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.

Case Characterization and Perceptions of Athletic Trainers Regarding Medical Disqualification Following Concussion.

CONTEXT: Medical disqualification (MDQ) following concussion is a challenging decision clinicians may encounter with little evidence-based guidance. OBJECTIVE: We aimed to 1) describe the MDQ following concussion cases athletic trainers (ATs) have been involved in, 2) describe beliefs about MDQ following concussion, and 3) explore factors that ATs believed should be involved in the MDQ following concussion process. DESIGN: Mixed methods. SETTING: Online cross-sectional survey with follow-up semi-structured interviews. PARTICIPANTS: ATs (n=502) employed at the collegiate setting completed a survey (completion rate=82.3%, n=413/502; male=175, 34.9%; female=235, 46.8%, prefer not to answer=4, 0.8%; no response=88, 17.5%; age=35.3±10.8 years). Twenty participants were also interviewed (males=13, 65.0%; females=7, 35.0%; average age=40.7±11.0years). DATA COLLECTION AND ANALYSIS: Participants completed a cross-sectional survey comprised of three sections of MDQ experience and specific case information, MDQ beliefs, and demographic items. We also interviewed participants that completed the survey and indicated involvement in at least one MDQ following concussion case. We addressed aims 1 and 2 using descriptive statistics and aim 3 with a five-cycle content analysis. RESULTS: Nearly half of respondents had been involved in an MDQ case following concussion (49.0% n=246; not involved=51.0%, n=256). ATs who had been involved in at least one MDQ case had involvement in an average of 2.3±1.9 cases (n=241). Participants often described many factors they believed should influence the MDQ decision including sport type, concussion history and recovery, health-related quality of life, and academic performance. CONCLUSIONS: Our findings highlight that nearly half of participants were involved in an MDQ case following concussion and navigated this process without guidelines. Given this, multiple factors were considered to evaluate the patient's well-being holistically. The number of ATs involved in MDQ cases following concussion and factors that guided this process warrant further research to develop evidence-based recommendations that assist clinicians in these difficult decisions.

The Interval Between Concussions Does Not Influence Time to Asymptomatic or Return to Play: A CARE Consortium Study.

INTRODUCTION: The purpose of this study was to determine if the time interval between two concussive events influences the number of days to asymptomatic status, days to return to play, or performance on common post-concussion assessments following the second concussion. METHODS: Data from 448 collegiate athletes and service academy cadets with two concussions (time between concussions: median 295.0 days [interquartile range: 125.0-438.2]), 40.0% female) were analyzed from Concussion Assessment Research and Education (CARE) Consortium institutions between 2014 and 2020. Days between concussions was the primary predictor variable. Primary outcome measures included time to asymptomatic and time to return to play following the second concussion. Secondary outcome measures included total number of symptoms, total symptom severity, Balance Error Scoring System total score, and Standardized Assessment of Concussion total score within 48 h of their second concussion. RESULTS: Time between concussions did not significantly contribute to the multivariate time to asymptomatic (p = 0.390), time to return to play (p = 0.859), or the secondary outcomes (p-range = 0.165-0.477) models. Time to asymptomatic (p = 0.619) or return to play (p = 0.524) did not differ between same-season and different-season concussions. Sex significantly contributed to the return to play (p = 0.005) multivariate model. Delayed symptom onset and immediate removal from play/competition significantly contributed to the total number of symptoms (p = 0.001, p = 0.014) and symptom severity (p = 0.011, p = 0.022) multivariate models. CONCLUSION: These results suggest that in a population with a large period between injuries, the time between concussions may not be relevant to clinical recovery.

Optimizing Concussion Care Seeking: Connecting Care-Seeking Behaviors and Neurophysiological States Through Blood Biomarkers.

