Determinants of concussion diagnosis, symptomology, and resolution time in U.S. high school soccer players

Repetitive concussions promote microglia-mediated engulfment of presynaptic excitatory input associated with cognitive dysfunction

Concussions are a current health concern and account for the vast majority of head trauma. While symptoms after a single impact are usually transient, repetitive concussions, as often occur in sports, are responsible for persistent acute and chronic deficits. Here, we used a model of bilateral midline-centered concussions in mice to show that repetitive concussions selectively induce impairments in learning ability compared to single-impact injuries. Since microglial cells and their activation are considered key factors in degenerative pathology after brain trauma, we examined their structure and function after single and repetitive concussions in the cortex underlying the concussions and in the hippocampus. We found that only repetitive concussions led to a significant long-lasting structural activation of microglia and an increase in microglia-mediated engulfment of presynaptic excitatory synapses, while the elimination of inhibitory synapses was not altered. Since the density of excitatory input did not change during the 6-week study period, we hypothesize that there is a turnover of excitatory synapses following repetitive concussion that can be compensated for, anatomically but not behaviorally.

Determinants of symptom presentation and resolution following concussions in high school sports

Sport-related concussions (SRCs) are prevalent in high school (HS) sports, though the determinants of, and relationships between concussion symptoms in this population remain relatively unknown. We analysed SRC data captured within the HS RIO injury surveillance system during 2014/15-2018/19. We used Generalized Estimating Equations to simultaneously assess covariate predictors of symptom presentations and identify pairwise symptom associations and employed multivariable ordinal logistic regressions to determine symptom resolution time (SRT) predictors. Among the 8,969 concussions assessed, headaches (94.3%) and dizziness (73.3%) were the most prevalently reported symptoms. In 5,953 boys' concussion assessed, class year, event type and injury mechanism emerged as determinants of various concussion symptoms, while in 3,016 girls' concussions assessed, class year, event type, injury mechanism, and sport type emerged as significant symptom determinants. In both groups, difficulty concentrating, sensitivity to light, sensitivity to noise, and disorientation were symptoms with the strongest associations with other symptoms. Odds of longer SRT were higher with greater endorsement (i.e. counts) of the subset of symptoms with strongest cross-domain associations (ORadj. = 1.35; 95% CI = [1.30, 1.40]). Our findings provide valuable information for informing sideline and follow-up clinical concussion assessment algorithms in high school athletes.

Position comparison of sport-related concussions in female youth soccer players

OBJECTIVES

Youth soccer participation, particularly among females, continues to grow worldwide. With the high incidence of sport-related concussion (SRC) in soccer, it is important to investigate if SRC occurs disproportionally by positions. Our hypothesis was to see no positional differences in SRCs, SRC-related characteristics, and outcomes among in female youth soccer athletes.

METHODS

Data were prospectively collected from participants at a single sports medicine institution between August 2015-April 2021. Female participants aged 8-18 diagnosed with SRC sustained during an organized soccer practice, scrimmage, or game were separated into 4 groups based on position: Forward, Midfielder, Defender, and Goalkeeper. Demographics, medical history, injury-related details, and outcomes were reviewed. A chi-square test or Fisher's exact test was used for categorical variables. Continuous variables were compared with Mann-Whitney or Kruskal-Wallis test.

RESULTS

Two hundred fourteen participants were included: 52 Forwards, 65 Midfielders, 63 Defenders, and 34 Goalkeepers. There were no significant differences between the groups in age, race, ethnicity, or previous concussion history. Differences in mechanism existed with Goalkeepers most commonly reporting Head to Body Part. Goalkeepers, which make up 1/11 of the total positions on the field, had a significantly higher proportion of SRCs compared to Field Positions. (9.1% vs 15.9%)At 3-month post-enrollment, there were no significant differences in reported symptoms or return-to-play between the different positions.

