A prospective study of physician-observed concussions during junior ice hockey: implications for incidence rates

The Most Cited and Influential Publications Relating to Ice Hockey Since 2000 Focus Primarily on Concussion and Traumatic Brain Injuries

Purpose

To determine the most frequently cited articles relating to ice hockey since 2000 and conduct a bibliometric analysis of these publications.

Methods

The Clarivate Web of Knowledge database was used to gather data and generate a list of publications relating to "ice hockey" on June 20, 2022. Articles were filtered by the total number of citations accrued and were included or excluded on the basis of relevance to ice hockey; no date of publication, language, or journal restrictions. After the 50 most highly cited articles were identified, articles published before the year 2000 were excluded to avoid bias. The information analyzed from each article included author name (first and last), publication year, country of origin, institutional affiliation (of the first and last author), journal name, research design, main research topic, competition level, and the level of evidence.

Results

Ultimately, 46 studies were included in this analysis. The total number of citations was 8,267 times with an average of 179.7 citations per article. The most cited article was cited 926 times. The articles came from 5 different countries, with the United States and Canada comprising 27 and 13 articles, respectively. All articles were published in English. The American Journal of Sports Medicine published the greatest number of articles. The most studied topic was concussion/traumatic brain injury (n = 26). Professional hockey was the most studied level of competition (n = 15), while college followed (n = 13). Three institutions, University of Calgary, Dartmouth School of Medicine, and University of North Carolina at Chapel Hill were responsible for 32.6% of the top articles (n = 15).

Conclusions

The majority of the most cited articles relating to ice hockey are cohort studies, review articles, and epidemiological studies originating from the United States or Canada. The majority of publications included in the analysis focused on concussion and traumatic brain injury prevalence, identification, diagnosis, outcomes, and prevention, as well as the most studied level of competition was professional, but the greatest number of participants arose from the youth and high school level.

Level of Evidence

Level IV, cross-sectional study.

Craniofacial and traumatic brain injuries in mixed martial arts

Objective: Mixed-Martial-Arts (MMA) has witnessed a rapid growth over the recent years. This study aims to explore the patterns and trends of head injuries in MMA.Design: Descriptive epidemiological study.Setting: Ringside physician reports of the Ultimate Fighting Championship (UFC) fights between 2016 and 2019 (inclusive) were screened. Data were extracted from the Nevada State Athletic Commission (NSAC) database. Play-by-play video analysis was also conducted.Participants: UFC fighters involved in fights sanctioned by the NSAC, between 2016 and the end of 2019 (N = 816).Independent variables: Sex, location of head injury, type of head injury, injury mechanism, number of significant head strikes, type of finish, and weight division.Main outcome measures: Head injury rates were calculated. A one-way analysis of variance (ANOVA) was used to explore any statistically significant differences between injury rates of different locations, types, and types of finishes. An independent t-test was used to determine whether any significant differences existed between the two sexes, and a Joinpoint regression analysis was used to determine the statistical significance of the trends of head injury rates across different weight divisions. P-values <0.05 were considered significant (95% CI).Results: A total of 288 head injuries in 408 fights were recorded during our study period. Head injury rate constituted 35 injuries per 100 athletic-exposures (AE) in sanctioned fights. Traumatic brain injuries (TBI) were the most common type of injury, with a rate of 16 per 100AE, significantly greater than that of fractures (p = 0.003). Males had a head injury rate of 37 per 100AE, higher than that of females which was 23 per 100AE. Technical Knockout (TKO)/ Knockout(KO) was the type of finish with the highest rate of head injuries, significantly greater than that of decision or submission (p < 0.001). In general, head injury rates were higher as weight divisions increased.Conclusion: Head injuries are prevalent in MMA. Preventive measures need to be implemented to ensure fighter safety and limit injury risk.

Maxillofacial Trauma in the Ultimate Fighting Championship

PURPOSE

The Ultimate Fighting Championship (UFC) is an American mixed martial art (MMA) company. This study aims to characterize patterns and trends of maxillofacial injuries in MMA.

MATERIALS AND METHODS

The study design is a retrospective cohort study. Study sample consisted of fighters that suffered injuries during the matches from January 2015 to December 2019 (N = 259). The Athletic Commissions and corresponding fighting regulatory departments from 16 states and 24 countries were screened for medical reports released by UFC ringside physicians. Predictor variables were sex, weight division, injury location, injury type, and fight outcome (i.e., Technical Knockout/Knockout, Submission, Decision). Primary outcome variables were need for medical suspension and duration of medical suspension, secondary outcome variable was frequency of injury. Chi-square test was used to determine any statistical significance between predictor variables. One-way analysis of variance was used to determine any statistically significant differences between medical suspension times, sex, injury location, type of injury, weight divisions and fight outcome throughout the years. P value less than .05 (95% confidence interval [CI]) was considered statistically significant.

RESULTS

A total of 259 fighters suffered injuries. Of the 319 total injuries, 291 (91.2%) occurred in male fighters, and 28 (8.8%) in females. Middle facial third injuries were the most common for both males and females; lower facial third injuries were proportionally similar. The male weight division with the longest medical suspensions were the light heavyweight (110.68 days) and welterweight (108.25 days) (P < .10166); the female weight division with the longest medical suspension was strawweight (88.92 days) and shortest was bantamweight (81.75 days) (P < .921123).

CONCLUSIONS

Upper and midface trauma was predominant with fractures concentrated in the light heavyweight and welterweight divisions. Medical suspensions duration were longer in the light heavyweight and welterweight divisions.

Epidemiology of Concussions in High School Boys' Ice Hockey, 2008/09 to 2016/17 School Years

OBJECTIVE

This study examined the epidemiology of concussions in high school boys' ice hockey during the 2008/09 to 2016/17 school years.

DESIGN

Prospective cohort study. Athletic trainers from an average 33 high schools annually reported boys' ice hockey concussion and athlete-exposure (AE) data for the High School Reporting Information Online system.

SETTING

Convenience sample of high school boys' ice hockey programs during the 2008/09 to 2016/17 school years.

PATIENTS OR OTHER PARTICIPANTS

High school boys' ice hockey players (aged ∼14-18 years).

INDEPENDENT VARIABLES

Concussion data on event type, injury mechanism, symptom resolution time, and time loss were obtained.

MAIN OUTCOME MEASURES

Concussion rates with 95% confidence intervals (CIs) and distributions were calculated.

RESULTS

Overall, 348 concussions were reported in boys' ice hockey during the 2008/09 to 2016/17 academic years, leading to a concussion rate of 0.68/1000 AEs (95% CI, 0.61-0.75). Most occurred in competitions (85.6%), particularly after the first period (72.1% of all competition concussions). Among practice concussions, most occurred after the first hour of practice (60.0%). Most concussions were due to player contact (47.7%) and boards/glass contact (31.9%). Although 69.0% of concussed athletes had symptoms resolve in less than 7 days, only 14.1% returned to activity within a week.