BACKGROUND: Timely and appropriate medical care after concussion presents a difficult public health problem. Concussion identification and treatment rely heavily on self-report, but more than half of concussions go unreported or are reported after a delay. If incomplete self-report increases exposure to harm, blood biomarkers may objectively indicate this neurobiological dysfunction. PURPOSE/HYPOTHESIS: The purpose of this study was to compare postconcussion biomarker levels between individuals with different previous concussion diagnosis statuses and care-seeking statuses. It was hypothesized that individuals with undiagnosed concussions and poorer care seeking would show altered biomarker profiles. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Blood samples were collected from 287 military academy cadets and collegiate athletes diagnosed with concussion in the Advanced Research Core of the Concussion Assessment, Research and Education Consortium. The authors extracted each participant's self-reported previous concussion diagnosis status (no history, all diagnosed, ≥1 undiagnosed) and whether they had delayed or immediate symptom onset, symptom reporting, and removal from activity after the incident concussion. The authors compared the following blood biomarkers associated with neural injury between previous concussion diagnosis status groups and care-seeking groups: glial fibrillary acidic protein, ubiquitin c-terminal hydrolase-L1 (UCH-L1), neurofilament light chain (NF-L), and tau protein, captured at baseline, 24 to 48 hours, asymptomatic, and 7 days after unrestricted return to activity using tests of parallel profiles. RESULTS: The undiagnosed previous concussion group (n = 21) had higher levels of NF-L at 24- to 48-hour and asymptomatic time points relative to all diagnosed (n = 72) or no previous concussion (n = 194) groups. For those with delayed removal from activity (n = 127), UCH-L1 was lower at 7 days after return to activity than that for athletes immediately removed from activity (n = 131). No other biomarker differences were observed. CONCLUSION: Individuals with previous undiagnosed concussions or delayed removal from activity showed some different biomarker levels after concussion and after clinical recovery, despite a lack of baseline differences. This may indicate that poorer care seeking can create neurobiological differences in the concussed brain.

Improving concussion education: do athletic trainer opinions match expert consensus?

CONTEXT: The NCAA-DoD Mind Matters Challenge created "useful and feasible" consensus recommendations to improve concussion care-seeking behavior in collegiate athletes and military cadets. Given athletic trainers' (ATs') role as providers of concussion education and medical care, it is important to understand if they agree with the expert panel that the recommendations are useful and feasible. OBJECTIVE: To describe and compare secondary school (SS) and collegiate setting ATs' perceptions of the utility and feasibility of the NCAA-DoD Mind Matters Challenge recommendations on improving concussion education. DESIGN: Cross-sectional study. SETTING: Electronic survey. PATIENTS OR OTHER PARTICIPANTS: Five hundred and fifteen (515) ATs (age 40.7±12.4, 53.1% female gender) practicing in the SS (60.6%) or collegiate (38.4%) setting. MAIN OUTCOME MEASURE(S): An online survey asked participants about their awareness of the statement followed by 17 pairs of Likert-item questions regarding each recommendation's utility and feasibility with responses ranging from No (1) to Yes (9). Mimicking the consensus process, we defined consensus as a mean rating ≥7.00. We compared utility and feasibility rating responses between SS and collegiate setting participants using Mann-Whitney U tests with ι=.05. RESULTS: Two-thirds (66.6%) of participants were unaware of the consensus statement. Participants felt all recommendations were useful (all means≥7.0); however, 4 recommendations related to collaborating with stakeholders did not meet the feasibility cutoff (mean range=6.66-6.84). SS ATs rated lower feasibility related to educational content (p-value range=.001-.014), providing patient education throughout recovery (p=.002), and promoting peer intervention (p=.019), but higher utility (p=.007) and feasibility (p=.002) for providing parent education compared to collegiate ATs. CONCLUSIONS: The NCAA-DoD Mind Matters Challenge recommendations require further dissemination. ATs rated collaboration with stakeholders as a feasibility barrier. SS ATs require more resources for educational content, messaging, and promoting peer intervention, but find educating athletes' parents more useful and feasible than collegiate ATs.

Trunk and lower extremity biomechanics differ between female athletes with and without a concussion history.

