Young age as a modifying factor in sports concussion management: what is the evidence?

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.

Recovery After Sport-Related Concussion in Collegiate Athletes With Self-Reported Pre-Injury Migraines

Pre-injury migraines might be a risk factor for prolonged recovery after sport-related concussion (SRC). We sought to examine whether a pre-injury history of migraines is associated with worse recovery following SRC in collegiate athletes. Data were collected through a prospective concussion surveillance system in 11 National Collegiate Athletic Association (NCAA) Division III college athletic programs between September 2014 and March 2020. Our primary independent variable, pre-injury migraines, were self-reported by the athletes. Between those with and without migraines, the outcomes of days to return-to-learn (RTL) without academic accommodations and return-to-play (RTP) were compared using Mann-Whitney U tests. Each athlete's RTL and RTP status was dichotomized (i.e., returned vs. not returned) at various time points for RTL (i.e., 7/14/21/28 days) and RTP (i.e., 14/21/28/56 days). Chi-squared tests were performed to compare the proportions of RTL and RTP status between groups. Multivariable regressions analyzed potential predictors of RTL and RTP adjusting for age, gender, prior concussions, other health conditions, and symptom severity. Of 1409 athletes with an SRC, 111 (7.9%) had a pre-injury history of migraines. Compared with those without migraines, those with migraines had longer median (interquartile range [IQR]) days to RTL (migraines = 7.0 [3.0-12.3] vs. no migraines = 5.0 [2.0-10.0], U = 53,590.5, p = 0.022). No differences were found in RTP between the two groups (migraines = 16.0 [10.0-33.0] vs. nχo migraines 15.0 [11.0-23.0], U = 38,545.0, p = 0.408). Regarding RTL, significantly lower proportions of athletes in the migraine group had fully RTL, without accommodations, at ≤14 days (77.5% vs. 85.2%, χ2 = 4.33, p = 0.037), ≤21 days (85.3% vs. 93.0%, χ2 = 7.99, p = 0.005), and ≤28 days (88.2% vs. 95.6%, χ2 = 10.60, p = 0.001). Regarding RTP, a significantly lower proportion of athletes in the migraine group RTP at ≤28 days (72.0% vs. 82.7%, χ2 = 5.40, p = 0.020) and ≤56 days (84.0% vs. 93.0%, χ2 = 8.19, p = 0.004). In a multivariable model predicting RTL that was adjusted for age, gender, acute concussion symptoms, and other health variables (e.g., attention-deficit/hyperactivity disorder [ADHD], history of mental health difficulties), pre-injury history of migraine was associated with longer RTL (β = 0.06, p = 0.030). In a multivariable model predicting RTP, pre-injury history of migraine was not associated with RTP (β = 0.04, p = 0.192). In collegiate athletes, pre-injury migraine history was independently associated with longer RTL but not RTP. When comparing the proportions of those with successful RTP by days, significantly lower proportions of those with migraines showed successful RTP at ≤28 days and ≤56 days. Futures studies should study the generalizability of our findings in other school levels.

Systematic Review Examining the Reporting of Race and Ethnicity in Sport-Related Concussion Studies

OBJECTIVE

Sport-related concussion (SRC) is an evolving public health concern among youth athletes. Despite emerging evidence that race and ethnicity are important factors in determining concussion outcomes, studies examining race and ethnicity are limited. We conducted a systematic review to (1) determine the prevalence of SRC studies in which participants' race or ethnicity is reported, (2) describe how race and ethnicity are used within each study, and (3) assess predictive factors for the reporting of race and ethnicity.

DATA SOURCES

PubMed, Embase, PsycINFO, and CINAHL databases.

STUDY SELECTION

Study inclusion criteria were (1) primary and peer-reviewed research; (2) related to the diagnosis, treatment, or recovery of SRC; (3) involving school-aged athletes (ages 5 to 25); and (4) with 25 or more participants. The search was performed in March 2021 and included only studies published after March 2013.

