Head acceleration event exposure and cognitive and functional outcomes: a comparison of multiple football seasons.

Athletes in contact sports are exposed to repetitive impacts as an inherent part of sport. There is concern over the accumulative effect; however, much is still unknown regarding their short-term effects. This study investigated impact accumulation and outcomes over three seasons (2015, 2017, 2019) in NCAA Football Bowl Subdivision players. Impacts were recorded using helmet accelerometers, and virtual reality testing (VR) was done across the season. Incidence rates for impacts (total; ≥25 G to <80 G; ≥80 G) all significantly differed by season (p < 0.05). VR scores changed across the seasons, specifically significant decreases in spatial memory (p < 0.05) in 2015, significant changes in balance and spatial memory (p < 0.05) in 2017, and no significant changes in 2019. Linear regressions predicting VR change score by impact incidence rate were nonsignificant. Monitoring exposure to impacts and changes in outcomes is useful; however, results are fluid, and many factors could indirectly have protective effects on athletes.

KIAA0319 Genotype Predicts the Number of Past Concussions in a Division I Football Team: A Pilot Study.

This candidate gene study evaluated the relationship of a past history of concussion with single nucleotide polymorphisms (SNPs) in nine genes in a small cohort (N = 87) of a nationally ranked Division I football team. Genes and SNPs studied were selected based on their published connection to brain injury and brain development, as well as impulsivity. We used multinomial logistic regression analysis (MLRA) to quantify how well genotype predicted the number of previously diagnosed concussions (three categories: none, one, two or more), while covarying race and number of years participating in football. The rs4504469 SNP for KIAA0319 was the only locus that significantly predicted number of previously diagnosed concussions (p = 0.005, meeting Bonferroni correction for multiple comparisons). The KIAA0319 results raise the hypothesis that having the CT or TT genotype of KIAA0319 may be predictive of a lower incidence of previously diagnosed concussion. This finding raises a number of hypotheses for future pre-clinical research, particularly whether alterations in neural organization related to KIAA0319 rs4504469 lead to reduced susceptibility for lasting head trauma, or greater resilience in the face of repeated subconcussive injury.

Elevations in MicroRNA Biomarkers in Serum Are Associated with Measures of Concussion, Neurocognitive Function, and Subconcussive Trauma over a Single National Collegiate Athletic Association Division I Season in Collegiate Football Players.

This prospective controlled observational cohort study assessed the performance of a novel panel of serum microRNA (miRNA) biomarkers on indicators of concussion, subconcussive impacts, and neurocognitive function in collegiate football players over the playing season. Male collegiate student football athletes participating in a Division I Football Bowl Subdivision of the National Collegiate Athletic Association (NCAA) were enrolled. There were a total of 53 participants included in the study, 30 non-athlete control subjects and 23 male collegiate student football athletes. Neurocognitive assessments and blood samples were taken within the week before the athletic season began and within the week after the last game of the season and measured for a panel of pre-selected miRNA biomarkers. All the athletes had elevated levels of circulating miRNAs at the beginning of the season compared with control subjects (p < 0.001). Athletes with the lowest standard assessment of concussion (SAC) scores at the beginning of the season had the highest levels of miRNAs. The area under the curve (AUC) for predicting pre-season SAC scores were miR-195 (0.90), miR-20a (0.89), miR-151-5p (0.86), miR-505* (0.85), miR-9-3p (0.77), and miR-362-3p (0.76). In athletes with declining neurocognitive function over the season, concentrations of miRNAs increased over same period. There were significant negative correlations with miR-505* (p = 0.011), miR-30d (p = 0.007), miR-92 (p = 0.033), and (p = 0.008). The miRNAs correlating with balance problems were miR-505* (p = 0.007), miR-30d (p = 0.028), and miR-151-5p (p = 0.023). Those correlating with poor reaction times were miR-20a (0.043), miR-505* (p = 0.049), miR-30d (p = 0.031), miR-92 (p = 0.015), and miR-151-5p (p = 0.044). Select miRNAs were associated with baseline concussion assessments at the beginning of the season and with neurocognitive changes from pre to post-season in collegiate football players. Should these findings be replicated in a larger cohort of athletes, these markers could potentially serve as measures of neurocognitive status in athletes at risk for concussion and subconcussive injuries.

The effect of repetitive subconcussive collisions on brain integrity in collegiate football players over a single football season: A multi-modal neuroimaging study.

The cumulative effect of repetitive subconcussive collisions on the structural and functional integrity of the brain remains largely unknown. Athletes in collision sports, like football, experience a large number of impacts across a single season of play. The majority of these impacts, however, are generally overlooked, and their long-term consequences remain poorly understood. This study sought to examine the effects of repetitive collisions across a single competitive season in NCAA Football Bowl Subdivision athletes using advanced neuroimaging approaches. Players were evaluated before and after the season using multiple MRI sequences, including T1-weighted imaging, diffusion tensor imaging (DTI), arterial spin labeling (ASL), resting-state functional MRI (rs-fMRI), and susceptibility weighted imaging (SWI). While no significant differences were found between pre- and post-season for DTI metrics or cortical volumes, seed-based analysis of rs-fMRI revealed significant (p < 0.05) changes in functional connections to right isthmus of the cingulate cortex (ICC), left ICC, and left hippocampus. ASL data revealed significant (p < 0.05) increases in global cerebral blood flow (CBF), with a specific regional increase in right postcentral gyrus. SWI data revealed that 44% of the players exhibited outlier rates (p < 0.05) of regional decreases in SWI signal. Of key interest, athletes in whom changes in rs-fMRI, CBF and SWI were observed were more likely to have experienced high G impacts on a daily basis. These findings are indicative of potential pathophysiological changes in brain integrity arising from only a single season of participation in the NCAA Football Bowl Subdivision, even in the absence of clinical symptoms or a diagnosis of concussion. Whether these changes reflect compensatory adaptation to cumulative head impacts or more lasting alteration of brain integrity remains to be further explored.

Cervical neurapraxia in elite athletes: evaluation and surgical treatment. Report of five cases.

OBJECT: Neurapraxia, transient posttraumatic paralysis of the motor and/or sensory tracts in the spinal cord, may be a career-ending event in an athlete. Management, rehabilitation, and return-to-play decisions remain controversial. METHODS: Five elite football players were evaluated after experiencing episodes of neurapraxia. All patients experienced bilateral paresthesias--three in all four extremities and two in the upper extremities--lasting a few minutes to more than 24 hours. Transient motor deficits occurred in two individuals but caused no permanent sequelae. Neuroimaging confirmed the presence of herniated discs, focal cord compression, and no parenchymal changes in all cases. All patients underwent anterior cervical microdiscectomy and fusion, and cervical plates were placed in four. After aggressive rehabilitation and confirmation of fusion ranging from 9 weeks to 8 months postoperatively, the players were allowed to return to active play. Two of the players developed recurrent career-ending disc herniations, one above and the other below the fusion level. One player required repeated spinal cord decompression. CONCLUSIONS: Neurologically intact athletes with focal cord compression due to a single-level herniated disc may safely return to football after undergoing decompressive surgery and confirmation of fusion. It appears, however, that there may be an increased chance of repeated herniation above or below a fused level.