CONTEXT: Athletes with a history of concussion are at a greater risk for lower extremity musculoskeletal injury. Female athletes may be at an even greater risk. Previous landing biomechanics research post-concussion has focused on the lower extremities, but the trunk plays a crucial role as an injury risk factor. OBJECTIVE: To compare lower extremity and trunk biomechanics during jump landing and cutting maneuvers between female athletes with and without a concussion history. DESIGN: Cross-sectional. SETTING: Biomechanics laboratory. PARTICIPANTS: Our study included 26 athletes with (age:19.0±1.3years, BMI:22.6±2.0kg/m2, time since most recent concussion: median=37.5 months [interquartile range (25.0, 65.8)]), and 38 athletes without (age:19.0±1.1years, BMI:22.1±1.8kg/m2) a concussion history. MAIN OUTCOME MEASURES: Peak kinetics (vertical ground reaction force, vertical loading rate, external knee abduction moment, external knee flexion moment) and kinematics (trunk flexion angle, trunk lateral bending angle, dorsiflexion angle, knee flexion angle, knee abduction angle, hip flexion angle) were obtained during the eccentric portion of the task. Separate 2 (group) × 2 (limb) between-within analyses of covariance compared outcomes between groups. We covaried for time since most recent concussion and limb which had a history of musculoskeletal injury. RESULTS: Athletes with a concussion history displayed a greater nondominant knee abduction angle compared to their dominant limb (p=0.010, np2=0.107) and athletes without a concussion history nondominant limb (p=0.023, np2=0.083) during the jump landing. Athletes with a concussion history displayed less trunk lateral bending during cutting compared with athletes without a concussion history (p=0.005, np2=0.126). CONCLUSIONS: Our results indicate landing biomechanics are different between female athletes with and without a concussion history. This may be due to impairments in neuromuscular control post-concussion which may ultimately increase the risk of subsequent lower extremity injury, although further research is warranted given the cross-sectional nature of our study.

Longitudinal Assessment of Postconcussion Driving: Evidence of Acute Driving Impairment.

BACKGROUND: Current medical practices and recommendations largely ignore the safety of postconcussion driving, even though commonly used measures of neurocognition, balance, and vestibulo-ocular function show impairment. PURPOSE: To compare simulated driving between patients with concussion and controls throughout concussion recovery using a case-control design. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 26 concussed and 23 control Division I collegiate athletes completed a driving simulation assessment at 3 time points (within 72 hours, asymptomatic, and return to sport). Cumulative driving simulation outcome variables included total number of collisions, speed exceedances, stop signs missed, lane excursions, total drive time, percentage of time over the speed limit, and percentage of time out of the lane. The mean speed, standard deviation of speed (SDS), lateral lane position, and standard deviation of lateral lane position (SDLP) were examined for each of the 11 drive segments. Outcomes were compared using generalized linear mixed models with random intercepts by participant with Poisson or normal distributions. RESULTS: Within 72 hours of injury, the concussion group committed more lane excursions (median difference, 2; P = .003), exhibited greater SDS while avoiding a child pedestrian crossing the road (Cohen d = 0.73; P = .011), drove ~7 inches (~18 cm) closer to the centerline during a residential left curve (d = 0.90; P = .015), and had greater SDLP while navigating around a car crash compared with controls (d = 0.72; P = .016). When asymptomatic, the concussion group committed fewer speed exceedances (median difference, 2; P = .002) and had lower SDLP while navigating through a traffic light compared with controls (d = 0.60; P = .045). No differences were evident at return to sport. Groups did not differ in total collisions at any time point. CONCLUSION: The concussion group showed more impaired driving patterns within 72 hours of injury, drove more conservatively once asymptomatic, and had similar driving performance at the time they returned fully to sport. Clinicians should consider these findings when discussing driving with patients acutely after concussion. Further research is needed to determine whether on-road collision risk is elevated after concussion.

Cognition Uniquely Influences Dual-Task Tandem Gait Performance Among Athletes With a Concussion History.

BACKGROUND: After a concussion, there are unique associations between static balance and landing with cognition. Previous research has explored these unique correlations, but the factor of time, dual-task, and different motor tasks leave gaps within the literature. The purpose of this study was to determine the associations between cognition and tandem gait performance. HYPOTHESIS: We hypothesized that athletes with a concussion history would display stronger associations compared with athletes without a concussion history between cognition and tandem gait. STUDY DESIGN: Cross-sectional. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 126 athletes without (56.3% female; age, 18.8 ± 1.3 years; height, 176.7 ± 12.3 cm; mass, 74.8 ± 19.0 kg) and 42 athletes with (40.5% female; age, 18.8 ± 1.3 years; height, 179.3 ± 11.9 cm; mass, 81.0 ± 25.1 kg) concussion history participated. Cognitive performance was assessed with CNS Vital Signs. Tandem gait was performed on a 3-meter walkway. Dual-task tandem gait included a concurrent cognitive task of serial subtraction, reciting months backward, or spelling words backward. RESULTS: Athletes with a concussion history exhibited a larger number of significant correlations compared with athletes without a concussion history for cognition and dual-task gait time (4 significant correlations: rho-range, -0.377 to 0.358 vs 2 significant correlations: rho, -0.233 to 0.179) and dual-task cost gait time (4 correlations: rho range, -0.344 to 0.392 vs 1 correlation: rho, -0.315). The time between concussion and testing did significantly moderate any associations (P = 0.11-0.63). Athletes with a concussion history displayed better dual-task cost response rate (P = 0.01). There were no other group differences for any cognitive (P = 0.13-0.97) or tandem gait (P = 0.20-0.92) outcomes. CONCLUSION: Athletes with a concussion history display unique correlations between tandem gait and cognition. These correlations are unaffected by the time since concussion. CLINICAL RELEVANCE: These unique correlations may represent shared neural resources between cognition and movement that are only present for athletes with a concussion history. Time does not influence these outcomes, indicating the moderating effect of concussion on the correlations persists long-term after the initial injury.