CONCLUSION

In youth female soccer players, goalkeepers sustained a higher proportion of sport-related concussions compared to field players based upon the composition of a soccer team. The mechanism of injury also differed among the different soccer positions. However, no differences in concussion characteristics, outcomes, or RTP were seen across the different soccer positions.

Concussion Symptomatology by Symptom Resolution Time in US High School Athletes: Findings From the National Athletic Treatment, Injury and Outcomes Network High School Surveillance Program (NATION-SP)

CONTEXT

Concussions incurred during high school athletics are a significant health concern, and studies examining concussions with a symptom resolution time (SRT) of 15 to 28 days have been limited.

OBJECTIVE

To compare concussions that had an SRT of 15 to 28 days with concussions that had an SRT of greater than 28 days among US high school athletes.

DESIGN

Descriptive epidemiology study.

SETTING

Secondary school athletic training clinics.

PATIENTS OR OTHER PARTICIPANTS

Secondary school athletes.

MAIN OUTCOME MEASURE(S)

Concussion frequency, symptom number, and symptom prevalence.

RESULTS

Among all 917 reported concussions (of which 50.8% had missing SRT), 88 had an SRT recorded as 15 to 28 days, and 29 had an SRT recorded as greater than 28 days. Greater frequencies of concussions with an SRT of 15 days or more were reported in boys' sports (n = 78) than girls' sports (n = 39). Boys' football (51.7%) and girls' basketball (11.5%) accounted for the largest proportions of all reported concussions with an SRT of 15 to 28 days; boys' football (58.6%) accounted for the greatest proportion of concussions reported with an SRT greater than 28 days. The average number of symptoms was 6.3 ± 3.4 for concussions with an SRT of 15 to 28 days and 7.2 ± 3.8 for those with an SRT greater than 28 days. The most frequently reported symptoms in concussions with both SRT of 15 to 28 days and greater than 28 days were headache, dizziness, sensitivity to light, and difficulty concentrating. The prevalence of irritability was higher in concussions with an SRT of 15 to 28 days as compared with concussions with an SRT greater than 28 days (26.1% versus 13.8%); visual problems (48.3% versus 35.2%) and hyperexcitability (24.1% versus 15.9%) were more prevalent in concussions with an SRT greater than 28 days, although differences were not statistically significant.

CONCLUSIONS

Symptom prevalence and total count were comparable between concussions with an SRT of 15 to 28 days and those with an SRT of greater than 28 days with no statistically significant difference, suggesting that symptom burdens within these groups are more similar than they are different.

Qualitative data on triggers and coping of sensory hypersensitivity in acquired brain injury patients: A proposed model

Sensory hypersensitivity (SHS) is a frequently heard complaint after acquired brain injury (ABI) and is related to reduced quality of life and physical and mental health. This study aimed to identify triggers for SHS after ABI and investigate how individuals cope with SHS. Nineteen adults with ABI took part in 45-min individual interviews. Data were audio-recorded and transcribed verbatim. Inductive thematic analysis revealed five themes: (1) A mismatch between resources and demands, (2) Altered experience of ordinary stimuli, (3) It affects all aspects of living, (4) Avoid, approach, accept, (5) It's highly heterogeneous. A model explaining the impact of triggers on subjective SHS after ABI is proposed, which states that SHS arises from a mismatch between the demands of a sensory environment (triggers) and the available biopsychosocial resources of an individual to meet these demands. The elicited SHS can affect and be affected by levels of fatigue, which limits the resources and creates a loop. Coping strategies can act on various stages of this model, i.e., to reduce the mismatch and potentially alter the loop. This model can contribute to the identification of mechanisms behind SHS in ABI patients and other populations, ultimately leading to evidence-based treatments.

Mechanisms of Injury Leading to Concussions in Collegiate Soccer Players: A CARE Consortium Study

BACKGROUND

Few previous studies have investigated how different injury mechanisms leading to sport-related concussion (SRC) in soccer may affect outcomes.

