Epidemiology of Sport-Related Concussions in High School Athletes: National Athletic Treatment, Injury and Outcomes Network (NATION), 2011-2012 Through 2013-2014

Epidemiology of Concussion in the National Football League, 2015-2019

BACKGROUND

Concussion in American football, and specifically the National Football League (NFL) is a major area of interest and key focus for injury prevention. Complete and accurate characterization of when, how, and to whom these injuries occur can facilitate injury reduction efforts. Existing studies of concussion in the NFL use publicly available data, potentially limiting data quality and the inferences that can be made.

HYPOTHESIS

Concussion incidence in the NFL decreased across the 2015-2019 seasons.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 4.

METHODS

Concussion incidence, including counts, one-season risk, and rates per game and player-plays, among active NFL players from 2015 to 2019 is described by year, season, play type, and roster position.

RESULTS

A total 1302 concussions were identified from 2015 to 2019 among 1004 players. Of these, 80% occurred in NFL games. The average annual incidence of in-season game concussions changed over the study period, from 230.7 per season (2015-2017) to 177.0 per season (2018-2019); this represented a 23% decrease in game settings (P < 0.01). Practice concussions fluctuated across the years of the study from 38 to 67 per season (average = 50.8/season). There were 70.6 concussions per 100 preseason games, which was slightly higher than the regular season rate per game of 61.7. Overall, there were 790 regular season game concussions across 4,657,243 player-plays and 114,428 player-games during the 5-year study. In regular season games, the majority of concussions were sustained on running and passing plays (n = 119/season), and the highest average rate per play occurred on kickoffs (0.69/100 plays). Defensive secondary (cornerbacks, safeties, and generic defensive backs) and offensive line incurred the most concussions, and the highest rates of concussion were among tight ends and wide receivers.

CONCLUSION AND RELEVANCE

Concussions in the NFL are a key focus for player safety. Concussion reduction strategies were implemented before 2018, after which there was a sustained 2-year decrease in concussion incidence, providing a new benchmark from which to work toward further injury reduction.

A Longitudinal Observation of the Influence of Michigan Sports Concussion Law on Parents' Knowledge and Perception of Sport-Related Concussion

INTRODUCTION

In 2013, Michigan enacted legislation requiring parents and athletes to receive educational material concerning sport-related concussion (SRC). The aim of this study was to examine trends in concussion knowledge of parents from one community following implementation of Michigan's Sports Concussion Laws (MSCL).

METHODS

A convenience sample of parents of students from a suburban school district were surveyed via district email at one year and five years post MSCL implementation. Results were compared to an equivalent 33-item survey obtained prior to the law. Individual questions were compared between the three surveys using Chi-square analysis with statistical significance observed at p < 0.05.

RESULTS

A total of 381 responses were obtained from the one-year post-MSCL (1yMSCL) and 178 in the five-year post-MSCL (5yMSCL) survey. Awareness of district policy regarding concussion was significantly higher after implementation of the MSCL (i.e., 77% at 1yMSCL and 71% at 5yMSCL) compared to prior 18% pre-MSCL (p < 0.0001). Respondents to the 5yMSCL survey were also significantly more aware of medical guidelines surrounding "return to play" after SRC compared to 1yMSCL (84.8% v 78.7%, p = 0.01). At 5yMSCL, significantly more respondents agreed that head injuries could cause more brain damage to children than adults (86.5% v 78.7% at 1yMSCL, p = 0.03). Finally, most parents at both survey periods rated the concussion educational material as the most helpful information source regarding SRC.

CONCLUSIONS

Based on these results, parental knowledge awareness appears to have increased concerning awareness of medical guidelines for SRC and potential brain damage risks to children after enactment of the MSCL.

Sport Contact Level Affects Post-Concussion Neurocognitive Performance in Young Athletes

OBJECTIVE

Contact level affects the incidence of sports-related concussion. However, the effects of contact level on injury severity and recovery are less clear and are the focus of this study.

METHOD

Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) for athletes aged 12-22 was performed at baseline (n = 10,907 for 7,058 athletes), after suspected concussion determined by physicians or athletic trainers (n = 5,062 for 4,419 athletes), and during follow-up visits (n = 3,264 for 2,098 athletes). Athletes played contact/collision (CC), limited contact (LC), and noncontact (NC) sports. Injury incidence, severity, and recovery were measured using raw and change from baseline neurocognitive test scores. Comparisons between groups used univariate analysis and multivariable regression controlling for demographic variables.

RESULTS

Compared to CC athletes, LC and NC athletes showed decreased suspected concussion incidence. At initial post-injury testing, all neurocognitive test scores were similar between groups except changes from baseline for processing speed were improved for LC compared to CC athletes. Upon follow-up testing, raw neurocognitive scores were better for NC compared to the contact collision athletes in verbal memory, processing speed, total symptom score, migraine cluster, cognitive cluster, and neuropsychiatric cluster scores. For change from baseline scores, LC athletes exhibited better performance on verbal memory, processing speed, and reaction time but also showed higher neuropsychiatric scores than CC athletes.

CONCLUSION

Neurocognitive scores between contact levels were similar at the first post-injury test. However, follow up showed many improved scores and symptoms for limited and NC sports compared to CC sports, which may indicate faster recovery.

Sport Concussion Assessment Tool Symptom Inventory: Healthy and Acute Postconcussion Symptom Factor Structures

CONTEXT

Previous researchers have examined factor structures for common concussion symptom inventories. However, they failed to discriminate between the acute (<72 hours) and subacute (3 days-3 months) periods after concussion. The Sport Concussion Assessment Tool (SCAT) is an acute assessment that, when compared with other concussion symptom inventories, includes or excludes symptoms that may result in different symptom factors.

OBJECTIVE

The primary purpose was to investigate the symptom factor structure of the 22-item SCAT symptom inventory in healthy, uninjured and acutely concussed high school and collegiate athletes. The secondary purpose was to document the frequency of the unique SCAT symptom inventory items.

DESIGN

Case series.

SETTING

High school and college.

PATIENTS OR OTHER PARTICIPANTS

A total of 1334 healthy, uninjured and 200 acutely concussed high school and collegiate athletes.

MAIN OUTCOME MEASURE(S)

Healthy, uninjured participants completed the SCAT symptom inventory at a single assessment. Participants in the acutely concussed sample completed the SCAT symptom inventory within 72 hours after concussion. Two separate exploratory factor analyses (EFAs) using a principal component analysis and varimax extraction method were conducted.

RESULTS

A 3-factor solution accounted for 48.1% of the total variance for the healthy, uninjured sample: cognitive-fatigue (eg, feeling "in a fog" and "don't feel right"), migraine (eg, neck pain and headache), and affective (eg, more emotional and sadness) symptom factors. A 3-factor solution accounted for 55.0% of the variance for the acutely concussed sample: migraine-fatigue (eg, headache and "pressure in the head"), affective (eg, sadness and more emotional), and cognitive-ocular (eg, difficulty remembering and balance problems) symptom factors.

CONCLUSIONS

The inclusion of unique SCAT symptom inventory items did not alter the symptom factor structure for the healthy, uninjured sample. For the acutely concussed sample, all but 1 unique SCAT symptom inventory item (neck pain) loaded onto a factor.

An Examination of Perceived Pressure From Stakeholders on Concussion Reporting Intentions and Behavior in Ice Hockey Athletes

OBJECTIVE

We aimed to assess whether perceived pressure predicts concussion reporting intentions and behavior in youth, high school, and collegiate ice hockey athletes, and, secondarily, whether perceived pressure from stakeholders differed between sex or level of play.

SETTING

Online survey.

PARTICIPANTS

One hundred fifty-two ice hockey athletes (males: n = 96, 63.2%; females: n = 55, 36.2%; missing: n = 1, 0.7%; age = 14.04 ± 3.6 years).

DESIGN

Cross-sectional.

MAIN MEASURES

Respondents answered a survey that elicited information about demography, perceived pressure from 6 stakeholders, and concussion reporting intentions and behavior. For the first aim, we used a generalized linear model to determine whether perceived pressure from any stakeholder predicted intention (symptom reporting, concussion reporting, and intention beliefs) or behavior ("all concussions," "not obvious concussions"; α < .05) while controlling for level of play. To determine whether pressure from any stakeholder predicted symptom reporting behavior, we used logistic regression while controlling for level of play. For the second aim, to examine sex differences in perceived pressure from each stakeholder, we employed Mann-Whitney tests and to examine level of play differences, we used Kruskal-Wallis tests.

RESULTS

Controlling for level of play, a 1-point increase in perceived pressure from parents and athletic administrators decreased concussion reporting intentions by 0.92 (P = .004) and 1.09 (P = .005) points, respectively. Perceived pressure from a sports medicine professional decreased intention beliefs by 0.17 (P = .029) points. Perceived pressure from stakeholders did not predict symptom reporting (P = .440) or "not obvious concussion" reporting (P = .655) behavior. We observed no difference in perceived pressure across stakeholders (all P values >.05); however, collegiate ice hockey respondents perceived greater pressure from coaches than youth or high school athletes (P < .001). We noted no other differences in perceived pressure across levels of play (all P values >.05).

CONCLUSIONS

Concussion reporting intentions were negatively influenced by perceived pressure from parents, athletic administrators, and sports medicine professionals, but these findings did not translate to reporting behavior.

