Home » Underreporting of Concussions: Is Monitoring Head Impact Exposure A Way Around The Problem?

Underreporting of Concussions: Is Monitoring Head Impact Exposure A Way Around The Problem?


One of the biggest hurdles to appropriate clinical management of sports concussion is identifying athletes for an initial assessment on the sports sideline.  Many sports concussion go undetected, say experts, either because athletes don't recognize that they have symptoms of concussion [19] or fail to self-report such symptoms, or because sideline personnel or game officials lack the necessary training and experience to identify an athlete requiring assessment.

Early identification on the sports sideline of suspected concussion is critical because, in most cases, athletes who are immediately removed from contact or collision sports after suffering a concussion or other traumatic brain injury (TBI) will recover without incident fairly quickly (although a 2012 study [5] suggests that full cognitive function may take longer to return for high school student-athletes, especially girls). If an athlete is allowed to keep playing, however, their recovery is likely to take longer, and they are at increased risk of long-term problems (e.g. early dementia, depression, more rapid aging of the brain, and in rare cases, chronic traumatic encephalopathy, and in extremely rare instances, catastrophic injury or death.

Chronic under-reporting 

The evidence that concussions are significantly underreported, and that increased education alone is not likely to solve the problem anytime soon, is substantial. [1-4, 9,10, 13, 16-18-22]  For instance: 

  • An oft-cited 2004 study [1] pegged the percentage of concussions that weren't reported at more than 50%;
  • A 2010 study [2] of two Canadian junior ice hockey teams comprised of athletes ranging in ages from 16 to 21 found that for every concussion self-reported by the players or identified by the coaches or on-the-bench medical personnel physician observers in the stands picked up seven, a rate of 21.5 concussions per 1,000 man-games, or nearly seven times greater than the 3.1 concussions per 1,000 man-games reported in an earlier study of NCAA Division I hockey programs; [3]
  • A 2012 anonymous online survey [4] of college athletes at the University of Pennsylvania reported that 27% of athletes in contact sports said they had hidden a concussion to stay in a game, and more than half (54%) said they would be extremely unlikely or unlikely to report a concussion in a game situation, similar to the 30.4% of athletes who admitted to continuing to play while experiencing symptoms after being hit in the head reported in a 2003 study, with the percentage of football players exhibiting this behavior even higher (61.2%). [10]
  • A 2012 study [9] of men's and women's university hockey teams in Canada found a significantly higher concussion rate than previous studies, which the authors noted, had depended on either the retrospective self-reporting of athletes who are reluctant to report their injuries or the judgment of a certified athletic trainer.  
  • A 2013 study [13] of 120 high school football players, 30 of whom had suffered a concussion and 82 of whom had reported receiving prior concussion education, found that, while most correctly recognized the symptoms of concussion and 9 out of 10 recognized the risk of serious injury if they returned to play too quickly:
    • an astounding 91 percent felt that it was okay for an athlete to play with a concussion
    • 75 percent said they would play through any injury to win a game
    • 53 percent said they would "always or sometimes continue to play with a headache sustained from an injury,"
    • Only 54 percent would "always or sometimes report symptoms of a concussion to their coach," and
    • Only 4 in 10 would tell their coach immediately if they had concussion symptoms.G-force comparison
  • A 2013 study [16] found that as many as four out of ten of possible concussions sustained by high school athletes are never reported to a coach or medical professional, with less than one in seven 'bell-ringers' being reported;
    • A total of 89 athletes (53.3%) recalled having at least one possible concussion or bell-ringer event duiring their high school years. Of the 89 athletes, only 15 (16.9%)  said they reported all concussive bell-ringer events to a coach or medical professional;
    • Of the 84 recalled concussions, only 41 (48.8%) were reported to a coach or medical professional;
    • Participants recalled a total of 584 bell-ringer events; of these only 72 (12.3%) were reported;
    • Athletes reported only 22.8% of concussion or bell-ringer events to a coach or medical professiona which occurred during games. 
    • Of the 348 concussion or bell-ringer events occuring during practice, only 40 (11.5%) were reported;
    • 37.7% of the athletes indicated that they had continued participating in a practice or game at least once while experiencing signs and symptoms of concussion.
    • Consistent with the 2004 study [1] athletes gave as the reason for not reporting that:
      • they did not think the injury was serious enough to report (70.2%);
      • they did not want to be removed from the game (36.5%);
      • they did not want to let down teammates (27.0%)
      • they did not want to let down coaches (23.0%);
      • they did not know the event was a concussion (14.9%); or
      • they did not want to be removed from practice (13.5%).
  • Another 2013 study [18] found that, among male college hockey players who suspected that they had a concussion during the previous season but did not report their injury:
    • fully half (50.6%) stated that they did not report it because they did not know it was a concussion;
    • 7 out of 10 (69.7%) because they did not think it was serious enough;
    • close to half (48.3%) because they did not want to be pulled out of the game or practice; and
    • a third (32.6%) because they did not want to let down their teammates. 

