Progress and Future Directions of the NCAA-DoD Concussion Assessment, Research, and Education (CARE) Consortium and Mind Matters Challenge at the US Service Academies

Assessment of an eye-tracking tool to discriminate between concussed and not concussed professional male rugby players: a cohort study

OBJECTIVES

Concussion is a common injury in rugby union ('rugby') and yet its diagnosis is reliant on clinical judgment. Oculomotor testing could provide an objective measure to assist with concussion diagnosis. NeuroFlex® evaluates oculomotor function using a virtual-reality headset. This study examined differences in NeuroFlex® performance in clinician-diagnosed concussed and not concussed elite male rugby players over three seasons.

METHODS

NeuroFlex® testing was completed alongside 140 head injury assessments (HIAs) in 122 players. The HIA is used for suspected concussion events. Of these 140 HIAs, 100 were eventually diagnosed as concussed, 38 were not concussed (2 were unclear) Eight of the 61 NeuroFlex® metrics were analysed as they were comparable at all time points. These eight metrics, from three oculomotor domains (vestibulo-ocular reflex, smooth pursuit and saccades), were tested for their ability to distinguish between concussed and not concussed players using mean difference / odds ratios and corresponding 95% confidence intervals (CI's). General and generalised linear mixed models, accounting for baseline test performance, were used to determine any meaningful differences in concussed and not concussed players. The diagnostic accuracy of these differences was provided by the area under the receiver operating curve (AUC).

RESULTS

Only one of the eight metrics (number of saccades, smooth pursuit domain) had clear differences in performance between concussed and not concussed players at the HIA during the match (odds ratio: 0.76, 95%CI: 0.54-0.98) and after 48 hours (0.74, 95%CI: 0.52-0.96). However, the direction of this difference was contrary to clinical expectations (concussed performed better than not concussed) and the AUC for this outcome was also poor (0.52).

CONCLUSION

NeuroFlex® was unable to distinguish between concussed and not concussed players in this elite male cohort. Future research could study other cohorts, later time points before return to play, and the tool's role in rehabilitation.

Factors Associated With Return to Activity After Concussion Among Female Service Academy Members: Findings From the NCAA-DoD CARE Consortium

INTRODUCTION

Service academy members are at high risk for concussions as a result of participation in both sports and military-specific training activities. Approximately 17% of active duty service members are female, and they face unique challenges in achieving timely recovery from concussions. Understanding the unique characteristics affecting return to unrestricted activity (RTA) among female service academy members is imperative for the ever-growing proportion of females across the U.S. military. The goal of this analysis was to determine how specific injury and individual characteristics of concussion affect 2 RTA protocol events in female service academy members: time to protocol initiation and time to protocol completion.

MATERIALS AND METHODS

All data were collected as part of the National Collegiate Athletic Association (NCAA) and the DoD Concussion Assessment, Research and Education Consortium. We examined data from female U.S. military service academy members at the 4 U.S. Service Academy sites who sustained a concussion between Fall 2014 and Spring 2020 (N = 752). Return to unrestricted activity protocol initiation time was defined as the time from injury to when cadets were cleared to begin gradual RTA, while RTA protocol completion time was defined as the time from injury to when cadets were cleared to RTA. Multivariable Cox regression analyses were used to determine the effect of 4 characteristics on RTA event times: (1) service academy members' NCAA status (e.g., student athlete), (2) prior history of concussion, (3) reporting time of concussion, and (4) sport-related concussion (SRC) or non-SRC. Because of missing data, 520 cadets were included in the model of RTA protocol initiation and 556 were included in the model of RTA protocol completion. Chi-squared analyses assessed interactions between reporting time, NCAA status, and SRC or non-SRC.

RESULTS

Service academy members who were NCAA athletes (hazard ratio [95% CI](HR [95% CI]): 1.58 [1.32, 1.90]), immediately reported their injury (HR [95% CI]: 1.40 [1.18, 1.67]), or had an SRC (HR [95% CI]: 1.29 [1.08, 1.54]) were significantly more likely to have initiated or completed the RTA protocol on any given day post-concussion compared to those who were not NCAA athletes, delayed reporting their injury, or had a non-SRC, respectively. We observed that among those with SRCs, a greater proportion of NCAA service academy members immediately reported their injury (53.9%) compared to non-NCAA (37.3%, P < .001); there was no difference in the proportion of NCAA and non-NCAA service academy members with non-SRCs who immediately reported their injury (P = .18).