Preseason Cerebrovascular Function in Adolescent Athletes

The purpose of this study was to investigate the effects of sport participation, concussion history, and age of first exposure to football on preseason cerebrovascular function in adolescent athletes. Athletes (n = 53, age = 15.8 ± 1.2 years) were examined based on three exposure groupings: (1) sport participation (football vs. non-collision), (2) concussion history (none vs. ≥ 1), and (3) age of first exposure (football participants only). Transcranial Doppler assessed cerebrovascular reactivity (CVR) and neurovascular coupling (NVC), and separate independent samples t-tests evaluated group differences in CVR and NVC outcomes. Separate univariate linear regressions determined how age of first exposure related to CVR and NVC outcomes. Linear mixed effects models assessed group differences in CVR and NVC relative response curves. Differential response to NVC visual task response was significantly greater in non-collision sport athletes (F_1,2946 = 38.69, p < 0.0001) and athletes without a concussion history (F_1,2946 = 25.23, p < 0.0001). Older age of first exposure significantly predicted reduced breath-holding CVR response (F_1,1560 = 2.92, p = 0.03). Healthy adolescent athletes have similar pre-season cerebrovascular function despite different sport participation and concussion history. However, age of first exposure may predict CVR in adolescent football athletes. Developmental literature identifies cerebrovascular function as dynamically changing throughout adolescence. Our study provides fundamental data informing the clinical meaningfulness of short- and long-term physiological function changes.

Data-Driven Risk Classification of Concussion Rates: A Systematic Review and Meta-Analysis

BACKGROUND

Concussion is a growing public health concern and generating concussion prevention programs depends on identifying high-risk sports and characteristics. Identifying the roles of sport, sex, and participation level (e.g., high school versus collegiate athletics) in concussion risk would facilitate more informed decision-making regarding sports participation and generate better targeted prevention strategies.

OBJECTIVES

The current study's objectives were to: (1) determine the magnitude and hierarchy of sports-related concussion (SRC) risk across an array of events and (2) evaluate the modifying roles of sex, participation level, and session type on SRC rates.

METHODS

A literature search was conducted on PubMed, searching concussion studies published between 2001 and December 2019. Inclusion criteria for studies required: (1) concussion occurred during sport, (2) that the SRC was clinically diagnosed, and (3) athlete exposures and concussions could be extracted or estimated. A study was excluded if it: (1) was not an original research article, (2) was not written in English language, (3) was an animal study, (4) did not have enough data to calculate SRC rates, (5) included professional or youth sample, and/or (6) contained data collected prior to 2001. The meta-analysis and meta-regression analyses were fit using a random effects model.

RESULTS

Search results returned 2695 unique research articles, with 83 studies included in analyses. Sport, sex, participation level, and session type all significantly influenced SRC rates. Overall, rugby had the highest concussion rate and was classified as the highest risk sport (28.25 concussions per 10,000 athlete exposures). Overall, females had a higher concussion rate than males. Only lacrosse demonstrated a higher concussion rate for males compared to females. Collegiate athletes had higher concussion rates than high school athletes. Games were associated with 2.01 more concussions per 10,000 AEs than practices.

CONCLUSIONS

This meta-analysis demonstrated rugby has the highest concussion risk, followed by American Football, ice hockey, and wrestling. Concussion risk was influenced by sport, sex, participation, and session. Identifying the factors and environments that influence concussion risk can facilitate risk reduction and prevention strategies.

Head Impact Telemetry System's Video-based Impact Detection and Location Accuracy

PURPOSE

This study aimed to quantify the Head Impact Telemetry (HIT) System's impact detection and location measurement accuracy using an impact biomechanics data set paired with video of high school football special teams plays.

METHODS

The head impact biomechanics data set and video were collected from 22 high school football players, wearing HIT System instrumented helmets, competing in 218 special teams plays over a single high school football season. We used two separate video analysis approaches. To quantify the impact detection accuracy, we evaluated the video for head impacts independently of the impact data collection triggers collected by the HIT System. Video-observed impacts matched to valid and invalid head impacts by the HIT System algorithm were categorized as true positives, false positives, false negatives, and true negatives. To quantify impact location accuracy, we analyzed video-synchronized head impacts for impact location independent of the HIT System's impact location measurement and quantified the estimated percent agreement of impact location between the HIT System recorded impact location and the impact location observed on video.

RESULTS

The HIT System's impact-filtering algorithm had 69% sensitivity, 72% specificity, and 70% accuracy in categorizing true and non-head impact data collection triggers. The HIT System agreed with video-observed impact locations on 64% of the 129 impacts we analyzed (unweighted k = 0.43, 95% confidence interval = 0.31-0.54).

CONCLUSION

This work provides data on the HIT System's impact detection and location accuracy during high school football special teams plays using game video analysis that has not been previously published. Based on our data, we believe that the HIT System is useful for estimating population-based impact location distributions for special teams plays.

Examination of Reaction Time Deficits Following Concussion: A Systematic Review and Meta-analysis

BACKGROUND

Reaction time (RT) deficits are reported following concussion, but it is unknown when these deficits normalize to pre-injury status. It is also unclear how factors such as RT measurement technique and participant characteristics influence post-concussion RT.

OBJECTIVE

The purpose of this systematic review and meta-analysis was to (1) characterize acute post-concussion (0-3 days) RT impairments, (2) examine RT recovery over time, and (3) explore moderating factors related to acute RT impairment following concussion.

METHODS

Database searches (PubMed, CINAHL, EBSCOhost) were conducted according to PRISMA guidelines for articles published in English from January 2002 to March 2019. Studies compared baseline-to-post-injury RT within individuals (within-subject) and/or RT in concussed individuals to non-concussed controls (between-subject). Sixty studies met inclusion criteria, reporting on a total of 9688 participants with 214 discrete RT effects (Hedges' d; between-subject: N = 29, k = 129; within-subject: N = 42, k = 85). Of the 214 effects, 93 occurred in the acute (0-3 days) post-injury timeframe (k = 47 between-subject). Numerous demographic [sex, age, concussion history, population type (athlete, military, and general population), athlete level (high school, college), and sport], and method-based (RT test and measure type, computerized neurocognitive testing platform, concussion definition, and time post-injury) moderators were examined for mean effect influence. Mixed-effects multi-level modeling with restricted-maximum-likelihood estimation was used to account for nested effects and high heterogeneity for the pooled effect size (D+).

RESULTS

Significant medium-magnitude RT deficits were observed acutely for between- (D+ = - 0.7279, 95% CI - 0.9919, - 0.4639, I² = 88.66, p < 0.0001) and within-subject (D+ = - 0.7472, 95% CI - 0.9089, - 0.5855, I² = 89.21, p < 0.0001) effect models. RT deficits were present at the sub-acute and intermediate-term timeframes for between-subject effects (sub-acute: D+ = - 0.5655, 95% CI - 0.6958, - 0.4352, p < 0.0001; intermediate-term: D+ = - 0.3219, 95% CI - 0.5988, - 0.0450, p = 0.0245). No significant RT mean effect was observed for the between-subject model at the long-term timeframe, indicating RT recovery among concussed participants relative to controls (D+ = 0.3505, 95% CI - 0.4787, 1.1797, p = 0.3639). Sex was a significant moderator for between-subject effects, with every 1% male sample size increase demonstrating - 0.0171 (95% CI - 0.0312, - 0.0029, p = 0.0193) larger RT deficits. Within-subject effect models resulted in RT measure type (simple: [D+ = - 0.9826] vs. mixed: [D+ = - 0.6557], p = 0.0438) and computerized neurocognitive testing platforms (ANAM: [D+ = - 0.3735] vs. HeadMinder CRI: [D+ = - 1.4799] vs. ImPACT: [D+ = - 0.6749], p = 0.0004) having significantly different RT-deficit magnitudes. No other moderators produced significantly different RT-deficit magnitudes (between-subject: [p ≥ 0.0763], within-subject: [p ≥ 0.1723]).

CONCLUSIONS

Robust RT deficits were observed acutely following concussion. Minimal magnitude differences were noted when comparing between- and within-subject effects, suggesting that pre-injury baselines may not add clinical value in determining post-injury RT impairment. RT deficits persisted up till the intermediate-term (21-59 days post-injury) timeframe and indicate lingering deficits exist. Mean effect size differences were observed between RT measure types and computerized neurocognitive testing platforms; however, all categories displayed negative effects consistent with impaired RT following concussion. Clinical interpretation suggests that measuring RT post-concussion is more important than considering the RT method employed so long as reliable and valid tools are used. PROSPERO Registration #CRD42019119323.

Time-to-Event Analyses: Return to Unrestricted Participation After Sport-Related Concussion in a Cohort of High School Athletes

CONTEXT

Understanding time loss resulting from sport-related concussion (SRC) within individual sports allows high school athletic trainers to provide accurate and evidence-based clinical information. Currently, research regarding patterns of clinical recovery outcomes in high school student-athletes across sports is lacking.

OBJECTIVE

To describe the time to authorized unrestricted return to participation (RTP) after SRC in a large cohort of high school student-athletes in a variety of sports using a time-to-event analysis.

DESIGN

Descriptive epidemiology study.

SETTING

Aggregate injury and player exposure data from the Michigan High School Athletic Association Head Injury Reporting System.

PATIENTS OR OTHER PARTICIPANTS

High school student-athletes.

MAIN OUTCOME MEASURE(S)

Dates for SRC injury events and authorized unrestricted RTP were entered into the Head Injury Reporting System for each case and were used to calculate time to unrestricted RTP. Survival analysis indicated the time to authorized RTP for males and females in weekly increments across sports and academic years. Separate Kaplan-Meier analyses adjusted for SRC cases with a history of concussion also identified the proportions of student-athletes who obtained authorized medical clearance in weekly increments.