CONCLUSIONS

Most concussions occurred within the second and third periods. Preventive strategies that counter an increased risk of concussion due to a greater intensity of gameplay coupled with increased fatigue may be warranted. Moreover, athletes may further benefit from prevention efforts that focus on anticipating impacts during gameplay.

A Cohort Study of the Temporal Stability of ImPACT Scores Among NCAA Division I Collegiate Athletes: Clinical Implications of Test-Retest Reliability for Enhancing Student Athlete Safety

OBJECTIVE

In this study we examined the temporal stability of the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) within NCAA Division I athletes across various timepoints using an exhaustive series of statistical models.

METHODS

Within a cohort design, 48 athletes completed repeated baseline ImPACT assessments at various timepoints. Intraclass correlation coefficients (ICC) were calculated using a two-way mixed effects model with absolute agreement.

RESULTS

Four ImPACT composite scores (Verbal Memory, Visual Memory, Visual Motor Speed, and Reaction Time) demonstrated moderate reliability (ICC = 0.51-0.66) across the span of a typical Division I athlete's career, which is below previous reliability recommendations (0.90) for measures used in individual decision-making. No evidence of fixed bias was detected within Verbal Memory, Visual Motor Speed, or Reaction Time composite scores, and minimal detectable change values exceeded the limits of agreement.

CONCLUSIONS

The demonstrated temporal stability of the ImPACT falls below the published recommendations, and as such, fails to provide robust support for the NCAA's recommendation to obtain a single preparticipation cognitive baseline for use in sports-related concussion management throughout an athlete's career. Clinical interpretation guidelines are provided for clinicians who utilize baseline ImPACT scores for later performance comparisons.

The influence of education in decision making concerning athlete’s return to sport following a concussion injury: A systematic review

Objectives

Concussions have emerged as one of the most prevalent and controversial injuries sustained within the sporting context. The objective of this review was to determine the influence that education has on decision making concerning athlete’s return to sport following a concussion injury and if the risk is worth it in the eyes of the athletes.

Study design

Systematic review.

Methods

A rapid literature review was performed in PubMed, CINAHL, SPORTDiscus, Embase and Web of Science looking for articles that discussed concussions and any three of the four following search terms: (a) decision making, (b) education/knowledge, (c) sport/return to sport and (d) risk.

Results

Sixteen of 1243 articles were included in this review based on eligibility criteria. Ten were cohort studies, four were cross-sectional studies and two were qualitative research. There was a good agreement between the authors for all studies when determining risk of bias, presenting a Cohen’s κ of 0.901 (95% CI, 0.834, 0.968), p <  0.001.

Conclusion

Education can make a difference in athlete’s decision making process to return to sport; however, their awareness of the health risks that they put themselves in by returning to sport too soon is clouded by other external and internal factors. What is not fully understood is why do they put themselves at this risk? Further studies should explore athletes’ risk aversion behaviour and how it impacts their decision to return to sport following a concussion.

Losing the identity of a hockey player: the long-term effects of concussions

AIM

To describe what suffering multiple concussions meant for former semi-professional or professional hockey players who were forced to end their career.

RESULTS

Nine former Swedish hockey players, who once played on national or professional teams were interviewed. The interviews were analyzed with reference to hermeneutic phenomenology to interpret and explain their experiences. The theme of losing one's identity as a hockey player was constructed from five subthemes: being limited in everyday life, returning to the hockey stadium as soon as possible, forming a post career identity, lacking understanding and support, and preventing injuries by respecting other players.

CONCLUSION

The former hockey players struggled with developing their off-the-ice identities and with finding other sources of meaning for their lives.

Development of an Eco-Friendly Head Impact Protection Device

Nowadays, the number of people practising contact sports has increased. In many of them, using head protective equipment is not mandatory, even if the use of headbands could increase the level of safety regarding several types of traumatic brain injuries. Many commercial solutions are currently available, based on plastic-based foams providing a decent level of protection and comfort to the user. This work introduces the use of agglomerated cork as an eco-friendly alternative to synthetic foams but at least keeping safety levels. Cork is a natural cellular material that has been showing excellent crashworthiness properties. In this study, cork agglomerate density is carefully chosen to be incorporated into a protective headband. Results are compared against three other commercial headbands. For each one, the risk of brain injury was analysed for different injury thresholds and impact energies. The results clearly demonstrate that the cork-based apparel may provide comparable, and in some cases, better performances, outlasting the commercial ones.

Remote concussion history does not affect visually-guided reaching in young adult females

Aim:

We examined the long-term effects of concussions in young adult females on visuomotor behavior during a visually-guided reaching task of various complexities.

Materials & methods:

20 females with a history of longer than 6 months since a concussion and 20 healthy females quickly and accurately performed a delayed reach to a previously cued target.

Results:

As both cognitive and motor load increased, task performance decreased for both groups (p < 0.05). However, contrary to our primary hypothesis, no differences in task performance were found between the two experimental groups (p > 0.05).

Conclusion:

The young adult females with a remote history of concussion demonstrated no deficits in visuomotor behavior on an attention-mediated reaching task as compared with control participants.

Current literature is inconclusive regarding the long-term effects of concussion. Some have argued that the differing results are due to many uncontrolled factors in study design. In this study, 20 females with a history of concussion more than 6 months ago and 20 healthy females performed a reaching task under different levels of difficulty. As the reaching task got harder, both groups had greater difficulty doing the task quickly and accurately (p < 0.05). Surprisingly, however, no differences in reaching performance existed between the two groups (p > 0.05). Young adult females with a remote history of concussion demonstrated no greater problems with complicated reaching tasks when compared with control participants when experimental conditions are tightly controlled.

Musculoskeletal and head injuries in the Ultimate Fighting Championship (UFC)

OBJECTIVES

Mixed martial arts (MMA) has witnessed a surge in popularity worldwide. This study explores the musculoskeletal and head injuries sustained in the professional fights of the Ultimate Fighting Championship (UFC), and establishes associations between injury profiles and impactful contributory factors.

METHODS

The Nevada State Athletic Commission database was screened for ringside physician reports of UFC fights between January 2016 and July 2018. Information on the fighter's gender, weight, injury, way of finish, and match result were collected. Injury rates were calculated and statistical analyses were conducted to determine significant associations among variables. P-values <0.05 were considered significant (95% CI).

