In parallel with recognition of concussions as an increasing occurrence in sports the development of tools to help guide decision-making during sporting events has become a priority. Ideally, patients with concussions would be evaluated and cleared by physicians and this remains the medical recommendation. Both National Football League (NFL) and collegiate athletics in the United States have the resources to implement these protective personnel due to the robust financial revenue streams from media contracts. The NFL requires teams to have a neurologist or neurosurgeon on the sidelines. Many collegiate sports have designated trainers that work with athletes throughout the season. Conversely, amateur leagues and most importantly youth sports lack the presence of clinicians or trainers with the ability to detect and intervene on a player's behalf. This underscores the ground level need and the opportunity for a basic yet highly predictive sideline test that can be performed by laypersons during a game to determine concussive as well as sub-concussive events.
Most researchers believe that the rate of concussion injury in sport is underreported due to the lack of a test to help establish the existence of a concussion. King et al, J of Neurological Sciences 326 (2013) pgs 59-63. describe a prospective observational cohort study using a visual assessment tool to identify concussions that occurred throughout a season of a club level premier team of the New Zealand amateur rugby union. Researchers first administered a previous concussion history questionnaire to each of the 37 players (age; 22.0 ± 4.0 yr.), a baseline Post-Concussion Symptom Scale (PCSS), and two trials of the King-Devick (KD) visual screening test to obtain baseline readings prior to any match participation. Over the course of the season, all players were to complete a KD test every post-match to test for unrecognized concussion incidents and any players who exhibited any signs of concussion or were suspected of having a head injury were removed from play and administered the KD test. Additionally, in order to address the concern of fatigue as a contributing factor to the decline of a KD score, players were administered the KD test two minutes after a modified repeat high intensity endurance test (RHIET), which included a series of intensive sprints.
The baseline evaluation tests showed significantly more players (81.1%) reporting a previous sport related concussion than those who did not report a previous concussion, with an average of 4.0 ± 2.8 concussions per player in the previous three years. Over a season of 24 games with a match exposure of 478.8 hours, there were a total of 22 recorded concussive incidents. Five concussive incidents were witnessed (11 per 1000 match hours) and 17 unrecognized concussive incidents (37 per 1000 match hours) were reportedly identified with the KD test (Table 1 from paper). A decline in KD test taking time of about 5 seconds was indicative of changes in oculomotor function associated with mild-traumatic brain injury. These results are significant in that they show a large disparity between witnessed and identified concussions and unrecognized concussive incidents with meaningful head injury, which when combined amount to a ten-fold increase in the previously reported concussion injury rate. Further, the results of the KD test following RHIET showed a lowering of the baseline by a mean of 1.2 seconds, which suggest that fatigue does not contribute to a longer KD test time and actually improved KD score post exercise.
The need for sideline rapid assessment of mild head injury is fundamental to limiting the deleterious effects of repeated impacts to the head. The great majority of athletes are at the youth sports level and not in collegiate or professional sports, which leaves many important decisions to be made by parents and coaches on the sideline. This structural element of sport is unlikely to change since allocating medically trained people to youth sports will require unavailable financial resources. Accordingly, empowering adults to administer a simple, rapid, yet effective test is paramount to preventing repeated head injury. As increasing evidence suggests that even mild impact to the head can lead to accruing neuropathology, it may be prudent to routinely perform sideline testing for players involved in even modest collisions. This could help avoid return to play of athletes with sub-concussive impacts as knowledge about head injury continues to evolve.