RESULTS

A total of 15 821 SRCs, 10 375 (65.6%) in males and 5446 (34.4%) in females, were reported during the 2015-2016 through 2018-2019 academic years. The median time to authorized unrestricted RTP was 11 days for all patients. Approximately 30% of concussed student-athletes were not cleared for unrestricted RTP by 14 days after their SRC diagnosis, with 13% taking longer than 21 days to return to unrestricted RTP after SRC.

CONCLUSIONS

The results from this multisite, state-based injury surveillance system indicated that it is not abnormal for high school student-athletes to take longer than 14 days to fully recover from an SRC. This information may be useful for educating high school student-athletes and sport stakeholders, normalizing SRC recovery trajectory perceptions, and establishing realistic RTP timeline expectations.

Emergency Department Visits From 2014 to 2018 for Head Injuries in Youth Non-Tackle Football Compared With Other Sports

Background

Non-tackle football (ie, flag, touch, 7v7) is purported to be a lower-risk alternative to tackle football, particularly in terms of head injuries. However, data on head injuries in non-tackle football are sparse, particularly among youth participants.

Purpose

To describe the epidemiology of  emergency department visits for head injuries due to non-tackle football among youth players in the United States and compare the data with basketball, soccer, and tackle football.

Study Design

Descriptive epidemiology study.

Methods

Injury data from 2014 to 2018 were obtained from the National Electronic Injury Surveillance System database. Injury reports coded for patients aged 6 to 18 years and associated with basketball, football, or soccer were extracted. Data were filtered to include only injuries to the head region, specifically, the head, ear, eyeball, mouth, or face. Football injuries were manually assigned to "non-tackle" or "tackle" based on the injury narratives. Sports & Fitness Industry Association data were used to estimate annual sport participation and calculate annual injury rates per 100,000 participant-years.

Results

A total of 26,770 incident reports from 2014 to 2018 were analyzed. For head region injuries in non-tackle football, the head was the most commonly injured body part, followed by the face; the most common diagnosis was a laceration, followed by concussion and internal injury (defined as an unspecified head injury or internal head injury [eg, subdural hematoma or cerebral contusion]). The most common contacting object was another player. The projected national rate of head region injuries was lowest for non-tackle football across the 4 sports. In particular, the projected rate of injuries to the head for non-tackle football (78.0 per 100,000 participant-years) was less than one-fourth the rates for basketball (323.5 per 100,000 participant-years) and soccer (318.2 per 100,000 participant-years) and less than one-tenth the rate for tackle football (1478.6 per 100,000 participant-years).

Conclusion

Among youth in the United States aged 6 to 18 years who were treated in the emergency department for injuries related to playing non-tackle football, the most common diagnosis for injuries to the head region was a laceration, followed by a concussion. Head region injuries associated with non-tackle football occurred at a notably lower rate than basketball, soccer, or tackle football.

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.

Isometric Cervical Muscular Strength in Pediatric Athletes With Multiple Concussions

OBJECTIVE

To compare maximal cervical muscle strength among athletes with a history of 2 or more concussions relative to athletes with no history of a previous concussion.

DESIGN

Athletes in the 2 groups were frequency-matched. Linear mixed models were used to test for differences in peak isometric flexion, extension, left lateral flexion, and right lateral flexion cervical muscle torque between groups.

SETTING

Pediatric sports medicine clinic.

PARTICIPANTS

Athletes with a history of multiple concussions (n = 16) and athletes with no previous concussion history (n = 17). INTERVENTIONS (OR ASSESSMENT OF RISK FACTORS OR INDEPENDENT VARIABLES):: Concussion history (group), age, sex, neck girth, and height.

MAIN OUTCOME MEASURES

Peak isometric torque measured with a stationary isokinetic dynamometer during a 3-second isometric hold.

RESULTS

There was no significant difference in peak flexion [mean difference: 21.2%, 95% confidence interval (CI): -6.6% to 57.4%, P = 0.1413], extension (mean difference: 17%, 95% CI, -6.8% to 47.1%, P = 0.1667), left lateral (mean difference: 4.4%, 95% CI, -16.9% to 31.1%, P = 0.7011), or right lateral (mean difference: 9.3%, 95% CI, -14.5% to 39.8%, P = 0.4627) isometric torque in the concussion group relative to the control group. Across all muscle actions, neck torque was significantly (P < 0.05) higher in male compared with female athletes. Increasing neck girth was also associated with a significant (P < 0.05) increase in neck torque.

CONCLUSIONS

There was no evidence of a consistent cervical muscle strength deficit among athletes with a history of 2 or more concussions relative to athletes with no previous history of a concussion. Age, neck girth, and sex were significantly associated with cervical muscle strength.

CLINICAL RELEVANCE

Isometric cervical muscle strength testing may not be a reliable test for differentiating athletes with a history of multiple concussions relative to athletes with no history of concussions in the pediatric and adolescent population. Our study presents a reliable methodology for testing cervical muscle strength among young athletes.

The Effects of On-Field Heat Index and Altitude on Concussion Assessments and Recovery Among NCAA Athletes

BACKGROUND

Recent literature has indicated altitude may be a protective factor for concussion but it is unknown whether altitude or heat index affects recovery.

OBJECTIVE

To examine whether on-field heat index and altitude at the time of injury alter acute (< 48 h) concussion assessments, days-to-asymptomatic, and days-to-return-to-play in collegiate athletes following concussion.

METHODS

Collegiate athletes (n = 187; age = 19.7 ± 1.4 years; male = 70.6%) underwent baseline assessments across 30 universities and experienced a concussion in this retrospective cohort study. Altitude (m) and heat index (°C) at the time and location of injury were determined using valid online database tools. Acute concussion assessments included the Sport Concussion Assessment Tool (SCAT) symptom inventory, Balance Error Scoring System (BESS), and the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). We used multiple linear regression models to determine whether heat index and altitude predicted each acute assessment outcome, days-to-asymptomatic, and days-to-return-to-play.

RESULTS

Collegiate athletes were concussed at a 181.1 m (range - 0.6 to 2201.9 m) median altitude and 17.8 °C (range - 6.1 to 35.6 °C) median heat index. Altitude did not predict (p ≥ 0.265) any outcomes. Every one-degree increase in heat index reduced days-to-asymptomatic (p = 0.047; R² = 0.06) and days-to-return-to-play (p = 0.006; R² = 0.09) by 0.05 and 0.14 days, respectively. Heat index and altitude did not explain significant variance in SCAT, BESS, and ImPACT composite scores (p's = 0.20-0.922).

CONCLUSION

Our findings suggest that on-field altitude and heat index at the time of injury do not contribute to clinically meaningful changes on acute assessments or concussion recovery. On-field altitude and heat index do not appear to significantly alter assessment outcomes or clinical recovery, suggesting that environmental factors at altitudes below < 2500 m are negligible outcomes for researchers and clinicians to consider post-concussion.

The Effects of Anticipation and Visual and Sensory Performance on Concussion Risk in Sport: A Review

Sports-related concussions pose a significant public health concern, and preventative measures are needed to help reduce risk in sport. Vision training could be a suitable prevention strategy for sports-related concussion to help improve athletes’ abilities to scan the visual field for oncoming objects or opponents and thus anticipate head impacts. By accurately anticipating impacts, athletes can prepare for impact or attempt to avoid the collision altogether. The purpose of this review is to explore the relationships between anticipation, visual and sensorimotor performance and head accelerations, as well as to examine the efficacy of vision training programmes in reducing concussion risk in sport. Anticipation of head impacts has been shown to help reduce linear and rotational head accelerations, particularly for mild-to-moderate severity head impacts, but less so for severe head impacts. There is conflicting evidence regarding the influences visual and sensorimotor performance and oculomotor behaviour have on concussion risk. However, preliminary research indicates vision training may help reduce concussion rates in collegiate American Football players. Therefore, this promising area of research warrants further investigation, particularly the role of anticipation and visual and sensory performance on reducing concussion risk in non-helmeted contact sports.

Characteristics of Pediatric Mild Traumatic Brain Injury and Recovery in a Concussion Clinic Population

IMPORTANCE

Pediatric mild traumatic brain injury (TBI) and concussion are a public health challenge with up to 30% of patients experiencing prolonged recovery. Pediatric patients presenting to concussion clinics often have ongoing impairments and may be at increased risk for persistent symptoms. Understanding this population is critical for improved prognostic estimates and optimal treatment.

OBJECTIVE

To describe pediatric patients presenting to concussion clinics and characterize factors associated with their recovery.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study included patients enrolled at multicenter concussion specialty clinics from the Four Corners Youth Consortium from December 2017 to July 2019, with up to 12-month follow-up. Patients were eligible if they were aged 5 to 18.99 years with a diagnosis of mild TBI or concussion presenting to participating clinics within 8 weeks of injury. Patients were excluded if the patient or their parents were unable to read or sign the consent document, or if the patient had a Glasgow Coma Scale score less than 13 or a penetrating injury. Data were analyzed from February 2019 to April 2020.

EXPOSURES

Diagnosis of mild TBI or concussion.

MAIN OUTCOMES AND MEASURES

This study used National Institute of Neurological Disorders and Stroke common data elements, including data on demographic characteristics, injury details, history, neurological and neuropsychological assessments, and treatment.