RESULTS

A total of 291 injuries were recorded in 285 fights from nine weight divisions. The overall injury rate was 51 per 100 athletic exposures (AE). Males predominantly partook in 249 matches (87%) and had higher injury rates (54 injuries per 100 AE) than females (30 injuries per 100 AE). Decision was the most common way a match ended. Knockouts (KOs) were significantly higher in males (36%) than in females (14%, P = 0.0007). Submissions were significantly higher in females (36%) than in males (16%, P = 0.001). Head injuries (67%) were the most common injuries reported with a rate of 34 per 100 AE. Upper limb injuries were significantly higher in females (40%) than in males (14%, P = 0.0003). Lower limb injuries were significantly higher in males (19%) than in females (5%, P = 0.01). Head injuries were significantly associated with KOs (P < 0.0001). Upper limb injuries (P = 0.032) and lower limb injuries (P = 0.034) were significantly associated with matches that ended with Decision. Trend-line analyses showed that as weight division increases, overall injury rates, head injuries, lower limb injuries, and KOs' frequency increase, whereas upper limb injuries, Submission frequency, and Decision frequency decrease.

CONCLUSION

MMA has a high injury rate. Gender, way of finish, and weight play an important role in predicting fight outcomes and injury profiles. Injury prevention policies must be entertained to limit injury risk in MMA.

The Natural History of Postconcussion Recovery Among High School Athletes

OBJECTIVE

Evaluate postconcussive symptom reporting and recovery.

SETTING

Public high school.

PARTICIPANTS

Unmatched controls (n = 760); students who sustained a sports-related concussion (n = 77); matched controls (gender, grade, sport) (n = 77).

DESIGN

Prospective longitudinal cohort study.

OUTCOME MEASURE

Immediate Postconcussion Assessment and Cognitive Testing.

RESULTS

At baseline, athletes who went on to sustain concussions were more likely than unmatched controls to be younger (P = .02), male (P = .001), and participate in different sports (P < .0001) such as football (concussed = 52%, unmatched controls = 20%). Differences were also noted regarding a previous history of concussion (P = .045; concussed athletes = 26%; unmatched control athletes = 16%) and lifetime number of concussions (P = .05). At baseline, those whose sustained concussions during the study period were more likely than matched controls to report numbness (P = .01) and concentration problems (P = .01) and more likely than unmatched controls to report dizziness (P = .02), sensitivity to light (P = .01), sensitivity to noise (P = .002), and numbness (P = .02). However, when data were reanalyzed and those with a previous history of concussion were removed, differences between those who sustained concussions during the study period and matched controls were no longer significant; when compared to unmatched controls, sensitivity to light (P = .01) and vision problems (P = .04) remained significant. Among those who sustained concussions, median time to recovery was 6 days (95% confidence interval: 4-9), and 71 out of 77 (92%) recovered by the fourth postinjury evaluation (median: 20 days postinjury).

CONCLUSIONS

Course and time frame of recovery were variable. Data also suggest that a previous history of concussion may be contributing to baseline symptom reporting and highlight the potential enduring impact of history of concussion on sensorimotor function. However, further research as to whether preinjury measures of sensorimotor function may increase understanding regarding concussion risk is warranted.

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

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

American Medical Society for Sports Medicine position statement on concussion in sport

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

Risk factors associated with injury and concussion in sanctioned amateur and professional mixed martial arts bouts in Calgary, Alberta

Background

There is limited literature that examines risk factors for injury and mild traumatic brain injury (mTBI) in mixed martial arts (MMA). An examination of previously unstudied bout and athlete characteristics that may pose health risks while partaking in this sport is warranted.

Hypothesis/purpose

To determine the incidence of injury and concussion, along with the identification of risk factors that contribute to injury and mTBI in amateur and professional MMA bouts in Calgary, Alberta.

Study design

A retrospective cohort study with case–control design.

Methods

Calgary amateur and professional MMA records were examined from 1 January 2010 to 31 December 2015. Descriptive statistics were used to describe the incidence of injury and concussion, along with univariate and multivariable logistic regression to identify risk factors for injury and mTBI.

Results

The injury rate per 100 athlete exposure (AE), the injury rate per 100 min of exposure and the concussion rate per 100 AE were 23.6 (95% CI 20.5 to 27.0), 4.1 (95% CI 3.48 to 4.70) and 14.7 (95% CI 11.8 to 17.2), respectively. The most common location of injury was the head and mTBI was the most common type of injury. Athletes whose bout was finished by a knockout/technical knockout, corner stoppage, draw, no contest or physician, and those whose country of origin was non-Canadian, were more likely to sustain an injury. No risk factors for concussion were shown to be significant.

Conclusion

Engaging in MMA exposes athletes to inherent risk and several recommendations are proposed to reduce these risks. Future prospective investigations are necessary to better delineate the findings in this study.

Understanding the psychiatric effects of concussion on constructed identity in hockey players: Implications for health professionals

OBJECTIVE

The following study was undertaken to investigate the effect of concussion and psychiatric illness on athletes and their caregivers.

METHODS

Semi-structured interviews with 20 ice hockey stakeholders (17 men and 3 women) including minor and professional players, coaches, parents, and physicians were conducted over two years (2012-2014). These interviews were analyzed using grounded theory.

RESULTS

From this analysis, a common biographical theme emerged whereby the subject's identity as a hockey player, constructed early in life over many years, was disrupted by concussion. Furthermore, some players underwent a biographical deconstruction when they experienced post-concussive mental illness, which was amplified by isolation, stigma from peers, and lack of a clear life trajectory. Many players obtained support from family and peers and were able to recover, as evidenced by the biographical reconstruction of their identity post-hockey concussion.

CONCLUSIONS AND IMPLICATIONS FOR PRACTICE

Understanding the process of biographical deconstruction and reconstruction has significant psychosocial treatment implications for both healthcare professionals and caregivers of this population. Specifically, the authors suggest that interpersonal psychotherapy (IPT) that focuses on role transitions may create opportunities to facilitate the process of biographical reconstruction and life transition.

Sex differences in white matter alterations following repetitive subconcussive head impacts in collegiate ice hockey players

Objective

Repetitive subconcussive head impacts (RSHI) may lead to structural, functional, and metabolic alterations of the brain. While differences between males and females have already been suggested following a concussion, whether there are sex differences following exposure to RSHI remains unknown. The aim of this study was to identify and to characterize sex differences following exposure to RSHI.

Methods

Twenty-five collegiate ice hockey players (14 males and 11 females, 20.6 ± 2.0 years), all part of the Hockey Concussion Education Project (HCEP), underwent diffusion-weighted magnetic resonance imaging (dMRI) before and after the Canadian Interuniversity Sports (CIS) ice hockey season 2011-2012 and did not experience a concussion during the season. Whole-brain tract-based spatial statistics (TBSS) were used to compare pre- and postseason imaging in both sexes for fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). Pre- and postseason neurocognitive performance were assessed by the Immediate Post-Concussion Assessment and Cognitive Test (ImPACT).

