facemask, log rolling the athlete, and lifting the athlete, will improve outcome. The helmet and shoulder pads should remain in place during transport unless specific indications require their removal, in which case a specific protocol should be strictly followed.

Pediatric sport-related concussion: a review of the clinical management of an oft-neglected population

Athletic concussion is a growing focus of attention for pediatricians. Although numerous literature reviews and clinical guidelines are now available pertaining to athletic concussion, few have focused on the pediatric athlete in particular. Sport-related concussions occur relatively frequently in children and adolescents, and primary health care providers are often responsible for coordinating clinical management. Here we summarize the scientific literature pertinent to the care of young athletes. We examine how concussion affects younger and older athletes differently at biomechanical, pathophysiological, neurobehavioral, and contextual levels. We also discuss important issues in clinical management, including preparticipation assessment, concussion evaluation and recovery tracking, and when and how to return pediatric athletes to play sports. We also briefly cover non-sport-related interventions (eg, school support). With proper management, most children and adolescents sustaining a sport-related concussion can be expected to recover fully.

A nonlinear dynamic approach for evaluating postural control: new directions for the management of sport-related cerebral concussion

Recent research suggests that traditional biomechanical models of postural stability do not fully characterise the nonlinear properties of postural control. In sports medicine, this limitation is manifest in the postural steadiness assessment approach, which may not be sufficient for detecting the presence of subtle physiological change after injury. The limitation is especially relevant given that return-to-play decisions are being made based on assessment results. This update first reviews the theoretical foundation and limitations of the traditional postural stability paradigm. It then offers, using the clinical example of athletes recovering from cerebral concussion, an alternative theoretical proposition for measuring changes in postural control by applying a nonlinear dynamic measure known as 'approximate entropy'. Approximate entropy shows promise as a valuable means of detecting previously unrecognised, subtle physiological changes after concussion. It is recommended as an important supplemental assessment tool for determining an athlete's readiness to resume competitive activity.

Concussion management by primary care providers

OBJECTIVE

To assess current concussion management practices of primary care providers.

METHODS

An 11 item questionnaire was mailed to primary care providers in the state of Maine, with serial mailings to non-respondents.

RESULTS

Over 50% of the questionnaires were completed, with nearly 70% of primary care providers indicating that they routinely use published guidelines as a tool in managing patients with concussion. Nearly two thirds of providers were aware that neuropsychological tests could be used, but only 16% had access to such tests within a week of injury.

CONCLUSIONS

Primary care providers are using published concussion management guidelines with high frequency, but many are unable to access neuropsychological testing when it is required.

Management of sport-related concussion in young athletes

Sport-related head injuries are a common clinical problem. Most head injuries in young athletes are mild traumatic brain injuries or concussions. The highest number of sport-related concussions has been reported in American football. In addition to the well described physical and psychosocial growth, there is ongoing neurocognitive development of the brain during childhood and through adolescence. This developmental process has direct implications in the assessment and management of head injuries in young athletes. Research on the management and long-term outcome following brain injuries in young athletes is limited. Traditionally, the assessment of concussion has been based on clinical history and physical and neurological examination. Increasingly, neuropsychological testing, especially computerised testing, is providing objective measures for the initial assessment and follow-up of young athletes following brain injuries. Numerous guidelines have been published for grading and return to play criteria following concussion; however, none of these have been prospectively validated by research and none are specifically applicable to children and adolescents.

A six year prospective study of the incidence and causes of head and neck injuries in international football

OBJECTIVE

To identify those risk factors that have the greatest impact on the incidence of head and neck injuries in international football.

METHOD

A case-control study of players sustaining head and neck injuries during 20 FIFA tournaments (men and women) from 1998 to 2004. Video recordings of incidents were used to identify a range of parameters associated with the incidents. Team physicians provided medical reports describing the nature of each injury. chi2 tests (p< or =0.01) and 95% confidence intervals were used to assess differences in distribution and incidence of injury, respectively.

