Characteristics of Pediatric Concussion across Different Mechanisms of Injury in 5 through 12-Year-Olds.

OBJECTIVE: To investigate characteristics of sport-related concussion (SRC), recreation-related concussion (RRC), and non-sport or recreation-related concussion (non-SRRC) in patients 5 through 12 years old, an understudied population in youth concussion. STUDY DESIGN: This retrospective, observational study included patients aged 5 through 12 years presenting to a specialty care concussion setting at ≤28 days post-injury form 2018 through 2022. The following characteristics were assessed: demographics, injury mechanism (SRC, RRC, or SRRC), point of healthcare entry, and clinical signs and symptoms. Kruskal-Wallis and chi-square tests were used to assess group differences. Post hoc pairwise comparisons were employed for all analyses (α=0.017). RESULTS: 1,141 patients reported at ≤28 days of injury (female=42.9%, median age=11, IQR=9-12) with the most common mechanism being RRC (37.3%), followed by non-SRRC (31.9%). More non-SRRCs (39.6%) and RRC (35.7%) were first seen in the emergency department (p<0.001) compared with SRC (27.9%). Patients with RRC and non-SRRC were first evaluated at specialists 4 and 6 days later than SRC (p<0.001). Patients with non-SRRC reported with higher symptom burden, more frequent visio-vestibular abnormalities, and more changes to sleep and daily habits (p<0.001) compared with RRC and SRC (p<0.001). CONCLUSIONS: In concussion patients 5 through 12 years, RRCs and non-SRRC were more prevalent than SRC, presenting first more commonly to the emergency department and taking longer to present to specialists. Non-SRRC had more severe clinical features. RRC and non-SRRC are distinct from SRC in potential for less supervision at time of injury and less direct access to established concussion health care following injury.

Menstrual Cycle Patterns After Concussion in Adolescent Patients.

OBJECTIVE: To describe menstrual cycle patterns in adolescents with concussion and investigate whether menstrual cycle phase at injury influenced postconcussion cycle pattern changes or concussion symptoms. STUDY DESIGN: Data were collected prospectively from patients aged 13-18 years presenting to a specialty care concussion clinic for an initial visit (≤28 days postconcussion) and, if clinically indicated, at a follow-up visit 3-4 months postinjury. Primary outcomes included menstrual cycle pattern change since injury (change/no change), menstrual cycle phase at time of injury (calculated using date of last period before injury), and symptom endorsement and severity, measured by Post-Concussion Symptom Inventory (PCSI). Fisher exact tests were used to determine the association between menstrual phase at injury and change in cycle pattern. Multiple linear regression was used to determine whether menstrual phase at injury was associated with PCSI endorsement and symptom severity, adjusting for age. RESULTS: Five hundred twelve postmenarchal adolescents were enrolled (age 15.2 ± 1.4 years), with 111 (21.7%) returning for follow-up at 3-4 months. Menstrual pattern change was reported by 4% of patients at initial visit and 10.8% of patients at follow-up. At 3-4 months, menstrual phase at injury was not associated with menstrual cycle changes (P = .40) but was associated with endorsement of concussion symptoms on the PCSI (P = .01). CONCLUSIONS: At 3-4 months' postconcussion, 1 in 10 adolescents experienced a change in menses. Menstrual cycle phase at injury was associated with postconcussion symptom endorsement. Leveraging a large sample of postconcussion menstrual patterns, this study represents foundational data regarding potential menstrual cycle effects of concussion in female adolescents.

Researcher degrees of freedom in statistical software contribute to unreliable results: A comparison of nonparametric analyses conducted in SPSS, SAS, Stata, and R.