Results

Significant differences between the sexes were primarily located within the superior longitudinal fasciculus (SLF), the internal capsule (IC), and the corona radiata (CR) of the right hemisphere (RH). In significant voxel clusters (p < 0.05), decreases in FA (absolute difference pre- vs. postseason: 0.0268) and increases in MD (0.0002), AD (0.00008), and RD (0.00005) were observed in females whereas males showed no significant changes. There was no significant correlation between the change in diffusion scalar measures over the course of the season and neurocognitive performance as evidenced from postseason ImPACT scores.

Conclusions

The results of this study suggest sex differences in structural alterations following exposure to RSHI. Future studies need to investigate further the underlying mechanisms and association with exposure and clinical outcomes.

Validity of the Immediate Post Concussion Assessment and Cognitive Testing (ImPACT)

BACKGROUND

The immediate post concussion assessment and cognitive testing (ImPACT) is the most widely used concussion assessment tool. Despite its popularity, it is unclear if validation studies for the ImPACT test covered all aspects of validity to support its widespread use in research and clinical practice.

OBJECTIVE

The purpose of this report is to review literature surrounding the validity and the utility of the ImPACT test.

DATA SOURCES AND APPRAISAL

A systematic review of relevant studies in PubMed, CINAHL, and PsycINFO was carried out. Studies were evaluated using the STROBE (strengthening the reporting of observational studies in epidemiology) or the STARD (standards for reporting of diagnostic accuracy) criteria.

RESULTS

The literature search yielded 5968 studies. Sixty-nine studies met the inclusion criteria and were included in the qualitative review. Although the convergent validity of ImPACT was supported, evidence of discriminant and predictive validity, diagnostic accuracy and responsiveness was inconclusive. The utility of the ImPACT test after acute symptom resolution was sparse. The review found many factors influenced the validity and utility of ImPACT scores.

CONCLUSION

Clinicians must consider the benefit of ImPACT testing for their patients on a case-by-case scenario and must take the psychometric properties of the test into account when interpreting results.

The use of ibuprofen and acetaminophen for acute headache in the postconcussive youth: A pilot study

Objective

Acute postconcussive headaches are problematic for children after mild traumatic brain injury. There are no evidence-based guidelines for their management. This pilot study aims to assess the feasibility and efficacy of routine analgesia administration.

Methods

A four-arm open-label randomized controlled trial pilot/feasibility study was conducted: (i) acetaminophen, (ii) ibuprofen, (iii) alternating acetaminophen and ibuprofen and (iv) a control group. Children and youth 8 to 18 years of age presenting to emergency department with headache within 48 hours of their first concussion were recruited consecutively and sequentially randomized. Children with abnormal neuroimaging, history of previous concussions and bleeding disorder were excluded. A headache survey was administered at recruitment. All participants were provided with standard concussion management education and were also instructed on how to use the headache diary for the 1-week study follow-up period. The diary captures (i) headache days, (ii) number of headaches, (iii) headache intensity and (iv) return-to-school information. Feasibility was assessed based on study recruitment and compliance.

Results

There were no feasibility concerns with the recruitment and no major compliance issues. Patients on acetaminophen, ibuprofen or both had significantly less headache days, episodes of headache and lower headache intensity than did the standard care group. Patients on both ibuprofen and acetaminophen (79.0%) and on ibuprofen alone (61.0%) were more likely to be back at school 1 week postinjury as compared with the acetaminophen group (33.3%) and the standard care group (21.1%).

Conclusion

Results showed routine analgesia administration was feasible and effective for postconcussive headache management. A larger full-scale randomized controlled trial is required to further assess the efficacy with longer follow-up, a wider variety of patients and more concussion related outcomes.

The Effect of the "Zero Tolerance for Head Contact" Rule Change on the Risk of Concussions in Youth Ice Hockey Players

BACKGROUND

Ice hockey is a popular winter sport in Canada. Concussions account for the greatest proportion of all injuries in youth ice hockey. In 2011, a policy change enforcing "zero tolerance for head contact" was implemented in all leagues in Canada.

PURPOSE

To determine if the risk of game-related concussions and more severe concussions (ie, resulting in >10 days of time loss) and the mechanisms of a concussion differed for Pee Wee class (ages 11-12 years) and Bantam class (ages 13-14 years) players after the 2011 "zero tolerance for head contact" policy change compared with players in similar divisions before the policy change.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The retrospective cohort included Pee Wee (most elite 70%, 2007-2008; n = 891) and Bantam (most elite 30%, 2008-2009; n = 378) players before the rule change and Pee Wee (2011-2012; n = 588) and Bantam (2011-2012; n = 242) players in the same levels of play after the policy change. Suspected concussions were identified by a team designate and referred to a sport medicine physician for diagnosis. Incidence rate ratios (IRRs) were estimated based on multiple Poisson regression analysis, controlling for clustering by team and other important covariates and offset by game-exposure hours. Incidence rates based on the mechanisms of a concussion were estimated based on univariate Poisson regression analysis.

RESULTS

The risk of game-related concussions increased after the head contact rule in Pee Wee (IRR, 1.85; 95% CI, 1.20-2.86) and Bantam (IRR, 2.48; 95% CI, 1.17-5.24) players. The risk of more severe concussions increased after the head contact rule in Pee Wee (IRR, 4.12; 95% CI, 2.00-8.50) and Bantam (IRR, 7.91; 95% CI, 3.13-19.94) players. The rates of concussions due to body checking and direct head contact increased after the rule change.

CONCLUSION

The "zero tolerance for head contact" policy change did not reduce the risk of game-related concussions in Pee Wee or Bantam class ice hockey players. Increased concussion awareness and education after the policy change may have contributed to the increased risk of concussions found after the policy change.

The Epidemiology of Concussions: Number and Nature of Concussions and Time to Recovery Among Female and Male Canadian Varsity Athletes 2008 to 2011

OBJECTIVE

To provide incidence rates and days to symptom resolution and cognitive recovery stratified by sex and sport at a Canadian institution.

STUDY DESIGN

A retrospective chart analysis.

SUBJECTS

Seven hundred fifty-nine varsity level athletes competing in men's football, men's and women's soccer, men's and women's volleyball, men's and women's basketball, men's and women's ice hockey, women's field hockey, women's rugby, men's and women's tennis, men's and women's water polo, men's and women's swimming, badminton, cross-country, and track and field in the 2008 to 2009 season through the 2010 to 2011 season.

MAIN OUTCOME MEASURES

Incidence of concussion, days to symptom recovery, and days to cognitive recovery as measured by clinical interpretation using the sports concussion assessment tool (SCAT)/SCAT2 and Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) with baseline and follow-up data.