Preinjury Measures Do Not Predict Future Concussion Among Collegiate Student-Athletes: Findings From the CARE Consortium.

ABSTRACT: This prospective cohort study aimed to determine whether preinjury characteristics and performance on baseline concussion assessments predicted future concussions among collegiate student-athletes. Participant cases (concussed = 2529; control = 30,905) completed preinjury: demographic forms (sport, concussion history, sex), Immediate Post-Concussion Assessment and Cognitive Test, Balance Error Scoring System, Sport Concussion Assessment Tool symptom checklist, Standardized Assessment of Concussion, Brief Symptom Inventory-18 item, Wechsler Test of Adult Reading, and Brief Sensation Seeking Scale. We used machine-learning logistic regressions with area under the curve, sensitivity, and positive predictive values statistics for univariable and multivariable analyses. Primary sport was determined to be the strongest univariable predictor (area under the curve = 64.3% ± 1.4, sensitivity = 1.1% ± 1.4, positive predictive value = 4.9% ± 6.5). The all-predictor multivariable model was the strongest (area under the curve = 68.3% ± 1.6, sensitivity = 20.7% ± 2.7, positive predictive value = 16.5% ± 2.0). Despite a robust sample size and novel analytical approaches, accurate concussion prediction was not achieved regardless of modeling complexity. The strongest positive predictive value (16.5%) indicated only 17 of every 100 individuals flagged would experience a concussion. These findings suggest preinjury characteristics or baseline assessments have negligible utility for predicting subsequent concussion. Researchers, healthcare providers, and sporting organizations therefore should not use preinjury characteristics or baseline assessments for future concussion risk identification at this time.

Special Report from the CDC Healthcare provider influence on driving behavior after a mild traumatic brain injury: Findings from the 2021 SummerStyles survey.

INTRODUCTION: Research shows that a mild traumatic brain injury (mTBI) impairs a person's ability to identify driving hazards 24 h post injury and increases the risk for motor vehicle crash. This study examined the percentage of people who reported driving after their most serious mTBI and whether healthcare provider education influenced this behavior. METHODS: Self-reported data were collected from 4,082 adult respondents in the summer wave of Porter Novelli's 2021 ConsumerStyles survey. Respondents with a driver's license were asked whether they drove right after their most serious mTBI, how safe they felt driving, and whether a doctor or nurse talked to them about when it was ok to drive after their injury. RESULTS: About one in five (18.8 %) respondents reported sustaining an mTBI in their lifetime. Twenty-two percent (22.3 %) of those with a driver's license at the time of their most serious mTBI drove within 24 h, and 20 % felt very or somewhat unsafe doing so. About 19 % of drivers reported that a doctor or nurse talked to them about when it was safe to return to driving. Those who had a healthcare provider talk to them about driving were 66 % less likely to drive a car within 24 h of their most serious mTBI (APR = 0.34, 95 % CI: 0.20, 0.60) compared to those who did not speak to a healthcare provider about driving. CONCLUSIONS: Increasing the number of healthcare providers who discuss safe driving practices after a mTBI may reduce acute post-mTBI driving. PRACTICAL APPLICATIONS: Inclusion of information in patient discharge instructions and prompts for healthcare providers in electronic medical records may help encourage conversations about post-mTBI driving.

Early Exercise is Associated with Faster Concussion Recovery Among Collegiate Athletes: Findings from the NCAA-DoD CARE Consortium.