Researcher degrees of freedom can affect the results of hypothesis tests and consequently, the conclusions drawn from the data. Previous research has documented variability in accuracy, speed, and documentation of output across various statistical software packages. In the current investigation, we conducted Pearson's chi-square test of independence, Spearman's rank-ordered correlation, Kruskal-Wallis one-way analysis of variance, Wilcoxon Mann-Whitney U rank-sum tests, and Wilcoxon signed-rank tests, along with estimates of skewness and kurtosis, on large, medium, and small samples of real and simulated data in SPSS, SAS, Stata, and R and compared the results with those obtained through hand calculation using the raw computational formulas. Multiple inconsistencies were found in the results produced between statistical packages due to algorithmic variation, computational error, and statistical output. The most notable inconsistencies were due to algorithmic variations in the computation of Pearson's chi-square test conducted on 2 × 2 tables, where differences in p-values reported by different software packages ranged from .005 to .162, largely as a function of sample size. We discuss how such inconsistencies may influence the conclusions drawn from the results of statistical analyses depending on the statistical software used, and we urge researchers to analyze their data across multiple packages to check for inconsistencies and report details regarding the statistical procedure used for data analysis.

The relationship between resilience and neurophysiological stress in Special Operations Forces combat service members.

Military resilience research is increasing due to the growing literature associating resilience with stress adaptation. This study aimed to investigate which physiological stress adaptation components were associated with resilience in Special Operations Forces combat service members. Special Operations Forces combat service members (n = 117) self-reported resilience (ER89) and lifetime clinician-confirmed mild traumatic brain injury history. Participants also underwent transcranial Doppler ultrasonography to measure middle cerebral artery velocity during rest and a breath-holding task. Neither resilience nor mild traumatic brain injury history was significantly associated with middle cerebral artery velocity percent increase following breath-holding; younger Special Operations Forces combat service members had a higher percent increase in middle cerebral artery velocity following a breath-holding task. Resilience was negatively associated with time to return to baseline middle cerebral artery velocity following peak velocity; whereas, mild traumatic brain injury history did not have a significant association. The Special Operations Forces combat service members that scored higher in resilience tended to return to baseline middle cerebral artery velocity following peak velocity faster than their less resilient counterparts. More resilient Special Operations Forces combat service members recovered faster from physiological stress (breath-holding) than less resilient counterparts. This is the first study to investigate resilience and cerebrovascular stress response and recovery in this population. Our initial findings indicated that the Ego Resiliency Scale may be an optimal resilience psychometric and should be used to evaluate effective military resilience trainings, which aim to improve performance and mental health.

Neurovascular Coupling in Acutely Concussed Adolescent Patients.

Neurovascular coupling (NVC) uniquely describes cerebrovascular response to neural activation and has demonstrated impairments following concussion in adult patients. It is currently unclear how adolescent patients experience impaired NVC acutely following concussion during this dynamic phase of physiological development. The purpose of this study was to investigate NVC in acutely concussed adolescent patients relative to controls. We recruited patients presenting to a sports medicine practice within 28 days of a concussion or a musculoskeletal injury (controls). Transcranial Doppler ultrasound was used to measure changes in patients' posterior cerebral artery (PCA) velocity in response to two progressively challenging visual tasks: (1) reading and (2) visual search. Each task was presented in five 1-min trials (20 sec eyes closed/40 sec eyes open). Resting PCA velocity data were derived by averaging PCA velocity across a 2-min baseline period that preceded the visual tasks. Filtered task data were converted to time-series curves representing 40 consecutive 1-sec averages for each trial. Curves were then averaged across the five trials and time-aligned to stimulus onset (eyes open) to generate a single ensemble-averaged 40-sec curve representing NVC response for each participant for each task. Independent t tests were used to assess group differences (concussion vs. control) in resting PCA velocity. Separate linear mixed-effects models were used to evaluate group differences (concussion vs. control) in NVC response profiles for both visual tasks and group-by-task interaction. Twenty-one concussion patients (female = 8 [38.1%]; age = 14.4 ± 1.9 years) and 20 controls (female = 7 [35.0%]; age = 14.4 ± 1.9 years) were included in our analysis. Average resting PCA velocity did not significantly differ between concussion patients (36.6 ± 8.0 cm/sec) and controls (39.3 ± 8.5 cm/sec) (t39 = 1.06; p = 0.30). There were no significant group differences in relative NVC response curves during the reading task (F1,1560 = 2.23; p = 0.14) or the visual search task (F1,1521 = 2.04; p = 0.15). In contrast, the differential response to task (e.g., increase from reading task to visual search task) was significantly greater in concussion patients than in controls (p < 0.0001). The NVC response to the visual search task was 7.1% higher than the response to reading in concussion patients relative to being 5.5% higher in controls. Our data indicate that concussed patients present with a significantly greater response to more difficult tasks than do controls, suggesting that concussed adolescents require increased neural resource allocation as task difficulty increases. The study provides insight into the neurophysiological consequences of concussion in adolescent patients.