RESULTS

A total of 81 concussions were reported and diagnosed among 759 athletes. Significantly, more female athletes were concussed than male athletes (13.08%-7.53%, respectively; P = 0.014) with the highest rates in women's rugby [incidence density (ID) = 20.00 concussions per athlete-season], women's ice hockey (ID = 18.67 per athlete-season), and men's basketball (ID = 20.00 per athlete-season). Sex differences in symptom recovery and cognitive recovery were not significant.

CONCLUSIONS

The incidence of concussion across multiple sports in a Canadian varsity athlete population is of concern. There are inconsistencies found between the time an athlete claims to have no symptoms and the time of neurocognitive recovery as measured by computerized neurocognitive testing. Therefore, objective computerized testing is recommended to ensure that athletes are functionally recovered before return to play.

SCAT2 and SCAT3 scores at baseline and after sports-related mild brain injury/concussion: qualitative synthesis with weighted means

Objective

Identify all Sport Concussion Assessment Tool (SCAT2/3) studies, compare baseline and postconcussion results.

Design

Systematic review (qualitative synthesis, weighted means).

Data sources

18 databases, 9 grey literature resources searched for SCAT2/3 data; 9150 articles identified, titles/abstracts assessed/data-entry independently by two reviewers.

Eligibility criteria for selecting studies

Any studies reporting partial/complete SCAT2/3 data.

Results

21 studies with data (partial/complete data 16 SCAT2 (4087 athletes); 5 SCAT3 (891). Newcastle-Ottawa risk-of-bias scale: studies with maximum possible score of 4, 85% scored 3 or 4; studies with maximum possible score of 6, 75% scored 5 or 6. SCAT2 high schoolers: weighted mean score for symptoms 18.46 (22=no symptoms), Balance Error Scoring System (BESS) 26.14, Standardised Assessment of Concussion (SAC) 26.00 and SCAT2 total 88.63. Collegiate/adults weighted means: symptoms 20.09, BESS 25.54, SAC 27.51 and total SCAT2 91.20. Between-study and within-study variability similar to those of the high schoolers. Limited variability between genders. Only 2 studies report baseline and postconcussion scores and 9 partial scores, but data are too limited to provide weighted average scores.

Conclusions

Group mean baseline SCAT scores for high school and collegiate athletes are similar, with minimal gender differences; baseline symptoms show more variability than other components. There are minimal data for elementary students and professionals, no data for adult non-collegiate athletes. Two studies provide preconcussion and postconcussion scores. No data on minimal significant clinical differences to guide players/coaches in withdrawing from a game in progress and deciding when recovery is complete and play can be resumed. The SCAT needs supplementing with clinical and neuropsychological return-to-play assessments.

The Impact of a Concussion-U Educational Program on Knowledge of and Attitudes about Concussion

Background: The diagnosis of a sports-related concussion is often dependent on the athlete self-reporting their symptoms. It has been suggested that improving youth athlete knowledge and attitudes toward concussion may increase self-reporting behaviour. The objective of this study was to determine if a novel Concussion-U educational program improves knowledge of and attitudes about concussion among a cohort of elite male Bantam and Midget AAA hockey players. Methods: Fifty-seven male Bantam and Midget AAA-level hockey players (mean age=14.52±1.13 years) were recruited from the local community. Each participant completed a modified version of the Rosenbaum Concussion Knowledge and Attitudes Survey–Student Version immediately before and after a Concussion-U educational presentation. Follow-up sessions were arranged 4 to 6 months after the presentation, and assessed retention of knowledge and attitude changes. Results: Forty-three players completed all three surveys. Concussion knowledge and attitude scores significantly (p<0.01) increased from pre- to post-presentation by 12.79 and 8.41%, respectively. At long-term follow-up, knowledge levels remained significantly (p<0.01) higher than baseline by 8.49%. Mean attitude scores were also increased at follow-up; however, this increase was not statistically significant. Conclusions: A Concussion-U educational program led to an immediate improvement in concussion knowledge and attitudes among elite male Bantam and Midget AAA hockey players. Increased knowledge was maintained at long-term follow-up, but improved attitude was not. Future studies should investigate whether similar educational programs influence symptom reporting and concussion incidence. In addition, they should focus on how to maintain improved concussion attitudes.

Aggression, Violence and Injury in Minor League Ice Hockey: Avenues for Prevention of Injury

Background

In North America, more than 800,000 youth are registered in organized ice hockey leagues. Despite the many benefits of involvement, young players are at significant risk for injury. Body-checking and aggressive play are associated with high frequency of game-related injury including concussion. We conducted a qualitative study to understand why youth ice hockey players engage in aggressive, injury-prone behaviours on the ice.

Methods

Semi-structured interviews were conducted with 61 minor ice hockey participants, including male and female players, parents, coaches, trainers, managers and a game official. Players were aged 13–15 playing on competitive body checking teams or on non-body checking teams. Interviews were manually transcribed, coded and analyzed for themes relating to aggressive play in minor ice hockey.

Results

Parents, coaches, teammates and the media exert a large influence on player behavior. Aggressive behavior is often reinforced by the player’s social environment and justified by players to demonstrate loyalty to teammates and especially injured teammates by seeking revenge particularly in competitive, body-checking leagues. Among female and male players in non-body checking organizations, aggressive play is not reinforced by the social environment. These findings are discussed within the framework of social identity theory and social learning theory, in order to understand players’ need to seek revenge and how the social environment reinforces aggressive behaviors.

Conclusion

This study provides a better understanding of the players’ motivations and environmental influences around aggressive and violent play which may be conducive to injury. The findings can be used to help design interventions aimed at reducing aggression and related injuries sustained during ice hockey and sports with similar cultures and rules.

The Sport Concussion Assessment Tool: a systematic review

OBJECTIVE

Over the last 2 decades, sport-related concussion (SRC) has garnered significant attention. Even with increased awareness and athlete education, sideline recognition and real-time diagnosis remain crucial. The need for an objective and standardized assessment of concussion led to the eventual development of the Sport Concussion Assessment Tool (SCAT) during the Second International Conference on Concussion in Sport in 2004, which is now in its third iteration (SCAT3). In an effort to update our understanding of the most well-known sideline concussion assessment, the authors conducted a systematic review of the SCAT and the evidence supporting its use to date.

METHODS

English-language titles and abstracts published between 1995 and October 2015 were searched systematically across 4 electronic databases and a review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines adapted for the review of a heterogeneous collection of study designs. Peer-reviewed journal articles were included if they reported quantitative data on any iteration of the SCAT, Standardized Assessment of Concussion (SAC), or modified Balance Error Scoring System (mBESS) data at baseline or following concussion in an exclusively athlete population with any portion older than 13 years of age. Studies that included nonathletes, only children less than 13 years old, exclusively BESS data, exclusively symptom scale data, or a non–SCAT-related assessment were excluded.

