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Background and Purpose: The purpose of the study is to characterize diffusion tensor imaging indices in the developing spinal cord, evaluating differences based on age and cord region. Describing the progression of DTI indices in the pediatric cord increases our understanding of spinal cord development., Materials and Methods: A retrospective analysis was performed on DTI acquired in 121 pediatric patients (mean, 8.6 years; range, 0.3-18.0 years) at Monroe Carell Jr. Children's Hospital at Vanderbilt from 2017 to 2018. Diffusion-weighted images (15 directions; b = 750 s/mm 2 ; slice thickness, 5 mm; in-plane resolution, 1.0 × 1.0 mm 2 ) were acquired on a 3T scanner in the cervicothoracic and/or thoracolumbar cord. Manual whole-cord segmentation was performed. Images were masked and further segmented into cervical, upper thoracic, thoracolumbar, and conus regions. Analyses of covariance were performed for each DTI-derived index to investigate how age affects diffusion across cord regions, and 95% confidence intervals were calculated across age for each derived index and region. Post hoc testing was performed to analyze regional differences., Results: Analyses of covariance revealed significant correlations of age with axial diffusivity, mean diffusivity, and fractional anisotropy (all, P < .001). There were also significant differences among cord regions for axial diffusivity, radial diffusivity, mean diffusivity, and fractional anisotropy (all, P < .001)., Conclusions: This research demonstrates that diffusion evolves in the pediatric spinal cord during development, dependent on both cord region and the diffusion index of interest. Future research could investigate how diffusion may be affected by common pediatric spinal pathologies., (© 2019 by American Journal of Neuroradiology.)

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.

Objective: While epilepsy studies rarely examine brainstem, we sought to examine the hypothesis that temporal lobe epilepsy (TLE) leads to subcortical arousal center dysfunction, contributing to neocortical connectivity and neurocognitive disturbances., Methods: In this case-control study of 26 adult patients with TLE and 26 controls, we used MRI to measure structural and functional connectivity of the cuneiform/subcuneiform nuclei (CSC), pedunculopontine nucleus, and ventral tegmental area. Ascending reticular activating system connectivity patterns were related to neuropsychological and disease measures., Results: Compared to controls, patients with TLE demonstrated reductions in ascending reticular activating system structural and functional connectivity, most prominently to neocortical regions ( p < 0.05, unpaired t tests, corrected). While reduced CSC structural connectivity was related to impaired performance IQ and visuospatial memory, diminished CSC functional connectivity was associated with impaired verbal IQ and language abilities ( p < 0.05, Spearman ρ, t tests). Finally, CSC structural connectivity decreases were quantitatively associated with consciousness-impairing seizure frequency ( p < 0.05, Spearman ρ) and the presence of generalized seizures ( p < 0.05, unpaired t test), suggesting a relationship to disease severity., Conclusions: Connectivity perturbations in brainstem arousal centers are present in TLE and may contribute to neurocognitive problems. These studies demonstrate the underappreciated role of brainstem networks in epilepsy and may lead to novel neuromodulation targets to treat or prevent deleterious brain network effects of seizures in TLE., (© 2018 American Academy of Neurology.)

Objective: Amid the public health controversy surrounding American football, a helmet that can reduce linear and rotational acceleration has the potential to decrease forces transmitted to the brain. The authors hypothesized that a football helmet with an outer shell would reduce both linear and rotational acceleration. The authors' objectives were to 1) determine an optimal material for a shock-absorbing outer shell and 2) examine the ability of an outer shell to reduce linear and/or rotational acceleration., Methods: A laboratory-based investigation was undertaken using an extra-large Riddell Revolution football helmet. Two materials (Dow Corning Dilatant Compound and Sorbothane) were selected for their non-Newtonian properties (changes in viscosity with shear stress) to develop an outer shell. External pads were attached securely to the helmet at 3 locations: the front boss, the side, and the back. The helmet was impacted 5 times per location at 6 m/sec with pneumatic ram testing. Two-sample t-tests were used to evaluate linear/rotational acceleration differences between a helmet with and a helmet without the outer shell., Results: Sorbothane was superior to the Dow Corning compound in force reduction and recovered from impact without permanent deformation. Of 5 different grades, 70-duro (a unit of hardness measured with a durometer) Sorbothane was found to have the greatest energy dissipation and stiffness, and it was chosen as the optimal outer-shell material. The helmet prototype with the outer shell reduced linear acceleration by 5.8% (from 75.4g to 71.1g; p < 0.001) and 10.8% (from 89.5g to 79.8g; p = 0.033) at the side and front boss locations, respectively, and reduced rotational acceleration by 49.8% (from 9312.8 rad/sec2 to 4671.7 rad/sed2; p < 0.001) at the front boss location., Conclusions: Sorbothane (70 duro) was chosen as the optimal outer-shell material. In the outer-shell prototype helmet, the results demonstrated a 5%-10% reduction in linear acceleration at the side and front boss locations, and a 50% reduction in rotational acceleration at the front boss location. Given the paucity of publicly reported helmet-design literature and the importance of rotational acceleration in head injuries, the substantial reduction seen in rotational acceleration with this outer-shell prototype holds the potential for future helmet-design improvements.