PURPOSE

To describe injury mechanisms and evaluate injury mechanisms as predictors of symptom severity, return to play (RTP) initiation, and unrestricted RTP (URTP) in a cohort of collegiate soccer players.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The Concussion Assessment, Research and Education (CARE) Consortium database was used. The mechanism of injury was categorized into head-to-ball, head-to-head, head-to-body, and head-to-ground/equipment. Baseline/acute injury characteristics-including Sports Concussion Assessment Tool-3 total symptom severity (TSS), loss of consciousness (LOC), and altered mental status (AMS); descriptive data; and recovery (RTP and URTP)-were compared. Multivariable regression and Weibull models were used to assess the predictive value of the mechanism of injury on TSS and RTP/URTP, respectively.

RESULTS

Among 391 soccer SRCs, 32.7% were attributed to a head-to-ball mechanism, 27.9% to a head-to-body mechanism, 21.7% to a head-to-head mechanism, and 17.6% to a head-to-ground/equipment mechanism. Event type was significantly associated with injury mechanism [χ2(3) = 63; P < .001), such that more head-to-ball concussions occurred in practice sessions (n = 92 [51.1%] vs n = 36 [17.1%]) and more head-to-head (n = 65 [30.8%] vs n = 20 [11.1]) and head-to-body (n = 76 [36%] vs n = 33 [18.3%]) concussions occurred in competition. The primary position was significantly associated with injury mechanism [χ2(3) = 24; P < .004], with goalkeepers having no SRCs from the head-to-head mechanism (n = 0 [0%]) and forward players having the least head-to-body mechanism (n = 15 [19.2%]). LOC was also associated with injury mechanism (P = .034), with LOC being most prevalent in head-to-ground/equipment. Finally, AMS was most prevalent in head-to-ball (n = 54 [34.2%]) and head-to-body (n = 48 [30.4%]) mechanisms [χ2(3) = 9; P = .029]. In our multivariable models, the mechanism was not a predictor of TSS or RTP; however, it was associated with URTP (P = .044), with head-to-equipment/ground injuries resulting in the shortest mean number of days (14 ± 9.1 days) to URTP and the head-to-ball mechanism the longest (18.6 ± 21.6 days).

CONCLUSION

The mechanism of injury differed by event type and primary position, and LOC and AMS were different across mechanisms. Even though the mechanism of injury was not a significant predictor of acute symptom burden or time until RTP initiation, those with head-to-equipment/ground injuries spent the shortest time until URTP, and those with head-to-ball injuries had the longest time until URTP.

Patterns and predictors of concussion symptom presentations in NCAA athletes

Sport-related concussion (SRC) is a complex injury, and SRCs are notably prevalent among National Collegiate Athletic Association (NCAA) athletes. We analysed SRCs and associated exposure data collected within the NCAA Injury Surveillance Program during 2014-2019. A total of 1,709 SRCs were reported with complete symptom profiles during the study period (Women's sports n = 499; Men's sports n = 1,210). Event type and academic class year most commonly predicted specific symptom presentations among athletes in men's sports, while symptom presentation among athletes in women's sports was most commonly predicted by class year and sport classification. We observed 78 and 69 significant pairwise symptom dependencies in men's and women's sports athletes, respectively; odds of longer symptom resolution time were higher with greater counts of symptoms with strongest cross-domain associations. Our findings highlight several contextual predictors of specific symptom presentations and identify parsimonious symptom subsets that may indicate protracted recovery among men's and women's sports athletes.

