Brain MRI scans of concussed university hockey players showed the protective tissue insulating brain cell fibers becomes jarred loose two weeks after injury—despite being cleared to return, research published in the Frontiers in Neurology revealed.
"This is the first solid evidence in humans that concussions loosen myelin," said Alex Rauscher, one of the authors of the study, in a release. "And it was detected two weeks after the concussion, when the players said they felt fine and were deemed ready to play through standard return-to-play evaluations. So athletes may be returning to play sooner than they should."
A team of University of British Columbia, in Vancouver, Canada-led researchers used previous study results published by Rauscher et al. which consisted of 45 ice-hockey player MRI brain scans performed before the start of the season.
That 2016 study included 11 players who sustained a concussion, and subsequently underwent follow-up scans: Eight received an MRI within three days, 10 players at 14 days and nine imaged at 60 days.
Results of that study demonstrated changes to the myelin in a specific area of the brain that helps the organ’s two hemispheres communicate.
The team retrospectively used quantitative susceptibility mapping and diffusion tensor imaging to better understand the myelin disruption.
What they found was a temporary loosening around nerve fibers that connect brain cells, according to the authors. However, that connection returned to normal when players were scanned two months post-concussion.
"These results show that there is some damage happening below the surface at least two weeks after a concussion," added lead author Alexander M. Weber, MD, in the release. "Passing a concussion test may not be a reliable indicator of whether their brain has truly healed. We might need to build in more waiting time to prevent any long-term damage."