CONCLUSIONS

A greater proportion of female service academy members who sustained SRCs and were NCAA athletes reported their injuries immediately, which was associated with a greater likelihood of RTA protocol initiation and completion on any given day after injury. This may be attributable to easy and timely access to medical personnel (e.g., athletic trainers) or the presence of individuals trained in identifying concussion (e.g., coaches). Future initiatives among female service academy members should include improved access to medical care across a variety of injury settings and education on the importance of early reporting after concussion.

Sex Differences Across Concussion Characteristics in US Service Academy Cadets: A CARE Consortium Study

OBJECTIVE

To describe sex differences in concussion characteristics in US Service Academy cadets.

DESIGN

Descriptive epidemiology study.

SETTING

Four US service academies.

PARTICIPANTS

2209 cadets (n = 867 females, n = 1342 males).

INDEPENDENT VARIABLE

Sex.

OUTCOME MEASURES

Injury proportion ratios (IPR) compared the proportion of injuries by sex (females referent) for injury situation, certainty of diagnosis, prolonged recovery, recurrent injuries, mental status alterations, loss of consciousness (LOC), posttraumatic amnesia (PTA), retrograde amnesia (RGA), motor impairments, delayed symptom presentation, and immediate reporting.

MAIN RESULTS

Concussions from varsity/intercollegiate sports [IPR of 1.73, 95% confidence interval (CI) 1.43-2.10] and intramurals (IPR of 1.53, 95% CI 1.02-2.32) accounted for a larger proportion in males, whereas concussions outside of sport and military activities accounted for a smaller proportion among males (IPR of 0.70, 95% CI 0.58-0.85). The proportion of concussions with prolonged recovery was lower among males (IPR of 0.69, 95% CI 0.60-0.78), while concussions with altered mental status (IPR of 1.23, 95% CI 1.09-1.38), LOC (IPR of 1.67, 95% CI 1.17-2.37), PTA (IPR of 1.94, 95% CI 1.43-2.62), and RGA (IPR of 2.14, 95% CI 1.38-3.31) accounted for a larger proportion among males. A larger proportion of concussions that were immediately reported was observed in males (IPR of 1.15, 95% CI 1.00-2.31). Proportions of other characteristics (e.g., recurrent injuries) were not different between sexes.

CONCLUSIONS

A higher proportion of concussions occurred outside of sport and military training for female cadets, who also displayed proportionally longer recovery times than males, despite males demonstrating a higher proportion of LOC, PTA, and RGA. Possible factors may include different mechanisms of injury outside of sport and military training, different biopsychosocial states associated with sex or injury context, and delayed injury reporting when outside of an observed environment, possibly secondary to perceived stigma about reporting injuries.

Cavitation in blunt impact traumatic brain injury

Traumatic brain injury (TBI) poses a major public health challenge. No proven therapies for the condition exist so protective equipment that prevents or mitigates these injuries plays a critical role in minimizing the societal burden of this condition. Our ability to optimize protective equipment depends on our capacity to relate the mechanics of head impact events to morbidity and mortality. This capacity, in turn, depends on correctly identifying the mechanisms of injury. For several decades, a controversial theory of TBI biomechanics has attributed important classes of injury to cavitation inside the cranial vault during blunt impact. This theory explains counter-intuitive clinical observations, including the coup-contre-coup pattern of injury. However, it is also difficult to validate experimentally in living subjects. Also, blunt impact TBI is a broad term that covers a range of different head impact events, some of which may be better described by cavitation theory than others. This review surveys what has been learned about cavitation through mathematical modeling, physical modeling, and experimentation with living tissues and places it in context with competing theories of blunt injury biomechanics and recent research activity in the field in an attempt to understand what the theory has to offer the next generation of innovators in TBI biomechanics.