RESULTS

The database search process yielded 549 abstracts, and 105 full-text articles were reviewed with 36 meeting criteria for inclusion. Nineteen studies were associated with the SAC, 1 was associated with the mBESS exclusively, and 16 studies were associated with a full iteration of the SCAT. The majority of these studies (56%) were prospective cohort studies. Male football players were the most common athletes studied. An analysis of the studies focused on baseline differences associated with age, sex, concussion history, and the ability to detect an SRC.

CONCLUSIONS

Looking toward the upcoming Concussion in Sport Group meeting in fall 2016, one may expect further revision to the SCAT3. However, based on this systematic review, the authors propose further, in-depth study of an already comprehensive concussion test, with acute, diagnostic, as well as long-term use.

Myelin Water Fraction Is Transiently Reduced after a Single Mild Traumatic Brain Injury--A Prospective Cohort Study in Collegiate Hockey Players

Impact-related mild traumatic brain injuries (mTBI) are a major public health concern, and remain as one of the most poorly understood injuries in the field of neuroscience. Currently, the diagnosis and management of such injuries are based largely on patient-reported symptoms. An improved understanding of the underlying pathophysiology of mTBI is urgently needed in order to develop better diagnostic and management protocols. Specifically, dynamic post-injury changes to the myelin sheath in the human brain have not been examined, despite ‘compromised white matter integrity’ often being described as a consequence of mTBI. In this preliminary cohort study, myelin water imaging was used to prospectively evaluate changes in myelin water fraction, derived from the T2 decay signal, in two varsity hockey teams (45 players) over one season of athletic competition. 11 players sustained a concussion during competition, and were scanned at 72 hours, 2 weeks, and 2 months post-injury. Results demonstrated a reduction in myelin water fraction at 2 weeks post-injury in several brain areas relative to preseason scans, including the splenium of the corpus callosum, right posterior thalamic radiation, left superior corona radiata, left superior longitudinal fasciculus, and left posterior limb of the internal capsule. Myelin water fraction recovered to pre-season values by 2 months post-injury. These results may indicate transient myelin disruption following a single mTBI, with subsequent remyelination of affected neurons. Myelin disruption was not apparent in the athletes who did not experience a concussion, despite exposure to repetitive subconcussive trauma over a season of collegiate hockey. These findings may help to explain many of the metabolic and neurological deficits observed clinically following mTBI.

Incidence of Concussion in Youth Ice Hockey Players

BACKGROUND

Ice hockey is a fast-paced collision sport that entails both intentional (ie, body checking) and incidental contact that may involve the head. The objective of this study was to determine the incidence of concussions in relation to games/practices and age among competition-level youth ice hockey players (ages 12-18 years).

METHODS

Participants included 397 youth ice hockey players from Western Pennsylvania; Boston, Massachusetts; and Birmingham, Alabama, during the 2012-2013 and 2013-2014 youth ice hockey seasons. Incidence rates (IRs) and incidence rate ratios (IRRs) of concussion were calculated for games/practices and age groups.

RESULTS

A total of 23 369 (12 784 practice/10 585 game) athletic exposures (AEs) involving 37 medically diagnosed concussions occurred. More than 40% of concussions involved illegal contact. The combined IR for games and practices was 1.58 concussions per 1000 AEs. The IRR was 2.86 times (95% confidence interval 0.68-4.42) higher during games (2.49 per 1000 AEs) than practices (1.04 per 1000 AEs).

CONCLUSIONS

The overall IR for concussion in youth ice hockey was comparable to those reported in other youth collision sports. The game-to-practice IRR was lower than previously reported in ice hockey and other youth sports, although more concussions per exposure occurred in games compared with practices. Younger players had a higher rate of concussions than older players.

Sport-Related Concussion Reporting and State Legislative Effects

OBJECTIVE

To investigate concussion rates and reporting frequencies in high school and collegiate athletes in 2013, compare results to those obtained from 1999 to 2002, and examine to what extent the 2012 Wisconsin state concussion law affected reporting in 2013.

DESIGN

Retrospective 2013 survey compared with prior survey.

SETTING

High schools and colleges in the Milwaukee, Wisconsin, area.

PARTICIPANTS

Athletes (N = 784) from multiple sports were surveyed in 2013. Football players (N = 1532) from 1999 to 2002 completed the same measure.

MAIN OUTCOME MEASURES

Both surveys assessed concussion history, concussion incidence during the current season, whether incident concussions were reported, who concussions were reported to, and reasons for not reporting. The 2013 survey also assessed awareness of the Wisconsin state law and its effect on reporting.

RESULTS

Rates of concussion in the surveyed season were comparable to previous findings from 1999 to 2002 (16.6% vs 15.3%, P = 0.558). Notably, athletes were significantly more likely to report their concussions in 2013 (70.6% vs 47.3% previously, P = 0.011). Among high school athletes surveyed, 59.5% were aware of the Wisconsin state law, with 55.1% stating it would make them more likely to report a concussion.

CONCLUSIONS

Rates of concussion for 1 sport season have not changed significantly over the past 14 years. The percentage of concussions that are reported to someone has increased significantly. Awareness of the Wisconsin state law does not fully account for the increase in concussion reporting.

CLINICAL RELEVANCE

Given the finite amount of knowledge regarding the influence of concussion-related cultural and legal changes, these findings will help to inform clinicians of the current concussion milieu from the perspective of athletes. It will inform practitioners involved in concussion management to what extent athletes are aware of and report concussions.

Norms, athletic identity, and concussion symptom under-reporting among male collegiate ice hockey players: a prospective cohort study

BACKGROUND

Many athletes fail to report concussion symptoms to coaches or medical personnel, putting them at risk for potentially catastrophic neurologic consequences if additional brain trauma is sustained prior to full recovery.

PURPOSE

The purpose of this study was to determine whether concussion reporting norms prior to the start of the athletic season predicted reporting symptoms of a possible concussion during the season, and whether this association was moderated by athletic identity.

METHODS

Members of six National Collegiate Athletic Association Division 1 men's ice hockey teams (n = 116) completed written surveys before and after the 2012-2013 collegiate ice hockey season.

RESULTS

Participants who at pre-season perceived that "most athletes" were likely to report symptoms of a concussion were themselves more likely to report symptoms during the season. Athletic identity weakly moderated this association.

CONCLUSIONS

Perceived reporting norms may be an important target of interventions aimed at reducing symptom under-reporting among athletes.

Hockey STAR: A Methodology for Assessing the Biomechanical Performance of Hockey Helmets

Optimizing the protective capabilities of helmets is one of several methods of reducing brain injury risk in sports. This paper presents the experimental and analytical development of a hockey helmet evaluation methodology. The Summation of Tests for the Analysis of Risk (STAR) formula combines head impact exposure with brain injury probability over the broad range of 227 head impacts that a hockey player is likely to experience during one season. These impact exposure data are mapped to laboratory testing parameters using a series of 12 impact conditions comprised of three energy levels and four head impact locations, which include centric and non-centric directions of force. Injury risk is determined using a multivariate injury risk function that incorporates both linear and rotational head acceleration measurements. All testing parameters are presented along with exemplar helmet test data. The Hockey STAR methodology provides a scientific framework for manufacturers to optimize hockey helmet design for injury risk reduction, as well as providing consumers with a meaningful metric to assess the relative performance of hockey helmets.