RESULTS

A total of 600 patients were consecutively enrolled, among whom 324 (54.0%) were female and 435 (72.5%) were adolescents (ie, aged 13-18 years). A higher proportion of girls and women (248 patients [76.5%]) were adolescents compared with boys and men (187 patients [67.8%]) (P = .02), and girls and women reported significantly more preexisting anxiety compared with boys and men (80 patients [26.7%] vs 46 patients [18.7%]; P = .03). Significantly more adolescents reported preexisting migraines compared with preadolescents (82 patients [20.9%] vs 15 patients [10.9%]; P = .01). Girls and women recovered more slowly than boys and men (persistent symptoms after injury: week 4, 217 patients [81.6%] vs 156 patients [71.2%]; week 8, 146 patients [58.9%] vs 89 patients [44.3%]; week 12, 103 patients [42.6%] vs 58 patients [30.2%]; P = .01). Patients with history of migraine or anxiety or depression recovered more slowly than those without, regardless of sex.

CONCLUSIONS AND RELEVANCE

These findings suggest that identification of subgroups of pediatric patients with mild TBI or concussion at risk for prolonged recovery could aid in better prognostic estimates and more targeted treatment interventions.

Awareness of Concussion-Education Requirements, and -Management Plans and Concussion Knowledge in High School and Club Sport Coaches

Context

A growing number of high-school–aged athletes participate on club sport teams. Some, but not all, state concussion laws apply to both interscholastic and private sport organizations. However, concussion education, management plans, and knowledge have not been examined in club coaches who coach high school-aged athletes.

Objective

To determine if differences in concussion education, management plans, and knowledge exist between high school coaches and coaches of club sport teams.

Design

Cross-sectional study.

Setting

Online survey.

Patients or Other Participants

A total of 769 coaches (497 high school coaches, 272 club coaches coaching high school-aged athletes; 266 women [34.6%], 503 men [65.4%]) completed an anonymous online questionnaire.

Main Outcome Measure(s)

The questionnaire consisted of demographic and team information, requirements for concussion-education and -management plans, and concussion knowledge.

Results

High school coaches were more likely than club coaches to report that their organizing bodies or leagues required them to receive concussion-education information (97.4% versus 80.4%; P &lt; .001) and that their organizing bodies or leagues had a concussion-management plan (94.0% versus 70.2%; P &lt; .001). High school coaches were more likely than club coaches to correctly agree that most concussions resolve in 7 to 10 days (48.6% versus 40.1%; P = .02) and disagree that loss of consciousness is required to diagnose a concussion (87.1% versus 80.9%; P = .02).

Conclusions

Club coaches were less likely to be aware of requirements for concussion-education and -management plans from their parent organizations and scored lower on specific concussion-knowledge questions than high school coaches despite the same education requirements across groups under their state concussion laws. These results raise concerns regarding the proper management of concussions in club sports and suggest a need for greater oversight and enforcement of state laws in the club sport setting.

Landing Biomechanics in Adolescent Athletes With and Without a History of Sports-Related Concussion

Recent evidence suggests previously concussed athletes are at greater risk for lower-extremity (LE) injuries than are controls. However, little is known regarding the influence of sports-related concussion (SRC) on landing biomechanics that may provide a mechanistic rationale for LE injury risk. The purpose of this investigation was to examine LE drop-landing biomechanics in adolescent athletes with and without a previous SRC history. Participants included 10 adolescent athletes with an SRC history and 11 controls from multiple sports. Three-dimensional kinematic and kinetic data associated with LE injury risk were analyzed across 5 trials for 30- and 60-cm landing heights. Multivariate analyses indicated group differences in landing patterns from the 30- (P = .041) and 60-cm (P = .015) landing heights. Follow-up analyses indicated that concussed adolescent athletes demonstrated significantly less ankle dorsiflexion and knee flexion versus controls when performing drop landings. Our findings suggest that previously concussed adolescent athletes complete drop-landing maneuvers with ankle and knee joint kinematic patterns that suggest greater risk for LE injury. While limitations such as sport variety and explicit LE injury history are present, the results of this study provide a possible biomechanical rationale for the association between SRC and LE injury risk.

Concussion Knowledge, Attitudes, and Self-Reporting Intentions in Youth Athletes

CONTEXT

Although it has been suggested that developmental and sociological factors play a role in concussion reporting, the empirical evidence related to this is limited.

OBJECTIVE

To examine the influences of sex, school level, school location, concussion-reporting history, and socioeconomic status on concussion-related knowledge, attitudes, and reporting intentions among middle school and high school athletes.

DESIGN

Cross-sectional study.

SETTING

Master students and High School athletes attending pre-participation examinations (PPEs) were asked to complete paper-based surveys.

PATIENTS OR OTHER PARTICIPANTS

Overall, 541 athletes representing 18 sports returned fully completed surveys.

MAIN OUTCOME MEASURE(S)

Outcomes were concussion-related knowledge, perceived seriousness, positive feelings about reporting, and self-reporting intentions. We examined group differences in these outcomes across levels of the explanatory variables of sex, school level (middle school versus high school), school location (urban versus rural), concussion self-reporting history (yes or no), and socioeconomic status (free or reduced-price lunch versus no free or reduced-price lunch) using Wilcoxon rank sum tests. Then we used multivariable ordinal logistic regression models to identify predictors of higher score levels for each outcome. Odds ratio (OR) estimates with 95% confidence intervals (CIs) excluding 1.00 were deemed significant.

RESULTS

Odds of higher levels of knowledge were higher in urban versus rural school student-athletes (ORAdjusted = 1.81; 95% CI = 1.03, 3.17), and lower in student-athletes on free or reduced-price lunch versus those not on free or reduced-price lunch (ORAdjusted = 0.52; 95% CI = 0.36, 0.77). Similarly, odds of higher levels of seriousness were lower in male versus female student-athletes (ORAdjusted = 0.48; 95% CI = 0.32, 0.72). Further, odds of higher levels of self-reporting intentions were lower among male versus female student-athletes (ORAdjusted = 0.53; 95% CI = 0.37, 0.75).

CONCLUSIONS

Developmental and sociological factors were differentially associated with concussion-related knowledge, attitudes, and self-reporting intentions. These results can inform medical providers, parents, and coaches with regard to context-specific clinical assessments of concussion symptoms.

Predictors of in-school and out-of-school sport injury prevention: A test of the trans-contextual model

The current study aimed to predict secondary school students’ motivation toward sport injury prevention in “in‐school” and “out‐of‐school” contexts, and their sport injury prevention behavior at 3‐month follow‐up using the trans‐contextual model (TCM). Hong Kong secondary school students (N = 1566; mean age = 13.34 years, range = 11 to 19; female = 49.42%) were recruited. Participants were asked to complete a survey comprising previously validated scales measuring TCM constructs at baseline and a measure of sport injury prevention behavior at follow‐up three months later. Structural equation modeling (SEM) was used to examine the hypothesized paths among TCM constructs. A SEM specifying hypothesized paths among TCM variables showed acceptable fit with the data (χ²(29) = 418.55, CFI = .93, TLI = .90, and RMSEA = .09, 90% CI [.09, .10], and SRMR = .05). Findings supported tenets of the TCM: the effects of perceived autonomy support from PE teachers on in‐school autonomous motivation toward injury prevention, the trans‐contextual relationship between students' “in‐school” and “out‐of‐school” autonomous motivation toward injury prevention, and the effects of autonomous motivation toward injury prevention on social cognitive variables and subsequent sport injury prevention behaviors. Results supported the tenets proposed within the TCM in predicting students' “in‐school” and “out‐of‐school” autonomous motivation toward sport injury prevention. Findings underscore the potential importance of autonomy support from PE teachers in facilitating students’ sport injury prevention behaviors. Further longitudinal and intervention research is warranted to establish temporal and causal effects of TCM variables in sport injury prevention.

Clinical Detection and Recovery of Vestibular and Oculomotor Impairments Among Amateur Athletes Following Sport-Related Concussion: A Prospective, Matched-Cohort Study

OBJECTIVE

To (1) quantify the diagnostic accuracy of the vestibular/oculomotor screening (VOMS), and (2) determine the recovery of vestibular and oculomotor impairments exhibited by concussed athletes compared with nonconcussed athletes using the VOMS.

SETTING

Clinical assessment laboratory.

PARTICIPANTS

Amateur athletes who were diagnosed with sport-related concussion by emergency department physicians, and non-concussed, control athletes.

DESIGN

Prospective, longitudinal study.

MAIN MEASURES

Participants were assessed 1 week following sport-related concussion, upon clearance to return-to-sporting activity, and 2 weeks following return-to-sporting activity by a study investigator who administered the VOMS. We calculated test sensitivity, specificity, and positive and negative predictive values to estimate the diagnostic accuracy of the VOMS. We performed a mixed-design analysis of variance to assess differences in VOMS symptom scores reported by concussed athletes compared with control athletes.

RESULTS

Fifty concussion participants and 50 control participants completed the study. The VOMS demonstrated sensitivity and specificity of 96% and 46%, respectively, and produced positive and negative predictive values of 64% and 92%, respectively. The concussion group exhibited a significantly greater symptom provocation change score from baseline than the control group for all test domains of the VOMS only in the first week following concussion.

CONCLUSION

The VOMS may be most useful as a clinical screening tool to rule out, rather than confirm, the presence of sport-related concussion. The VOMS may be appropriate to inform the recovery of vestibular and oculomotor impairments exhibited by concussed individuals over time.

Estimated age of first exposure to American football and outcome from concussion

OBJECTIVE

To examine the association between estimated age at first exposure (eAFE) to American football and clinical measures throughout recovery following concussion.

