The Vulnerable Window in Concussion: A Challenge in Determining Safe Return to Play

Morgan Williams

John DiFiori, Professor at UCLA and Head Team Physician of their Department of Intercollegiate Athletics gave a challenging glimpse into the world of sports-related concussions. One profound fact Professor DiFiori opened with was that there is legislation in all fifty states surrounding concussion management- especially as it pertains to high school students (DiFiori, 2016). Although I am not a huge sports fan in general, my immediate understanding was that concussions are both serious and common. What exactly is a concussion? Essentially a subset of Traumatic Brain Injury Brain Injury (Semple et al., 2015). The pathophysiology of this condition includes the release of neurotransmitters, and irregular ion fluxes with and efflux of potassium(K) and an influx of calcium (Ca) (DiFiori, 2016). There is also a decline in the brain’s ability to utilize glucose which leads to a lessened cerebral flow (DiFiori, 2016). Symptoms include headache, fatigue, nausea, fatigue, balance problems, anxiety, difficulty concentrating, and more (Semple et al., 2015). Despite how common and serious this injury is, there is still a surprising amount on this subject still being learned, and there are still many challenges. One of those Professor DiFiori shared with us is the actual reporting of concussions (or potential concussions) is less than perfect. Sometimes athletes do not recognize the symptoms, and other times they do, they hide them because they want to continue playing. A lot of responsibility is notably on the coaches as well. In one of the video clips of a past UCLA football game, the audience was shown a prime example of a player who noticeably hit his head on the ground during the game, not being taken on the sidelines and checked out, but continuing to play. Looking at the player’s eyes it was obvious that he was fighting to remain focused after the blows, at one point visibly shaking his head and blinking his eyes as to ward of the haze of confusion after he was knocked to the ground. The risky part in loving the the sports these athletes play is that in wanting to remain in play, and win, acknowledging a concussion may fall lower on the priority list. The bottom line is that after a concussion the brain is believed to be in a much more vulnerable state. The question for these players is when is this state improved and when can the player return to the game?


Despite how common and serious this type of injury is, especially in sports there is still much to be learned about when playing can definitively be resumed for the player. In describing the return to play (RTP) protocol, Professor DiFiori discussed the present 6 best practice steps and then described some different initiatives being used. This includes graded exercises. The problem with these approaches is that the tests are not definitive. DiFiori has even seen players who ‘dumb themselves down’ when taking the initial assessment as to offset their feedback in the case that they have a concussion and are given the assessment again (DiFiori, 2016). There is much believed to be at risk in a player returning to play before they have properly healed. Current research supports that if a second concussion happens within 1-3 days the cognitive function was significantly worse and the individual was more likely to have long term learning impairments. If the second concussion happened after 10 days (for an adult athlete), it is as if they are experiencing a concussion for the first time (Choe et al., 2012). Yet there is no science that backs a definitive 10-day rule for athletes with concussions. Yet the RTP protocol as it is, is still a challenge. First and fore most it is based on the two “yet to be proven concepts” (Choe et al., 2012) mentioned above (although it is it is increasingly supported by clinical and laboratory research as mentioned throughout this paper). That is, that a concussed individual is more likely to get another concussion, and repeat injuries within a short window may cause cumulative brain damage (Semple et al., 2015). While rest is the first step in this protocol, and seems the obvious choice, there is evidence that using rest to promote CNS recovery in a previously active athlete may actually cause withdrawal and growth of trophic factors. A study on rats yielding the ultimate finding (when transferred to brain –injured humans) that rest may create a situation where BNDF expression is low causing and environment where greater neural damage is possible (Semple et al., 2015). All in all, Professor DiFiori’s talk gave a very in-depth update on the current state of concussion management in athletes. One that, along with the readings, illuminated the great strides and findings that have allowed for increased and accurate recognition and treatment of the injury, and one that illuminated the great strides still in play. It is apparent that we are only just beginning to fully appreciate how concussions might influence the structural integrity and functioning of the brain. All in all, there is still much to be learned about the intricate and magnificent brain, in hopes of definitively pinpointing a concussion and its full recovery as to build a more definitive RTP protocol for the athletes that love these sports despite their risks.




Choe, Meeryo C., et al. “A pediatric perspective on concussion pathophysiology.” Current Opinion in Pediatrics 24.6 (2012): 689-695.


DiFiori, J. (2016, February 16). The Vulnerable Window in Concussion: A Challenge in Determining Safe Return To Play. Lecture
presented in McCook Auditorium, Hartford, CT.


Semple, Bridgette D., et al. “Repetitive concussions in adolescent athletes–translating clinical and experimental research into perspectives on rehabilitation strategies.” Frontiers in neurology 6 (2015).


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