"The findings concerning identification and reporting," said the authors of a 2013 study, [17] are particularly alarming given the growing body of both short-term and long-term issues associated with concussive injuries, such as psychological issues, school-related problems, increased risk of subsequent concussions and potential quality-of-life issues associated with concussions."

Reasons largely cultural

Despite increased awareness about concussions in recent years, some of those involved in contact and collision sports still don't seem as concerned as they should be about the risks.  The Canadian hockey study, [2] for example, "described a culture in which concussions were not treated as a serious health issue or, it seemed, an issue at all. Players described being under pressure from their coaches to continue playing even when they'd been told by medical professionals that they'd suffered concussions and should take time off."

The attitudes of some of the Canadian hockey parents was even more puzzling. One told the research team that it should leave the team and let his child go back to thinking about hockey instead of the potential for injury." [2]  "The reluctance to report concussion symptoms and to follow protocols [were] likely results from certain cultural factors such as athletes asserting their masculinity by playing through the discomfort of an injury, and a belief that winning is more important than an athlete's long-term health," said lead author, Paul Echlin, M.D. There is no reason to believe that athletes playing football and other contact and collision sports in the United States are any different.

While all but three states now have laws requiring immediate removal from play of athletes with concussion signs or symptoms and prohibit same-day return to play for those with suspected concussion, some are concerned that such laws may have the perverse effect of making the under-reporting problem even worse, fearing that an athlete is going to be even less likely to self-report experiencing concussion symptoms and more likely to hide symptoms from teammates, game officials and sideline personnel if they know that a suspected concussion may sideline them for the rest of the game.

Education and changing the culture: can they work?

Many concussion experts [3,13,16] recognize that concussion education, while important, is not likely to increase reporting by itself - a fact buttressed by the findings of several recent studies [13, 14, 16,17,18] that suggest that greater concussion knowledge alone does not change reporting attitudes - and that a multi-pronged approach to the problem is required, including creating a safe reporting environment and working to change the culture.

"Clinicians, parents, and coaches should make concussion education and awareness a priority, and address factors to provide a more optimal concussion-reporting environment," says Johna Register-Mihalik, Ph.D, LAT, ATC,  Adjunct Assistant Professor in the Department of Exercise and Sport Science at the University of North Carolina at Chapel Hill and lead author of the one of the recent studies on underreporting. [16]

Register-Mihalik and her colleagues say both are needed, because, as acknowledged in the study, "knowledge alone does not equal behavior."  In other words, she says,"individuals may understand and believe that concussion is a serious injury and even a medical concern; however, if they also believe that their peers or coaches will take issue with their reporting their injury or that they may lose substantial playing time, they may still choose not to report the injury."  

"Parents also play a key role in driving coaches to be aware and to create this environment at home," Register-Mihalik told MomsTEAM.  "Certainly, the culture of the 'warrior mentality' plays a role in not reporting these events," she observed, "but some of it is also an awareness issue, and we have a great opportunity, with so much attention around concussion, to increase knowledge in this area."

Progress, but long way to go

"We are certainly seeing changes at many levels of sport in the right direction, but still have a long way to go." Register-Mihalik told MomsTEAM.  "I do think there are things we can continue to do in the here and now that will result in immediate effects, especially when local individuals are advocates for concussion education and sport safety. However, it is true that historically culture change does take years."