METHODS

Participants were recruited across 30 colleges and universities as part of the National Collegiate Athletic Association (NCAA)-Department of Defense Concussion Assessment, Research and Education Consortium. There were 294 NCAA American football players (age 19 ± 1 years) evaluated 24-48 hours following concussion with valid baseline data and 327 (age 19 ± 1 years) evaluated at the time they were asymptomatic with valid baseline data. Participants sustained a medically diagnosed concussion between baseline testing and postconcussion assessments. Outcome measures included the number of days until asymptomatic, Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) composite scores, Balance Error Scoring System (BESS) total score, and Brief Symptom Inventory 18 (BSI-18) subscores. The eAFE was defined as participant's age at the time of assessment minus self-reported number of years playing football.

RESULTS

In unadjusted regression models, younger eAFE was associated with lower (worse) ImPACT Visual Motor Speed (R ² = 0.031, p = 0.012) at 24-48 hours following injury and lower (better) BSI-18 Somatization subscores (R ² = 0.014, p = 0.038) when the athletes were asymptomatic. The effect sizes were very small. The eAFE was not associated with the number of days until asymptomatic, other ImPACT composite scores, BESS total score, or other BSI-18 subscores.

CONCLUSION

Earlier eAFE to American football was not associated with longer symptom recovery, worse balance, worse cognitive performance, or greater psychological distress following concussion. In these NCAA football players, longer duration of exposure to football during childhood and adolescence appears to be unrelated to clinical recovery following concussion.

Prospective analysis of craniofacial soccer incidents during FIFA competitions: an observational study

The aim of this prospective epidemiological study was to evaluate the occurrence of incidents involving the craniofacial region of soccer players during three official FIFA competitions. The craniofacial incidents were identified by video analysis of all 144 matches of two FIFA World Cups (2014/2018) and the 2017 FIFA Confederations Cup. Data collection included incident type, incident severity, site affected, incident cause and referee decision. The multivariate Poisson regression model was performed to analyze the associations between covariates. A total of 238 incidents were observed in the craniofacial region (1.6 incidents/match), representing a rate of 48.5 incidents per 1000 hours. At least 80.6% of the matches presented at least one incident, and, in more than 60%, the referee's decision was no foul. According to severity, 26.8% of the incidents were classified as having mild or high severity. Incidents involving lacerations or fracture presented higher severity compared with hits (IRR 3.45[95%CI: 1.89-6.30]). Head-to-head impacts showed an incidence of severe incidents twice as high as those involving upper extremities (IRR 2.01[95%CI:1.07-3.76]). A high number of craniofacial incidents were observed in the last FIFA competitions. Head-to-head impacts and lacerations or fractures were associated with higher incident severity.

Concussion Symptom Characteristics and Resolution in 20 United States High School Sports, 2013/14-2017/18 Academic Years

BACKGROUND

High school (HS) sport-related concussions (SRCs) remain a public health concern in the United States.

OBJECTIVE

To describe patterns in symptom prevalence, symptom resolution time (SRT), and return-to-play time (RTP) for SRCs sustained in 20 HS sports during the 2013/14-2017/18 academic years.

METHODS

A convenience sample of athletic trainers reported concussion information to the HS RIOTM surveillance system. Symptom prevalence, average number of symptoms, and SRT and RTP distributions were examined and compared by event type (practice, competition), injury mechanism (person contact, nonperson contact), sex, and contact level (collision, high contact, and low contact) with chi-square tests and Wilcoxon rank-sum tests.

RESULTS

Among all SRCs (n = 9542), headache (94.5%), dizziness (73.8%), and difficulty concentrating (56.0%) were commonly reported symptoms. On average, 4.7 ± 2.4 symptoms were reported per SRC. Overall, 51.3% had symptoms resolve in <7 d, yet only 7.9% had RTP < 7 d. Differential prevalence of amnesia was seen between practice and competition-related SRCs (8.8% vs 13.0%; P < .001); nonperson-contact and person-contact SRCs (9.3% vs 12.7%; P < .001); and female and male SRCs in low-contact sports (5.8% vs 17.5%; P < .001). Differential prevalence of loss of consciousness was seen between practice and game-related SRCs (1.3% vs 3.2%; P < .001); and female and male SRCs in high contact sports (1.2% vs 4.0%; P < .001). Differential longer SRT (>21 d) was seen between new and recurrent SRCs (9.4% vs 15.9%; P < .001).

CONCLUSION

Headache was the most commonly reported symptom. Notable group differences in the prevalence of amnesia, loss of consciousness, and SRT may be associated with more severe SRCs, warranting further attention.

Longitudinal Assessment of Depressive Symptoms After Sport-Related Concussion in a Cohort of High School Athletes

BACKGROUND

The long-term effect of sport-related concussion on mood in adolescent athletes is largely unknown.

HYPOTHESIS

Longitudinal measures of depression will worsen acutely after sport-related concussion and improve with concussion symptom resolution.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A population-based sample of 2160 high school athletes from 31 urban, suburban, and rural high schools completed preseason baseline concussion symptom evaluation and Patient Health Questionnaire-9 (PHQ-9) assessments over 2 years. Athletic trainers recorded onset of sport-related concussion, and concussed athletes completed the PHQ-9 assessment within 24 to 72 hours, 7 days, date of return to sport, 3 months, 6 months, and 12 months after sport-related concussion. Scores at each time point were compared to baseline with mixed-effects models and repeated-measures analysis of variance. Sex-based differences were assessed using mixed-effect models.

RESULTS

Of the 2160 athletes enrolled in the study, 125 (5.8%; 80 males, 45 females) sustained a sport-related concussion. PHQ-9 scores worsened from baseline at 24 to 72 hours (+1.05; 95% CI, 0.26-1.84; P = 0.003) and 7 days (+0.91; 95% CI, 0.23-1.60; P = 0.006). However, PHQ-9 scores improved from baseline to date of return to sport (-1.38; 95% CI, -2.20 to -0.55; P < 0.001), 3 months (-1.08; 95% CI, -1.88 to -0.28; P = 0.003), 6 months (-1.19; 95% CI, -2.04 to -0.34; P = 0.001), and 12 months after sport-related concussion (-0.76; 95% CI, -1.43 to -0.08; P = 0.028). Female athletes reported more severe concussion symptoms 24 to 72 hours after sport-related concussion compared with male athletes (female, 20.5 [interquartile range (IQR), 10.0-36.2]; male, 9.0 [IQR, 4.0-19.5]; P = 0.003). Neither PHQ-9 scores nor change in PHQ-9 scores differed between male and female athletes at any time point.

CONCLUSION

Sport-related concussion did not worsen longitudinal measures of depressed mood in this cohort of high school athletes.

CLINICAL RELEVANCE

Emotional symptoms are common after sport-related concussion, but typically resolve by return to sport.

Bibliometric study of traumatic brain injury rehabilitation

Purpose: This paper aims to present a bibliometric analysis of scientific documents in the field of traumatic brain injury rehabilitation.Methods: Web of Science was used to collect bibliographic data of traumatic brain injury rehabilitation documents from 1983 until the end of 2017.Results: Of a total of 6069 documents retrieved, 78.2% were journal articles. The average annual growth of the documents as of the year 2000 was 9.4%. The most frequent subject categories in this field were Rehabilitation, Neurosciences and Neurology, Sport Sciences, Psychology, and General and Internal Medicine. The most active journal was Brain Injury. More than 50% of the documents were published in 10 journals. The most prolific and impactful institutions were from the USA, Australia and Canada. Traumatic brain injury, rehabilitation, brain injury, stroke and outcome were the most commonly used keywords. Mild traumatic brain injury and concussion were the topics receiving attention in recent years.Conclusion: Traumatic brain injury rehabilitation is a young and constantly growing field. Since the late 1990s, traumatic brain injury rehabilitation documents published yearly comprised about 3-4% of all rehabilitation documents. It was shown that review papers and proceedings have more impact than journal articles, and collaborative papers receive more citations. It was also revealed that knowledge does not become obsolete rapidly in this field.

Assessment of Long-Term Effects of Sports-Related Concussions: Biological Mechanisms and Exosomal Biomarkers

Concussion or mild traumatic brain injury (mTBI) in athletes can cause persistent symptoms, known as post-concussion syndrome (PCS), and repeated injuries may increase the long-term risk for an athlete to develop neurodegenerative diseases such as chronic traumatic encephalopathy (CTE), and Alzheimer's disease (AD). The Center for Disease Control estimates that up to 3.8 million sport-related mTBI are reported each year in the United States. Despite the magnitude of the phenomenon, there is a current lack of comprehensive prognostic indicators and research has shown that available monitoring tools are moderately sensitive to short-term concussion effects but less sensitive to long-term consequences. The overall aim of this review is to discuss novel, quantitative, and objective measurements that can predict long-term outcomes following repeated sports-related mTBIs. The specific objectives were (1) to provide an overview of the current clinical and biomechanical tools available to health practitioners to ensure recovery after mTBIs, (2) to synthesize potential biological mechanisms in animal models underlying the long-term adverse consequences of mTBIs, (3) to discuss the possible link between repeated mTBI and neurodegenerative diseases, and (4) to discuss the current knowledge about fluid biomarkers for mTBIs with a focus on novel exosomal biomarkers. The conclusions from this review are that current post-concussion clinical tests are not sufficiently sensitive to injury and do not accurately quantify post-concussion alterations associated with repeated mTBIs. In the current review, it is proposed that current practices should be amended to include a repeated symptom inventory, a cognitive assessment of executive function and impulse control, an instrumented assessment of balance, vestibulo-ocular assessments, and an improved panel of blood or exosome biomarkers.