A systematic review of the biomarker S100B: implications for sport-related concussion management

OBJECTIVE

Elevated levels of the astroglial protein S100B have been shown to predict sport-related concussion. However, S100B levels within an athlete can vary depending on the type of physical activity (PA) engaged in and the methodologic approach used to measure them. Thus, appropriate reference values in the diagnosis of concussed athletes remain undefined. The purpose of our systematic literature review was to provide an overview of the current literature examining S100B measurement in the context of PA. The overall goal is to improve the use of the biomarker S100B in the context of sport-related concussion management.

DATA SOURCES

PubMed, SciVerse Scopus, SPORTDiscus, CINAHL, and Cochrane.

STUDY SELECTION

We selected articles that contained (1) research studies focusing exclusively on humans in which (2) either PA was used as an intervention or the test participants or athletes were involved in PA and (3) S100B was measured as a dependent variable.

DATA EXTRACTION

We identified 24 articles. Study variations included the mode of PA used as an intervention, sample types, sample-processing procedures, and analytic techniques.

DATA SYNTHESIS

Given the nonuniformity of the analytical methods used and the data samples collected, as well as differences in the types of PA investigated, we were not able to determine a single consistent reference value of S100B in the context of PA. Thus, a clear distinction between a concussed athlete and a healthy athlete based solely on the existing S100B cutoff value of 0.1 μg/L remains unclear. However, because of its high sensitivity and excellent negative predictive value, S100B measurement seems to have the potential to be a diagnostic adjunct for concussion in sports settings. We recommend that the interpretation of S100B values be based on congruent study designs to ensure measurement reliability and validity.

A review of neuroimaging findings in repetitive brain trauma

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease confirmed at postmortem. Those at highest risk are professional athletes who participate in contact sports and military personnel who are exposed to repetitive blast events. All neuropathologically confirmed CTE cases, to date, have had a history of repetitive head impacts. This suggests that repetitive head impacts may be necessary for the initiation of the pathogenetic cascade that, in some cases, leads to CTE. Importantly, while all CTE appears to result from repetitive brain trauma, not all repetitive brain trauma results in CTE. Magnetic resonance imaging has great potential for understanding better the underlying mechanisms of repetitive brain trauma. In this review, we provide an overview of advanced imaging techniques currently used to investigate brain anomalies. We also provide an overview of neuroimaging findings in those exposed to repetitive head impacts in the acute/subacute and chronic phase of injury and in more neurodegenerative phases of injury, as well as in military personnel exposed to repetitive head impacts. Finally, we discuss future directions for research that will likely lead to a better understanding of the underlying mechanisms separating those who recover from repetitive brain trauma vs. those who go on to develop CTE.

Hockey STAR: A Methodology for Assessing the Biomechanical Performance of Hockey Helmets

Optimizing the protective capabilities of helmets is one of several methods of reducing brain injury risk in sports. This paper presents the experimental and analytical development of a hockey helmet evaluation methodology. The Summation of Tests for the Analysis of Risk (STAR) formula combines head impact exposure with brain injury probability over the broad range of 227 head impacts that a hockey player is likely to experience during one season. These impact exposure data are mapped to laboratory testing parameters using a series of 12 impact conditions comprised of three energy levels and four head impact locations, which include centric and non-centric directions of force. Injury risk is determined using a multivariate injury risk function that incorporates both linear and rotational head acceleration measurements. All testing parameters are presented along with exemplar helmet test data. The Hockey STAR methodology provides a scientific framework for manufacturers to optimize hockey helmet design for injury risk reduction, as well as providing consumers with a meaningful metric to assess the relative performance of hockey helmets.

The Sport Concussion Education Project. A brief report on an educational initiative: from concept to curriculum

Current research on concussion is primarily focused on injury identification and treatment. Prevention initiatives are, however, important for reducing the incidence of brain injury. This report examines the development and implementation of an interactive electronic teaching program (an e-module) that is designed specifically for concussion education within an adolescent population. This learning tool and the accompanying consolidation rubric demonstrate that significant engagement occurs in addition to the knowledge gained among participants when it is used in a school curriculum setting.

Pilot Randomized Evaluation of Publically Available Concussion Education Materials

Many states and sports leagues are instituting concussion policies aimed at reducing risk of morbidity and mortality; many include mandates about the provision of concussion education to youth athletes. However, there is limited evidence if educational materials provided under these typically vague mandates are in fact effective in changing concussion risk-related behavior or any cognition predictive of risk-related behavior. The purpose of this pilot randomized controlled study was to conduct a theory-driven evaluation of three publically available concussion education materials: two videos and one informational handout. Participants were 256 late adolescent males from 12 teams in a single league of ice hockey competition in the United States. Randomization of educational condition occurred at the team level. Written surveys assessing postimpact symptom reporting behavior, concussion knowledge, and concussion reporting cognitions were completed by participants immediately before receiving their educational intervention, 1 day after, and 1 month after. Results indicated no change in any measure over any time interval, with the exception of perceived underreporting norms. In one of the video conditions, perceived underreporting norms increased significantly 1 day after viewing the video. Possible content and viewing environment-related reasons for this increase are discussed. Across all conditions, perceived underreporting norms increased 1 month after intervention receipt, raising the possibility that late in the competitive season underreporting may be perceived as normative. The need for the development of theory-driven concussion education materials, drawing on best practices from health behavior scholars, is discussed.

Head Trauma in Mixed Martial Arts

BACKGROUND

Mixed martial arts (MMA) is a full combative sport with a recent global increase in popularity despite significant scrutiny from medical associations. To date, the empirical research of the risk of head injuries associated with this sport is limited. Youth and amateur participation is growing, warranting investigation into the burden and mechanism of injuries associated with this sport.

PURPOSE

(1) To determine the incidence, risk factors, and characteristics of knockouts (KOs) and technical knockouts (TKOs) from repetitive strikes in professional MMA; and (2) to identify the mechanisms of head trauma and the situational factors that lead to KOs and TKOs secondary to repetitive strikes through video analysis.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Competition data and video records for all KOs and TKOs from numbered Ultimate Fighting Championship MMA events (n = 844) between 2006 to 2012. Analyses included (1) multivariate logistic regression to investigate factors associated with an increased risk of sustaining a KO or TKO secondary to repetitive strikes and (2) video analysis of all KOs and TKOs secondary to repetitive strikes with descriptive statistics.