DATA EXTRACTION

For each article, we looked at whether race and ethnicity were reported, and if so, which races or ethnicities were mentioned. For each race or ethnicity mentioned, we extracted the corresponding sample size and how they were used as variables in the study.

DATA SYNTHESIS

Of 4583 studies screened, 854 articles met inclusion criteria. Of the included articles, 132 (15.5%) reported race, and 65 (7.6%) reported ethnicity, whereas 721 (84.4%) reported neither. When examining the demographic characteristics of the 132 studies that reported race, 69.8% of athletes were White. Additionally, 79.5% of these studies used race solely as a demographic descriptor as opposed to a main exposure or covariate of interest. Studies published more recently were more likely to report race. Further, studies in specific study or journal topics and specific geographic locations of the authors were more likely to report race.

CONCLUSIONS

Reporting of race and ethnicity is limited in current SRC literature. Future authors should improve the reporting of race and ethnicity, diversify study samples by focusing on enrolling athletes from underrepresented groups, and consider the potential effect of race and ethnicity as social determinants of health on risk factors, recovery, and long-term sequelae after SRC.

Factors Associated With Additional Clinic Visits in the Treatment of Sports-Related Concussion

OBJECTIVE

To evaluate the variables associated with additional concussion clinic visits before discharge to athletic trainer (AT).

DESIGN

Retrospective cohort study.

SETTING

Multidisciplinary Sports Concussion Center.

PATIENTS

Patients ages 12 to 23 years presenting with a sport-related concussion between January 11, 2017, and January 10, 2020, and were discharged to an AT.

METHODOLOGY

Our main outcome variable was being discharged to AT after the initial clinic visit versus those who attended additional clinic visits before AT discharge. We examined the influence of age, sex, initial visit symptom score, family and personal history of psychiatric disorders and migraines, history of prior concussions, and other variables on this outcome.

RESULTS

Of 524 patients, 236 were discharged to AT after the initial clinic visit, while 288 patients required additional clinic visits. The additional visit group had higher initial visit symptom scores ( P = 0.002), head imaging performed more frequently ( P < 0.02), a family history of psychiatric disorders and/or migraines ( P < 0.001, P < 0.001), more often reported a prior concussion ( P = 0.02), and was younger ( P = 0.014) compared with the one visit group. In a multiple variable model, the family history of psychiatric disorders [odds ratio (OR), 3.12 (95% CI, 1.531-6.343), P = 0.002], prior concussions [OR, 1.39 (95% CI, 1.020-1.892), P = 0.037], greater initial symptom score [OR, 1.05 (95% CI, 1.031-1.058), P < 0.001], and younger age [OR, 0.87 (95% CI, 0.773-0.979), P = 0.021] were strongly associated with additional visits.

CONCLUSIONS

Among athletes treated at a regional sports concussion center, family history of psychiatric disorders, increased symptom score at initial visit, prior concussions, and younger age were each uniquely associated with needing additional clinic visits at the time of initial assessment. Understanding these variables may guide treatment protocols for optimal care.

Effects of prior concussion on symptom severity and recovery time in acute youth concussion

OBJECTIVE

Many studies have identified factors associated with increased symptom burden and prolonged recovery after pediatric and adolescent concussion. Few have systematically examined the effects of prior concussion on these outcomes in patients with concussion due to any mechanism. An improved understanding of the short- and long-term effects of a multiple concussion history will improve counseling and management of this subgroup of patients.

METHODS

A retrospective review of adolescent and young adult acute concussion patients presenting to the multidisciplinary concussion clinic between 2018 and 2019 was conducted at a single center. Patient demographic data, medical history including prior concussion, initial symptom severity score (SSS), injury mechanisms, and recovery times were collected. Univariate and multivariable analyses were conducted to identify associations of history of prior concussion and patient and injury characteristics with symptom score and recovery time.

