One of the biggest hurdles to appropriate clinical management of sports concussion [1] 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 or are reluctant and/or refuse to self-report such symptoms [2], 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 [3].
If an athlete is allowed to continue playing after concussion, however, their recovery is likely to take longer, and they may be at increased risk of long-term problems [4] (e.g. early dementia, depression, more rapid aging of the brain [5], and in rare cases, chronic traumatic encephalopathy [4], and, in extremely rare instances, catastrophic injury or death [6].
The evidence that concussions are significantly under-reported [7] is substantial. [1-9] As a 2013 research paper [7] and a number of other recent studies[12-15] show, education alone [8] (or at least that which focuses on educating athletes about the signs and symptoms of concussion and not changing attitudes about reporting behavior) does not appear capable of solving the problem, because the reasons for under-reporting are largely cultural [9], [2,3,9,10, 12-15] leading the paper's author to conclude that "other approaches might be needed to identify injured athletes."
One way, I believe, to address the problem of under-reporting and increase the chances a concussion will be identified early on the sports sideline may be to rely less on athletes themselves to remove themselves from games or practices by reporting concussion symptoms (which the most recent study shows occurs at a shockingly low rate,[9] or on game officials and sideline observers to observe signs of concussion and call for a concussion assessment, but to employ technology to increase the chances that a concussion will be identified by employing impact sensors designed to monitor head impact exposure in terms of the force of hits (both linear and rotational), number, location, and cumulative impact, in real time at all levels of football, and in other helmeted and non-helmeted contact and collision sports, where practical, to help identify high-risk impacts and alert medical personnel on the sideline so they can consider performing a concussion assessment.
Contrary to some media reports, impact sensors used in this fashion are not intended to replace sideline observers, game officials, coaches, and teammates, who, if they observe an athlete exhibiting signs of concussion, can trigger a sideline screening for concussion using one or more assessment tools (eg. SAC [10], SCAT3 [11], BESS [12], King-Devick [13], Maddocks questions [14]), but simply to be another tool in the concussion toolbox or, put another way, another set of eyes. Like those assessment tools, the fact that a sensor triggers an alert - or fails to set off an alert - is not intended to rule an athlete in or out of action or in any way diagnose concussion.[11]
"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, in an editorial in the March 2012 Clinical Journal of Sports Medicine, [12] but "permit early intervention, potentially in advance of an injury, rather than simply as a management tool postinjury."
While equipping a team with impact devices may be cost-prohibitive,[15] and while impact monitoring will not eliminate brain injuries altogether, the benefits of early identification and prevention of further injury are numerous, writes Greenwald:
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 is now in the Riddell InSite Impact Response System [16] - 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.
Greenwald is not alone in trumpeting the potential benefit of impact sensors in identifying athletes for sideline screening for concussion. Writing about head impact sensors in the March 2013 issue of the British Journal of Sports Medicine,[13] Jeffrey S. Kutcher, MD, of the Department of Neurology and Michigan Neurosport at the University of Michigan, concurs that the "development of easily deployable sport equipment-based accelerometer systems ... provide[s] [a] potentially useful, clinical information."
"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.'"
"Although an on-board accelerometer system may not be able to accurately predict injury," says Kutcher, "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."
Kutcher also sees a second a second potential clinical benefit of impact monitoring systems, one which "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." [13]
A study by researchers at the University of Michigan[15] views such suggestions as having "merit," noting 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 instrumentation both practical and feasible."
A number of top concussion researchers also believe that real-time monitoring of impacts could help reduce the total amount of brain trauma from repeated subconcussive blows by identifying athletes sustaining a large number of such hits due to improper blocking or tackling technique. In a recent article on SI.com [17], Kevin Guskiewicz, PhD, ATC, Kenan Distinguished Professor and Director of the Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center at The University of North Carolina at Chapel Hill, pointed to a third practical use for impact sensors outside of the research arena: to help coaches and other personnel identify athletes who are sustaining a high number of high force impacts, especially to the top front of their helmets that appear to be the most worrisome from a brain trauma standpoint, as a result of poor tackling or blocking technique. "If a player is observed repeatedly sustaining larger impacts to the crown of his head," he told SI, "coaches will work with him on adjusting his technique," said Guskiewicz.
Using impact sensors as a teaching tool isn't just happening at the college level. It is happening in high school football, too. After Purdue researchers [18][16] found that high school football linemen who sustained a high number of high impact sub-concussive hits over the course of a season were the ones suffering impairment of their visual memory, the information led at least one player to change his blocking technique.
Tom Talavage, the lead author of the Purdue study, told PBS's Frontline in a 2011 interview [19], that he thought that at least 50 percent of the high impact hits linemen and linebackers were sustaining were due to poor technique. "Some of the players that we have on our team [do] have not very good technique, to be quite honest. And what you'll find is, they will launch into a play, and they will lead with their helmet. Other players will more correctly keep their head up, try to get their arms up as a blocking technique, or when they're rushing, they will try to get their arms up as a means to push the offensive lineman out of the way. Those technique differences lead to a very large difference in the total number of blows experienced and where those blows are experienced on the head."