"One approach ... is to start at the youngest ages of sport so that individuals carry good attitudes about sports safety and concussion throughout their lives. It is also important that, in addition to this bottom up approach, that we have things trickle down from the top so that information is flowing in both directions, creating a more comprehensive safety network across sport."

"Now that we have many people attentive to concussion, we need to make sure the right message is getting to the right people, in communities of all types. This involves community networking including parents, coaches, administrators and medical professionals at the local, state, regional and national levels working together," Register-Mihalik concluded.

Can technology help?

Recognizing that Increased education, by itself, does not appear to be effective in increasing the rate of self-reporting by athletes, has lead some, including Brit Anderson, MD, an emergency medicine fellow at Cincinnati Children's Hospital and the lead author of one of the most recent studies, to conclude that "other approaches, such as an increased use of sideline screening by coaches or athletic trainers, might be needed to identify injured athletes." [14]

Some also believe that one of the ways to combat the problem of under-reporting may be to avoid relying so much on athletes to honestly self-report, or on game officials and/or sideline observers to call for a concussion assessment, but to instead employ technology to get around the problem altogether through widespread real-time monitoring of head impact exposure (e.g. number, severity, location, and cumulative impact) at all levels of football, and other helmeted and non-helmeted contact and collision sports where practical, to identify high risk impacts and alert medical personnel on the sideline to perform a concussion assessment. [6,11,12,15] 

"The identification of a potentially injurious impact or series of impacts via real-time monitoring of head impact exposure in athletes may [not only] facilitate the early recognition and management of brain injury in helmeted sports," argues Richard M. Greenwald, PhD of the Thayer School of Engineering at Dartmouth College, lead author of an editorial in the March 2012 Clinical Journal of Sports Medicine, [6] but "permit early intervention, potentially in advance of an injury, rather than simply as a management tool postinjury."

Benefits of real-time hit monitoring  

While monitoring is designed to help in early identification of concussion and will not prevent brain injuries from occuring in the initial instance, the benefits of early identification, including prevention of further injury, are numerous:

  • Sideline personnel will benefit from objective data that might inform their medical decisions; [6,11,13,15]
  • Parents will benefit from reduced reliance on honest self-reporting of concussion symptoms by athletes and of the less-than-perfect observational skills of sideline management in spotting signs of concussion;
  • Teams will benefit by having healthy, unimpaired athletes on the field more often; and
  • The student-athlete and professional athlete will benefit the most from reduced exposure to potentially injurious blows and from the "conundrum of having to self-report an injury that they may not recognize as being potentially injurious or dangerous in the moment of competition."  

As co-founder of Simbex, LLC, the Lebanon, New Hampshire company that makes the HITS (Head Impact Telemetry System) - a peer-reviewed, scientifically-validated technology used by researchers in biomechanical studies to measure head impacts on the playing field, and a version of which has been incorporated into Riddell's new InSite Impact Sensing System - Greenwald knows a thing or two about the technology of head impact exposure monitoring.  That his company might benefit from the widespread monitoring he and his colleagues at Simbex propose in the editorial, however, does not make their recommendation any less important. 

Writing about head impact sensors in the March 2013 issue of the British Journal of Sports Medicine, [11] Jeffrey S. Kutcher, MD, of the Department of Neurology and Michigan Neurosport at the University of Michigan, observes that the "development of easily deployable sport equipment-based accelerometer systems ... provide[s] two unique and potentially useful, clinical opportunities:

The first is the ability to monitor impacts during the course of an athletic event for the purpose of screening for potential injury. Although many researchers have analyzed impact counts and characteristics across a variety of settings in the hopes of establishing force 'thresholds' for injury, no such threshold has been discovered.  As efforts to improve impact-monitoring accuracy continue, however, so will the search for the 'concussion threshold.'  At the same time, there may be a separate, but similar role for the real-time tracking of impact forces.  Although an on-board acceleromter system may not be able to accurately predict injury, it may have utility as a screening device by alerting sideline personnel of an impact that has occurred above a predetermined magnitude that triggers either observation or clinical evaluation of an athlete.  Although there are currently no published studies to support the use of impact sensor systems in this manner, and a 'concussion threshold' is unknown, the potential clinical utility should be carefully considered.