RESULTS

A total of 266 patients with an average age of 15.4 years (age range 13-27 years) were included. Prior concussion was reported in 35% of patients. The number of prior concussions per patient was not significantly associated with presenting symptom severity, recovery time, or recovery within 28 days. Male sex and sports-related concussion (SRC) were associated with lower presenting SSS and shorter recovery time on univariate but not multivariable analysis. However, compared to non-sport concussion mechanisms, SRC was associated with 2.3 times higher odds of recovery within 28 days (p = 0.04). A history of psychiatric disorders was associated with higher SSS in univariate analysis and longer recovery time in univariate and multivariable analyses. Multivariable log-linear regression also demonstrated 5 times lower odds of recovery within 28 days for those with a psychiatric history.

CONCLUSIONS

The results of this study demonstrated that an increasing number of prior concussions was associated with a trend toward higher presenting SSS after youth acute concussion but did not show a significant association with recovery time or delayed (> 28 days) recovery. Presence of psychiatric history was found to be significantly associated with longer recovery and lower odds of early (≤ 28 days) recovery. Future prospective, long-term, and systematic study is necessary to determine the optimal counseling and management of adolescent and young adult patients with a history of multiple concussions.

Using a Likelihood Heuristic to Summarize Conflicting Literature on Predictors of Clinical Outcome Following Sport-Related Concussion

OBJECTIVE

To introduce a new methodology for summarizing the results from systematic reviews-a likelihood heuristic-to the field of sport-related concussion.

DATA SOURCES

We applied the likelihood heuristic to the results of a systematic review published by Iverson et al (2017), containing 101 studies, on the predictors of worse clinical outcome following sport-related concussion.

STUDY SELECTION

We re-examined 5 individual prognostic factors that are of clinical interest and for which there is conflicting literature (female sex = 44 studies, prior concussion history = 41 studies, loss of consciousness = 31 studies, post-traumatic amnesia = 25 studies, and retrograde amnesia = 10 studies).

DATA EXTRACTION

For each prognostic factor, likelihood ratios were generated using the (1) number of significant and nonsignificant studies, (2) study power, (3) alpha level, and (4) prior probability that the alternative hypothesis was true.

DATA SYNTHESIS

Assuming each study had 80% power and an alpha level of 5%, observing the reported number of conflicting studies for female sex, prior concussion history, and retrograde amnesia is substantially more likely if each prognostic factor is associated with worse clinical outcome following sport-related concussion. For loss of consciousness, the observed number of conflicting studies is more likely if loss of consciousness is not associated with worse clinical outcome following sport-related concussion. A secondary analysis incorporating potentially more realistic study parameters of statistical power (45%) and alpha level (25%) generates weaker likelihood evidence that the observed numbers of studies for each prognostic factor are associated with worse clinical outcome following sport-related concussion than they are not.

CONCLUSIONS

Using a likelihood heuristic with 80% power and 5% alpha level, there is very strong likelihood evidence that female sex, prior concussion history, and retrograde amnesia are associated with worse clinical outcome following sport-related concussion. The strength of likelihood evidence that prognostic factors are associated with worse clinical outcome reduces when statistical power is lower and alpha level is inflated.

Research Evaluating Sports ConcUssion Events-Rapid Assessment of Concussion and Evidence for Return (RESCUE-RACER): a two-year longitudinal observational study of concussion in motorsport

INTRODUCTION

Concussion is a clinical diagnosis, based on self-reported patient symptoms supported by clinical assessments across many domains including postural control, ocular/vestibular dysfunction, and neurocognition. Concussion incidence may be rising in motorsport which, combined with unresolved challenges to accurate diagnosis and lack of guidance on the optimal return-to-race timeframe, creates a difficult environment for healthcare practitioners.