Postinjury Outcomes After Non-Sport-Related Concussion: A CARE Consortium Study.

CONTEXT: Concussion research has primarily focused on sport-related mechanisms and excluded non-sport-related mechanisms. In adult populations, non-sport-related concussions (non-SRCs) demonstrated worse clinical outcomes compared with sport-related concussions (SRCs); however, investigations of non-SRCs in college-aged patients are limited. OBJECTIVES: To examine clinical outcomes in collegiate athletes with non-SRCs compared with SRCs and explore sex differences in outcomes among collegiate athletes with non-SRCs. DESIGN: Prospective cohort study. SETTING: Clinical setting. PATIENTS OR OTHER PARTICIPANTS: A total of 3500 athletes were included (n = 555 with non-SRCs, 42.5% female) from colleges or universities and service academies participating in the National Collegiate Athletic Association Department of Defense Concussion Assessment, Research and Education (CARE) Consortium. MAIN OUTCOME MEASURE(S): Dichotomous outcomes (yes or no) consisted of immediate reporting, mental status alterations, loss of consciousness, posttraumatic amnesia, retrograde amnesia, motor impairments, delayed symptom presentation, and required hospital transport. Continuous outcomes were symptom severity, days with concussion symptoms, and days lost to injury. Data were collected within 24 to 48 hours of injury and at return to play. Adjusted relative risks (ARRs) compared the likelihood of dichotomous outcomes by mechanism and by sex within patients with non-SRCs. Multivariate negative binomial regressions were used to assess group differences in continuous variables. RESULTS: Athletes with non-SRCs were less likely to report immediately (ARR = 0.73, 95% CI = 0.65, 0.81) and more likely to report delayed symptom presentation (ARR = 1.17, 95% CI = 1.03, 1.32), loss of consciousness (ARR = 3.15, 95% CI = 2.32, 4.28), retrograde amnesia (ARR = 1.77, 95% CI = 1.22, 2.57), and motor impairment (ARR = 1.45, 95% CI = 1.14, 1.84). Athletes with non-SRCs described greater symptom severity, more symptomatic days, and more days lost to injury (P < .001) compared with those who had SRCs. Within the non-SRC group, female athletes indicated greater symptom severity, more symptomatic days, and more days lost to injury (P < .03) than male athletes. CONCLUSIONS: Athletes with non-SRCs had worse postinjury outcomes compared with those who had SRCs, and female athletes with non-SRCs had worse recovery metrics than male athletes. Our findings suggest that further investigation of individuals with non-SRCs is needed to improve concussion reporting and management.

The effect of a home exercise program on visio-vestibular function in concussed pediatric patients.