The second potential clinical benefit of impact monitoring systems stems not from the idea of monitoring impacts for the presence of an acute injury-generating hit, but from the potential advantage of accurately cataloguing the number of hits and post-impact head acceleration being experienced by an athlete over time.  Some have suggested that the idea of a 'hit count' that is kept for athletes over the course of a game, practice, week, month, season or career.  This concept is fairly new and, as yet does not have published data to suggest that any particular level or number of hits has significant clinical meaning for any particular sport or position.  Nonetheless, individual athletes may feel there is a benefit to having an estimate of forces their brain experiences over time. 

Most recently, a study by researchers at the University of Michigan[23] (including Dr. Kutcher) notes that, while sensors may currently be beyond the reach of most football programs, a "number of companies are developing innovative, low-cost technologies that will make [such] instrumentation both practical and feasible."  

Not all agree

Not surprisingly, some concussion experts take a more cautious approach to the use of impact sensors, although some of the opposition may be due to a belief that sensors will be use to diagnose concussions, rather than a tool to alert sideline personnel to impacts that might warrant screening for concussion. 

Despite finding that underreporting continues to be what she wrote in two 2013 studies to be an "alarming" [17] and  "overwhelming" problem,[16] Johna Register-Mihalik, Ph.D, LAT, ATC,  Senior Research Associate at WakeMed and Adjunct Assistant Professor at UNC-Chapel Hill, told MomsTEAM that the the reason the use of impact sensors was not among the recommendations she and her co-authors in those studies made to address the problem of chronic underreporting was that she viewed "the use of impact sensors in concussion detection, as the science, although a growing field of information, is just not quite there in how these may best be used from a clinical standpoint and across all sport settings."(emphasis supplied).

"As it stands, there is no absolute threshold for concussive injury and while these sensors may identify individuals who receive a certain type of hit or impact, we do not yet know if those impacts not identified by a set threshold may lead to concussion. In many ways, this may provide a false sense of security, in that 'if the sensor didn't go off, I must not have a concussion.'"

Register-Mihalik recognized that "there is certainly potential for this type of technology to have great implications in the identification of concussion as the science advances," but, she argued, "we need more scientific and unbiased evidence of their ability to detect concussion before they are widely used and recommended in all settings. Until that time, there are some good examples of identification techniques of having trained observers, a parent advocate and continuing to promote concussion education that we know will increase identification rates." (emphasis supplied).


Note: two impact sensor systems Impakt Protective's Shockbox and i1 Biometrics' Vector mouth guard (then called the Hammerhead) are featured in MomsTEAM's new high school football concussion documentary, "The Smartest Team: Making High School Football Safer," which premiered on Oklahoma Educational Television on August 14, 2013 and has been airing on PBS stations across the country since that time.  

For more information about the Shockbox helmet sensor, Vector mouth guard and other impact sensing systems, visit MomsTEAM's impact sensor product guide

1. McCrea M, Hammeke T, Olsen G, et. al.  Unreported concussion in high school football players: implications for prevention.  Clin J. Sport Med 2004;14:13-17.

2. Echlin P, Tator C, et al. A prospective study of physician-observed concussions during junior ice hockey: implications for incidence rates.  Neurosurg Focus 2010;29(5):E4.

3. Cantu R, Concussions and Our Kids (Houghton Mifflin Harcourt 2012), citing Flick K, Lyman S, Marx RG. American collegiate men's ice hockey: an analysis of injuries. Am J Sports Med 2005;33:183-187.

4. Dziemianowicz M, Kirschen MP, Pukenas BA, Laudano E, Balcer LJ, Galetta SL. Sport-Related Concussion Testing. Curr Neurol Neurosci Rep 2012 (published online July 13, 2012)(DOI:10.1007/s11910-012-0299-y).

5. Covassin T, Harris W, Parker T, Kontos A.  The Role of Age and Sex in Symptoms, Neurocognitive Performance, and Postural Stability in Athletes After Concussion.  Am J Sp Med 2012;20(10)(DOI: 10.1177/0363546512444554)(published on line ahead of print on April 26, 2012)(accessed May 15, 2012). 