METHODS AND ANALYSIS

Research Evaluating Sports ConcUssion Events-Rapid Assessment of Concussion and Evidence for Return (RESCUE-RACER) evaluates motorsports competitors at baseline (Competitor Assessment at Baseline; Ocular, Neuroscientific (CArBON) study) and post-injury (Concussion Assessment and Return to motorSport (CARS) study), including longitudinal data. CArBON collects pre-injury neuroscientific data; CARS repeats the CArBON battery sequentially during recovery for competitors involved in a potentially concussive event. As its primary outcome, RESCUE-RACER will develop the evidence base for an accurate trackside diagnostic tool. Baseline objective clinical scoring (Sport Concussion Assessment Tool-5th edition (SCAT5)) and neurocognitive data (Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT)) will be assessed for specificity to motorsport and relationship to existing examinations. Changes to SCAT5 and ocular, vestibular, and reaction time function (Dx 100) will be estimated by the reliability change index as a practical tool for trackside diagnosis. Neuropsychological (Cambridge Neuropsychological Test Automated Battery (CANTAB)) assessments, brain MRI (7 Tesla) and salivary biomarkers will be compared with the new tool to establish utility in diagnosing and monitoring concussive injuries.

ETHICS AND DISSEMINATION

Ethical approval was received from East of England-Cambridge Central Research Ethics Committee (18/EE/0141). Participants will be notified of study outcomes via publications (to administrators) and summary reports (funder communications). Ideally, all publications will be open access.

TRIAL REGISTRATION NUMBER

February 2019 nationally (Central Portfolio Management System 38259) and internationally (ClinicalTrials.gov NCT03844282).

Machine Learning in Modeling High School Sport Concussion Symptom Resolve

INTRODUCTION

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

BDNF expression increases without changes in play behavior following concussion in juvenile rats (Rattus Norvegicus)

PURPOSE

Young children have a high risk of concussion or mild traumatic brain injury (mTBI). Children often appear healthy soon after mTBI, but some have pervasive cognitive and/or motor impairments. Understanding underlying mechanisms recruited after concussion may help for return to play protocols and mitigating what might be lifelong impairments.

METHODS

We investigated molecular and behavioral changes in a rat model of childhood concussion. Rats received an injury or sham procedure at an age approximately equivalent to the human period of early childhood. Social play was analyzed for behavioral differences. Tissue from the right motor cortex (impacted), left motor cortex, and medial prefrontal cortex were analyzed for brain derived neurotrophic factor (BDNF) protein.

RESULTS

Play behavior was not significantly different between conditions. BDNF levels were much higher in both the right and left motor cortices of the mTBI group compared to medial prefrontal cortex, which is relatively remote from the impact site, within the mTBI group and all tissue collected from the sham group.

CONCLUSIONS

There is ongoing plastic change at the cellular level in both the impacted area and the well-connected contralateral area after a concussion, suggesting compensatory mechanisms after injury are still at play.

The Association Between Premorbid Conditions in School-Aged Children With Prolonged Concussion Recovery

The association between preexisting anxiety, depression, and/or neurodevelopmental disorders and symptom duration among younger children who sustain concussions is not well known. The authors conducted a prospective cohort study of 569 patients presenting to a pediatric neurology clinic with the diagnosis of concussion. The authors measured associations between symptom duration and premorbid conditions, as well as gender, age, mechanism of injury, and other factors. Premorbid conditions were common in both age groups. On univariate modeling female gender, age >12 years, and premorbid conditions were associated with longer symptom duration. On multivariable modeling, females and patients ≤12 years old with a history of headaches, migraines, or a history of psychiatric conditions took significantly longer to recover than those without such conditions. Premorbid conditions are associated with a prolonged recovery from concussion among those patients ≤12 years old.

Predictors of clinical recovery from concussion: a systematic review

OBJECTIVE

A systematic review of factors that might be associated with, or influence, clinical recovery from sport-related concussion. Clinical recovery was defined functionally as a return to normal activities, including school and sports, following injury.

DESIGN

Systematic review.

