The Role of Body Mass Index on Physical Activity, Symptoms, and Related Outcomes Following Pediatric Concussion.

OBJECTIVE: To determine the step count and self-reported activity levels for obese and non-obese pediatric patients following concussion and predict self-reported symptoms, quality of life, and psychological health over time. STUDY DESIGN: Participants completed the Post-Concussion Symptom Scale (PCSS), Pediatric Quality of Life (PedsQL), and Behavioral Symptom Inventory-18 (BSI-18) at an initial visit (<72 hours), 3-5 days post-injury, 10-18 days post-injury, and 1 and 2 months post-injury. Physical activity data (eg, step count) were collected via a commercial actigraph. Participants were categorized into obese and non-obese body mass index (BMI) groups based on age- and sex-adjusted growth standards. Mann Whitney U tests compared groups while nonparametric series regression models examined the effect of obese BMI and average daily step count on PCSS, PedsQL, and BSI-18 outcomes at 1- and 2-months post-injury. RESULTS: 194 participants were included: 153 (78.9%; M=14.6 ± 2.4 years; 50% female) in the non-obese group and 41 (21.1%; M=14.2 ± 2.0 years; 44% female) in the obese group. The obese group had a 22.8% lower average daily step count in the week post-injury (p=0.02). At 2-months, there was a significant association between obese BMI and worse PCSS total score (p=0.042), PedsQL (p=0.017), and BSI-18 anxiety (p=0.046). Average daily step count in the first week post-injury was associated with a higher PCSS total score at 2 months (p=0.031). CONCLUSIONS: Pediatric patients following concussion with an obese BMI had a lower daily average step count in the week after injury and exhibited worse concussion symptoms, quality of life, and anxiety at 2 months compared with those with a non-obese BMI.

Career duration and later-life health conditions among former professional American-style football players.

OBJECTIVES: Career duration is often used as a metric of neurotrauma exposure in studies of elite athletes. However, as a proxy metric, career length may not accurately represent causal factors, and associations with health outcomes may be susceptible to selection effects. To date, relationships between professional American-style football (ASF) career length and postcareer health remain incompletely characterised. METHODS: We conducted a survey-based cross-sectional cohort study of former professional ASF players. Flexible regression methods measured associations between self-reported career duration and four self-reported health conditions: pain, arthritis, mood and cognitive symptoms. We also measured associations between career duration and four self-reported ASF exposures: prior concussion signs and symptoms (CSS), performance enhancing drugs, intracareer surgeries and average snaps per game. Models were adjusted for age and race. RESULTS: Among 4189 former players (52±14 years of age, 39% black, 34% lineman position), the average career length was 6.7±3.9 professional seasons (range=1-20+). We observed inverted U-shaped relationships between career duration and outcomes (all p<0.001), indicating that adverse health effects were more common among men with intermediate career durations than those with shorter or longer careers. Similar findings were observed for play-related exposures (eg, CSS and snaps). CONCLUSIONS: Relationships between ASF career duration and subsequent health status are non-linear. Attenuation of the associations among longer career players may reflect selection effects and suggest career length may serve as a poor proxy for true causal factors. Findings highlight the need for cautious use of career duration as a proxy exposure metric in studies of former athletes.

Association of obesity with mild traumatic brain injury symptoms, inflammatory profile, quality of life and functional outcomes: a TRACK-TBI Study.

OBJECTIVES: Obesity is associated with chronic inflammation, which may impact recovery from mild traumatic brain injury (mTBI). The objective was to assess the role of obesity in recovery of symptoms, functional outcome and inflammatory blood biomarkers after mTBI. METHODS: TRACK-TBI is a prospective study of patients with acute mTBI (Glasgow Coma Scale=13-15) who were enrolled ≤24 hours of injury at an emergency department of level 1 trauma centres and followed for 12 months. A total of 770 hospitalised patients who were either obese (body mass index (BMI) >30.0) or healthy mass (BMI=18.5-24.9) were enrolled. Blood concentrations of high-sensitivity C reactive protein (hsCRP), interleukin (IL) 6, IL-10, tumour necrosis factor alpha; Rivermead Post-Concussion Symptoms Questionnaire (RPQ), Quality of Life After Brain Injury and Glasgow Outcome Score-Extended reflecting injury-related functional limitations at 6 and 12 months were collected. RESULTS: After adjusting for age and gender, obese participants had higher concentrations of hsCRP 1 day after injury (mean difference (MD)=0.65; 95% CI: 0.44 to 0.87, p<0.001), at 2 weeks (MD=0.99; 95% CI: 0.74 to 1.25, p<0.001) and at 6 months (MD=1.08; 95% CI: 0.79 to 1.37, p<0.001) compared with healthy mass participants. Obese participants had higher concentrations of IL-6 at 2 weeks (MD=0.37; 95% CI: 0.11 to 0.64, p=0.006) and 6 months (MD=0.42; 95% CI: 0.12 to 0.72, p=0.006). Obese participants had higher RPQ total score at 6 months (MD=2.79; p=0.02) and 12 months (MD=2.37; p=0.049). CONCLUSIONS: Obesity is associated with higher symptomatology at 6 and 12 months and higher concentrations of blood inflammatory markers throughout recovery following mTBI.