Talavage said that, when one of the offensive lineman who was found to have been functionally impaired after sustaining a high number of subconcussive blows - impairment which persisted beyond the season - decided to change his technique, he experienced a drastic reduction in the number of blows he sustained to the top front of his head and a moderate reduction in the total number of helmet hits.
The result was that, after the second season, "his neurocognitive testing never detected any deficits, and from an imaging perspective we saw substantially less change in his fMRI activity. There's still some, because he's still getting hit, but his technique changed the distribution."
Research suggests that the cumulative effect of subconcussive impacts may increase the risk of long-term neurodegenerative diseases such as CTE, PD, AD, MCI and ALS. While researchers continue to look for the concussion "holy grail" in the form of specific impact thresholds above which concussions are highly likely and/or the number of impacts or the magnitude of impacts per week or per season that substantially increase the risk of long term brain injury, impact sensor technology is available right now to do what we can to reduce total brain trauma by using impact data to identify kids who need more coaching so they can learn how to tackle and block without using their helmets.
Not surprisingly, some concussion scientists and researchers take a more cautious approach to the use of impact sensors. Despite finding that underreporting continues to be what she wrote in two 2013 studies to be an "alarming" [14] and "overwhelming" problem, [10] Johna Register-Mihalik, told MomsTEAM that the the reason the use of impact sensors was not among the recommendations she and her co-authors made to address the problem 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."
"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."
Editor's Note: two real-time impact monitoring systems, Impakt Protective's Shockbox [20]and i1 Biometrics' Hammerhead (now called Vector) impact sensing mouthguard [21], are featured in MomsTEAM's 2013 PBS documentary of concussions in high school football, "The Smartest Team: Making High School Football Safer." [22] As of June 2015 MomsTEAM/SmartTeams has field tested seven brands over four years with football players ages 5-17.
For a guide to selected impact sensor products, click here [23].
For answers to frequently asked questions about impact sensors, click here [24].
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. 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.
6. 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
7. 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.
8. 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 [25])(accessed May 7, 2013)
9. 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)
10. Register-Mihalik JK, Linnan LA, Marshall SW, Valovich McLeod TC, Mueller FO, Guskiewicz KM. Using theory to understand high school aged athletes' intentions to report sport-related concussion: Implications for concussion education initiatives. Brain Injury 2013;27(7-8):878-886.
11.Giza C, Kutcher J, Ashwal S, et. al. Summary of evidence-based guideline update: Evaluation and management of concussion in sports: Report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology 2013 (published online ahead of print March 18, 2013): DOI:10.1212/WNL.ob013e31828d57dd (accessed March 23, 2013)
12. 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.
13. 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.
14. 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)
15. 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).
16. Talavage TM, Nauman E, Breedlove EL, et al. Functionally-detected cognitive impairment in high school football players without clinically diagnosed concussion.J Neurotrauma 2013;doi:10.1089/neu.2010.1512 (e-publ April 11, 2013).
Links:
[1] https://www.momsteam.com/node/130
[2] https://www.momsteam.com/node/6349
[3] https://www.momsteam.com/node/3227
[4] https://www.momsteam.com/node/3289
[5] https://www.momsteam.com/node/5481
[6] https://www.momsteam.com/node/208
[7] https://www.momsteam.com/node/4804
[8] https://www.momsteam.com/node/5075
[9] https://www.momsteam.com/node/5835
[10] https://www.momsteam.com/node/215
[11] https://www.momsteam.com/node/1335
[12] https://www.momsteam.com/node/221
[13] https://www.momsteam.com/node/6204
[14] https://www.momsteam.com/node/6150
[15] https://www.momsteam.com/node/2987
[16] https://www.momsteam.com/node/6077
[17] http://mmqb.si.com/2013/10/22/nfl-helmets-head-injury-concussion/
[18] https://www.momsteam.com/node/4492
[19] http://www.pbs.org/wgbh/pages/frontline/football-high/interviews/tom-talavage.html
[20] https://www.momsteam.com/node/6072
[21] https://www.momsteam.com/node/6074
[22] http://www.thesmartestteam.com
[23] https://www.momsteam.com/node/6073
[24] https://www.momsteam.com/node/6747
[25] http://online.wsj.com/article/PR-CO-20130506-904595.html
[26] https://www.momsteam.com/health-safety/sports-concussion-safety/impact-sensors/hit-count-impact-sensors-buying-guide
[27] https://www.momsteam.com/problem-underreporting-concussions-helmet-sensors-solution-to-problem
[28] https://www.momsteam.com/health-safety/six-pillars-concussion-risk-management-momsteam-approach
[29] https://www.momsteam.com/health-safety/seven-ways-to-reduce-risk-of-brain-trauma-in-contact-and-collision-sports
[30] https://www.momsteam.com/sub-concussive/sub-concussive-hits-growing-concern-in-youth-sports
[31] https://www.momsteam.com/concussions/impact-sensors-frequently-asked-questions