Concussion Epidemiology in Youth Sports: Sports Study of a Statewide High School Sports Program

BACKGROUND

Current research on concussion incidence in youth athletes (age <18 years) is small and limited by variability in injury reporting and diagnostic methodology.

HYPOTHESIS

Concussion injuries commonly occur in high school sports programs. The likelihood of concussion among student-athletes (aged 13-18 years) depends on the sport they are participating in as well as the sex of the athlete.

STUDY DESIGN

Descriptive epidemiology study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A retrospective analysis of all Hawaii high school athletes aged 13 to 18 years participating in 14 sports from 2011 through 2017 was performed as part of a statewide standardized concussion assessment and management program.

RESULTS

A total of 5993 concussions were identified among 92,966 athletes. The overall concussion rate was 0.96 (95% CI, 0.94-0.99). Girls' judo had the highest concussion rate (1.92; 95% CI, 1.68-2.17) followed by football (1.60; 95% CI, 1.53-1.66). The concussion rate for boys (1.0; 95% CI, 0.97-1.03) was higher than that for girls (0.91; 95% CI, 0.87-0.95); however, in 4 of the 5 sports in which both girls and boys participated, girls had a higher rate of concussion injury.

CONCLUSION

The likelihood of concussion among student-athletes aged 13 to 18 years may be higher than previously thought and varies depending on sport and sex.

CLINICAL RELEVANCE

Epidemiologic data on concussion injury in children and adolescents are useful in accurately determining the relative risks of high school sports participation and may be valuable in determining the appropriate allocation of health care and scholastic resources for student-athletes, as well as the impact of rule and training modifications designed to improve participant safety.

Sport-Related Concussion in Female Athletes: A Systematic Review

Background:

Female athletes are more susceptible to sport-related concussions (SRCs) and experience worse outcomes compared with male athletes. Although numerous studies on SRC have compared the outcomes of concussions in male and female athletes after injury, research pertaining to why female athletes have worse outcomes is limited.

Purpose:

To determine the factors that predispose female athletes to more severe concussions than their male counterparts.

Study Design:

Systematic review; Level or evidence, 3.

Methods:

A systematic review was performed according to PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines. The MEDLINE, EMBASE, CINAHL, PsychINFO, and Cochrane Library databases were systematically searched on July 5 to July 20, 2018. Included were cohort, case-control, and cross-sectional studies that examined the effects of concussive and subconcussive head impacts in only female athletes of all ages, regardless of competition level. These studies were further supplemented with epidemiologic studies. Exclusion criteria included narrative reviews, single case reports, abstracts and letters to the editor, and studies related to chronic traumatic brain injury.

Results:

A total of 25 studies met the inclusion criteria. Female athletes appear to sustain more severe concussions than male athletes, due in part to a lower biomechanical threshold tolerance for head impacts. Additionally, concussions may alter the hypothalamic-pituitary-ovarian axis, resulting in worse symptoms and amenorrhea. Although females are more likely to report concussions than males, underreporting still exists and may result in concussions going untreated.

Conclusion:

This systematic review demonstrates that female athletes may be more susceptible to concussion, have prolonged symptoms after a concussion, and are more likely to report a concussion than their male counterparts. However, underreporting still exists among female athletes. Possible factors that put female athletes at a higher risk for concussions include biomechanical differences and hormonal differences. To effectively prevent, diagnose, and treat concussions in female athletes, more research is required to determine when and how such injuries are sustained. Despite sex-based differences in the clinical incidence, reporting behavior, and outcomes of SRCs, female athletes remain an understudied population, resulting in lack of sex-specific treatment guidelines for female athletes postinjury.

Effects of a Single Concussion During the School Year on the Academic Performance and Neuropsychological Functioning of High School Athletes

There are very few studies examining the effects of sports-related concussion (SRC) on objective measures of school performance, such as grades or test scores. In this research, the grade point averages (GPAs) and scores of the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) of athletes who sustained an SRC during the school year were compared with those of athletes who did not have an SRC. Multivariate analysis of variance (MANOVA) revealed a significant linear decline in GPA of both groups across the school year, but indicated no difference in the GPA decline between the concussion and no concussion groups. The GPAs of the concussion and no concussion groups were not significantly different across the school year. Finally, no differences were found between the pre- and post-concussion ImPACT scores of the concussed athletes. This study found that an SRC during the school year did not affect the academic performance or neurocognitive test scores of high school athletes.

Early Aerobic Exercise for the Treatment of Acute Pediatric Concussions

Sport-related concussion is a common injury that has garnered the attention of the media and general public because of the potential for prolonged acute symptoms and increased risk for long-term impairment. Currently, a growing body of evidence supports the use of various therapies to improve recovery after a concussion. A contemporary approach to managing concussion symptoms is to use aerobic exercise as treatment. To date, several studies on both pediatric and adult patients have established that controlled aerobic exercise is a safe and effective way to rehabilitate patients experiencing delayed recovery after concussion. However, less is known about the utility of an early exercise protocol for optimizing recovery after acute concussion and reducing the risk for persistent postconcussive symptoms, particularly in pediatric populations. Thus, the purpose of our paper was to review and evaluate the available literature on the implementation of aerobic exercise for the treatment of acute pediatric concussion.

Women Are at Higher Risk for Concussions Due to Ball or Equipment Contact in Soccer and Lacrosse

BACKGROUND

There is ample evidence to suggest sex- and gender-based differences in the incidence of sports-related concussions. The mechanisms of concussion may vary between male and female athletes and contribute to this observed difference. Understanding the underlying etiology by pooling data from primary studies across different settings and sport types will inform interventions that can reduce concussion rates.

QUESTIONS/PURPOSES

Specifically, we asked: (1) In which sports are female athletes less likely to experience concussions from player contact? (2) In which sports are female athletes more likely to experience concussions because of ball or equipment contact?

METHODS

PubMed, EMBASE, and Cochrane Library databases were searched to identify articles published from January 2000 to December 2018. Ten studies met the inclusion criteria, which were studies that reported concussion incidence by mechanism for both male and female athletes. Exclusion criteria included non-English studies, conference abstracts, and studies on non-sports related concussions. The sports represented by the 10 studies included ice hockey (n = 4), soccer (n = 5), basketball (n = 4), baseball/softball (n = 4), and lacrosse (n = 5). The rate ratio was calculated as the incidence rate in female athletes/male athletes for each concussion mechanism or activity. Data were pooled using the DerSimonian-Laird random-effects model. Study quality was assessed with the Newcastle-Ottawa Scale.

RESULTS

Female athletes were at lower risk of player-contact-induced concussions in lacrosse (pooled rate ratio 0.33 [95% CI 0.25 to 0.43]; p < 0.001), basketball (pooled rate ratio 0.86 [95% CI 0.76 to 0.97]; p = 0.01), ice hockey (pooled rate ratio 0.64 [95% CI 0.56 to 0.73]; p < 0.001), soccer (pooled rate ratio 0.70 [95% CI 0.66 to 0.75]; p < 0.001), and soccer heading (pooled rate ratio 0.80 [95% CI 0.72 to 0.90]; p < 0.001); in these sports, men were at higher risk of concussions from player contact. Female athletes were more likely to experience concussions because of ball or equipment contact in lacrosse (pooled rate ratio 3.24 [95% CI 2.10 to 4.99]; p < 0.001), soccer (pooled rate ratio 2.04 [95% CI 1.67 to 2.49]; p < 0.001), and soccer heading (pooled rate ratio 2.63 [95% CI 1.84 to 3.77]; p < 0.001).

CONCLUSIONS

The mechanism or activity underlying concussions differs between male and female athletes across different sports. This finding remains the same regardless of whether there are rule differences between the men's and women's games. The implementation of other interventions are required to further ensure player safety, including protective head equipment, concussion prevention training, or rules limiting player contact in the men's game.

LEVEL OF EVIDENCE

Level III, retrospective study.

Participation in Physical Activity at Time of Presentation to a Specialty Concussion Clinic Is Associated With Shorter Time to Recovery

INTRODUCTION

Novel research suggests that children engaging in physical activity during recovery from concussion may recover more rapidly.

OBJECTIVE

To determine if level of physical activity at presentation to a rehabilitation-based concussion specialty clinic predicted days from injury to recovery.

DESIGN

Retrospective cohort.

SETTING

A concussion sub-specialty clinic at an academic institution.

PATIENTS

Retrospective review of medical records between September 2015 and February 2017 identified 178 children ages 6-17 years (mean age = 13.7 years; standard deviation [SD] = 2.7 years) who presented within 60 days of concussion and were ultimately deemed recovered and cleared to progress to full return to high-risk activities.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Physical activity at initial visit was classified as none-to-light (79%) versus moderate-to-heavy (21%). A doubly robust, inverse probability of exposure weighted linear regression model was used to examine the relationship between physical activity level and days to recovery, while adjusting for 10 demographic and clinical variables.

RESULTS

Children participating in moderate-to-heavy activity at initial evaluation in concussion clinic averaged recovery 21 days quicker (95% confidence interval [CI] -27.1, -15.5, P < .001) than children who were engaging in none-to-light activity. This finding did not change when removing children who were deemed recovered at the first visit (who may have initiated physical activity after becoming asymptomatic).

CONCLUSIONS

These data add to growing evidence that progressive physical activity during recovery from concussion does not appear to be harmful. Physical activity represents a modifiable variable in recovery, and physicians can potentially expedite symptomatic recovery by recommending noncontact physical activity as tolerated during concussion recovery.