BACKGROUND: Growing evidence indicates early exercise may improve symptoms and reduce clinical recovery time after concussion, but research examining collegiate student-athletes is scarce. OBJECTIVE: The aim of this study was to compare symptom recovery time, clinical recovery time, and persisting post-concussion symptom (i.e., symptoms ≥ 28 days) prevalence by the timing of light exercise initiation before the graded return to play (RTP) protocol among concussed participants. METHODS: Collegiate student-athletes (n = 1228; age 18.4 ± 0.9 years; 56.5% male, 76.3% division I; 33.7% ≥ 1 prior concussion) across 30 institutions enrolled in the CARE Consortium completed post-concussion assessments and were monitored over time. Symptom recovery (days from injury to symptom resolution) and clinical recovery (days from injury to return to play protocol completion) was determined by the student-athletes' clinicians. Student-athletes were categorized by timing of light exercise initiation. Early (< 2 days post-concussion; n = 161), typical (3-7 days post-concussion; n = 281), and late exercise (≥ 8 days post-concussion; n = 169) groups were compared with the no-exercise group (n = 617; i.e., did not exercise prior to beginning the RTP protocol) for all analyses. Multivariable Cox regression models with hazard ratios (HR) and survival curves and a multivariable binomial regression model with prevalence ratios (PR) compared recovery outcomes between exercise groups while accounting for covariates. RESULTS: Compared to the no-exercise group, the early exercise group was 92% more probable to experience symptom recovery (HR 1.92; 95% CI 1.57-2.36), 88% more probable to reach clinical recovery (HR 1.88; 95% CI 1.55-2.28) and took a median of 2.4 and 3.2 days less to recover, respectively. The late exercise group relative to the no-exercise group was 57% less probable to reach symptom recovery (HR 0.43; 95% CI 0.35-0.53), 46% less probable to achieve clinical recovery (HR 0.54; 95% CI 0.45-0.66) and took 5.3 days and 5.7 days more to recover, respectively. The typical exercise group did not differ in hazard for symptom or clinical recovery (p ≥ 0.329) compared with the no-exercise group. The prevalence of persisting post-concussion symptoms in the combined sample was 6.6%. Early exercise had 4% lower prevalence (PR 0.96, 95% CI 0.94-0.99) and typical exercise had 3% lower prevalence (PR 0.97, 95% CI 0.94-0.99) of persisting post-concussion symptoms, while the late exercise group had an elevated prevalence (PR 1.11, 95% CI 1.04-1.18) compared with the no-exercise group. CONCLUSION: Exercise < 2 days post-concussion was associated with more probable and faster symptom and clinical recovery, and lower persisting post-concussion symptom prevalence. When considering our findings and existing literature, qualified clinicians may implement early exercise into their clinical practice to provide therapeutic treatment and improve student-athlete recovery.

Quantifying head impact biomechanical differences between commonly employed cleaning levels: a critical research interpretation consideration.

INTRODUCTION: Wearable accelerometry devices quantify on-field frequency and severity of head impacts to further improve sport safety. Commonly employed post-data collection cleaning techniques may affect these outcomes. OBJECTIVE: Our purpose was to compare game impact rates and magnitudes between three different cleaning levels (Level-1: impacts recorded within start and end times, Level-2: impacts during pauses/breaks removed, Level-3: video verified) for male youth tackle football. METHODS: Participants (n = 23, age = 10.9 ± 0.3 yrs, height = 150.0 ± 8.3 cm, mass = 41.6 ± 8.4 kg) wore Triax SIM-G sensors throughout Fall 2019. Impact rates, ratios (IRRs), and 95% confidence intervals (95%CI) were used to compare levels. Random-effects general linear models were used to compare peak linear acceleration (PLA;g) and angular velocity (PAV;rads/s). RESULTS: Level-1 resulted in higher impact rates (4.57; 95%CI = 4.14-5.05) compared to Level-2 (3.09; 95%CI = 2.80-3.42; IRR = 1.48; 95%CI = 1.34-1.63) and Level-3 datasets (2.56; 95%CI = 2.30-2.85; IRR = 1.78; 95%CI = 1.60-1.98). Level-2 had higher impact rates compared to Level-3 (1.21; 95%CI = 1.08-1.35). Level-1 resulted in higher PAV than Level-2 and Level-3 (p < 0.001) datasets. PLA did not differ across datasets (p = 0.296). CONCLUSIONS: Head impact data should be filtered of pauses/breaks, and does not substantially differ outcome estimates compared to time-intensive video verification.

