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Background: Sport specialization is an important area of focus within pediatric sports medicine with studies relating specialization to the rising incidence of sport-related injuries. The relationship between sport specialization and concussion remains unexplored. Hypothesis/Purpose: The objective of this study was to assess the prevalence of sport specialization and its relationship to concussion in athletes seen in a tertiary concussion program. Methods: Athletes completed a sport specialization questionnaire as part of a comprehensive intake questionnaire and were classified into low, moderate, or high specialization groups using a previously published 3-point scale. Categories were derived from their responses to 3 binary questions: 1) Have you quit other sports to focus on 1 sport? 2) Do you train >8 months out of the year in 1 sport? 3) Do you consider your primary sport more important than other sports? Results: Of the 1,098 athletes, ages 8-19 years, who completed the questionnaire, 572 (52%) were female, 718 (65.5%) had a sports-related concussion (SRC) and 439 (40%) had a prior history of concussion. The cohort was categorized into low (n=568, 51.7%), moderate (n=339, 30.9%), or high (n=191, 17.4%) sport specialization groups. Athletes reported their primary sport was more important than other sports (702, 64%) and training >8 months out of the year in 1 sport (594, 54%) more commonly than quitting other sports to focus on 1 sport (270, 25%). Sport specialization differed by primary sport (Figure 1), but did not significantly differ when primary sport was grouped by level of contact (p=0.47). Sport specialization did not significantly differ by sex, race, or ethnicity, but significantly differed by insurance (p=0.014) and age (p=0.0001), with greater specialization among those with private insurance and adolescents, respectively. Moderately or highly specialized athletes were significantly more likely than less specialized athletes to present with a SRC compared to a non-SRC (p<0.0001) and to report prior history of concussion (p=0.005). After controlling for demographic and sport participation factors, only endorsement of training more than 8 months out of the year in one sport was significantly associated with SRC (p=0.001) and prior concussion (p=0.007). Conclusion: Sport specialization is prevalent among youth athletes with concussion. Training >8 months out of the year in a single sport is associated with SRC and prior history of concussion. Further research is warranted to evaluate how exposure among specialized athletes relates to concussion. [ABSTRACT FROM AUTHOR]

Background: A potential objective measure that may assist in identifying vision disorders after concussion is the pupillary light reflex (PLR), which is under autonomic control and contributes to normal convergence and accommodative function which is altered after concussion. This study sought to compare pupillometry measures in adolescents with concussion initially presenting for care in the early acute time frame (≤ 2 weeks post-concussion) to those presenting in the later acute time frame (4 ± 1 weeks). Hypothesis: To determine whether PLR metrics are similar or different between athletes with concussion presenting earlier (≤ 2 weeks post-concussion) for care vs. those presenting later for care (4 ± 1 weeks). Methods: Athletes, ages 12-18 years, with a diagnosis of sport-related concussion (n = 110) were recruited. 89 concussed subjects had their PLR assessment performed at an early acute time point ≤ 2 weeks after concussion, while 21 concussed subjects had their first assessment at a later acute time point (4 week±1 week). Pupillary dynamics were measured in response to a brief, step-input, white light stimulus (154 ms duration; 180 micro watts power) via a Neuroptics PLR-3000 hand-held, infrared, automated, monocular pupillometer (Neuroptics, Irvine, CA). The means of the PLR metrics were compared between groups with one-way Student's t test. Bonferroni correction was applied. Results: The baseline pupil diameter (mean ± SD) was significantly larger (p<0.05) for the subjects seen later 4 ± 1 week (5.09 mm ± 0.63) as compared to the cohort of subjects who presented earlier within 2 weeks after injury (4.72 ± 0.79mm). Average constriction velocity ACV for the later-presenting