Comparison of machine learning models to predict long-term outcomes after severe traumatic brain injury.

OBJECTIVE: An estimated 1.5 million people die every year worldwide from traumatic brain injury (TBI). Physicians are relatively poor at predicting long-term outcomes early in patients with severe TBI. Machine learning (ML) has shown promise at improving prediction models across a variety of neurological diseases. The authors sought to explore the following: 1) how various ML models performed compared to standard logistic regression techniques, and 2) if properly calibrated ML models could accurately predict outcomes up to 2 years posttrauma. METHODS: A secondary analysis of a prospectively collected database of patients with severe TBI treated at a single level 1 trauma center between November 2002 and December 2018 was performed. Neurological outcomes were assessed at 3, 6, 12, and 24 months postinjury with the Glasgow Outcome Scale. The authors used ML models including support vector machine, neural network, decision tree, and naïve Bayes models to predict outcome across all 4 time points by using clinical information available on admission, and they compared performance to a logistic regression model. The authors attempted to predict unfavorable versus favorable outcomes (Glasgow Outcome Scale scores of 1-3 vs 4-5), as well as mortality. Models' performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC) with 95% confidence interval and balanced accuracy. RESULTS: Of the 599 patients in the database, the authors included 501, 537, 469, and 395 at 3, 6, 12, and 24 months posttrauma. Across all time points, the AUCs ranged from 0.71 to 0.85 for mortality and from 0.62 to 0.82 for unfavorable outcomes with various modeling strategies. Decision tree models performed worse than all other modeling approaches for multiple time points regarding both unfavorable outcomes and mortality. There were no statistically significant differences between any other models. After proper calibration, the models had little variation (0.02-0.05) across various time points. CONCLUSIONS: The ML models tested herein performed with equivalent success compared with logistic regression techniques for prognostication in TBI. The TBI prognostication models could predict outcomes beyond 6 months, out to 2 years postinjury.

Interaction of admission platelet count with current medications and the risk for chronic subdural recurrence.

OBJECTIVE: Chronic subdural hematoma (cSDH) has a reported 10%-24% rate of recurrence after surgery, and prognostic models for recurrence have produced equivocal results. The objective of this study was to leverage a data mining algorithm, chi-square automatic interaction detection (CHAID), which can incorporate continuous, nominal, and binary data into a decision tree, to identify the most robust predictors of repeat surgery for cSDH patients. METHODS: This was a retrospective cohort study of all patients with SDH from two level 1 trauma centers at a single institution. All patients underwent cSDH evacuation performed by 15 neurosurgeons between 2011 and 2020. The primary outcome was the rate of repeat surgery for recurrent cSDH following the initial evacuation. The authors used CHAID to identify relevant predictors of repeat surgery, including age, sex, comorbidities, postsurgical complications, platelet count prior to the first procedure, midline shift prior to the first procedure, hematoma volume, and preoperative use of anticoagulants, antiplatelets, or statins. RESULTS: Sixty (13.8%) of 435 study-eligible patients (average age 74.0 years) had a cSDH recurrence. These patients had 2.0 times greater odds of having used anticoagulants. The final CHAID model had an overall accuracy of 87.4% and an area under the curve of 0.76. According to the model, the predictor with the strongest association with cSDH recurrence was admission platelet count. Approximately 26% of patients (n = 23/87) with an admission platelet count < 157 × 109/L had a cSDH recurrence, whereas none of the 44 patients with admission platelets > 313 × 109/L had a recurrence. Approximately 17% of patients in the 157-313 × 109/L platelet group who had used preoperative statins required a second procedure, which was associated with a 2.3 times increased risk for repeat surgery compared to those who had not used statins preoperatively. Among those who had not used preoperative statins, a platelet count ≤ 179 × 109/L on admission for the first procedure was the strongest differentiator for a second surgery (n = 5/22 [23%]), which increased the risk of recurrence by 4.5 times. Among the patients using preoperative statins, the use of anticoagulants was the strongest differentiator for requiring repeat surgery (n = 11/33 [33%]). CONCLUSIONS: The described model identified platelet count on admission as the most important predictor of repeat cSDH surgery, followed by preoperative statin use and anticoagulant use. Critical cutoffs for platelet count were identified, which future studies should evaluate to determine if they are modifiable or reflective of underlying disease states.