Motor vehicle crash concussion mechanism displays a greater total number of symptoms and greater affective symptom severity but no neurocognitive differences compared with sport-related concussion mechanism.

Previous research among adolescents has shown differences in symptoms and neurocognitive performance between sport-related (SRC) and motor vehicle crash (MVC) concussion mechanisms. Limited research has focused on young adults. The purpose of our study was to compare symptoms, balance, and neurocognitive performance between SRC and MVC mechanisms in young adults. Forty-three (58.1% female, age = 25.5 ± 3.2 years, days since concussion = 12.8 ± 12.7) and 26 (76.9% female, age = 24.1 ± 5.6 years, days since concussion = 12.6 ± 8.3) individuals with an SRC and MVC mechanism, respectively, participated. Primary outcome measures included the total number, severity, cluster (disorientation, migraine, lethargy, and affective) of post-concussion symptoms endorsed, Balance Error Scoring System (BESS), and CNS Vital Signs scores. Clusters are subgroups of symptoms used for targeted rehabilitation. We used independent t-tests and Mann-Whitney U tests to compare symptoms, BESS, and neurocognitive performance. Cliff's Delta effect size was interpreted as negligible (<0.15), small (0.15-0.33), medium (0.34-0.47), and large (≥0.48). There were no group differences for any demographic factors or preexisting conditions (p-range = 0.112-0.991). Participants with an MVC mechanism reported a greater number of total post-concussion symptoms (p = 0.025, Cliff's Delta = 0.32) and a more severe affective symptom cluster (p = 0.010, Cliff's Delta = 0.37). There were no group differences for BESS or neurocognitive performance after correcting for multiple comparisons. The MVC mechanism resulted in a greater total symptom burden relative to the SRC mechanism. Medical practitioners and individuals experiencing a concussion should know that concussions are heterogeneous within and across various mechanisms.

Computerized and functional reaction time in varsity-level female collegiate athletes with and without a concussion history.

OBJECTIVES: To 1) determine the association between computerized and functional reaction time, and 2) compare functional reaction times between female athletes with and without a concussion history. DESIGN: Cross-sectional study. METHODS: Twenty female college athletes with concussion history (age = 19.1 ±â€¯1.5 years, height = 166.9 ±â€¯6.7 cm, mass = 62.8 ±â€¯6.9 kg, median total concussion = 1.0 [interquartile range = 1.0, 2.0]), and 28 female college athletes without concussion history (age = 19.1 ±â€¯1.0 years, height = 172.7 ±â€¯8.3 cm, mass = 65.4 ±â€¯8.4 kg). Functional reaction time was assessed during jump landing and dominant and non-dominant limb cutting. Computerized assessments included simple, complex, Stroop, and composite reaction times. Partial correlations investigated the associations between functional and computerized reaction time assessments while covarying for time between computerized and functional reaction time assessments. Analysis of covariance compared functional and computerized reaction time, covarying for time since concussion. RESULTS: There were no significant correlations between functional and computerized reaction time assessments (p-range = 0.318 to 0.999, partial correlation range = -0.149 to 0.072). Reaction time did not differ between groups during any functional (p-range = 0.057 to 0.920) or computerized (p-range = 0.605 to 0.860) reaction time assessments. CONCLUSIONS: Post-concussion reaction time is commonly assessed via computerized measures, but our data suggest computerized reaction time assessments are not characterizing reaction time during sport-like movements in varsity-level female athletes. Future research should investigate confounding factors of functional reaction time.

Investigating post-mild traumatic brain injury neuromuscular function and musculoskeletal injury risk: A protocol for a prospective, observational, case-controlled study in service members and active individuals.