Determinants of Intention to Disclose Musculoskeletal Injury in Adolescent Athletes

CONTEXT

Although research indicates that the key to minimizing the effect of musculoskeletal injury, improving care, and mitigating long-term effects is to improve early injury care seeking, little is known about barriers to early musculoskeletal injury disclosure and care seeking.

OBJECTIVE

To identify which determinants predicted sport-related musculoskeletal (MSK) injury disclosure by adolescent athletes.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENTS OR OTHER PARTICIPANTS

A total of 564 adolescent athletes (58% male, age = 15.81 ± 1.8 years).

MAIN OUTCOME MEASURE(S)

Online survey exploring determinants of age, gender, race, socioeconomic status, injury knowledge, attitudes, perceived social norms, and perceived behavioral control surrounding MSK injury disclosure, intention to disclose MSK injury, and actual behavior of disclosing MSK injury.

RESULTS

Of the respondents, 457 (80.2%) reported having sustained ≥1 (mean = 3.2 ± 2.2; range = 1-10) MSK injuries related to sport. Those who endorsed having experienced an MSK injury disclosed not reporting or purposefully hiding 77% of their suspected MSK injuries. Several factors influenced a high intention to disclose MSK injury. Specifically, for each unit increase in total MSK injury knowledge (Exp[β] = 1.061, β=0.054, P = .020, 95% CI = 1.031, 1.221) and attitude (Exp[β] = 1.070, β = 0.064, P < .001, 95% CI = 1.027, 1.115) score, 6% and 7% increases in the likelihood of a high intention to disclose an MSK injury, respectively, were observed. Moreover, for each unit increase in the social norm score (Exp[β] = 1.178, β=0.164, P < .001, 95% CI = 1.119, 1.241), an 18% increase in the likelihood of a high intention to disclose an MSK injury was noted.

CONCLUSIONS

Designing interventions geared toward increasing the knowledge of signs and symptoms of MSK injury, improving attitudes surrounding disclosure, and better understanding the social context of disclosing MSK injuries may improve MSK injury disclosure behavior and reduce the associated social and economic burdens of these injuries.

Association Between Symptom Cluster Endorsement at Initiation of a Graduated Return-to-Activity Protocol and Time to Return to Unrestricted Activity After Concussion in United States Service Academy Cadets

BACKGROUND

The endorsement of symptoms upon initiation of a graduated return-to-activity (GRTA) protocol has been associated with prolonged protocols. It is unclear whether there are specific symptom clusters affecting protocol durations.

PURPOSE

To describe the endorsement of specific concussion symptom clusters at GRTA protocol initiation and examine the association between symptom cluster endorsement and GRTA protocol duration.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This study was conducted among cadets enrolled at 3 US service academies. Participants completed an evaluation upon GRTA protocol initiation. Participants endorsing symptoms were binarized based on 6 symptom clusters (cognitive, emotional, insomnia, physical, sensitivity, and ungrouped). The primary outcome of interest was GRTA protocol duration based on symptom cluster endorsement severity. Prevalence rates were calculated to describe symptom cluster endorsement. Kaplan-Meier survival estimates and univariate and multivariable Cox proportional hazards regression models were calculated for all 6 symptom clusters to estimate GRTA protocol duration while controlling for significant covariates.

RESULTS

Data from 961 concussed participants were analyzed. Of these, 636 participants were asymptomatic upon GRTA protocol initiation. Among the 325 symptomatic participants, the physical symptom cluster (80%) was most endorsed, followed by the cognitive (29%), insomnia (23%), ungrouped (19%), sensitivity (15%), and emotional (9%) clusters. Univariate results revealed a significant association between endorsing cognitive (hazard ratio [HR], 0.79; p = .001), physical (HR, 0.84; p < .001), insomnia (HR, 0.83; p = .013), sensitivity (HR, 0.70; p < .001), and ungrouped (HR, 0.75; p = .005) symptom clusters and GRTA protocol duration. Endorsing physical (HR, 0.84; p < .001) and sensitivity (HR, 0.81; p = .036) clusters maintained a significant association with GRTA protocol duration in the multivariable models.

CONCLUSION

Participants endorsing physical or sensitivity symptom clusters displayed GRTA protocols prolonged by 16% to 19% compared with participants not endorsing that respective cluster after controlling for significant covariates.