Sensory sensitivity after acquired brain injury: A systematic review

Patients with acquired brain injury frequently report experiencing sensory stimuli as abnormally under- (sensory hyposensitivity) or overwhelming (sensory hypersensitivity). Although they can negatively impact daily functioning, these symptoms are poorly understood. To provide an overview of the current evidence on atypical sensory sensitivity after acquired brain injury, we conducted a systematic literature review. The primary aim of the review was to investigate the behavioural and neural mechanisms that are associated with self-reported sensory sensitivity. Studies were included when they studied sensory sensitivity in acquired brain injury populations, and excluded when they were not written in English, consisted of non-empirical research, did not study human subjects, studied pain, related sensory sensitivity to peripheral injury or studied patients with a neurodegenerative disorder, meningitis, encephalitis or a brain tumour. The Web of Science, PubMed and Scopus databases were searched for appropriate studies. A qualitative synthesis of the results of the 81 studies that were included suggests that abnormal sensory thresholds and a reduced information processing speed are candidate behavioural mechanisms of atypical subjective sensory sensitivity after acquired brain injury. Furthermore, there was evidence for an association between subjective sensory sensitivity and structural grey or white matter abnormalities, and to functional abnormalities in sensory cortices. However, further research is needed to explore the causation of atypical sensory sensitivity. In addition, there is a need for the development of adequate diagnostic tools. This can significantly advance the quantity and quality of research on the prevalence, aetiology, prognosis and treatment of these symptoms.

Association of Sex With Adolescent Soccer Concussion Incidence and Characteristics

Importance

Because of the negative consequences of concussion, considerable research efforts have been directed toward understanding the risk factors for sport-related concussion (SRC) and its outcomes to better inform strategies for risk reduction. Girls are suggested to have an increased risk of concussion, warranting exploration into sex-dependent variations in concussion presentation and management, with the potential that this information might inform sex-specific rules directed toward risk reduction within sports.

Objective

To compare sex-associated differences in epidemiology and concussion management in adolescent soccer players within a prospective, longitudinal high school injury surveillance project.

Design, Setting, and Participants

This prospective, longitudinal cohort study assessed male and female soccer athletes from all high schools in the Michigan High School Athletic Association (MHSAA) during academic years 2016-2017 to 2018-2019.

Exposures

Sport-related concussion captured in the MHSAA Head Injury Reporting System.

Main Outcomes and Measures

Outcomes included details regarding each documented SRC event, including injury mechanism, immediate management, and return-to-play time. Multiple comparisons were made between male and female athletes regarding SRC risk, mechanism, short-term management, and outcomes.

Results

A total of 43 741 male and 39 637 female soccer athletes participated in MHSAA soccer during the 3 consecutive academic years of study (2016-2017: n = 751 schools; 2017-2018: n = 750 schools; and 2018-2019: n = 747 schools). During the 3 years of surveillance, 1507 of the 83 378 soccer athletes (1.8%) were reported to have SRC during soccer participation, including 557 boys (37.0%) and 950 girls (63.0%). Documented SRC risk in female soccer participants was greater than in male soccer participants (risk ratio, 1.88; 95% CI, 1.69-2.09; P < .001). Male soccer athletes most often sustained SRC from contact with another player (48.4%), whereas SRCs in female soccer players recorded in the Head Injury Reporting System were most often from nonplayer contact events (41.9%; P < .001). Adolescent male soccer players with a documented SRC were more likely to be removed from play on the day of injury (odds ratio, 1.54; 95% CI, 1.15-2.06; P = .004). Although the overall median time to return to play was 11 days (interquartile range [IQR], 7-15 days), male athletes typically returned 2 days earlier than female athletes (median, 10 [IQR, 7-14] days vs 12 [IQR, 7-16] days; Peto test P < .001).

Conclusions and Relevance

In this cohort study, sex-associated differences were revealed among adolescent soccer athletes in SRC risk, mechanism of injury, immediate management, and outcomes in injuries documented in a statewide injury reporting system. Thus, consideration might be given to sex-specific approaches to participation and concussion management in the sport.