Temporal Differences in Concussion Symptom Factors in Adolescents following Sports-Related Concussion.

OBJECTIVE: To evaluate temporal differences in concussion symptoms up to 30 days following a sports-related concussion. STUDY DESIGN: Adolescent and young adult athletes (n = 782) were separated based on time since injury at presentation as Early (0-7 days; n = 321, age: 15.4 ± 1.9 years, 51.7% female), Middle (8-14 days; n = 281, age: 15.8 ± 2.2 years, 54.8% female), and Late (15-30 days; n = 180, age: 15.6 ± 1.8 years, 52.8% female). All participants completed the 22-item Post-Concussion Symptom Scale at first visit. A confirmatory factor analysis was completed separately for each time since injury cohort using a 4-component model reported previously. RESULTS: The confirmatory factor analysis model fit was acceptable for Early, Middle, and Late (using cognitive-migraine-fatigue, affective, sleep, and somatic factors). Both affective (change = 0.30; P = .01; Cohen d = 0.30) and sleep (change = 0.51; P ≤ .001; Cohen d = 0.47) factors were significantly greater in the Late group compared with the Early, but not Middle, groups. The previously reported 4-factor symptom model, including cognitive-migraine-fatigue, affective, somatic, and sleep factors, was appropriate for adolescents up to 30 days' postinjury. However, adolescents who presented between 15 and 30 days' postinjury reported greater affective and sleep symptoms than those who presented within 1 week. CONCLUSIONS: Clinicians should consider these temporal differences when evaluating concussion symptoms in adolescents, as greater affective and sleep symptoms can be predictive of prolonged recovery/persistent complications.

The Role of Age, Sex, Body Mass Index, and Sport Type on the Dynamic Exertion Test in Healthy Athletes: A Cross-Sectional Study.

BACKGROUND: The dynamic exertion test (EXiT) was developed to help inform return to play after sport-related concussion, but some factors may threaten the internal validity of EXiT and affect clinical interpretation. OBJECTIVE: To compare age, sex, BMI, and sport types across EXiT physiological [pre-EXiT and post-EXiT percentage of maximum heart rate (HR %max) and blood pressure (BP)], performance (change-of-direction task completion time and committed errors), and clinical [symptoms and rating of perceived exertion (RPE)] outcomes among healthy adolescents and adults. STUDY DESIGN: Cross-sectional. METHODS: Eighty-seven participants ( F = 55, 37.4%) reported symptoms and RPE during the EXiT, which consists of a 12-minute treadmill running protocol, and the dynamic circuit, ball toss, box shuffle (SHUF) and carioca (CAR), zig zag (ZZ), proagility (PA), and arrow agility (AA) tasks. Independent samples t tests were conducted for pre-EXiT and post-EXiT HR %max and BP and change-of-direction task completion time and Mann-Whitney U tests for errors, symptoms, and RPE. A series of 1-way analysis of variance (ANOVAs) and Kruskal-Wallis H tests were conducted to compare collision, contact, and noncontact sport types. RESULTS: Adolescents had lower completion time across AA ( P = 0.01) and male athletes lower than female athletes on CAR, ZZ, PA, and AA ( P < 0.04). Male athletes reported greater RPE after the SHUF, CAR, and AA ( P < 0.03). HR %max , errors, and symptoms were equivocal across all subgroups ( P > 0.05). CONCLUSION: Age and sex should be considered in the interpretation of performance and clinical, but not physiological, EXiT outcomes. The EXiT is a standardized exercise assessment and generalizable to healthy athletes.

Differences in brain structure and theta burst stimulation-induced plasticity implicate the corticomotor system in loss of function after musculoskeletal injury.