cohort (3.35±0.45 mm/s) was significantly faster compared to the early-presenting cohort (3.04±0.59 mm/s). Similarly, maximum constriction velocity for the groups were significantly different (early 4.82±0.90 versus late 5.31±0.70 mm/s), even after Bonferroni correction (p<0.05), with alpha of 0.025. All the other pupillometric parameters were not different from each other. Conclusion: When comparing adolescents with concussion presenting early in the acute phase ≤ 2 weeks after concussion to those presenting later in the acute timeframe to care 4±1 weeks, those presenting later demonstrate enhancement of certain PLR metrics, namely larger baseline pupil diameter and faster average constriction velocity (ACV) and maximum constriction velocity (MCV). Differences in these PLR metrics in those presenting later in the acute timeframe may represent findings in those who are more likely to have persisting post-concussion symptoms, potentially shedding light on pathophysiological underpinnings of lingering symptoms. [ABSTRACT FROM AUTHOR]

Background: There is growing concern for the neurological effects of repetitive head impacts in sports, and girls' lacrosse represents a popular but understudied sport regarding head impact exposure. Current debate exists over the need for enhanced protective equipment, and it is important to quantify head impact exposure and biomechanics to inform policy discussions and rule changes for improved protection. Purpose: To quantify the head impact biomechanics, by impact mechanism and direction, of female high school lacrosse players during games using an instrumented mouthguard. Methods: A female high school varsity lacrosse team wore the Stanford Instrumented Mouthguard during competitive games for the 2019 season. Video footage was reviewed to confirm head impact events and remove false-positive recordings. For each impact event, the mechanism was coded as stick contact, player contact, fall, or ball contact, and the site was coded as face/jaw, forehead, crown, side, rear or indirect (i.e. body impact with no head contact). Head impact rates were calculated per athlete exposure (AE, defined as a single player participating in a game). Results: Sensor data were recorded for 15 players for 14 games and 97 AEs. During games, 31 sensor-recorded head impacts were video-confirmed resulting in a pooled average head impact rate of 0.32 impacts/AE. The 31 video-confirmed impacts were distributed among stick contacts (17, 54.8%), player contacts (12, 38.7%), and falls (2, 6.5%). There were no ball impacts. The associated peak kinematics are presented in Figure 1.1. The most common impact site was the side (11, 35.5%), followed by face/jaw (8, 25.8%), forehead (2, 6.5%), and crown (2, 6.5%). There were no impacts to the rear of the head and 8 (25.8%) impacts were indirect. The associated peak kinematics are presented in Figure 1.2. Conclusion: Stick impacts were the most common impact mechanism and resulted in the highest peak linear and angular kinematics, which may help explain why they are the most common cause of head injury in female lacrosse. By quantifying the head impact exposure, kinematics and mechanisms in female high school lacrosse, targeted injury preventions can be developed, such as rule changes and protective equipment. Figure 1.1. Peak linear acceleration (left) and peak angular velocity (right) presented for all impacts and then stratified by impact mechanism. Figure 1.2. Peak linear acceleration (left) and peak angular velocity (right) stratified by impact site. *Peak kinematics for impacts to the face/jaw were significantly higher than all other impact sites (p<0.05). [ABSTRACT FROM AUTHOR]

Background: A home exercise program (HEP) can provide an equitable and cost-effective method for therapy targeted towards visio-vestibular deficits that are common following concussion. It is unclear if pediatric patients prescribed a HEP demonstrate improved visio-vestibular function. Purpose: To explore if a HEP affects visio-vestibular function in concussed pediatric patients. Methods: This observational study included 1,041 patients (614 female(59.0%); age=14.0±2.5 years) reporting to a specialty care concussion center for an initial visit within 28 days of injury and a first follow-up visit within 60 days of injury. All patients completed a Visio-Vestibular Examination (VVE) at