RESULTS

In total, 248 head and neck injuries were recorded of which 163 were identified and analysed on video sequences. The commonest injuries were contusions (53%), lacerations (20%), and concussions (11%). The incidence of all head and neck injuries was 12.5/1000 player hours (men 12.8, women 11.5) and 3.7 for lost-time injuries (men 3.5, women 4.1). The commonest causes of injury involved aerial challenges (55%) and the use of the upper extremity (33%) or head (30%). The unfair use of the upper extremity was significantly more likely to cause an injury than any other player action. Only one injury (a neck muscle strain) occurred as a result of heading the ball throughout the 20 tournaments equivalent to 0.05 injuries/1000 player hours.

CONCLUSIONS

Players' actions most likely to cause a head or neck injury were the use of the upper extremity or the head but in the majority of cases these challenges were deemed to be fair and within the laws of the game.

The effect of divided attention on gait stability following concussion

BACKGROUND

The need to identify functional impairment following a brain injury is critical to prevent re-injury during the period of recovery. While many neuropsychological tests have been developed to assess cognitive performance, relatively little information on gait and dynamic stability is available on motor task performance for young adults following concussion. This study was performed to investigate the effect of divided attention following concussion on various gait variables. It was hypothesized that, when compared to uninjured controls, concussed subjects would demonstrate deficits in maintenance of dynamic stability.

METHODS

Ten subjects with Grade 2 concussion completed testing within 48 h of injury as well as 10 age-, height-, weight-, and activity-matched controls. The gait protocol consisted of level walking under two conditions: (1) undivided attention (single-task) and (2) while simultaneously completing simple mental tasks (dual-task). Whole-body motion data were collected using a six-camera motion analysis system. A 13-segment biomechanical model was used to compute whole body center of mass motion and velocity.

FINDINGS

Walking with a concurrent cognitive task resulted in significant changes in gait and center of mass measurements for both groups. Concussed subjects were found to be able to conservatively adjust their whole body center of mass motion to maintain dynamic stability while walking without divided attention. However, while walking with divided attention, subjects with concussion demonstrated a significantly greater medio-lateral center of mass sway.

INTERPRETATION

These data suggest that the ability to control and maintain stability in the frontal plane during walking is diminished under divided attention in individuals following a concussion.

Medicolegal issues in sports medicine

This article reviews medicolegal issues in sports medicine. Nonmusculoskeletal medical conditions discussed include cardiac abnormalities, heat illness, and concussion in the athlete. Musculoskeletal injuries with the greatest potential for litigation, knee dislocation, and cervical spine trauma, are also reviewed. We provide legal case examples and discuss evaluation and treatment strategies to assist the medical team in the care of athletes.

The college athlete

Participation in sports is important to many college students. Student athletes come from different levels of previous sport experience as they enter collegiate athletics. The primary source of student medical care is the campus student health center. The health care providers at student health centers attend to many of the sports-related concerns of student athletes. Preparticipation evaluation provides an opportunity to assess the general health of the student athlete and to identify conditions that might increase the risk of further injury. Sudden cardiac death and sports-associated concussions have generated much interest and are reviewed in this article. Other areas reviewed here include use of drugs and supplements, ankle sprains, acute knee ligament injuries, back pain, and shoulder impingement syndrome.

Sport-related concussion: factors associated with prolonged return to play

OBJECTIVE

To assess predictive value of concussion signs and symptoms based on return-to-play timelines.

DESIGN

Physician practice study without diagnosis that includes presentation, initial and subsequent treatment, and management of concussion.

SETTING

National multisite primary care sports medicine provider locations.

PARTICIPANTS

Twenty-two providers at 18 sites; 101 athletes (91 men, 10 women in the following sports: 73 football, 8 basketball, 8 soccer, 3 wrestling, 2 lacrosse, 2 skiing, 5 others; 51 college, 44 high school, 4 professional, and 2 recreational).

MAIN OUTCOME MEASUREMENTS

Duration of symptoms, presence of clinical signs, and time to return to play following concussion.

RESULTS

One hundred one concussions were analyzed. Pearson chi2 analysis of common early and late concussion symptoms revealed statistical significance (P < 0.05) of headache >3 hours, difficulty concentrating >3 hours, any retrograde amnesia or loss of consciousness, and return to play >7 days. There appeared to be a trend in patients with posttraumatic amnesia toward poor outcome, but this was not statistically significant.