INTRODUCTION: Musculoskeletal injury (MSKI) risk is increased following mild traumatic brain injury (mTBI). Increased MSKI risk is present up to 2 years following post-mTBI return-to-duty/activity relative to both non-mTBI peers and to their pre-mTBI selves across a range of populations, including military service members, and professional, college and high school athletes. Despite the well documented increased post-mTBI MSKI risk, the underlying neuromuscular mechanisms contributing to this increased risk have yet to be definitively determined. A number of potential mechanisms have been suggested (eg, aberrant kinematics, dynamic balance impairments, lower voluntary muscle activation), but none have been confirmed with a comprehensive, prospective study. This study aims to: (1) elucidate the neuromuscular control mechanisms following mTBI that contribute to increased MSKI risk, and (2) prospectively track patient outcomes (up to 12 months; MSKI occurrences and patient-reported outcomes (PRO)). METHODS AND ANALYSIS: This is a multicentre prospective, case-matched control observational study to identify deficiencies in neuromuscular function following mTBI that may contribute to increased MSKI risk. Participants (aim to recruit 148, complete data collection on 124) will be classified into two cohorts; mTBI and control. All participants will undergo longitudinal (initial, 6 weeks post-initial, 12 weeks post-initial) comprehensive three-dimensional biomechanical (jump-landing; single leg hop; cut; gait), neuromuscular (interpolated twitch technique, muscular ramp contraction) and sensory (joint repositioning; light touch sensation) assessments to elucidate the underlying neuromuscular control mechanisms post-mTBI that may contribute to increased MSKI. Occurrences of MSKI and PROs (National Institutes of Health Patient-Reported Outcome Measurement Information System: Physical Function, Pain Interference, Depression, Anxiety; Brief Resilience Scale; Tampa Scale of Kinesiophobia), will be tracked monthly (up to 1 year) via electronic data capture platforms. ETHICS AND DISSEMINATION: The study received approval from the Walter Reed National Military Medical Center Institutional Review Board. Results will be made available to the associated funding agency and other researchers via conference proceedings and journal articles. TRIAL REGISTRATION NUMBER: NCT05122728.

Single-Leg Hop Stabilization Throughout Concussion Recovery: A Preliminary Biomechanical Assessment.

CONTEXT: Aberrant movement patterns among individuals with concussion history have been reported during sport-related movement. However, the acute postconcussion kinematic and kinetic biomechanical movement patterns during a rapid acceleration-deceleration task have not been profiled and leaves their progressive trajectory unknown. Our study aimed to examine single-leg hop stabilization kinematics and kinetics between concussed and healthy-matched controls acutely (≤7 d) and when asymptomatic (≤72 h of symptom resolution). DESIGN: Prospective, cohort laboratory study. METHODS: Ten concussed (60% male; 19.2 [0.9] y; 178.7 [14.0] cm; 71.3 [18.0] kg) and 10 matched controls (60% male; 19.5 [1.2] y; 176.1 [12.6] cm; 71.0 [17.0] kg) completed the single-leg hop stabilization task under single and dual task (subtracting by 6's or 7's) at both time points. Participants stood on a 30-cm tall box set 50% of their height behind force plates while in an athletic stance. A synchronized light was illuminated randomly, queuing participants to initiate the movement as rapidly as possible. Participants then jumped forward, landed on their nondominant leg, and were instructed to reach and maintain stabilization as fast as possible upon ground contact. We used 2 (group) × 2 (time) mixed-model analyses of variance to compare single-leg hop stabilization outcomes separately during single and dual task. RESULTS: We observed a significant main group effect for single-task ankle plantarflexion moment, with greater normalized torque (mean difference = 0.03 N·m/body weight; P = .048, g = 1.18) for concussed individuals across time points. A significant interaction effect for single-task reaction time indicated that concussed individuals had slower performance acutely relative to asymptomatic (mean difference = 0.09 s; P = .015, g = 0.64), while control group performance was stable. No other main or interaction effects for single-leg hop stabilization task metrics were present during single and dual task (P ≥ .051). CONCLUSIONS: Greater ankle plantarflexion torque coupled with slower reaction time may indicate stiff, conservative single-leg hop stabilization performance acutely following concussion. Our findings shed preliminary light on the recovery trajectories of biomechanical alterations following concussion and provide specific kinematic and kinetic focal points for future research.

King-Devick Sensitivity and Specificity to Concussion in Collegiate Athletes.