both time points, which consisted of 9 maneuvers: smooth pursuit, horizontal/vertical saccades and gaze stability, binocular convergence, left/right monocular accommodation, and complex tandem gait. Patients were given a HEP at initial visit which consisted of exercises, including saccades, gaze stability, convergence, and balance, and instructed to complete these exercises 1-2 times daily. At follow-up, patients were asked to report their progress with the HEP, which was categorized as 1) has not done the HEP, 2) is currently doing the HEP, or 3) has completed the HEP. Primary outcomes included HEP status at first follow-up, VVE subtests (normal/abnormal), and total VVE (abnormal=2+ abnormal subtests). Separate chi-square tests with Bonferroni corrections were used to determine if the proportion of abnormal VVE outcomes was associated with HEP status (α=0.017 a priori). Results: At initial visit, 812 (77.6%) patients presented with abnormal total VVE. The proportion of abnormal subtests at initial visit ranged from 16.0% (right monocular accommodation) to 77.4% (horizontal gaze stability). At first follow-up, the proportion of abnormal total VVE did not differ among patients reporting not doing the HEP (101(62.0%)), patients currently doing the HEP (516(69.0%)), and patients who had completed the HEP (51(69.0%)). However among VVE subtests, a lower proportion of patients who completed the HEP presented with abnormal smooth pursuit (7.5%), horizontal (3.8%) and vertical (3.8%) saccades, and complex tandem gait (0%) relative to patients who were currently doing the HEP (P≤0.003) and to patients not doing the HEP (P≤0.01). Conclusions: Our findings indicate that patients who completed the HEP presented with better aspects of visio-vestibular function (smooth pursuit, saccades, and complex tandem gait) relative to those who did not start or were currently doing the HEP. This suggests that a HEP may be effective in reducing visio-vestibular dysfunction following concussion. Additional research investigating cost-effective concussion management tools is needed to improve patient outcomes. [ABSTRACT FROM AUTHOR]

Background: Exercise intolerance is a manifestation of autonomic nervous system (ANS) dysfunction after concussion. Accommodative amplitude (AA) may be a useful clinical proxy for ANS dysfunction since accommodation is controlled by the ciliary muscle, which is innervated by parasympathetic fibers of the ANS. Hypothesis/Purpose: To determine if concussion influences autonomic control of accommodative amplitude (AA) by comparing measurements before and after exercise in adolescent sport-related concussion (SRC). Methods: Secondary analysis of data from a randomized controlled trial of aerobic exercise after adolescent SRC. Accommodation was measured before and after the Buffalo Concussion Treadmill Test (BCTT). Fisher's exact tests were used to compare AA before and after exercise, while Wilcoxon rank sum was used to assess the relationship between AA and time until clinical recovery. Results: 99 participants (64.6% male, median age 15.7 (IQR 14.5, 16.8)) had AA measured before and after the BCTT at the initial post-injury visit (median 6 days (IQR 4, 8)). Abnormal AA, defined using Hofstetter's age-adjusted formula, was present in 43 (43.4%) pre-exercise and in 45 (45.5%) post-exercise. Abnormal pre- and post-exercise AA were significantly associated (p < 0.001). AA improved with exercise for 9 participants (i.e., changed from abnormal to normal) while it worsened with exercise for 11 (i.e. normal to abnormal). Low heart rate threshold (HRt), defined as HR less than 135 bpm at test cessation due to symptom exacerbation, was significantly associated with abnormal post- (p = 0.005) but not pre-exercise AA (p = 0.225). Participants with abnormal post-exercise AA had significantly longer time to clinical recovery (median 20.5 days (IQR 14.5, 32)) than those with normal post-exercise AA (median 14 days (IQR 10.75, 21.75)) (p = 0.008). Conclusion: Abnormal post-exercise AA is associated with delayed recovery after SRC. Adolescents with low exercise tolerance are more likely to have abnormal AA after exercise, suggesting that concussion-related autonomic dysfunction is precipitated by an aerobic exercise stress test. Abnormal AA after exercise may provide prognostic utility in concussion. [ABSTRACT FROM AUTHOR]