Background: A visio-vestibular home exercise program (VV-HEP) can provide an equitable and cost-effective method for therapy targeted towards visio-vestibular deficits that are common following concussion. The effects of a VV-HEP on improving concussion symptoms and visio-vestibular function are unclear. Purpose: Determine the effect of VV-HEP on symptoms and visio-vestibular function in concussed pediatric patients. Methods: This study included 527 patients [294 female (55.8%); age = 14.4 ± 2.1 years] reporting to a specialty care concussion center within 28 days of injury and for a first follow-up within 60 days of injury. Patients completed the Post-Concussion Symptom Inventory (PCSI) and Visio-Vestibular Examination (VVE). Patients were prescribed the VV-HEP at initial visit, with exercises including saccades, gaze stability, convergence, and balance, and instructed to complete these 1-2 times/day. At follow-up, patients self-reported their VV-HEP progress as (1) has not done, (2) in progress, or (3) completed. Primary outcomes included VV-HEP progress at follow-up, PCSI endorsement and severity, VVE subtests (normal/abnormal), and total VVE score (abnormal = 2 + abnormal subtests). Kruskal-Wallis tests and chi-square were used to determine if concussion symptoms or the proportion of abnormal VVE outcomes, respectively, were associated with VV-HEP status. Post-hoc pairwise comparisons with Bonferonni corrections were used to determine concussion symptom (α = 0.017 a priori) and VVE (α = 0.005 a priori) differences in VV-HEP status. Results: At follow-up, patients who had completed the VV-HEP reported lower symptom endorsement (median = 1, IQR = 0-3) and lower symptom severity (median = 1, IQR = 0-4) relative to patients who had not started the VV-HEP (endorsement median = 7, IQR = 1-13, p < 0.0001; severity median = 15.5, IQR = 2-32.5, p < 0.0001) and those in progress (endorsement median = 8, IQR = 3-14, p < 0.0001; severity median = 15, IQR = 4-30, p < 0.0001). A lower proportion of patients who completed the VV-HEP reported with abnormal vestibular-ocular reflex (22.2%), tandem gait (0%), and total VVE score (22.2%) relative to those who had not started or those in progress (p < 0.005). Conclusion: Our findings indicate that patients who completed the VV-HEP had lower symptom burden and improved visio-vestibular function relative to those who did not start or were in progress. This suggests that a VV-HEP can effectively reduce visio-vestibular dysfunction following concussion and may serve as a means to minimize inequities in access to care.

Sex Differences in Recovery Trajectories of Assessments for Sport-Related Concussion Among NCAA Athletes: A CARE Consortium Study.

OBJECTIVES: The purpose of this study was to determine sex differences in recovery trajectories of assessments for sport-related concussion using Concussion Assessment, Research and Education (CARE) Consortium data. METHODS: National Collegiate Athletic Association athletes (N = 906; 61% female) from sex-comparable sports completed a pre-season baseline assessment and post-sport-related concussion assessments within 6 h of injury, 24-48 h, when they initiated their return to play progression, when they were cleared for unrestricted return to play, and 6 months post-injury. Assessments included the Standardized Assessment of Concussion, Balance Error Scoring System, Brief Symptom Inventory-18, Immediate Post-concussion Assessment and Cognitive Testing (ImPACT), Sport Concussion Assessment Tool-3 symptom evaluation, Clinical Reaction Time, King-Devick test, Vestibular Ocular Motor Screen, 12-item Short-Form Health Survey, Hospital Anxiety and Depression Scale, and Satisfaction with Life Scale. RESULTS: Only the Vestibular Ocular Motor Screen Total Symptom Score at the 24-48 h timepoint (p = 0.005) was statistically significantly different between sexes. Specifically, female athletes (mean = 60.2, 95% confidence interval [CI] 51.5-70.4) had higher Vestibular Ocular Motor Screen Total Symptom Scores than male athletes (mean = 36.9, 95% CI 27.6-49.3), but this difference resolved by the time of return-to-play initiation (female athletes, mean = 1.8, 95% CI 1.1-2.9; male athletes, mean = 4.1, 95% CI 1.5-10.9). CONCLUSIONS: Sport-related concussion recovery trajectories for most assessments were similar for female and male National Collegiate Athletic Association athletes except for Vestibular Ocular Motor Screen symptoms within 48 h of sport-related concussion, which was greater in female athletes. Female athletes had a greater symptom burden across all timepoints, suggesting that cross-sectional observations may indicate sex differences despite similar recovery trajectories.

Influence of concussion history and age of first concussion on visio-vestibular function.