Comparison of head impact measurements via an instrumented mouthguard and an anthropometric testing device

The purpose of this study was to determine and compare the efficacy of head impact measurements via an electronic sensor framework, embedded within a mouthguard, against an anthropometric testing device. Development of the former is in response to the growing issue of head impacts and concussion in rugby union. Testing was conducted in a vehicle safety laboratory using a standard impact protocol utilising the headforms of anthropometric testing devices. The headforms were subjected to controlled front and side impacts. For each impact, the linear acceleration and rotational velocity was measured over a 104-ms interval at a frequency of 1 kHz. The magnitude of peak linear acceleration and peak rotational velocity was determined from the measured time-series traces and statistically compared. The peak linear acceleration and rotational velocity had intraclass correlation coefficients of 0.95 and 0.99, respectively. The root-mean-square error between the measurement systems was 4.3 g with a standard deviation of 3.5 g for peak linear acceleration and 0.7 rad/s with a standard deviation of 0.4 rad/s for rotational velocity. Bland and Altman analysis indicated a systematic bias of 2.5 g and − 0.5 rad/s and limits of agreement (1.96 × standard deviation) of ± 13.1 g and ± 1.25 rad/s for the instrumented mouthguard. These results provide the basis on which the instrumented mouthguard can be further developed for deployment and application within professional rugby, with a view to accurately and reliably quantify head collision dynamics.

The effect of cognitive dual-tasks on dynamic postural sway during gait using inertial measurement units

OBJECTIVE

To investigate the influence of cognitive dual-tasks on dynamic postural sway variability, measured with a single inertial measurement unit, in healthy collegiate athletes during dual-task gait.

APPROACH

Thirty-four athletes ambulated down and back a 10-meter course. Root mean square values of postural sway acceleration were calculated for four sway-planes. Single and dual-task trial times were calculated from gait initiation to termination. Single and dual-task root mean square values were compared using Wilcoxon signed rank tests for each sway plane to determine significance. The relative difference between each sway measures and trial times for single and dual-task gait (i.e. dual-task cost was calculated). Spearman's correlation was used to analyze the association between dual-task cost of sway and trial time data.

MAIN RESULTS

During dual-task conditions, participants ambulated slower and demonstrated a significant reduction in root mean square sway in all planes of motion. The greatest decreases were in the medial-lateral (Z = -4.83, p < 0.001, ES = -0.83) and superior-inferior planes (Z = -4.93, p < 0.001, ES = -0.85). Increased trial time cost was associated with a decrease in dual-task cost of postural sway (p < 0.05).

SIGNIFICANCE

Performing a cognitive task while ambulating decreased postural sway variability in task-relevant planes of motion compared to single-task conditions. Reduced dual-task cost of sway variability during gait was associated with maintained trial times between single and dual-tasks. These data support the use of instrumented dual-task gait assessment to evaluate postural sway variability.

Long-term mortality and causes of death among patients with mild traumatic brain injury: a 5-year multicenter study

Objective: Undergoing mild traumatic brain injury (mTBI) increases mortality risk, but it is unclear what drives this finding. This study explored associations with mortality in patients with mTBI.Methods: This was a retrospective study of patients with mTBI and controls admitted to six level 1 trauma centers in 1/1/2009-12/31/2013. Mortality data were from the CDC National Death Index. Patients with mTBI were identified by ICD-9 code, Glasgow Coma Scale 13-15, Injury Severity Score (ISS) <16, and loss of consciousness ≤1 hour. Controls had hospital length of stay ≤24 hours, ISS<16, and no head injury.Results: This study included 964 patients with mTBI and 5,567 controls. mTBI was associated with a 47% increased 5-year mortality risk (HR = 1.47, 95% CL 1.08-2.01). Patients with mTBI were more likely to die of a neurodegenerative disease (17% vs 11%, P = .119). Cardiovascular (HR = 1.80, 95% CL 1.17-2.77), neurological (HR = 3.33, 95% CL 2.07-5.38), and respiratory (HR = 1.70, 95% CL 1.01-2.86) comorbidities were associated with mortality in patients with mTBI.Conclusions: Patients with mTBI are at increased mortality risk in the 5 years post-injury. Mortality in patients with mTBI was most influenced by preexisting conditions.

Incidence of seizure exacerbation and injury related to football participation in people with epilepsy

INTRODUCTION

There is scant evidence to quantify the risk of contact sports such as football to patients with epilepsy. This retrospective review was performed to evaluate the incidence of injuries or seizure exacerbation related to football participation in patients with epilepsy.

METHODS

Between the years 1994 and 2004, 157,709 consecutive clinic notes were searched for mention of "football" and "epilepsy" or "seizure". Resulting notes were reviewed to quantify the number of seizure exacerbations and the number of injuries in this cohort.

RESULTS

Seven of 44 subjects with epilepsy (15.9%) experienced injury while playing football. Four of 32 (12.5%) patients experienced seizure exacerbation during a time when they were concurrently participating in football though 3 of these patients stopped taking or were weaned off of their antiepileptic drugs (AEDs). One in 32 patients with epilepsy (3.1%) had an exacerbation of seizures while playing football and consistently taking AEDs.

CONCLUSION

The risk of injury and seizure exacerbation due to participation in football for patients with epilepsy is low. Clinicians should use their best judgment in deciding whether contact sports increase risks for a particular patient based on individual seizure frequency, concurrent neurological and medical issues, and medication adverse effects.

Clinical versus Functional Reaction Time: Implications for Postconcussion Management

PURPOSE

This study aimed to examine the association between clinical and functional reaction time (RT) assessments with and without simultaneous cognitive tasks among healthy individuals.

METHODS

Participants (n = 41, 49% female; 22.5 ± 2.1 yr; 172.5 ± 11.9 cm; 71.0 ± 13.7 kg) completed clinical (drop stick, Stroop) and functional (gait, jump landing, single-leg hop, anticipated cut, unanticipated cut) RT assessments in random order. All RT assessments, except Stroop and unanticipated cut, were completed under single- (movement only) and dual-task conditions (movement and subtracting by 6s or 7s). Drop stick involved catching a randomly dropped rod embedded in a weighted disk. Stroop assessed RT via computerized neurocognitive testing. An instrumented walkway measured gait RT when center-of-pressure moved after random stimulus. All other functional RT assessments involved participants jumping forward and performing a vertical jump (jump landing), balancing on one leg (single-leg hop), or a 45° cut in a known (anticipated cut) or unknown (unanticipated cut) direction. RT was determined when the sacrum moved following random visual stimulus. Pearson correlation coefficients and a 5 × 2 repeated-measures ANOVA compared RT assessments and cognitive conditions.

RESULTS

Stroop RT outcomes did not significantly correlate with functional RT assessments (r range = -0.10 to 0.24). A significant assessment by cognitive task interaction (F4,160 = 14.01; P < 0.001) revealed faster single-task RT among all assessments compared with dual-task (mean differences, -0.11 to -0.09 s; P < 0.001), except drop stick (P = 0.195). Single-leg hop (0.58 ± 0.11 s) was significantly slower compared with jump landing (0.53 ± 0.10 s), anticipated cut (0.49 ± 0.09 s), gait (0.29 ± 0.07 s), and drop stick (0.21 ± 0.03 s; P values ≤ 0.001). Dual-task assessments were significantly slower than single-task assessments (mean difference, 0.08 s; P < 0.001).

CONCLUSIONS

Clinical and functional RT assessments were not correlated with each other, suggesting that sport-like RT is not being assessed after concussion. Functional and dual-task RT assessments may add clinical value and warrant further exploration after concussion.

Pre-frontal Cortex Oxygenation Changes During Aerobic Exercise in Elite Athletes Experiencing Sport-Related Concussion

Aims: Recent research suggests that aerobic exercise can be performed safely within the first week following a concussion injury and that early initiation of exercise may speed recovery. To better understand the physiological changes during a concussion, we tested the hypothesis that mild-to-intense exercise testing can be performed within days immediately following injury, and can be used to discern differences between the concussed and normal healthy state. Thus, the purpose was to observe the cerebral hemodynamic responses to incremental exercise testing performed acutely post-concussion in high-performance athletes. Methods: This study was a within- and between-experimental design, with seven male university ice hockey teams participating. A subgroup of five players acted as control subjects (CON) and was tested at the same time as the 14 concussed (mTBI) players on Day 2, 4, and 7 post-concussion. A 5-min resting baseline and 5-min exercise bouts of mild (EX1), moderate (EX2), and high (EX3) intensity exercise were performed on a cycle ergometer. Near-infrared spectroscopy was used to monitor pre-frontal cortex oxy-haemoglobin (HbO2), deoxy-haemoglobin (HHb), and total blood volume (tHb) changes. Results: ANOVA compared differences between testing days and groups, and although large percentage changes in HbO2 (20-30%), HHb (30-40%), and tHb (30-40%) were recorded, no significant (p ≤ 0.05) differences in cerebral hemodynamics occurred between mTBI vs. CON during aerobic exercise testing on any day post-injury. Furthermore, there was a linear relationship between exercise intensity vs. cerebral hemodynamics during testing for each day (r 2 = 0.83-0.99). Conclusion: These results demonstrate two novel findings: (1) mild-to-intense aerobic exercise testing can be performed safely as early as Day 2 post-concussion injury in a controlled laboratory environment; and (2) evidence-based objective measures such as cerebral hemodynamics can easily be collected using near-infrared spectroscopy (NIRS) to monitor physiological changes during the first-week post-injury. This research has important implications for monitoring physiological recovery post-injury and establishing new rehabilitation guidelines.