Traumatic musculoskeletal injury (MSI) may involve changes in corticomotor structure and function, but direct evidence is needed. To determine the corticomotor basis of MSI, we examined interactions among skeletomotor function, corticospinal excitability, corticomotor structure (cortical thickness and white matter microstructure), and intermittent theta burst stimulation (iTBS)-induced plasticity. Nine women with unilateral anterior cruciate ligament rupture (ACL) 3.2 ± 1.1 yr prior to the study and 11 matched controls (CON) completed an MRI session followed by an offline plasticity-probing protocol using a randomized, sham-controlled, double-blind, cross-over study design. iTBS was applied to the injured (ACL) or nondominant (CON) motor cortex leg representation (M1LEG) with plasticity assessed based on changes in skeletomotor function and corticospinal excitability compared with sham iTBS. The results showed persistent loss of function in the injured quadriceps, compensatory adaptations in the uninjured quadriceps and both hamstrings, and injury-specific increases in corticospinal excitability. Injury was associated with lateralized reductions in paracentral lobule thickness, greater centrality of nonleg corticomotor regions, and increased primary somatosensory cortex leg area inefficiency and eccentricity. Individual responses to iTBS were consistent with the principles of homeostatic metaplasticity; corresponded to injury-related differences in skeletomotor function, corticospinal excitability, and corticomotor structure; and suggested that corticomotor adaptations involve both hemispheres. Moreover, iTBS normalized skeletomotor function and corticospinal excitability in ACL. The results of this investigation directly confirm corticomotor involvement in chronic loss of function after traumatic MSI, emphasize the sensitivity of the corticomotor system to skeletomotor events and behaviors, and raise the possibility that brain-targeted therapies could improve recovery.NEW & NOTEWORTHY Traumatic musculoskeletal injuries may involve adaptive changes in the brain that contribute to loss of function. Our combination of neuroimaging and theta burst transcranial magnetic stimulation (iTBS) revealed distinct patterns of iTBS-induced plasticity that normalized differences in muscle and brain function evident years after unilateral knee ligament rupture. Individual responses to iTBS corresponded to injury-specific differences in brain structure and physiological activity, depended on skeletomotor deficit severity, and suggested that corticomotor adaptations involve both hemispheres.

A Randomized Controlled Trial of Precision Vestibular Rehabilitation in Adolescents following Concussion: Preliminary Findings.

OBJECTIVE: To compare the effectiveness of a 4-week precision vestibular rehabilitation intervention compared with a behavioral management control intervention for adolescents with vestibular symptoms/impairment within 21 days of a concussion. STUDY DESIGN: This study used double-blind, randomized controlled trial design involving adolescent (12-18 years) patients with a diagnosed sport/recreation-related concussion with vestibular symptoms/impairment from a concussion-specialty clinic between October 2018 and February 2020. Eligible participants were randomized in a 1:1 to either a 4-week vestibular intervention group (VESTIB) or a behavioral management control group (CONTROL). CONTROLS (n = 25) were prescribed behavioral management strategies (eg, physical activity, sleep, hydration, nutrition, stress management) and instructed to perform stretching/physical activity (eg, walking, stationary cycle) 30 minutes/day. VESTIB (n = 25) were prescribed precision vestibular rehabilitation exercises and instructed to perform at-home exercises for 30 minutes/day. Primary outcomes were improvement in Vestibular/Ocular Motor Screening vestibular items (ie, horizontal/vertical vestibular-ocular reflex, visual motion sensitivity) at 4 weeks postenrollment. RESULTS: We screened 310 and enrolled a total of 55 (18%) adolescent patients who were randomized to one of the interventions. Fifty of fifty-five (91%) participants completed all aspects of the study protocol. Participants in VESTIB improved significantly across the intervention period in horizontal (mean difference-1.628; 95% CI [-3.20, -0.06]; P = .04) and vertical (mean difference-2.24; 95% CI [-4.01, -0.48]; P = .01) vestibular-ocular reflex, but not visual motion sensitivity (mean difference-2.03; 95% CI [-4.26, 0.19]) of the Vestibular/Ocular Motor Screening score compared with CONTROLS. CONCLUSIONS: Overall, the vestibular intervention group experienced greater clinical improvements in vestibular symptoms/impairment than controls across the 4-week intervention. TRIAL REGISTRATION: ClinicalTrials.gov: NCT03555370.

A Within-Subjects Comparison of Clinical Outcomes for Patients' First and Second Concussions.

