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OBJECTIVE: Previous studies have shown that clinically asymptomatic high-acceleration head impacts (HHIs) may be associated with neuronal and axonal injury, as measured by advanced imaging and biomarkers. Unfortunately, these methods of measurement are time-consuming, invasive, and costly. A quick noninvasive measurement tool is needed to aid studies of head injury and its biological impact. Quantitative pupillometry is a potential objective, rapid, noninvasive measurement tool that may be used to assess the neurological effects of HHIs. In this study, the authors investigated the effect of HHIs on pupillary metrics, as measured using a pupillometer, in the absence of a diagnosed concussion. METHODS: A prospective observational cohort study involving 18 high school football athletes was performed. These athletes were monitored for both the frequency and magnitude of head impacts that they sustained throughout a playing season by using the Head Impact Telemetry System. An HHI was defined as an impact exceeding 95g linear acceleration and 3760 rad/sec2 rotational acceleration. Pupillary assessments were performed at baseline, midseason, after occurrence of an HHI, and at the end of the season by using the NeurOptics NPi-200 pupillometer. The Sport Concussion Assessment Tool, 5th Edition (SCAT5), was also used at each time point. Comparisons of data obtained at the various time points were calculated using a repeated-measures analysis of variance and a t-test. RESULTS: Seven athletes sustained HHIs without a related diagnosed concussion. Following these HHIs, the athletes demonstrated decreases in pupil dilation velocity (mean difference 0.139 mm/sec; p = 0.048), percent change in pupil diameter (mean difference 3.643%; p = 0.002), and maximum constriction velocity (mean difference 0.744 mm/sec; p = 0.010), compared to measurements obtained at the athletes' own midseason evaluations. No significant changes occurred between the SCAT5 subtest scores calculated at midseason and those after a high impact, although the effect sizes (Cohen's d) on individual components ranged from 0.41 to 0.65. CONCLUSIONS: Measurable changes in pupil response were demonstrated following an HHI. These results suggest that clinically asymptomatic HHIs may affect brain reflex pathways, reflecting a biological injury previously seen when more invasive methods were applied.
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OBJECTIVEThis prospective observational cohort study of high-school football athletes was performed to determine if high-acceleration head impacts (HHIs) that do not result in clinically diagnosed concussion still lead to increases in serum levels of biomarkers indicating traumatic brain injury (TBI) in asymptomatic athletes and to determine the longitudinal profile of these biomarkers over the course of the football season.METHODSSixteen varsity high-school football athletes underwent baseline neurocognitive testing and blood sampling for the biomarkers tau, ubiquitin C-terminal hydrolase L1 (UCH-L1), neurofilament light protein (NF-L), glial fibrillary acidic protein (GFAP), and spectrin breakdown products (SBDPs). All athletes wore helmet-based accelerometers to measure and record head impact data during all practices and games. At various time points during the season, 6 of these athletes met the criteria for HHI (linear acceleration > 95g and rotational acceleration > 3760 rad/sec2); in these athletes a second blood sample was drawn at the end of the athletic event during which the HHI occurred. Five athletes who did not meet the criteria for HHI underwent repeat blood sampling following the final game of the season. In a separate analysis, all athletes who did not receive a diagnosis of concussion during the season (n = 12) underwent repeat neurocognitive testing and blood sampling after the end of the season.RESULTSTotal tau levels increased 492.6% ± 109.8% from baseline to postsession values in athletes who received an HHI, compared with 164% ± 35% in athletes who did not receive an HHI (p = 0.03). Similarly, UCH-L1 levels increased 738.2% ± 163.3% in athletes following an HHI, compared with 237.7% ± 71.9% in athletes in whom there was no HHI (p = 0.03). At the end of the season, researchers found that tau levels had increased 0.6 ± 0.2 pg/ml (p = 0.003) and UCH-L1 levels had increased 144.3 ± 56 pg/ml (p = 0.002). No significant elevations in serum NF-L, GFAP, or SBDPs were seen between baseline and end-of-athletic event or end-of-season sampling (for all, p > 0.05).CONCLUSIONSIn this pilot study on asymptomatic football athletes, an HHI was associated with increased markers of neuronal (UCH-L1) and axonal (tau) injury when compared with values in control athletes. These same markers were also increased in nonconcussed athletes following the football season.
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OBJECTIVE The authors of recent concussion guidelines have sought to form a consensus on injury management, but it is unclear if they have been effective in conveying this information to the public. Many parents and athletes obtain medical recommendations via the Internet. This review is aimed at evaluating consistency between online resources and published guideline statements in postconcussion return-to-play (RTP) decisions. METHODS Five websites were selected through a Google search for RTP after concussion, including a federal government institution (Centers for Disease Control and Prevention) website, a national high school association (National Federation of State High School Associations) website, a popular nationally recognized medical website for patients (WebMD), a popular parent-driven website for parents of children who participate in sports (MomsTeam), and the website of a private concussion clinic (Sports Concussion Institute), along with a university hospital website (University of Michigan Medicine). Eight specific items from the Zurich Sport Concussion Consensus Statement 2012 were used as the gold standard for RTP recommendations. Three independent reviewers graded each website for each of the 8 recommendations (A = states guideline recommendations appropriately; B = mentions guideline recommendation; C = does not mention guideline recommendation; F = makes inappropriate recommendation). RESULTS A grade of A was assigned for 45.8% of the recommendations, B for 25.0%, C for 25.0%, and F for 4.2%. All the websites were assigned an A grade for the recommendation of no RTP on the day of injury. Only 1 website (WebMD) mentioned medication usage in conjunction with the Zurich statement, and only 2 websites (Sports Concussion Institute and University of Michigan Medicine) mentioned appropriate management of persistent symptoms. None of these websites commented correctly on all 8 guideline recommendations. CONCLUSIONS Online resources are inconsistent in relaying guideline recommendations for RTP and provide a potential source of confusion in the management of concussion for athletes and their parents, which can result in inappropriate RTP decisions.