CONCLUSIONS

When evaluating concussion, symptoms of headache >3 hours, difficulty concentrating >3 hours, retrograde amnesia, or loss of consciousness may indicate a more severe injury or prolonged recovery; great caution should be exercised before returning these athletes to play.

Return to play following sports-related concussion

This article provides a review of current important issues in the management of athletes who have sustained a concussion during athletic competition. Recent research in the area of concussion management is reviewed with specific reference to the side line evaluation of concussion and the follow-up of the athlete during the recovery period. The use of neuropsychological testing in sports is also reviewed. A systematic protocol for the management of sports related concussion is presented.

Head injuries presenting to emergency departments in the United States from 1990 to 1999 for ice hockey, soccer, and football

STUDY OBJECTIVE

To examine the number and rates of head injuries occurring in the community as a whole for the team sports of ice hockey, soccer, and football by analyzing data from patients presenting to US emergency departments (EDs) from 1990 to 1999.

DESIGN

Retrospective analysis.

MAIN OUTCOME MEASURES

Data compiled for the US Consumer Product Safety Commission using the National Electronic Injury Surveillance System were used to generate estimates for the total number of head injuries, concussions, internal head injuries, and skull fractures occurring on a national level from the years 1990 to 1999. These data were combined with yearly participation figures to generate rates of injuries presenting to the ED for each sport.

RESULTS

There were an estimated 17,008 head injuries from ice hockey, 86,697 from soccer, and 204,802 from football that presented to US EDs from 1990 to 1999. The total number of concussions presenting to EDs in the United States over the same period was estimated to be 4820 from ice hockey, 21,715 from soccer, and 68,861 from football. While the rates of head injuries, concussions, and combined concussions/internal head injuries/skull fractures presenting to EDs per 10,000 players were not always statistically similar for all 3 sports in each year data were available, they were usually comparable.

CONCLUSION

While the total numbers of head injuries, concussions, and combined concussions/skull fractures/internal head injuries presenting to EDs in the United States are different for ice hockey, soccer, and football for the years studied, the yearly rates for these injuries are comparable among all 3 sports.

Grade 1 or "ding" concussions in high school athletes

BACKGROUND

Recent concussion management guidelines have suggested that athletes with mild (grade 1) concussions may be returned to play if asymptomatic for 15 minutes. The purpose of this study was to assess the utility of a current concussion management guideline in classifying and managing mild concussion.

HYPOTHESIS

High school athletes diagnosed with a grade 1 concussion will demonstrate measurable decline in neuropsychological functioning that persists during the 1st week of recovery.

STUDY DESIGN

Prospective study designed to evaluate neuropsychological functioning both prior to and following concussion.

METHODS

Forty-three high school athletes completed neuropsychological test performance and symptom ratings prior to the season and at two times during the 1st week following mild concussion.

RESULTS

Thirty-six hours after injury, mildly concussed high school athletes demonstrated a decline in memory (P < 0.003) and a dramatic increase in self-reported symptoms (P < 0.00001) compared to baseline performance.

CONCLUSIONS

Athletes with grade 1 concussion demonstrated memory deficits and symptoms that persisted beyond the context in which they were injured. These data suggest that current grade 1 return-to-play recommendations that allow for immediate return to play may be too liberal.

CLINICAL RELEVANCE

A reconsideration of current concussion grading systems appears to be warranted.

Mild traumatic brain injury in children: practice guidelines for emergency department and hospitalized patients. The Trauma Program, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine

Mild traumatic brain injury (MTBI) is a frequent occurrence in children. Current practice in treating such injuries varies in terms of evaluative studies, length of observation, need for inpatient hospitalization, sports restrictions, and follow-up. A multidisciplinary panel of experts from a level I pediatric trauma center was convened to develop and implement a clinical pathway to improve the quality and consistency of care provided to children after MTBI. The clinical pathway, based on current literature and expert consensus, provides a management guideline for the management of MTBI in the emergency department through discharge. The algorithm provides reasonable management options based on the child's clinical presentation, history, and age. Exemplary care of children and their families after MTBI includes appropriate patient/family education. Standardized discharge instructions for MTBI were developed to provide comprehensive information in a succinct and easy-to-read format. The instructions for home management focus on expected symptoms and guidance for when to seek further medical attention. They also incorporate injury prevention, return to sports guidelines, and resources for additional information.