OBJECTIVES: To examine the difference between an individual's first and second concussion using a comprehensive, multidomain assessment including symptoms, neurocognitive, vestibular, ocular, and individual demographic and medical history risk factors associated with protracted recovery. SETTING: Concussion Specialty Clinic. PARTICIPANTS: Seventy-three patients (aged 13-21 years; 57% female) diagnosed with 2 separate concussions (380.5 ± 278.7 days between injuries) from August 2016 to August 2018. DESIGN: Retrospective within-subjects cohort study. MAIN MEASURES: ImPACT, PCSS, and Vestibular-Ocular Motor Screen (VOMS) at each visit. Patients were divided into "normal" (≤30 days) and "protracted" recovery (>30 days) for χ2 analyses. RESULTS: There were no differences between the first and second injuries in recovery time, VOMS, visual and verbal memory, or reaction time. Visual motor speed scores were higher at the second injury time point and reported sleep symptoms were higher at the first injury time point. In addition, participants reported to the clinic on average 3 days earlier for an evaluation for their second injury. Results from χ2 analyses indicated that female sex predicted protracted recovery (>30 days) from concussion at the first injury time point (OR = 4.1; 95% CI, 1.5-11.6; P = .006). CONCLUSIONS: The findings provide preliminary evidence that there is no clinical difference between patients' first and second concussions when both injuries were treated through a concussion specialty clinic.

Network Analysis of Research on Mild Traumatic Brain Injury in US Military Service Members and Veterans During the Past Decade (2010-2019).

OBJECTIVE: To evaluate trends in the extant literature on mild traumatic brain injury (mTBI) in military service members and veterans using network analysis based on a comprehensive search of original, peer-reviewed research articles involving human participants published between January 1, 2010, and December 31, 2019. Specifically, we employed network analysis to evaluate associations in the following areas: (1) peer-reviewed journals, (2) authors, (3) organizations/institutions, and (4) relevant key words. PARTICIPANTS: Included studies were published in peer-reviewed journals available on Web of Science database, using US military service members or veterans. DESIGN: Bibliometric network analytical review. MAIN MEASURES: Outcomes for each analysis included number of articles, citations, total link strength, and clusters. RESULTS: The top publishing journals were (1) Journal of Head Trauma and Rehabilitation, (2) Military Medicine, (3) Brain Injury, (4) Journal of Neurotrauma, and (5) Journal of Rehabilitation Research and Development. The top publishing authors were (1) French, (2) Lange, (3) Cooper, (4) Vanderploeg, and (5) Brickell. The top research institutions were (1) Defense and Veterans Brain Injury Center, (2) Uniformed Services University of the Health Sciences, (3) University of California San Diego, (4) Walter Reed National Military Medical Center, and (5) Boston University. The top co-occurring key words in this analysis were (1) posttraumatic stress disorder (PTSD), (2) persistent postconcussion symptoms (PPCS), (3) blast injury, (4) postconcussion syndrome (PCS), and (5) Alzheimer's disease. CONCLUSIONS: The results of this network analysis indicate a clear focus on veteran health, as well as investigations on chronic effects of mTBI. Research in civilian mTBI indicates that delaying treatment for symptoms and impairments related to mTBI may not be the most precise treatment strategy. Increasing the number of early, active, and targeted treatment trials in military personnel could translate to meaningful improvements in clinical practices for managing mTBI in this population.

Minimum detectable change and false positive rates of the vestibular/ocular motor screening (VOMS) tool: an NCAA-DoD care consortium analysis.

OBJECTIVE: To derive minimum detectable change (MDC) across individual Vestibular-Ocular Motor Screening (VOMS) items and VOMS overall score in 17-25 years old collegiate athletes and to examine false positive rates. METHOD: Participants (n = 378) completed VOMS pre-season for two consecutive years. MDC was identified for individual VOMS symptom items and NPC distance (cm). Both total and change methods of VOMS scoring were included in analysis. RESULTS: Regarding total scoring, MDC for ocular VOMS symptom items was 1 and MDC for vestibular VOMS symptoms items was 2. MDC for NPC was 4 cm and for VOMS overall score was 10. Regarding change scoring, MDC for each VOMS symptom item was 1, and for VOMS overall score was 8. False positives ranged from 5.3% to 15.9%. CONCLUSIONS: This study presents MDCs for each VOMS item and overall VOMS score, using total and change scoring. These values can be considered true change outside measurement error with 95% confidence in a 17-25 year old collegiate athlete population.

Does Concussion Affect Perception-Action Coupling Behavior? Action Boundary Perception as a Biomarker for Concussion.