Risk of Upper Extremity Musculoskeletal Injury Within the First Year After a Concussion

Background

Emerging evidence suggests that athletes and military personnel are at increased risk for lower extremity musculoskeletal injury after a concussion; however, the association between concussion and subsequent upper extremity (UE) musculoskeletal injury is unknown.

Purpose

To prospectively examine the association between concussion and UE musculoskeletal injury risk within the first year after returning to unrestricted activity.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 316 cases of concussion 42% (132/316 women) were observed among 5660 Concussion Assessment, Research and Education Consortium participants at the United States Military Academy from May 2015 to June 2018. Active injury surveillance within the cohort was conducted for 12 months after unrestricted return to activity to identify any incident cases of acute UE musculoskeletal injury. Injury surveillance during the follow-up period was also conducted for nonconcussed controls who were matched by sex and competitive sport level. Univariate and multivariable Cox proportional hazards regression models were used to estimate hazard ratios between concussed cases and nonconcussed controls for time to UE musculoskeletal injury.

Results

During the surveillance period, 19.3% of concussed cases and 9.2% of nonconcussed controls sustained a UE injury. In the univariate model, concussed cases were 2.25 times (95% CI, 1.45-3.51) more likely to sustain a UE injury during the 12-month follow-up period when compared with the nonconcussed controls. In the multivariable model, adjusted for history of concussion, sport level, somatization, and history of UE injury, concussed cases were 1.84 times (95% CI, 1.10-3.07) more likely to sustain a UE injury during the surveillance period compared with nonconcussed controls. Sport level remained an independent risk factor for UE musculoskeletal injury; however, concussion history, somatization, and history of UE injury were not independent risk factors.

Conclusion

Concussed cases were more than twice as likely to sustain an acute UE musculoskeletal injury within the first 12 months after unrestricted return to activity when compared with nonconcussed controls. The higher hazard of injury remained in the concussed group after adjusting for other potential risk factors.

Association Between Symptom Burden at Initiation of a Graduated Return to Activity Protocol and Time to Return to Unrestricted Activity After Concussion in Service Academy Cadets

BACKGROUND

Current consensus and position statements recommend that concussed patients be asymptomatic upon the initiation of the graduated return to activity (RTA) protocol. However, a significant number of concussed patients are beginning their RTA protocols while endorsing symptoms.

PURPOSE

To characterize symptom endorsement at the beginning of the RTA protocol and examine the association between symptom endorsement and RTA protocol duration in service academy cadets.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A prospective cohort study was conducted with cadets at 3 US service academies. Postconcussion symptom inventories were recorded upon the initiation of an RTA protocol. The Sport Concussion Assessment Tool Symptom Inventory was used to classify participants into 3 groups (0 symptoms, 1 symptom, and ≥2 symptoms) upon the initiation of the RTA protocol. The primary outcome of interest was RTA protocol duration. Kaplan-Meier survival estimates were calculated to estimate RTA protocol duration by symptom endorsement, sex, varsity status, academic break, and time to graduated RTA initiation. Univariate and multivariable Cox proportional hazards models were used to estimate the association between symptom endorsement at the initiation of the RTA protocol and RTA protocol duration (α < .05).

RESULTS

Data were analyzed from 966 concussed cadets (36% women). Headache (42%) and faintness/dizziness (44%) were the most commonly endorsed symptoms on the Sport Concussion Assessment Tool-Third Edition and the Brief Symptom Inventory-18, respectively. Univariate results revealed a significant association between endorsing ≥2 symptoms and RTA protocol duration. In the multivariable model, endorsing ≥2 symptoms maintained a statistically significant association with RTA protocol duration. Significant associations were observed between RTA protocol duration and nonvarsity status (27% longer), women (15% longer), academic breaks (70% longer), and time to the initiation of the RTA protocol (1.1% longer daily incremental increase) after controlling for covariates.

CONCLUSION

Symptom endorsement at the initiation of an RTA protocol was associated with RTA protocol duration. Cadets who had returned to preinjury baseline symptom burden or improved from baseline symptom burden and endorsed ≥2 symptoms at the initiation of the RTA protocol took longer to RTA.