OBJECTIVES: To assess if abnormalities on visio-vestibular examination (VVE) are associated with concussion history (first vs. repeat) or age of first concussion in acutely concussed adolescents. DESIGN: Cross-sectional. METHODS: Data were queried from the Children's Hospital of Philadelphia Minds Matter concussion registry. Patients aged 14-18 years old presenting for their initial visit to the specialty care concussion program within 28 days of injury were included. Demographics, including age, sex, concussion history, and age of first concussion, were collected before the exam. The VVE consisted of 9 subtests: smooth pursuit, horizontal/vertical saccades and vestibulo-ocular reflex (VOR), binocular convergence, left/right monocular accommodation, and complex tandem gait. Primary outcomes included VVE subtests (normal/abnormal), and total VVE score (abnormal = 2+ abnormal subtests). RESULTS: Among 1051 patients included (female = 604(57.5 %); age = 15.6 ±â€¯1.2; median lifetime concussions = 1 [IQR = 1,3]), 518 had repeat concussion. Controlling for age and sex, first vs. repeat concussion was not associated with any VVE subtest or total score (Total VVE Score RR = 1.35, 99.5%CI = 0.70,2.61). Of those with repeat concussion, 190 had valid age of first concussion data. Controlling for age, sex, and number of lifetime concussions, age of first concussion was not significantly associated with any VVE subtest or total score (Total VVE Score RR = 1.11, 99.5%CI = 0.78,1.57). CONCLUSIONS: Adolescents with concussion history present with similar visio-vestibular function to those with no concussion history. Additionally, clinical effects of early age of first concussion may not be evident in children. This study provides foundational data regarding potential cumulative effects of concussion in younger athletes.

Pre- and post-season visio-vestibular function in healthy adolescent athletes.

OBJECTIVE: To evaluate pre - to post-season differences in individual subtests of the Visio-Vestibular Examination (VVE) in healthy middle and high school athletes. METHODS: This prospective cohort study recruited participants from a private suburban United States secondary school. Participants completed a demographic questionnaire prior to the start of their season. A proxy for head impact exposure was estimated by incorporating previously published head impact frequencies by team and sport. The VVE was completed pre - and post-season and consisted of 9 subtests: smooth pursuit, horizontal/vertical saccades and gaze stability, binocular convergence, left/right monocular accommodation, and complex tandem gait. Generalized estimating equations were employed to assess the relative risk of an abnormal VVE outcome based on testing session (pre - vs. post-season). RESULTS: Participants included middle and high school athletes (n = 115; female = 59 (51.3%); median age at first assessment = 14.9 years, [IQR = 13.6, 16.0]) during 2017/18 - 2019/20 school years. During pre-season testing, accommodation (10.0%) and complex tandem gait (9.2%) had the largest proportion of abnormal outcomes, while smooth pursuits (10.6%) and convergence (9.5%) had the largest proportion of abnormal outcomes post-season. When assessing the effect of testing session on the relative risk of any abnormal VVE subtest, there were no significant findings (P ≥ 0.25). Additionally, there were no significant effects of testing session when adjusting for estimated head impact exposure for any VVE subtest (P ≥ 0.25). CONCLUSIONS: Visio-vestibular function as measured by the VVE does not change from pre - to post-season in otherwise healthy adolescent athletes. Our findings suggest that the VVE may be stable and robust to typical neurodevelopment occurring in this dynamic age group and help inform post-injury interpretation of visio-vestibular impairments.

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 (F1,2946 = 38.69, p < 0.0001) and athletes without a concussion history (F1,2946 = 25.23, p < 0.0001). Older age of first exposure significantly predicted reduced breath-holding CVR response (F1,1560 = 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.

Repetitive Head Impact Exposure and Cerebrovascular Function in Adolescent Athletes.