BACKGROUND: After a concussion, athletes may be at increased risk of musculoskeletal injuries. Altered perception of action boundaries (ABP), or the limits of one's action capabilities, is one possible mechanism for this increase in injury risk after concussion. OBJECTIVE: To evaluate differences in symptoms, neurocognitive, vestibular/oculomotor, and action boundary function between subjects with no concussion history (NoHx) and concussion history (ConcHX). DESIGN: Cross-sectional study. SETTING: Laboratory at the University of Pittsburgh. PARTICIPANTS: ConcHx (n = 22; age: 21.8 ± 3.0 years, height: 174.0 ± 8.3 cm, and mass: 77.8 ± 14.8 kg) and NoHx athletes (n = 24; age: 21.6 ± 2.0 years, height: 176.0 ± 10.0 cm, and mass: 72.0 ± 15.3 kg). INTERVENTION: Immediate Postconcussion Assessment and Cognitive Testing (ImPACT) and Post-Concussion Symptom Scale (PCSS), Vestibular-Ocular Motor Screening (VOMS) tool, and the Perception-Action Coupling Task (PACT). The PACT measures the accuracy of ABP. MAIN OUTCOME MEASURES: Neurocognitive domain scores, PCSS, VOMS subdomain symptom gain, ABP accuracy, and actualization. RESULTS: ConcHx reported 2.7 ± 1.5 previous concussions occurring on average 263.8 ± 228.9 days prior. ConcHx was higher on several VOMS items including vertical/horizontal saccades (P = 0.001; P = 0.05), vertical/horizontal vestibular-ocular reflex (P < 0.001; P = 0.04), and visual motion sensitivity (P < 0.001). Average PACT movement time (P = 0.01) and reaction time (P = 0.01) were longer in ConcHx. CONCLUSIONS: These findings provide preliminary support for impaired vestibular/oculomotor function and ABP in ConcHx compared with NoHx. The current results may enhance our understanding of the mechanisms for increased musculoskeletal injury risk after concussion.

Influence of Sleep Dysfunction on Concussion Assessment Outcomes Among Adolescent Athletes After Concussion and Healthy Controls.

BACKGROUND: Sleep dysfunction (SD) is associated with a high symptom burden and lower neurocognitive performance after concussion and on baseline testing without injury. However, few studies have compared concussed athletes and controls with and without SD on clinical outcomes. OBJECTIVE: To evaluate differences in clinical outcomes among both concussed athletes and matched controls with and without SD. DESIGN: Retrospective cross-sectional study. PARTICIPANTS: Participants aged 12 to 20 years were recruited from a concussion clinic (n = 50 patients) and research registry/flyers (n = 50 healthy age-/sex-matched controls). Participants were categorized by self-reported SD into one of 4 groups: sport-related concussion (SRC) + SD, SRC only, SD only, and controls. MAIN OUTCOME MEASURES: Post-Concussion Symptom Scale (PCSS), Vestibular/Oculomotor Screening (VOMS), and neurocognitive testing (Immediate Postconcussion Assessment Cognitive Test). RESULTS: Compared with the SRC only group, the SRC + SD group performed worse on all neurocognitive domains, had a higher total symptom score, and endorsed more symptoms on most VOMS items. In addition, the SRC + SD group was at an increased likelihood of having at least 1 abnormal VOMS item compared with SRC only group. The SRC only group had neurocognitive test scores and symptom reports statistically similar to the SD only group. CONCLUSION: Sleep dysfunction after concussion is related to worse neurocognitive performance and higher concussion symptom reporting. This study extended findings to suggest vestibular symptomology is worse among athletes with SD after injury compared to injured athletes without SD. Similar performances on concussion assessments for the SRC only and SD only groups suggest SD may appear similar to clinical presentation of concussion, even at baseline in the absence of SRC.

Fixational eye movements following concussion.