Concussion in Professional Football: Reconstruction of Game Impacts and Injuries

OBJECTIVE

Concussion in professional football was studied with respect to impact types and injury biomechanics. A combination of video surveillance and laboratory reconstruction of game impacts was used to evaluate concussion biomechanics.

METHODS

Between 1996 and 2001, videotapes of concussions and significant head impacts were collected from National Football League games. There were clear views of the direction and location of the helmet impact for 182 cases. In 31 cases, the speed of impact could be determined with analysis of multiple videos. Those cases were reconstructed in laboratory tests using helmeted Hybrid III dummies and the same impact velocity, direction, and head kinematics as in the game. Translational and rotational accelerations were measured, to define concussion biomechanics. Several studies were performed to ensure the accuracy and reproducibility of the video analysis and laboratory methods used.

RESULTS

Concussed players experienced head impacts of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 miles/h). There was a rapid change in head velocity of 7.2 +/- 1.8 m/s (16.1 +/- 4.0 miles/h), which was significantly greater than that for uninjured struck players (5.0 +/- 1.1 m/s, 11.2 +/- 2.5 miles/h; t = 2.9, P < 0.005) or striking players (4.0 +/- 1.2 m/s, 8.9 +/- 2.7 miles/h; t = 7.6, P < 0.001). The peak head acceleration in concussion was 98 +/- 28 g with a 15-millisecond half-sine duration, which was statistically greater than the 60 +/- 24 g for uninjured struck players (t = 3.1, P < 0.005). Concussion was primarily related to translational acceleration resulting from impacts on the facemask or side, or falls on the back of the helmet. Concussion could be assessed with the severity index or head injury criterion (the conventional measures of head injury risk). Nominal tolerance levels for concussion were a severity index of 300 and a head injury criterion of 250.

CONCLUSION

Concussion occurs with considerable head impact velocity and velocity changes in professional football. Current National Operating Committee on Standards for Athletic Equipment standards primarily address impacts to the periphery and crown of the helmet, whereas players are experiencing injuries in impacts to the facemask, side, and back of the helmet. New tests are needed to assess the performance of helmets in reducing concussion risks involving high-velocity and long-duration injury biomechanics.

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

OBJECTIVE

To prospectively measure the relative risk of cerebral concussion among those with a history of concussion compared with those having no previous concussions by using a population of high school and college football players.

DESIGN

A representative national sample of high school and college football players was followed for two football seasons over a 2-yr period (1997-1998) as part of a national football injury surveillance project. There were a total of 15,304 player-seasons and over 1 million athlete-exposures to the possibility of injury in practices and games; 975 of the player-seasons (6.4%) had a history of concussion in the previous 5 yr.

RESULTS

There were 572 concussions recorded, 161 among those with a history (16.5%) and 411 among those with no history (2.9%). Relative risk for individuals with a history of concussion is 5.8 times greater than for individuals with no history (95% confidence interval, 4.8-6.8).

CONCLUSION

This large prospective cohort study indicates the risk of sustaining a cerebral concussion is nearly six times greater for individuals with a history of concussion than for individuals with no such history.

Acute and long-term management of sports-related closed head injuries

Aggressive participation in athletics is rewarded in many ways in our society. As long as there is such strong impetus for participation in athletics, the risks of head injuries for participants will remain. Important strides made in understanding of the pathophysiology of head injuries may lead to improved treatment strategies in the future. In light of the current lack of effective therapies, however, the best options remain injury prevention, early and appropriate recognition, and limitation of subsequent, further injury. Frequently the medical staff is encouraged to allow the athlete to return to play based on the desires of the coach, team, fans, parents, and even the athlete himself. A thorough understanding of the potentially serious risks of repetitive injury, however, mandates that only a proper conservative period of observation and evaluation will best serve the competitor.