The purpose of this study was to determine how subconcussive head impact exposure in high school collision sport student-athletes influenced cerebrovascular function. Transcranial Doppler was used to assess pre- to post-season changes in: (1) resting middle (MCA) and posterior cerebral arteries (PCA), (2) cerebrovascular reactivity (CVR) via breath-holding index (BHI), vasomotor reactivity response (VMRr) and overall MCA response curve, and (3) neurovascular coupling (NVC) via NVC response magnitude and overall PCA response curve. Fifty-three high school-aged athletes (age = 15.8 ± 1.2years, height = 175.8 ± 8.1cm, mass = 69.4 ± 13.5kg) were recruited into two groups (collision vs. non-collision sport). All participants completed a pre-season cerebrovascular function assessment. Following a 4- to 5-month window (118.6 ± 12.2 days), 48 athletes from the original sample (age = 16.0 ± 1.2 years, height = 175.5 ± 8.1 cm, mass = 68.6 ± 4.0 kg) repeated the cerebrovascular assessment. There were no group differences in any cerebrovascular measures at pre-season testing (p > 0.05). At post-season testing, collision sport athletes demonstrated greater positive change in BHI (t44 = -2.21, p = 0.03) while non-collision sport athletes demonstrated greater negative change in the NVC response magnitude to the reading task (t44 = 1.98, p = 0.048), and lower overall PCA response curve to the reading task (F1,2710 = 101.54, p < 0.001). All other pre- to post-season change values were non-significant (p > 0.05). Our data indicate that single-season changes in cerebrovascular outcomes may differ between collision and non-collision sport athletes. Although the clinical interpretation is still unclear, our study demonstrates that CVR and NVC assessments may be sensitive to the dynamic cerebrovascular changes occurring in adolescent athletes. Future research should continue to assess these outcomes following both subconcussive head impact exposure and throughout the recovery trajectory following concussion.

Epidemiology of Injuries in National Collegiate Athletic Association Women's Track and Field: 2014-2015 Through 2018-2019.

CONTEXT: Women's track and field events at the National Collegiate Athletic Association level have grown in popularity in recent years, and track and field athletes are vulnerable to a broad range of potential injuries. BACKGROUND: Routine examination of track and field injuries is important for identifying emerging patterns in injury incidence. METHODS: Exposure and injury data collected in the National Collegiate Athletic Association Injury Surveillance Program during the 2014-2015 to 2018-2019 academic years were analyzed. Injury counts, rates, and proportions were used to describe injury characteristics, and injury rate ratios were used to examine differential injury rates. RESULTS: The overall injury rate was 2.20 per 1000 athlete exposures; the competition injury rate was higher than the practice injury rate (injury rate ratio = 1.73; 95% confidence interval = 1.51, 1.97). Hamstring tears (8.9%), medial tibial stress syndrome (5.4%), and lateral ligament complex tears (4.2%) were the most reported injuries. CONCLUSIONS: Given the results of this study, further attention may be directed toward factors associated with noncontact injury risk in the competitions. The changing injury rates of most reported injuries also warrant monitoring post 2018-2019.

Epidemiology of Injuries in National Collegiate Athletic Association Men's Track and Field: 2014-2015 Through 2018-2019.

CONTEXT: College athletes have been competing in championship track and field events since 1921; the numbers of competing teams and participating athletes have expanded considerably. BACKGROUND: Monitoring injuries of men's track and field athletes using surveillance systems is critical in identifying emerging injury-related patterns. METHODS: Exposure and injury data collected in the National Collegiate Athletic Association Injury Surveillance Program during the 2014-2015 through 2018-2019 academic years were analyzed. Injury counts, rates, and proportions were used to describe injury characteristics; injury rate ratios were used to examine differential injury rates. RESULTS: Overall, men's track and field athletes were injured at a rate of 2.37 per 1000 athlete-exposures; injuries occurred at a higher rate during competition compared with practice. Most injuries were to the thigh (26.2%), lower leg (17.3%), or knee (10.7%) and were caused by noncontact (37.2%) or overuse (31.5%) mechanisms. The most reported injury was hamstring tear (14.9%). SUMMARY: The etiologies of thigh and lower-leg injuries warrant further attention in this population. Future researchers should also separately examine injury incidence during indoor and outdoor track and field seasons.