Employing Standardised Methods to Compare Injury Risk Across Seven Youth Team Sports

Injury surveillance systems seek to describe injury risk for a given sport, in order to inform preventative strategies. This often leads to comparisons between studies, although these inferences may be inappropriate, considering the range of methods adopted. This study aimed to describe the injury epidemiology of seven youth sports, enabling valid comparisons of injury risk. Consistent methods were employed across seven sports [male American football, basketball, soccer, rugby league, rugby union; female soccer and rugby union] at a high school in England. A 24-hour time-loss injury definition was adopted. Descriptive statistics and injury incidence (/1000 match-hours) are reported. In total, 322 injuries were sustained by 240 athletes (mean age=17.7±1.0) in 10 273 player-match hours. American football had a significantly greater injury incidence (86/1000 h; 95% CI 61-120) than all sports except female rugby union (54/1000 h; 95% CI 37-76). Concussion was the most common injury (incidence range 0.0-26.7/1000 h), while 59% of injuries occurred via player contact. This study employed standardized data collection methods, allowing valid and reliable comparisons of injury risk between youth sports. This is the first known study to provide epidemiological data for female rugby union, male basketball and American football in an English youth population, enabling the development of preventative strategies.

Understanding Traumatic Brain Injury in Females: A State-of-the-Art Summary and Future Directions

In this report, we identify existing issues and challenges related to research on traumatic brain injury (TBI) in females and provide future directions for research. In 2017, the National Institutes of Health, in partnership with the Center for Neuroscience and Regenerative Medicine and the Defense and Veterans Brain Injury Center, hosted a workshop that focused on the unique challenges facing researchers, clinicians, patients, and other stakeholders regarding TBI in women. The goal of this "Understanding TBI in Women" workshop was to bring together researchers and clinicians to identify knowledge gaps, best practices, and target populations in research on females and/or sex differences within the field of TBI. The workshop, and the current literature, clearly highlighted that females have been underrepresented in TBI studies and clinical trials and have often been excluded (or ovariectomized) in preclinical studies. Such an absence in research on females has led to an incomplete, and perhaps inaccurate, understanding of TBI in females. The presentations and discussions centered on the existing knowledge regarding sex differences in TBI research and how these differences could be incorporated in preclinical and clinical efforts going forward. Now, a little over 2 years later, we summarize the issues and state of the science that emerged from the "Understanding TBI in Women" workshop while incorporating updates where they exist. Overall, despite some progress, there remains an abundance of research focused on males and relatively little explicitly on females.

Microglia dynamics in adolescent traumatic brain injury

Repetitive, mild traumatic brain injuries (RmTBIs) are increasingly common in adolescents and encompass one of the largest neurological health concerns in the world. Adolescence is a critical period for brain development where RmTBIs can substantially impact neurodevelopmental trajectories and life-long neurological health. Our current understanding of RmTBI pathophysiology suggests key roles for neuroinflammation in negatively regulating neural health and function. Microglia, the brain’s resident immune population, play important roles in brain development by regulating neuronal number, and synapse formation and elimination. In response to injury, microglia activate to inflammatory phenotypes that may detract from these normal homeostatic, physiological, and developmental roles. To date, however, little is known regarding the impact of RmTBIs on microglia function during adolescent brain development. This review details key concepts surrounding RmTBI pathophysiology, adolescent brain development, and microglia dynamics in the developing brain and in response to injury, in an effort to formulate a hypothesis on how the intersection of these processes may modify long-term trajectories.

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.

Sports- or Physical Activity-Related Concussions and Feelings of Sadness or Hopelessness Among U.S. High School Students: Results From the 2017 Youth Behavior Risk Survey

For this study, we explored the association between high school students' reported history of sport- or physical activity-related concussions and persistent feelings of sadness or hopelessness. Data from the 2017 national Youth Risk Behavior Survey (YRBS; N = 14,765) was used for this analysis. YRBS is administered to high school students throughout the country every 2 years. Findings from this study demonstrate that the prevalence of persistent feelings of sadness or hopelessness was 36.4% among students who reported sustaining one or more concussions. Compared to students who did not report having sustained a concussion, the odds of persistent feelings of sadness or hopelessness were significantly higher among students who had sustained one or more concussions (AOR = 1.41). These findings support the need for continued efforts by school nurses and other health care providers to identify students with a history of concussion and assess their mental health needs.