Incidence reporting via online high school concussion surveillance by certified athletic trainers and school nurses, 2015-2018

BACKGROUND

There is an increasing concern over adolescent concussions in sports due to risks of long-term negative effects. This study analyzed data over three school years on reported concussion incidence rates by season, high school grade levels and gender, and reported symptoms by school nurses versus athletic trainers, from New Jersey student-athlete concussion data available from an online school-based surveillance system.

METHODS

School nurses and athletic trainers reported 300 concussions within five days from when each occurred over three school years, 2015-2018, in team sports and physical education in New Jersey high schools. Analysis was further conducted on symptoms and number of symptoms reported by school nurses versus school athletic trainers for each documented student-athlete concussion. Estimated concussion incidence rates were calculated using state agency verified school enrollment data.

FINDINGS

Concussions most commonly occurred during fall, followed by spring, then winter. Concussion incidence rates ranged from 6.3/1000 (4.99, 7.55) - 9.1/1000 (7.27, 10.98) students over the three school years of the study. Athletic trainers completed 86% of the reports while nurses completed 11% (position or title of 3%, or n = 7, were not disclosed); the values were similar when considering only fall pre-season and regular season sports (88, 10, 2%, respectively). On average, across the three school years, athletic trainers reported about 3.5 symptoms per report while nurses reported 2.7 (values in fall seasons only were 3.7 and 3.1, respectively.) CONCLUSIONS: Certified athletic trainers, compared to school nurses, more often completed concussion report forms and reported more symptoms per injured student, perhaps due partly to closer contact and immediate care provided after injury. Additionally, this study had a higher concussion incidence rate during fall sports seasons compared to winter and spring. Future research can further improve our understanding of concussions among adolescent student-athletes to better inform concussion identification, management and recovery protocols.

Machine Learning in Modeling High School Sport Concussion Symptom Resolve

INTRODUCTION

Concussion prevalence in sport is well recognized, so too is the challenge of clinical and return-to-play management for an injury with an inherent indeterminant time course of resolve. A clear, valid insight into the anticipated resolution time could assist in planning treatment intervention.

PURPOSE

This study implemented a supervised machine learning-based approach in modeling estimated symptom resolve time in high school athletes who incurred a concussion during sport activity.

METHODS

We examined the efficacy of 10 classification algorithms using machine learning for the prediction of symptom resolution time (within 7, 14, or 28 d), with a data set representing 3 yr of concussions suffered by high school student-athletes in football (most concussion incidents) and other contact sports.

RESULTS

The most prevalent sport-related concussion reported symptom was headache (94.9%), followed by dizziness (74.3%) and difficulty concentrating (61.1%). For all three category thresholds of predicted symptom resolution time, single-factor ANOVA revealed statistically significant performance differences across the 10 classification models for all learners at a 95% confidence interval (P = 0.000). Naïve Bayes and Random Forest with either 100 or 500 trees were the top-performing learners with an area under the receiver operating characteristic curve performance ranging between 0.656 and 0.742 (0.0-1.0 scale).

CONCLUSIONS

Considering the limitations of these data specific to symptom presentation and resolve, supervised machine learning demonstrated efficacy, while warranting further exploration, in developing symptom-based prediction models for practical estimation of sport-related concussion recovery in enhancing clinical decision support.

Preventing injuries must be a priority to prevent disease in the twenty-first century

Injuries continue to be the leading cause of morbidity and mortality for children, adolescents, and young adults aged 1-24 years in industrialized countries in the twenty-first century. In this age group, injuries cause more fatalities than all other causes combined in the United States (U.S.). Importantly, many of these injuries are preventable. Annually in the U.S. there are >9 million emergency department visits for injuries and >16,000 deaths in children and adolescents aged 0-19 years. Among injury mechanisms, motor vehicle crashes, firearm suicide, and firearm homicide remain the leading mechanisms of injury-related death. More recently, poisoning has become a rapidly rising cause of both intentional and unintentional death in teenagers and young adults aged 15-24 years. For young children aged 1-5 years, water submersion injuries are the leading cause of death. Sports and home-related injuries are important mechanisms of nonfatal injuries. Preventing injuries, which potentially cause lifelong morbidity, as well as preventing injury deaths, must be a priority. A multi-pronged approach using legislation, advancing safety technology, improving the built environment, anticipatory guidance by clinical providers, and education of caregivers will be necessary to decrease and prevent injuries in the twenty-first century.

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

BACKGROUND

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

PURPOSE

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

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

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

RESULTS

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

CONCLUSION

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

Relative Head Impact Exposure and Brain White Matter Alterations After a Single Season of Competitive Football: A Pilot Comparison of Youth Versus High School Football

OBJECTIVE

Youth athletes are believed to be more susceptible to white matter (WM) degradation resulting from head impact exposure relative to high school (HS) athletes; this hypothesis has not been objectively tested. The purpose of this study was to determine preseason to postseason changes in WM integrity from repetitive head impacts for youth football (YFB) players compared with HS football players during a competitive football season.

DESIGN

Prospective cohort.

SETTING

One season of YFB (grades 7 and 8) and varsity HS football (grades 10-12).

PATIENTS OR OTHER PARTICIPANTS

Twelve YFB (13.08 ± 0.64 years) and 21 HS (17.5 ± 0.78 years) athletes.

INTERVENTIONS

Participants completed 2 magnetic resonance imaging sessions: preseason and postseason. Head impact exposure was recorded during practice and games using a helmet-mounted accelerometer.

MAIN OUTCOME MEASURES

Tract-based spatial statistics were used to evaluate group differences in preseason to postseason changes in diffusion tensor imaging, including fractional anisotropy and mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD).

RESULTS

The HS group exhibited significant preseason to postseason reductions in MD, AD, and RD (P < 0.05, corrected) in widespread WM areas. Significant WM reductions for the YFB group were only observed for AD (P < 0.05, corrected), but was more limited in extent compared with HS.

CONCLUSIONS

Significant preseason to postseason AD reduction was found in both YFB and HS groups after one season of competitive play. Our results did not confirm recent speculation that younger children are more susceptible to the deleterious effects of repetitive head impacts compared with their older counterparts.

Concussion Incidence and Trends in 20 High School Sports

BACKGROUND

Ongoing monitoring of concussion rates and distributions is important in assessing temporal patterns. Examinations of high school sport-related concussions need to be updated. This study describes the epidemiology of concussions in 20 high school sports during the 2013-2014 to 2017-2018 school years.

METHODS

In this descriptive epidemiology study, a convenience sample of high school athletic trainers provided injury and athlete exposure (AE) data to the National High School Sports-Related Injury Surveillance Study (High School Reporting Information Online). Concussion rates per 10 000 AEs with 95% confidence intervals (CIs) and distributions were calculated. Injury rate ratios and injury proportion ratios examined sex differences in sex-comparable sports (soccer, basketball, baseball and softball, cross country, track, and swimming). We also assessed temporal trends across the study period.

RESULTS

Overall, 9542 concussions were reported for an overall rate of 4.17 per 10 000 AEs (95% CI: 4.09 to 4.26). Football had the highest concussion rate (10.40 per 10 000 AEs). Across the study period, football competition-related concussion rates increased (33.19 to 39.07 per 10 000 AEs); practice-related concussion rates decreased (5.47 to 4.44 per 10 000 AEs). In all sports, recurrent concussion rates decreased (0.47 to 0.28 per 10 000 AEs). Among sex-comparable sports, concussion rates were higher in girls than in boys (3.35 vs 1.51 per 10 000 AEs; injury rate ratio = 2.22; 95% CI: 2.07 to 2.39). Also, among sex-comparable sports, girls had larger proportions of concussions that were recurrent than boys did (9.3% vs 6.4%; injury proportion ratio = 1.44; 95% CI: 1.11 to 1.88).

CONCLUSIONS

Rates of football practice-related concussions and recurrent concussions across all sports decreased. Changes in concussion rates may be associated with changes in concussion incidence, diagnosis, and management. Future research should continue to monitor trends and examine the effect of prevention strategies.

Sex-Based Differences in the Incidence of Sports-Related Concussion: Systematic Review and Meta-analysis

CONTEXT

The incidence of sports-related concussion in females has been increasing in recent years.

OBJECTIVE

To conduct a meta-analysis on sex-based differences in concussion incidence in various sports and to determine the effects of study design (retrospective vs prospective), setting (competition vs practice), and population (university and above vs high school and below) via a meta-regression.

DATA SOURCES

PubMed (Medline), EMBASE, and Cochrane Library databases were searched from January 2000 to January 2018.

STUDY SELECTION

Studies reporting sports-related concussion incidence data for both males and females (age ≥10 years) were included.

STUDY DESIGN

Systematic review with meta-analysis and meta-regression.

LEVEL OF EVIDENCE

Level 4.

METHODS

The rate ratio was calculated as the concussion rate in females/males. Data were pooled using the DerSimonian-Laird random-effects model.

RESULTS

Thirty-eight studies met the eligibility criteria and were included in the meta-analysis. Soccer and basketball demonstrated significantly higher incidence of concussions in females compared with males (rate ratio [95% CI], 1.76 [1.43-2.16] and 1.99 [1.56-2.54], respectively; P < 0.01). Sex-based differences in concussion incidence rates for baseball/softball, ice hockey, lacrosse, swimming/diving, and track and field were not statistically significant. In the meta-regression analysis, there were no significant effects on the rate ratio when evaluating study design, setting, and population.

CONCLUSION

Concussion incidence rates were significantly higher in females than in males for soccer and basketball.