Epidemiology of Injuries in National Collegiate Athletic Association Women's Gymnastics: 2014-2015 Through 2018-2019.

CONTEXT: Women's gymnastics athletes in the National Collegiate Athletic Association (NCAA) constitute a unique population of NCAA athletes given the nature and dynamics of the sport. BACKGROUND: Routine examination of women's gymnastics injuries is important for identifying the evolving burden of injuries in this sport. METHODS: Exposure and injury data collected in the NCAA Injury Surveillance Program during 2014-2015 through 2018-2019 were analyzed. Injury counts, rates, and proportions were used to describe injury characteristics; injury rate ratios were used to examine differential injury rates. RESULTS: The overall injury rate was 8.00 per 1000 athlete-exposures; injury incidence was greater in competitions than in practices (injury rate ratio = 1.84; 95% CI = 1.48, 2.29), though practice injury rates increased during 2015-2016 through 2018-2019. Most injuries were classified as strains (16.5%), sprains (16.4%), and inflammatory conditions (12.3%), with overuse injuries prevalent among practice injuries (22.5%). Concussions (8.4%) were the most commonly reported specific injury. SUMMARY: The increasing trend in practice injury incidence is noteworthy although competition injury rates were higher overall. Findings also suggest that the etiologies of overuse injuries and inflammatory conditions as well as the biomechanical aspects of concussions warrant further attention.

Neurovascular Coupling in Special Operations Forces Combat Soldiers.

The purpose of this study was to investigate how concussion history affects neurovascular coupling in Special Operations Forces (SOF) combat Soldiers. We studied 100 SOF combat Soldiers [age = 33.5 ± 4.3 years; height = 180.4 ± 6.0 cm; 55 (55.0%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to assess neurovascular coupling (NVC) via changes in posterior cerebral artery (PCA) velocity in response to a reading and a visual search task. Baseline TCD data were collected for 2 min. NVC was quantified by the percent change in overall PCA response curves. We employed linear mixed effect models using a linear spline with one knot to assess group differences in percent change observed in the PCA velocity response curves between SOF combat Soldiers with and without a concussion history. Baseline PCA velocity did not significantly differ (t98 = 1.28, p = 0.20) between those with and without concussion history. Relative PCA velocity response curves did not differ between those with and without a concussion history during the reading task (F1,98 = 0.80, p = 0.37) or the visual search task (F1,98 = 0.52, p = 0.47). When assessing only SOF combat Soldiers with a concussion history, differential response to task was significantly greater in those with 3 or more concussions (F1,4341 = 27.24, p < 0.0001) relative to those with 1-2 concussions. Despite no main effect of concussion history on neurovascular coupling response in SOF combat Soldiers, we observed a dose-response based on lifetime concussion incidence. While long-term neurophysiological effects associated with head impact and blast-related injury are currently unknown, assessing NVC response may provide further insight into cerebrovascular function and overall physiological health.

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.

Sex and Sport Differences in College Lacrosse and Soccer Head Impact Biomechanics.

PURPOSE: Sport-related head impact biomechanics research has been male-centric and focused primarily on American football and ice hockey, which do not address popular sports in which both sexes participate. The purpose of this study was to quantify college female and male lacrosse and soccer head impact biomechanics. METHODS: Head impact biomechanics were collected from college lacrosse and soccer players across two Division 1 college athletic programs (96 female athletes, 141 male athletes; age, 19.8 ± 1.3 yr; height, 174.8 ± 9.2 cm; mass, 72.4 ± 11.7 kg). We deployed helmetless head impact measurement devices (X2 Biosystems xPatch) before each event. Peak linear and rotational accelerations were log-transformed for random intercepts general linear mixed models, and subsequently categorized based on impact magnitude for additional categorical analyses. RESULTS: Most linear (69.4%) and rotational (72.3%) head impact accelerations sustained by our study cohort were categorized as mild. On average, male athletes sustained impacts with higher linear accelerations than females (P = 0.04), and lacrosse athletes sustained higher linear acceleration impacts than soccer athletes (P = 0.023). Soccer athletes sustained significantly higher-magnitude impacts during competitions versus practices (linear, P < 0.001, rotational, P < 0.001), whereas lacrosse athletes sustained higher-magnitude impacts during practices versus competition (linear, P < 0.001; rotational, P < 0.001). Male athletes sustained higher accelerations in competitions versus practice (linear, P = 0.004; rotational, P < 0.001), whereas female athletes sustained higher accelerations in practice versus competitions (linear, P < 0.001; rotational, P = 0.02). There were no interactions between sex and sport on impact magnitude. CONCLUSIONS: Male athletes and lacrosse athletes experience higher-magnitude head impacts. Given the limited literature in this area, future research should continue characterizing head impact biomechanics in women's and nonhelmeted sports as well as validate nonhelmeted head impact technologies.