6. Greenwald R, Chu J, Beckwith J, Crisco J.  A Proposed Method to Reduce Underreporting of Brain Injury in Sports.  Clin J Sport Med 2012; 22(2):83-85.

7. Jadischke, R. (2012) Football helmet fitment and its effect on helmet performance.  MS Thesis, Department of Biomedical Engineering, Wayne State University. 

8. King A. (2012). A Review of the Star Report by Rowson and Duma. Wayne State University, College of Engineering & School of Medicine.

9. Echlin PS, Skopelja EN, Worsley R et. al.  A prospective study of physician-observed concussion during a varsity university ice hockey season: incidence and neuropsychological changes. Part 2 of 4.  Neurosurg Focus 2012;33(6):E2

10. Kaut KP, DePompei R, Kerr J. Congeni J. Reports of head injury and symptom knowledge among college athletes: implications for assessment and educational intervention.  Clin J Sport Med 2003;13:213-221. 

11. Kutcher J, McCrory, Davis G, et al.  What evidence exists for new strategies or technologies in the diagnosis of sports concussion and assessment of recovery?  Br J Sports Med 2013;47:299-303. 

12. Broglio SP, Eckner JT, Surma T, Kutcher JS. Post-Concussion Cognitive Declines and Symptomatology Are Not Related To Concussion Biomechanics in High School Football Players.  J Neurotrauma 2011;28:1-8. 

13. Anderson B, Pomerantz W, Mann J, Gittelman M. "I Can't Miss the Big Game": High School (HS) Football Players' Knowledge and Attitudes about Concussions. Paper presented at the Annual meeting of the Pediatric Academic Societies, Washington, D.C. May 6, 2013.

14. Wall Street Journal (2013). Study Raises Concerns That Teen Athletes Continue to Play with Concussion Symptoms (http://online.wsj.com/article/PR-CO-20130506-904595.html)(accessed May 7, 2013)

15.  Rowson S, Duma S. Brain Injury Prediction: Assessing the Combined Probability of Concussion Using Linear and Rotational Acceleration. Ann. Biomed. Eng. 2013;41(5):873-882

16.  Register-Mihalik JK, Guskiewicz KM, Valovich McLeod TC, Linnan LA, Meuller FO, Marshall SW.  Knowledge, Attitude, and Concussion-Reporting Behaviors Among High School Athletes: A Preliminary Study.  J Ath Tr. 2013;48(3):000-000. DOI:10.4085/1062-6050-48.3.20 (published online ahead of print)

17.  Register-Mihalik JK, Linnan LA, Marshall SW, Valovich McLeod TC, , Meuller FO, Guskiewicz KM.  Using theory to understand high school aged athletes' intentions to report sport-related concussions: Implications for concussion education initiatives.  Brain Inj. 2013;27(7-8):876-886. 

18.  Kroshus E, Daneshvar DH, Baugh CM, Nowinski CJ, Cantu RC. NCAA concussion education in ice hockey: an ineffective mandate. Br J Sports Med. 2013;doi:10.1136/bjsports-2013-092498 (epub. August 16, 2013)

19. Labotz M, Martin MR, Kimura IF, et al. A comparison of preparticipation evaluation history form and a symptom-based concussion survey in the identification of previous head injury in collegiate athletes.  Clin J Sports Med. 2005;15:73-78.

20. Williamson IJ, Goodman D. Converging evidence for the under-reporting of concussions in youth ice hockey.  Br J Sports Med 2006;40:128-132.

21. Kaut KP, DePompei R, Kerr J, et al. Reports of head injury and symptom knowledge among college athletes: implications for assessment and educational intervention.  Clin J Sports Med. 2003;13:213-221.

22. Meehan WP, Mannix RC, O'Brien MJ, Collins MW. The Prevalence of Undiagnosed Concussions in Athletes. Clin J Sports Med 2013;0:1-4 (epub ahead of print) 

23. Broglio SP, Martini D, Kasper L, Eckner JT, Kutcher JS.  Estimation of Head Impact Exposure in High School Football: Implications for Regulating Contact Practices.  Am J Sports Med 2013;20(10). DOI:10.1177/036354651302458 (epub September 3, 2013)

Posted May 15, 2012; most recently revised February 24, 2015