Sex-Related Differences in the Effects of Sports-Related Concussion: A Review

Sports-related concussion is a serious health challenge, and females are at higher risk of sustaining a sports-related concussion compared to males. Although there are many studies that investigate outcomes following concussion, females remain an understudied population, despite representing a large proportion of the organized sports community. In this review, we provide a summary of studies that investigate sex-related differences in outcome following sports-related concussion. Moreover, we provide an introduction to the methods used to study sex-related differences after sports-related concussion, including common clinical and cognitive measures, neuroimaging techniques, as well as biomarkers. A literature search inclusive of articles published to March 2020 was performed using PubMed. The studies were reviewed and discussed with regard to the methods used. Findings from these studies remain mixed with regard to the effect of sex on clinical symptoms, concussion-related alterations in brain structure and function, and recovery trajectories. Nonetheless, there is initial evidence to suggest that sex-related differences following concussion are important to consider in efforts to develop objective biomarkers for the diagnosis and prognosis of concussion. Additional studies on this topic are, however, clearly needed to improve our understanding of sex-related differences following concussion, as well as to understand their neurobiological underpinnings. Such studies will help pave the way toward more personalized clinical management and treatment of sports-related concussion.

Perceived social norms and concussion-disclosure behaviours among first-year NCAA student-athletes: implications for concussion prevention and education

Timely disclosure and identification of concussion symptoms are essential to proper care. Perceived social norms are a potential driving factor in many health-related decisions. The study purpose was to describe concussion disclosure behaviours and identify the association between perceived social norms and these disclosure behaviours. First-year student-athletes (n = 391) at two NCAA institutions completed a cross-sectional survey about concussion disclosure and disclosure determinants. Log-binomial regression models identified factors associated with concussion disclosure behaviour prevalence for: higher intention to disclose symptoms, disclosed all at time of injury, eventually disclosed all, and never participated with concussion symptoms. More favourable perceived social norms were associated with higher prevalence of intention to disclose (PR = 1.34; 95%CI: 1.18, 1.53) and higher prevalence of never participating in sports with concussion symptoms (PR = 1.50; 95%CI: 1.07, 2.10). Clinicians, coaches, sports administrators, and healthcare practitioners should be mindful of the need to create supportive social environments to improve concussion symptom disclosure.

Does baseline concussion testing aid in identifying future concussion risk?

The purpose was to determine differences in pre-season baseline performance between student-athletes who suffered a future sport-related concussion (fSRC) and those who did not. Collegiate student-athletes (82 fSRC, 82 matched control, age = 18.4 ± 0.8years, height = 172.7 ± 10.3 cm, mass = 80.1 ± 20.9 kg) completed baseline Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT), Balance Error Scoring System (BESS), and Standardized Assessment of Concussion (SAC). Results of the independent t-tests suggested there were no differences between the fSRC and the control groups for ImPACT composite scores (95% confidence intervals, Visual Memory: fSRC 70.4-75.9, Control 73.4-78.5, p = 0.134; Verbal Memory: fSRC 83.8-87.7, Control 85.7-89.9, p = 0.155; Reaction Time: fSRC 0.562-0.591, Control 0.580-0.614, p = 0.071; Visual Motor Speed: fSRC 38.5-41.1, Control 38.2-40.9, p = 0.757), BESS total errors (fSRC 11.3-13.7, Control 11.8-14.4, p = 0.483), or SAC (fSRC 26.6-27.4, Control 26.9-27.6, p = 0.394). Receiver operating characteristic (ROC) areas-under-the-curve were 0.417-0.515. Our findings suggest that baseline concussion assessments cannot be used to predict individuals who may sustain a fSRC.