Cerebrovascular Reactivity in Special Operations Forces Combat Soldiers.

The purpose of this study was to investigate how concussion history affects cerebrovascular reactivity (CVR) in Special Operations Forces (SOF) combat soldiers. We studied 104 SOF soldiers [age = 33.5 ± 4.3 years; height = 179.7 ± 6.3 cm; 59 (56.7%) with self-reported concussion history]. We employed transcranial Doppler (TCD) ultrasound to measure middle cerebral artery (MCA) velocity. Baseline TCD data were collected for 2 min. Changes in MCA velocity were measured in response to five breath-holding trials and five hyperventilation trials. Cerebrovascular reactivity was quantified by the breath-holding index (BHI), vasomotor reactivity reserve (VMRr), and percent change in overall response curves. Independent t tests were employed to assess group differences in BHI, and VMRr values. We employed mixed effects models with quadratic mean structures to assess group differences in percent change MCA velocity response curves. There were no significant group differences in BHI (t102 = 0.04, p = 0.97) or VMRr (t102 = -0.33, p = 0.75). There were no group differences in relative MCA velocity response curves during the breath-holding task (F1,5092 = 0.19, p = 0.66) or during the hyperventilation task (F1,5092 = 0.41, p = 0.52) between SOF soldiers with and without a self-reported concussion history. If CVR deficits exist immediately post-concussion, our study suggests that these deficits recover over time in this population. While long-term neurophysiological effects of blast-related injury are currently unknown, assessing CVR response may provide further insight into cerebrovascular function and overall physiological health following blast exposure.

The relationship between neurovascular coupling, vision and sensory performance, and concussion history in Special Operations Forces combat soldiers.

OBJECTIVE: To determine the relationship between neurovascular coupling (NVC), vision and sensory performance in Special Operations Forces (SOF) combat soldiers with and without concussion history. METHODS: We studied 61 SOF combat soldiers (male, age = 33.8 ± 3.7 years, n = 40 with concussion history [Median = 3; range = 1-10+]). We instrumented our participants with transcranial Doppler to quantify NVC response during reading and visual search tasks. All participants completed vision and sensory performance testing (Senaptec Sensory Station). We performed separate multiple regressions to determine if relationships between NVC and vision and sensory performance testing existed while controlling for concussion history, and to investigate the interaction between NVC and concussion history. RESULTS: Those with higher visual search NVC response magnitudes demonstrated significantly worse contrast sensitivity when controlling for concussion history (F1,60=4.57, ß = 0.03, p = .04, R2 = 12.6%). We did not observe any other significant relationships between NVC and visual and sensory performance tests nor did we observe any significant interactions between NVC and concussion history (p > .05). CONCLUSIONS: Heightened NVC response magnitudes are related to reduced contrast sensitivity in SOF combat soldiers. Because concussion history does not impact the relationships between outcomes, these measures may be utilized for performance evaluation at any point in a soldier's career. The lack of relationships between NVC response magnitude and some of the other vision and sensory performance outcomes suggests that implementing NVC assessment may add unique information and enable clinicians to detect physiological deficits that may otherwise go undetected.