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There are concerns about the effects of subconcussive head impacts in sport, but the effects of subconcussion on brain connectivity are not well understood. We hypothesized that college football players experience changes in brain functional connectivity not found in athletes competing in lower impact sports or healthy controls. These changes may be spatially heterogeneous across participants, requiring analysis methods that go beyond mass-univariate approaches commonly used in functional MRI (fMRI). To test this hypothesis, we analyzed resting-state fMRI data from college football (n = 15), soccer (n = 12), and lacrosse players (n = 16), and controls (n = 29) collected at preseason and postseason time points. Regional homogeneity (ReHo) and degree centrality (DC) were calculated as measures of local and long-range functional connectivity, respectively. Standard voxel-wise analysis and paired support vector machine (SVM) classification studied subconcussion's effects on local and global functional connectivity. Voxel-wise analyses yielded minimal findings, but SVM classification had high accuracy for college football's ReHo (87%, p = 0.009) and no other group. The findings suggest subconcussion results in spatially heterogeneous changes in local functional connectivity that may only be detectible with multivariate analyses. To determine if voxel-wise and SVM analyses had similar spatial patterns, region-average t-statistic and SVM weight values were compared using a measure of ranking distance. T-statistic and SVM weight rankings exhibited significantly low ranking distance values for all groups and metrics, demonstrating that the analyses converged on a similar underlying effect. Overall, this research suggests that subconcussion in football may produce local functional connectivity changes similar to concussion.

As concerns about head impact in American football have grown, similar concerns have started to extend to other sports thought to experience less head impact, such as soccer and lacrosse. However, the amount of head impact experienced in soccer and lacrosse is relatively unknown, particularly compared with the substantial amount of data from football. This pilot study quantifies and compares head impact from four different types of sports teams: college football, high school football, college soccer, and college lacrosse. During the 2013 and 2014 seasons, 61 players wore mastoid patch accelerometers to quantify head impact during official athletic events (i.e., practices and games). In both practices and games, college football players experienced the most or second-most impacts per athletic event, highest average peak resultant linear and rotational acceleration per impact, and highest cumulative linear and rotational acceleration per athletic event. For average peak resultant linear and rotational acceleration per individual impact, college football was followed by high school football, then college lacrosse, and then college soccer, with similar trends in both practices and games. In the four teams under study, college football players experienced a categorically higher burden of head impact. However, for cumulative impact burden, the high school football cohort was not significantly different from the college soccer cohort. The results suggest that head impact in sport substantially varies by both the type of sport (football vs. soccer vs. lacrosse) and level of play (college vs. high school)., Competing Interests: Author Disclosure Statement Max Wintermark is a member of the advisory board of the GE NFL project. All other authors have no conflicts of interest to report.

Background: Concussion and repetitive head impact in sports has increased interest and concern for clinicians, scientists, and athletes. Lacrosse is the fastest growing sport in the United States, but the burden of head impact in lacrosse is unknown., Purpose: The goal of this pilot study was to quantify head impact associated with practicing and playing collegiate lacrosse while subjects were fitted with wearable accelerometers., Study Design: Descriptive epidemiology study., Methods: In a single year, a collegiate cohort of 14 women's and 15 men's lacrosse players wore mastoid-patch accelerometers to measure the frequency and severity of head impacts during official practices and games. Average impact severity, mean number of impacts, and cumulative acceleration were evaluated, stratified by sport and event type., Results: Men's and women's collegiate lacrosse players did not significantly differ in the number of head impacts received during games (11.5 for men vs 9.2 for women) or practices (3.1 vs 3.1). Men's lacrosse players had significantly higher average head acceleration per impact during games compared with women (21.1g vs 14.7g) but not during practices (21.3g vs 18.1g). For both men and women, more impacts occurred during games than during practices (men, 11.5 vs 3.1; women, 9.2 vs 3.1), but impact severity did not significantly differ between events for either sport (men, 21.1g vs 21.3g; women, 14.7g vs 18.1g)., Conclusion: The study data suggest a higher impact burden during games compared with practices, but this effect is driven by the quantity rather than severity of impacts. In contrast, sex-based effects in impact burden are driven by average impact severity rather than quantity. Data collected from larger multisite trials and/or different age groups could be used to inform ongoing debates, including headgear and practice regulations, that might appreciably affect the burden of head impacts in lacrosse., Clinical Relevance: While most head impacts do not result in a clinical diagnosis of concussion, evidence indicates that subconcussive head impacts may increase susceptibility to concussion and contribute to long-term neurodegeneration., (© 2016 The Author(s).)

