Brain Recovery Continues Following Clinical Recovery among Athletes with Concussions

by | Nov 6, 2019 | 2017, Brain Health

Written by Joyce Smith, BS. This study finds that university athletes with concussions continued to exhibit changes in brain structure and function even after they received medical clearance to return to play, that the brain is lagging behind in terms of recovery from a concussion.

Concussions in sports activities and recreation is a growing health concern, with an estimated 1.6 to 3.8 million injuries occurring each year in the United States 1. The damage to brain tissue associated with all concussions can lead to altered brain functions and cognitive and emotional disturbances that are usually most severe during the first week post-injury 2. The medical decision of safe-return-to-play (RTP) after a sport concussion is largely based on self-reported symptoms, with medical clearance granted when the athlete is symptom free following a progressive exercise protocol 2. It is currently not known how objective markers of brain structure and function relate to clinical recovery.

A 2017 study 3 by Churchill and team from St. Michael’s Hospital in Toronto, ON, Canada was conducted to determine whether differences in brain structure and function at time of injury remain present at RTP. The team used advanced magnetic resonance imaging fMRI and Diffusion Tensor Imaging (DTI) to measure brain structure and function in 27 athletes within the first week after a concussion and again after they were medically cleared to return to play.  They compared those findings to a group of 27 uninjured varsity athletes. fMRI can detect regional fluctuations in blood oxygen levels within the brain and can measure functional connectivity within the brain. Diffusion Tensor Imaging (DTI) is an MRI-based neuroimaging technique that allows for the examination of white matter fibers connecting different parts of the brain (specifically and to measure fractional anisotrophy (FA) which measures the water diffusion in myelinated fibers and mean diffusability (MA) which quantifies total water diffusion). Most DTI studies of sport concussions report altered FA and MD within the first week of sustaining a concussion 4, along with significant white matter alterations months to years post-injury 5,6. In this study the changes in MRI measures from acute injury to RTP were compared to actual recovery time to test for specific markers of brain structure and function that are associated with a prolonged recovery time, specifically FA and MA.

The Churchill team found that brain changes seen in the first MRI scan at acute injury were still prevalent when athletes were cleared to RTP. These included persistent differences in the structure of the brains white, the fiber tracts that allow different parts of the brain to communicate with each other. Relative to controls, FA was reduced at acute injury and RTP (mean difference p<0.001 for both) while MD was increased at acute injury (mean difference p=0.004) and at RTP (mean difference p<0.001). Both FA and MD were further decreased, but not significantly from acute injury to RTP, indicating that alterations in FA and MD were still evident at time of medical clearance.

Differences in brain activity were also evident in areas associated with vision and planning, and for those athletes who took longer to recover, there were also changes in areas of the brain associated with bodily movement. Vision, planning and physical coordination are critical for athletes to avoid re-injury during participation in sports; however, the current study did not directly examine whether athletes would be at risk for further injury by returning to play when these brain changes were still present. Further research is needed to determine whether or not athletes need more time between acute injury and returning to play to fully recover.

Source: Churchill, Nathan W., Michael G. Hutchison, Doug Richards, General Leung, Simon J. Graham, and Tom A. Schweizer. “Neuroimaging of sport concussion: persistent alterations in brain structure and function at medical clearance.” Scientific reports 7, no. 1 (2017): 8297.

© The Author(s) 2017 Open Access. This article is licensed under a Creative Commons Attribution 4.0 International License, http://creativecommons.org/licenses/by/4.0/.

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Posted November 6, 2019.

Joyce Smith, BS, is a degreed laboratory technologist. She received her bachelor of arts with a major in Chemistry and a minor in Biology from  the University of Saskatchewan and her internship through the University of Saskatchewan College of Medicine and the Royal University Hospital in Saskatoon, Saskatchewan. She currently resides in Bloomingdale, IL.

References:

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  3. Churchill NW, Hutchison MG, Richards D, Leung G, Graham SJ, Schweizer TA. Neuroimaging of sport concussion: persistent alterations in brain structure and function at medical clearance. Sci Rep. 2017;7(1):8297.
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