The purpose of this study was to evaluate fixational eye movements (FEMs) with high spatial and temporal resolution following concussion, where oculomotor symptoms and impairments are common. Concussion diagnosis was determined using current consensus guidelines. A retinal eye-tracking device, the tracking scanning laser ophthalmoscope (TSLO), was used to measure FEMs in adolescents and young adults following a concussion and in an unaffected control population. FEMs were quantified in two fixational paradigms: (1) when fixating on the center, or (2) when fixating on the corner of the TSLO imaging raster. Fixational saccade amplitude in recent concussion patients (≤ 21 days) was significantly greater, on average, in the concussion group (mean = 1.03°; SD = 0.36°) compared with the controls (mean = 0.82°; SD = 0.31°), when fixating on the center of the imaging raster (t = 2.87, df = 82, p = 0.005). These fixational saccades followed the main sequence and therefore also had greater peak velocity (t = 2.86, df = 82, p = 0.006) and peak acceleration (t = 2.80, df = 82, p = 0.006). These metrics significantly differentiated concussed from controls (AUC = 0.67-0.68, minimum p = 0.005). No group differences were seen for the drift metrics in either task or for any of the FEMs metrics in the corner-of-raster fixation task. Fixational saccade amplitudes were significantly different in the concussion group, but only when fixating on the center of the raster. This task specificity suggests that task optimization may improve differentiation and warrants further study. FEMs measured in the acute-to-subacute period of concussion recovery may provide a quick (<3 minutes), objective, sensitive, and accurate ocular dysfunction assessment. Future work should assess the impact of age, mechanism of injury, and post-concussion recovery on FEM alterations following concussion.

Comparing Patient- and Clinician-Administered Near Point of Convergence After Concussion.

OBJECTIVE: (1) To compare patient- and clinician-administered measurements of near point of convergence (NPC) distance including the percentage of patients exceeding clinical cutoffs among concussed adolescents and (2) to assess the reliability of patient- and clinician-measured NPC distances. METHODS: A total of 762 patients (mean = 15.51, SD = 3.09 y) within 30 days of concussion participated. The NPC distance was measured consecutively with the patient and clinician controlling the fixation target. The differences between patient (PT) and clinician (CLIN) measurements and cases exceeding cutoffs (ie, ≥5 cm) were examined with a series of t tests and chi-square tests, respectively. Intraclass correlation coefficients and unbiased estimate of reliability were performed. RESULTS: The NPC measurements were similar, t(761) = -.26, P = .79, between the PT (mean = 3.52, SD = 3.77 cm) and CLIN (mean = 3.54, SD = 3.97 cm) conditions. The number of measurements that exceeded cutoffs was similar among the PT (2.5%; 19/762) and CLIN conditions (3%; 23/762) (P = .10), and the number of measurements classified as abnormal/invalid was also similar among the PT (2.5%; 19/762) and CLIN conditions (3%; 23/762) (P = .10). There was excellent reliability between the methods (intraclass correlation coefficients = .85, unbiased estimate of reliability = .92). CONCLUSION: The findings support the application of this assessment in clinical settings where the clinician may not have direct contact with their patient and rely on the patient (eg, telehealth).

Utility of a Postural Stability/Perceptual Inhibition Dual Task for Identifying Concussion in Adolescents.

CONTEXT: Research in the area of dual-task paradigms to assess sport-related concussion (SRC) status is growing, but additional assessment of this paradigm in adolescents is warranted. DESIGN: This case-control study compared 49 adolescent athletes aged 12-20 years with diagnosed SRC to 49 age- and sex-matched controls on visual-spatial discrimination and perceptual inhibition (PIT) reaction time tasks performed while balancing on floor/foam pad conditions. METHODS: The SRC group completed measures at a single time point between 1 and 10 days postinjury. Primary outcomes were dual-task reaction time, accuracy, and sway. General linear models evaluated differences between groups (P < .05). Logistic regression identified predictors of concussion from outcomes. Area under the curve evaluated discriminative ability of identifying SRC. RESULTS: Results supported significantly higher anterior-posterior (AP) sway values in concussed participants for visual-spatial discrimination and PIT when balancing on the floor (P = .03) and foam pad (P = .03), as well as mediolateral sway values on the floor during visual-spatial discrimination (P = .01). Logistic regression analysis (R2 = .15; P = .001) of all dual-task outcomes identified AP postural sway during the PIT foam dual task as the only significant predictor of concussed status (ß = -2.4; P = .004). Total symptoms (area under the curve = 0.87; P < .001) and AP postural sway on foam (area under the curve = 0.70; P = .001) differentiated concussed from controls. CONCLUSION: The AP postural sway on foam during a postural stability/PIT dual task can identify concussion in adolescents between 1 and 10 days from injury.

Association of acute vestibular/ocular motor screening scores to prolonged recovery in collegiate athletes following sport-related concussion.