Background: The effects of head impact in sports are of growing interest for clinicians, scientists, and athletes. Soccer is the most popular sport worldwide, but the burden of head impact in collegiate soccer is still unknown., Purpose: To quantify head impact associated with practicing and playing collegiate soccer using wearable accelerometers., Study Design: Descriptive epidemiological study., Methods: Mastoid patch accelerometers were used to quantify head impact in soccer, examining differences in head impact as a function of sex and event type (practice vs game). Seven female and 14 male collegiate soccer players wore mastoid patch accelerometers that measured head impacts during team events. Data were summarized for each athletic exposure, and statistical analyses evaluated the mean number of impacts, mean peak linear acceleration, mean peak rotational acceleration, and cumulative linear and rotational acceleration, each grouped by sex and event type., Results: There were no differences in the frequency or severity of head impacts between men's and women's soccer practices. For men's soccer, games resulted in 285% more head impacts than practices, but there were no event-type differences in mean impact severity. Men's soccer games resulted in more head impacts than practices across nearly all measured impact severities, which also resulted in men's soccer games producing a greater cumulative impact burden., Conclusion: Similar to other sports, men's soccer games have a greater impact burden when compared with practices, and this effect is driven by the quantity rather than severity of head impacts. In contrast, there were no differences in the quantity or severity of head impacts in men's and women's soccer practices. These data could prompt discussions of practical concern to collegiate soccer, such as understanding sex differences in head impact and whether games disproportionately contribute to an athlete's head impact burden., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: This study was funded by the University of Virginia Health System Research Award, NIH 2 T32 GM 8328-21, and the University of Virginia Department of Radiology and Medical Imaging. M.W. is a member of the advisory board of the GE NFL project.

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).)

Unlabelled: OBJECT IVE: This study directly compares the number and severity of subconcussive head impacts sustained during helmet-only practices, shell practices, full-pad practices, and competitive games in a National Collegiate Athletic Association (NCAA) Division I-A football team. The goal of the study was to determine whether subconcussive head impact in collegiate athletes varies with practice type, which is currently unregulated by the NCAA., Methods: Over an entire season, a cohort of 20 collegiate football players wore impact-sensing mastoid patches that measured the linear and rotational acceleration of all head impacts during a total of 890 athletic exposures. Data were analyzed to compare the number of head impacts, head impact burden, and average impact severity during helmet-only, shell, and full-pad practices, and games., Results: Helmet-only, shell, and full-pad practices and games all significantly differed from each other (p ≤ 0.05) in the mean number of impacts for each event, with the number of impacts being greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. The cumulative distributions for both linear and rotational acceleration differed between all event types (p < 0.01), with the acceleration distribution being similarly greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. For both linear and rotational acceleration, helmet-only practices had a lower average impact severity when compared with other event types (p < 0.001). However, the average impact severity did not differ between any comparisons of shell and full-pad practices, and games., Conclusions: Helmet-only, shell, and full-pad practices, and games result in distinct head impact profiles per event, with each succeeding event type receiving more impacts than the one before. Both the number of head impacts and cumulative impact burden during practice are categorically less than in games. In practice events, the number and cumulative burden of head impacts per event increases with the amount of equipment worn. The average severity of individual impacts is relatively consistent across event types, with the exception of helmet-only practices. The number of hits experienced during each event type is the main driver of event type differences in impact burden per athletic exposure, rather than the average severity of impacts that occur during the event. These findings suggest that regulation of practice equipment could be a fair and effective way to substantially reduce subconcussive head impact in thousands of collegiate football players.