Objective: To compare baseline scores of middle and high school students on the Sport Concussion Assessment Tool 2 (SCAT2) by sex and age., Design: Cross-sectional study., Setting: Single private school athletic program., Participants: Three hundred sixty-one middle and high school student-athletes., Intervention: Preseason SCAT2 was administered to student-athletes before athletic participation., Main Outcome Measures: Total SCAT2 score, symptoms, symptom severity, Glasgow coma scale, modified Balance Error Scoring System (BESS), coordination, and Standardized Assessment of Concussion (SAC) with subsections: Orientation, Immediate Memory, Concentration, and Delayed Recall., Results: No differences were found in total SCAT2 scores between sex (P = 0.463) or age (P = 0.21). Differences were found in subcomponents of the SCAT2. Twelve year olds had significantly lower concentration scores (3.3 ± 1.2) than 15 and 18 year olds (3.9 ± 1.0 and 4.2 ± 1.0, respectively). The 12 year olds also had the lowest percentage of correct responses for the SAC's concentration 5-digit (46%), 6-digit (21%), and months' backward (67%) tasks. Females presented with more symptoms (20.0 ± 2.2 vs. 20.6 ± 2.1 P = 0.007) better immediate memory (14.6 ± 0.9 vs. 14.3 ± 1.0, P = 0.022) and better BESS scores (27.2 ± 2.3 vs. 26.6 ± 2.6, P = 0.043) than their male counterparts., Conclusions: Normative values for total SCAT2 and subscale scores show differences in concentration between ages, whereas symptoms, BESS, and immediate memory differed between sexes. We also found that 12 year olds have increased difficultly with the advanced concentration tasks, which lends support to the development of a separate instrument, such as the Child-SCAT3. The presence of developmental differences in the younger age groups suggests the need for annual baseline testing., Clinical Relevance: Subtle differences between age and sex have been identified in many components of the SCAT2 assessment. These differences may support the current evolution of concussion assessment tools to provide the most appropriate test. Baseline testing should be used when available, and clinicians should be aware of potential differences when using normalized values.

Given the 2010 position statement issued by the American Academy of Neurology that neurologists be consulted on return-to-play decisions following a concussion, we surveyed members of the Child Neurology Society to asses clinical practice management of concussion among child neurologists. Among the 239 respondents, the majority continued to rely on the American Academy of Neurology's 1997 Practice Parameter to guide their decision-making process. Although the 2008 consensus statement from the Third International Conference on Concussion in Sport (Zurich Guidelines) is currently considered the most up-to-date guideline, few respondents relied exclusively on this guideline. More respondents who completed continuing medical education on concussion reported making clinical decisions based on the Zurich guidelines. The finding that child neurologists who completed continuing medical education had a greater familiarity with the more recently proposed consensus-based concussion guidelines supports the development of additional education in sports concussion at all levels of child neurology training.

Purpose: To determine if motor evoked potentials (MEPs), postconcussion signs and symptoms, and neurocognitive functions follow a similar recovery pattern after concussion., Methods: Nine collegiate athletes with acute concussion (>24 hours after injury) participated in this retrospective time series design. Transcranial magnetic stimulation was applied over the motor cortex, and MEPs were recorded from the contralateral upper extremity. Self-reported symptoms were evaluated using the Head Injury Scale, and the Concussion Resolution Index was used to assess neurocognitive function. All measures were repeated on days 3, 5, and 10 after injury., Results: Composite scores on the Head Injury Scale were significantly higher on day 1 after injury (F3,51 = 15.3; P = 0.0001). Processing speed on the Concussion Resolution Index was slower on days 1, 3, and 5 compared with that on day 10 (F3,24 = 6.75; P = 0.0002). Median MEP latencies were significantly longer on day 10 compared with day 1 after concussion (t8 = -2.69; P = 0.03). Ulnar MEP amplitudes were significantly smaller on day 3 after concussion compared with day 5 (t8 = -3.48; P = 0.008)., Conclusions: Acutely concussed collegiate athletes demonstrate changes in MEPs, which persist for up to 10 days after injury and do not follow the same recovery pattern as symptoms and neuropsychological test performance. The apparent differential rates of recovery most likely indicate different pathophysiological processes occurring in the immediate postconcussion period.

Background: Assessment of concussion is primarily based on self-reported symptoms, neurological examination and neuropsychological testing. The neurophysiologic sequelae and the integrity of the corticomotor pathways could be obtained by evaluating motor evoked potentials (MEPs)., Objectives: To compare MEPs obtained through transcranial magnetic stimulation (TMS) in acutely concussed and non-concussed collegiate athletes., Methods: Eighteen collegiate athletes (12 males, six females, aged 20.4 +/- 1.3 years) including nine subjects with acute concussion ( 0.05)., Conclusion: MEP abnormalities among acutely concussed collegiate athletes provide direct electrophysiologic evidence for the immediate effects of concussion.

Current consensus guidelines recommending physical and cognitive rest until a patient is asymptomatic after a sports concussion (ie, a mild traumatic brain injury) are being called into question, particularly for patients who are slower to recover and in light of preclinical and clinical research demonstrating that exercise aids neurorehabilitation. The pathophysiological response to mild traumatic brain injury includes a complex neurometabolic cascade of events resulting in a neurologic energy deficit. It has been proposed that this energy deficit leads to a period of vulnerability during which the brain is at risk for additional injury, explains why early postconcussive symptoms are exacerbated by cognitive and physical exertion, and is used to rationalize absolute rest until all symptoms have resolved. However, at some point, rest might no longer be beneficial and exercise might need to be introduced. At both extremes, excessive exertion and prolonged avoidance of exercise (physical and mental) have negative consequences. Individuals who have experienced a concussion need guidance for avoidance of triggers of severe symptoms and a plan for graduated exercise to promote recovery as well as optimal functioning (physical, educational, and social) during the postconcussion period. [ABSTRACT FROM AUTHOR]