RESULTS

During the study period, the KO rate was 6.4 per 100 athlete-exposures (AEs) (12.7% of matches), and the rate of TKOs secondary to repetitive strikes was 9.5 per 100 AEs (19.1% of matches), for a combined incidence of match-ending head trauma of 15.9 per 100 AEs (31.9% of matches). Logistic regression identified that weight class, earlier time in a round, earlier round in a match, and older age were risk factors for both KOs and TKOs secondary to repetitive strikes. Match significance and previously sustained KOs or TKOs were also risk factors for KOs. Video analysis identified that all KOs were the result of direct impact to the head, most frequently a strike to the mandibular region (53.9%). The average time between the KO-strike and match stoppage was 3.5 seconds (range, 0-20 seconds), with losers sustaining an average of 2.6 additional strikes (range, 0-20 strikes) to the head. For TKOs secondary to strikes, in the 30-second interval immediately preceding match stoppage, losers sustained, on average, 18.5 strikes (range, 5-46 strikes), with 92.3% of these being strikes to the head.

CONCLUSION

Rates of KOs and TKOs in MMA are higher than previously reported rates in other combative and contact sports. Public health authorities and physicians should be cognizant of the rates and mechanisms of head trauma. Preventive measures to lessen the risks of head trauma for those who elect to participate in MMA are described.

Hockey Concussion Education Project, Part 3. White matter microstructure in ice hockey players with a history of concussion: a diffusion tensor imaging study

OBJECT

The aim of this study was to examine the brain's white matter microstructure by using MR diffusion tensor imaging (DTI) in ice hockey players with a history of clinically symptomatic concussion compared with players without a history of concussion.

METHODS

Sixteen players with a history of concussion (concussed group; mean age 21.7 ± 1.5 years; 6 female) and 18 players without a history of concussion (nonconcussed group; mean age 21.3 ± 1.8 years, 10 female) underwent 3-T DTI at the end of the 2011-2012 Canadian Interuniversity Sports ice hockey season. Tract-based spatial statistics (TBSS) was used to test for group differences in fractional anisotropy (FA), axial diffusivity (AD), radial diffusivity (RD), and the measure "trace," or mean diffusivity. Cognitive evaluation was performed using the Immediate Postconcussion Assessment and Cognitive Test (ImPACT) and the Sport Concussion Assessment Tool-2 (SCAT2).

RESULTS

TBSS revealed a significant increase in FA and AD, and a significant decrease in RD and trace in several brain regions in the concussed group, compared with the nonconcussed group (p < 0.05). The regions with increased FA and decreased RD and trace included the right posterior limb of the internal capsule, the right corona radiata, and the right temporal lobe. Increased AD was observed in a small area in the left corona radiata. The DTI measures correlated with neither the ImPACT nor the SCAT2 scores.

CONCLUSIONS

The results of the current study indicate that a history of concussion may result in alterations of the brain's white matter microstructure in ice hockey players. Increased FA based on decreased RD may reflect neuroinflammatory or neuroplastic processes of the brain responding to brain trauma. Future studies are needed that include a longitudinal analysis of the brain's structure and function following a concussion to elucidate further the complex time course of DTI changes and their clinical meaning.

Epidemiology of concussion in sport: a literature review

OBJECTIVE

The purpose of this study was to summarize sport concussion incidence data, identify sports that present higher injury frequency, reveal the degree of risk in some lesser-known sports, and outline specific details within the sports literature that raise additional concerns, such as helmet-to-helmet contact and player positions that experience frequent impact.

METHODS

A systematic literature review of Pub Med using keyword search on injury, concussion, and sports was performed through May 2012. Abstracts were identified, selections were made based upon inclusion criteria, and full-length articles were obtained. Additional articles were considered following review of reference sections. Articles were reviewed and tabulated according to sport.

RESULTS

Two hundred eighty-nine articles were screened, and 62 articles were reviewed. The overall incidence of concussion in sport ranged from 0.1 to 21.5 per 1000 athletic exposures. The lowest incidence was reported in swimming and diving. Concussion incidence was highest in Canadian junior ice hockey, but elevated incidence in American football remains a concern because of the large number of participants.

CONCLUSIONS

The literature reviewed included incidence of concussion on the field of play under real-world conditions and influenced by the current culture of sport. The studies examined in this article show that there is risk of concussion in nearly every sport. Some sports have higher concussion frequency than others, which may depend upon the forces and roles of the positions played in these sports. Younger athletes have a higher incidence of concussion, and female incidence is greater than male in many comparable sports. Headgear may reduce concussion in some sports but may also give athletes a false sense of protection.

Knowledge, attitude, and concussion-reporting behaviors among high school athletes: a preliminary study

CONTEXT

Many athletes continue to participate in practices and games while experiencing concussion-related symptoms, potentially predisposing them to subsequent and more complicated brain injuries. Limited evidence exists about factors that may influence concussion-reporting behaviors.

OBJECTIVE

To examine the influence of knowledge and attitude on concussion-reporting behaviors in a sample of high school athletes.

DESIGN

Cross-sectional study.

SETTING

Participants completed a validated survey instrument via mail.

PATIENTS OR OTHER PARTICIPANTS

A total of 167 high school athletes (97 males, 55 females, 5 sex not indicated; age = 15.7 ± 1.4 years) participating in football, soccer, lacrosse, or cheerleading.

INTERVENTION(S)

Athlete knowledge and attitude scores served as separate predictor variables.

MAIN OUTCOME MEASURE(S)

We examined the proportion of athletes who reported continuing to participate in games and practices while symptomatic from possible concussion and the self-reported proportion of recalled concussion and bell-ringer events disclosed after possible concussive injury.

RESULTS

Only 40% of concussion events and 13% of bell-ringer recalled events in the sample were disclosed after possible concussive injury. Increased athlete knowledge of concussion topics (increase of 1 standard deviation = 2.8 points) was associated with increased reporting prevalence of concussion and bell-ringer events occurring in practice (prevalence ratio [PR] = 2.27, 95% confidence interval [CI] = 1.60, 3.21) and the reporting prevalence of bell-ringer-only events overall (PR = 1.87, 95% CI = 1.38, 2.54). Athlete attitude scores (increase of 1 standard deviation = 11.5 points) were associated with decreases in the proportion of athletes stating they participated in games (PR = 0.74, 95% CI = 0.66, 0.82) and practices (PR = 0.67, 95% CI = 0.59, 0.77) while symptomatic from concussions.

CONCLUSIONS

Most recalled concussion events in our study were not reported to a supervising adult. Clinicians should be aware that knowledge and attitude influence concussion reporting. Clinicians and administrators should make concussion education a priority and encourage an optimal reporting environment to better manage and prevent concussive injuries in young athletes.