CONTEXT: The King-Devick (K-D) test is used to identify oculomotor impairment after concussion. However, the diagnostic accuracy of the K-D test over time has not been evaluated. OBJECTIVES: To (1) examine the sensitivity and specificity of the K-D test at 0 to 6 hours postinjury, 24 to 48 hours postinjury, the beginning of a return-to-play (RTP) protocol (asymptomatic), unrestricted RTP, and 6 months postconcussion and (2) compare outcomes between athletes with and those without concussion across confounding factors (sex, age, sport contact level, academic year, learning disorder, attention-deficit/hyperactivity disorder, migraine history, concussion history, and test administration mode). DESIGN: Retrospective, cross-sectional design. SETTING: Multiple institutions in the Concussion Assessment, Research and Education Consortium. PATIENTS OR OTHER PARTICIPANTS: A total of 320 athletes with a concussion (162 men, 158 women; age = 19.80 ± 1.41 years) were compared with 1239 total collegiate athletes without a concussion (646 men, 593 women; age = 20.31 ± 1.18 years). MAIN OUTCOME MEASURE(S): We calculated the K-D test time difference (in seconds) by subtracting the baseline from the most recent time. Receiver operator characteristic (ROC) curve and area under the curve (AUC) analyses were used to determine the diagnostic accuracy across time points. We identified cutoff scores and corresponding specificity at both the 80% and 70% sensitivity levels. We repeated ROC with AUC analyses using confounding factors. RESULTS: The K-D test predicted positive results at the 0- to 6-hour (AUC = 0.724, P < .001), 24- to 48-hour (AUC = 0.701, P < .001), RTP (AUC = 0.640, P < .001), and 6-month postconcussion (AUC = 0.615, P < .001) tim points but not at the asymptomatic time point (AUC = 0.513, P = .497). The 0- to 6-hour and 24- to 48-hour time points yielded 80% sensitivity cutoff scores of -2.6 and -3.2 seconds (ie, faster), respectively, but 46% and 41% specificity, respectively. The K-D test had a better AUC when administered using an iPad (AUC = 0.800, 95% CI = 0.747, 0.854) compared with the spiral-bound card system (AUC = 0.646, 95% CI = 0.600, 0.692; P < .001). CONCLUSIONS: The diagnostic accuracy of the K-D test was greatest at 0 to 6 hours and 24 to 48 hours postconcussion but declined across subsequent postconcussion time points. The AUCs did not differentiate between groups across confounding factors. Our negative cutoff scores indicated that practice effects contributed to improved performance, requiring athletes to outperform their baseline scores.

Association between sports participation history and age of first exposure to high-risk sports with concussion history.

The purpose of this study was to examine the association between sports participation history, including estimated age of first exposure (eAFE) to high-risk sports, and concussion history in first year (i.e., freshmen) collegiate athletes. Athletes increased their odds of sustaining a pre-college concussion by 5% [odds ratio(OR) = 1.05 (95%CI:1.05-1.06)] for each additional year of contact sports participation - 24% of all student athletes reported one or more pre-college concussions. When eAFE was analysed dichotomously at age 12, a greater proportion of those who started playing football before age 12 reported a positive concussion history compared to those who started playing football at age 12 or later (Ð¥2 = 4.483, p = 0.034, Phi = 0.049). When eAFE was analysed continuously, later eAFE to women's high-risk sports was associated with a lower likelihood of sustaining a pre-college concussion [OR = 0.93 (95%CI:0.88-0.98)]. Our findings suggest that there is a relationship between eAFE to football and to women's high-risk sports and concussion history.

Youth Tackle Football Head-Impact Estimation by Players and Parents: Is the Perception the Reality?

CONTEXT: With growing concerns surrounding exposure to head impacts in youth tackle football, players and parents must understand the exposure level when assenting and consenting to participate. OBJECTIVE: To determine whether youth football players and parents could estimate on-field head-impact frequency, severity, and location. DESIGN: Prospective cohort study. SETTING: Football field. PATIENTS OR OTHER PARTICIPANTS: We administered a 10-question head-impact estimation tool to parents (n = 23; mean age = 36.5 years [95% CI = 31.7, 37.3 years]) and players (n = 16 boys; mean age = 11.1 years [95% CI = 10.3, 11.8 years]). MAIN OUTCOME MEASURE(S): Player on-field head-impact exposure was captured using the Triax SIM-G system. We determined the accuracy between player and parent estimates relative to on-field head-impact exposures using κ and weighted κ values. RESULTS: Youth tackle football players and parents did not accurately estimate on-field head-impact frequency (κ range = -0.09 to 0.40), severity (κ range = -0.05 to 0.34), or location (κ range = -0.30 to 0.13). Players and parents overestimated head-impact frequency in practices but underestimated the frequency in games. Both groups overestimated head-impact severity, particularly in games. Most players and parents underestimated the number of head impacts to the top of the head, particularly during practices. CONCLUSIONS: Underestimations of head-impact frequency in games and to the top of the head suggest that informed consent processes aimed at educating players and parents should be improved. Overestimations of head-impact frequency in practices and severity may explain declining rates of youth tackle football participation.