INTRODUCTION: Researchers have yet to explore the association of acute (i.e., within 3 days) post-injury VOMS scores and length of time until clearance to return to play in collegiate athletes. OBJECTIVE: The purpose was to determine if individual Vestibular/Ocular Motor Screening (VOMS) component symptom scores (e.g., smooth pursuits, convergence, vestibular-ocular reflex) can predict clearance to return to activity from a sport-related concussion. METHODS: Pre-season demographic and medical history and post-injury VOMS testing were collected (n = 79) on collegiate student-athletes following concussion. Impaired vestibulo-ocular function post-injury scores (≥2) were compared to normal scores using survival analysis, with days to clearance to return to sport as the outcome. RESULTS: Abnormal scores on smooth pursuits (p =.026), horizontal saccades (p =.025), vertical saccades (p =.028), and convergence (p =.031) were associated with lower probability of clearance in comparison with normal scores. Any score ≥2 predicted significantly greater days to clearance for return to play (13.1 days; 95% CI: 11.9-14.3; p = .025) compared with athletes with no abnormal test scores (9.6 days; 95% CI: 7.2-12.1, P =.014). DISCUSSION: Post-injury symptoms with VOMS smooth pursuit, saccades, and convergence is associated with increased time-to-clearance for return to sport in collegiate athletes.

Utility of a novel perceptual-motor control test for identification of sport-related concussion beyond current clinical assessments.

Clinically feasible metrics, that can inform the concussion recovery decision making process by evaluating a unique domain beyond current testing domains (e.g., balance, neurocognition, symptoms, vestibular/ocular function) are still in need. The purpose of this study was to compare perceptual-motor control in adolescent athletes ≤21 days of sport-related concussion and healthy controls and evaluate the association of perceptual-motor control to the outcomes of commonly-used sport-related concussion clinical assessments. Athletes (age: 12-18 years) with sport-related concussion (n = 48) and healthy controls (n = 24) completed the Perception-Action Coupling Task (PACT), whose outcomes are mean reaction, movement, initiation, response time, and accuracy. ImPACT outcomes are verbal/visual memory scores, motor processing speed, and reaction time. Vestibular-Ocular Motor Screen (VOMS) outcomes are symptoms from: smooth pursuit, horizontal/vertical saccades, near-point of convergence, horizontal/vestibular ocular-reflex, and visual motion sensitivity. CONCUSSED demonstrated ~5% deficit in overall perceptual-motor accuracy during PACT compared to CONTROLS (p = 0.03). PACT accuracy negatively correlated with smooth pursuits(r = -0.29), and horizontal (r = -0.35)/vertical (r = -0.30) saccades. The C5.0 decision tree determined PACT accuracy was the most relevant predictor of sport-related concussion when no visual motion sensitivity symptoms were reported and Visual Memory was >66. Perceptual-motor control tests may complement current sport-related concussion assessments when neurocognition and vestibular/ocular motor system are not grossly impaired.

Bilateral Quadriceps Strength Asymmetry Is Associated With Previous Knee Injury in Military Special Tactics Operators.

Eagle, SR, Keenan, KA, Connaboy, C, Wohleber, M, Simonson, A, and Nindl, BC. Bilateral quadriceps strength asymmetry is associated with previous knee injury in military special tactics operators. J Strength Cond Res 33(1): 89-94, 2019-Bilateral strength asymmetries have been related to lower-limb injury in athletes. Given that military populations often participate in recreational sport, in addition to a physically demanding workload, bilateral strength asymmetries may be related to injury in military populations. The purpose of this study was to determine whether isokinetic strength differs between Operators with/without self-reported knee injury (KI), and to examine the odds of displaying a lower-extremity strength asymmetry based on previous KI history. Operators (n = 150) self-reported injury history and performed isokinetic knee strength testing. Cohorts were separated by those who reported/not reported KI. Mean isokinetic knee strength and odds ratios, with subjects' KI history compared with strength differences: <10, 10-20, and >20%, were calculated. Operators who reported KI demonstrated larger bilateral knee extension (KE) strength differences compared with those who did not report an injury (injured: 13.5 ± 12.9% vs. noninjured: 8.1 ± 5.9%, p = 0.01). Operators with <10 or 10-20% KE strength difference had 76-77% reduced odds of previous KI, compared to those with >20% strength difference (p < 0.05). Operators with previous KI demonstrated bilateral differences in KE strength. Those with <10 or 10-20% strength differences had reduced odds of reporting previous KI. Strength and conditioning professionals should consider unilateral, targeted exercises in reducing bilateral asymmetry to rectify more balanced strength between limbs. Targeted exercise programs may improve bilateral strength differences and limit reinjury risk.