Sports Medicine Research: In the Lab & In the Field: Getting Knocked Out Could Knock Down More Than Your Record! (Sports Med Res)


Monday, October 7, 2013

Getting Knocked Out Could Knock Down More Than Your Record!

Diffusion measures indicate fight exposure-related damage to cerebral white matter in boxers and mixed martial arts fighters

Shin W, Mahmoud SY, Sakaie K, Banks SJ, Lowe M, Phillips M, Modic MT, Bernick C. AJNR Am J Neuroadiol. 2013; ahead of print.

Take Home Message: The number of knockouts, among boxers and mixed martial arts fighters predicted structural damage in the brain. This finding suggests that the number of knockouts a fighter endures in their career can predict how much microstructural damage the brain suffered.

Chronic traumatic encephalopathy is a degenerative brain tissue disease caused by cumulative head trauma that can only be definitively diagnosed postmortem. Due to the frequency of blows to the head, boxers and mixed martial arts fighters are prone to this syndrome. There are limited studies that investigate structural changes in brain tissues in fighters, and diffuse tensor imaging may be able to detect subtle structural changes that may reflect microstructural damage to the brain. Therefore, the authors assessed previous fight history and diffusion magnetic resonance (MR) imaging to evaluate the relationship between microstructural brain damage and fight-related exposure. A total of 155 male fighters (74 boxers and 81 mixed martial arts fighters),who had no visible abnormalities in the central nervous system on typical MR images had a baseline diffusion tensor imaging scan, and were followed up annually with diffusion tensor images for 4 years. For this initial study, the authors focused on the baseline MR images of the brain. The number knockouts among boxers and mixed martial arts fighters predicted damage within the white matter of the brain. There were more regions of the brain affected amongst boxers (e.g., corpus callosum, cingulate, amygdala) compared with mixed martial arts fighters (i.e., corpus callosum & posterior cingulate); however, there was a larger level of decreased diffusion (connectivity) within the region of the brain affected within mixed martial arts fighters. The number of fights did not predict structural changes in the brain of boxers or mixed martial arts fighters.

The number of knockouts, most predominantly among the boxers, predicted microstructural damage in the brain. This finding suggests that the number of knockouts a fighter endures in their career may predict how much microstructural damage the brain suffered. Specifically, it is not just how often they take on a professional fight, but how often they receive a severe blow. The style of fighting may reflect why more regions of the brain were affected in boxers compared to mixed martial arts fighters, since boxers specifically target the head. It was also interesting to note that in both groups the corpus callosum was affected. The corpus callosum is involved in allowing the right- and left-brain hemispheres to communicate; therefore, damage to this region could lead to cognitive dysfunction, which is one of the symptoms that characterize chronic traumatic encephalopathy. Future studies should include cognitive testing to evaluate if cognition is impaired down the line with future fights and potential knockouts. Health care providers should note that the number of knockouts the fighter has received when caring for them after a brain injury, and should educate the fighter about the possible repercussions of future knockouts.

Written by: Jane McDevitt PhD
Reviewed by: Jeffrey Driban

Questions for discussion: Do you think the length of their fights or concussion history would be predictors of structural damage? Do you think there should be a cut-off for how many knockouts a fighter can endure in their career?

Related Posts:

Shin W, Mahmoud SY, Sakaie K, Banks SJ, Lowe MJ, Phillips M, Modic MT, & Bernick C (2013). Diffusion Measures Indicate Fight Exposure-Related Damage to Cerebral White Matter in Boxers and Mixed Martial Arts Fighters. AJNR. American Journal of neuroradiology PMID: 23928146


Tyler Beers said...

Due to damage of the corpus callosum in both sports a future study should go in depth on the impact of the microstructural damage on the fighters' cognitive function. I also think there should be a study based off the concussion history of the athletes and how that can affect the athletes' cognition. But I am curious as to why there was a larger level of increased diffusion in the injured areas of the brain of martial arts athletes more than boxers. Is it due the the force of impact of the style of fighting?

Jane McDevitt said...

Yes a concussion history association study between microstructure damage would be a very good study to see if the number of previous concussion effects amount of microstructure damage. I would think there is! There was a larger number of areas of the brain that had more damage in boxers compared to MMA probably because the type of fighting. Boxers focus primarily on hitting the head, where MMA you could make them submit with an arm bar, leg bar, or choke hold.

Stephanie Huntsman said...

With regards to the structural damage question, I believe a concussion history would be a more accurate predictor than fight length, simply because the latter is not necessarily indicative of cumulative trauma to the head. Within TKD, we implement a 30-Day Out rule (from all activity) for concussions and KOs, minimum; and I know there are a variety of concussion DQs at the collegiate level (adherence to them, however, is a whole other monster.) With our growing knowledge surrounding concussions and traumatic brain injuries, I would support a cut-off. While such a cut-off could raise certain ethical issues, the argument we use to refuse AMA forms for head injuries is that the individual is experiencing an altered state of consciousness and is incapable of making an informed decision; something to this effect could be used to fortify and justify the "cut-off". Unfortunately, due to the nature of the sport and these athletes, it is unlikely that they will remove themselves completely from their respective activities (Or, transition, from boxing to MMA, for example--Some sort of global medical record would be necessary to reduce the likelihood of this), so some level of counseling and/or education should be incorporated as well.

Jane McDevitt said...

I agree with you. I am also very interested in their concussion history especially since I would imagine that every time they got KO would lead to a concussion. The article stated that they are following them prospectivly for 4 years so we may recieve more information about their documented concussions. They may not have included it in this study since the athletes may have needed to report the prior concussions, and that would have added recall bias. It is interesting to hear that you implement a 30 day out rule for all activity. I think that is great. In addition to the 30 days of rest are there any other return to play methods used? I have seen athletes that do not loose consciousness and do not return to play for upwards of 6 months because they are still symptomatic. Also, I am curious, at what point, or how many concussions do you believe it would be necessary to implelment a "cut-off" rule?

Stephanie Michel said...

When talking about structural damage, I agree with Stephanie, that history, rather than the length of fight would be a more accurate predictor of structural damage. No matter how long a fight is, the amount of impact sustained could be the same from a fight that lasts 30 seconds to a fight that lasts 5 minutes. There should be a cutoff to help protect the integrity of the brain. However, deciding when is difficult. Is there any studies done on whether one knockout compared to several leads to the same amount of structural damage? It is possible that the first knockout a boxer receives can be debilitating enough to cause microstructural damage. It is also possible that a boxer or fighter could receive several knockouts with no damage. It is hard to set a specific guideline when all brains are different.

Jane McDevitt said...

There are studies done that investigate 1 impact concussions and repeated impact concussions but none that I have seen within boxing. Most of these studies are done in soccer and football, and do not involve imaging. It is my opinion that the structural damage occurs when someone receives a concussion and does not let the brain heal and continues to receive head impacts. I feel that whether the concussion was sustained with 1 impact or due to several mild impacts if the brain has time to heal and does not get assaulted again during that time there would be no long term structural damage. This has not been proven so we will have to see what the imaging studies conclude.

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