DATA SOURCES

PubMed, PsycINFO, MEDLINE, CINAHL, Cochrane Library, EMBASE, SPORTDiscus, Scopus and Web of Science.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Studies published by June of 2016 that addressed clinical recovery from concussion.

RESULTS

A total of 7617 articles were identified using the search strategy, and 101 articles were included. There are major methodological differences across the studies. Many different clinical outcomes were measured, such as symptoms, cognition, balance, return to school and return to sports, although symptom outcomes were the most frequently measured. The most consistent predictor of slower recovery from concussion is the severity of a person's acute and subacute symptoms. The development of subacute problems with headaches or depression is likely a risk factor for persistent symptoms lasting greater than a month. Those with a preinjury history of mental health problems appear to be at greater risk for having persistent symptoms. Those with attention deficit hyperactivity disorder (ADHD) or learning disabilities do not appear to be at substantially greater risk. There is some evidence that the teenage years, particularly high school, might be the most vulnerable time period for having persistent symptoms-with greater risk for girls than boys.

CONCLUSION

The literature on clinical recovery from sport-related concussion has grown dramatically, is mostly mixed, but some factors have emerged as being related to outcome.

Executive dysfunction following a mild traumatic brain injury revealed in early adolescence with locomotor-cognitive dual-tasks

OBJECTIVE

To compare gait parameters between children in early adolescence (EA) with and without a mild traumatic brain injury (mTBI) during dual-task walking (DTW).

METHODS

Children in EA with mTBI (n = 14; six girls) were compared to those without (n = 13; five girls) while walking in different combinations of obstacle avoidance and cognitive dual-tasks. Gait speed and fluidity and their related dual-task costs (DTC) were analysed along with foot clearance and proximity to the obstacle.

RESULTS

No group effects were found for gait speed, proximity or clearance, but were found for fluidity DTC, specifically during the dual Stroop task and when crossing the deeper obstacle. There were also group differences for fluidity during the planning of obstacle avoidance for the narrow obstacle combined with the verbal fluency task and the deep obstacle with no cognitive task. Finally, gait fluidity showed group differences across unobstructed dual-task situations.

CONCLUSIONS

Gait fluidity may be a more sensitive variable than gait speed for revealing executive dysfunction following mTBI in EA. Assessing DTW in level walking also seems to show a potential to reveal executive dysfunctions in this age group. These results provide direction for future research on clinical assessment using DTW post-mTBI in adolescents.

Participation in Pre-High School Football and Neurological, Neuroradiological, and Neuropsychological Findings in Later Life: A Study of 45 Retired National Football League Players

BACKGROUND

A recent study found that an earlier age of first exposure (AFE) to tackle football was associated with long-term neurocognitive impairment in retired National Football League (NFL) players.

PURPOSE

To assess the association between years of exposure to pre-high school football (PreYOE) and neuroradiological, neurological, and neuropsychological outcome measures in a different sample of retired NFL players.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Forty-five former NFL players were included in this study. All participants prospectively completed extensive history taking, a neurological examination, brain magnetic resonance imaging, and a comprehensive battery of neuropsychological tests. To measure the associations between PreYOE and these outcome measures, multiple regression models were utilized while controlling for several covariates.

RESULTS

After applying a Bonferroni correction for multiple comparisons, none of the neurological, neuroradiological, or neuropsychological outcome measures yielded a significant relationship with PreYOE. A second Bonferroni-corrected analysis of a subset of these athletes with self-reported learning disability yielded no significant relationships on paper-and-pencil neurocognitive tests but did result in a significant association between learning disability and computerized indices of visual motor speed and reaction time.

CONCLUSION

The current study failed to replicate the results of a prior study, which concluded that an earlier AFE to tackle football might result in long-term neurocognitive deficits. In 45 retired NFL athletes, there were no associations between PreYOE and neuroradiological, neurological, and neuropsychological outcome measures.