Hockey Concussion Education Project, Part 2. Microstructural White Matter Alterations in Acutely Concussed Ice Hockey Players: A Longitudinal Free-Water MRI Study.
O. Pasternak, I. K. Koerte, S. Bouix, E. Fredman, T. Sasaki, M. Mayinger, and K. G. Helmer, A. M. Johnson, J. D. Holmes, L. A. Forwell, E. N. Skopelja, and M. E. Shenton, P. S. Echlin
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Concussion is a common injury in ice hockey and a health problem for the general population. Traumatic axonal injury
has been associated with concussions (also referred to as mild traumatic brain injuries), yet the pathological course that leads from
injury to recovery or to long-term sequelae is still not known. This study investigated the longitudinal course of concussion by
comparing diffusion MRI (dMRI) scans of the brains of ice hockey players before and after a concussion.
The 2011?2012 Hockey Concussion Education Project followed 45 university-level ice hockey players (both male
and female) during a single Canadian Interuniversity Sports season. Of these, 38 players had usable dMRI scans obtained in the
preseason. During the season, 11 players suffered a concussion, and 7 of these 11 players had usable dMRI scans that were taken
within 72 hours of injury. To analyze the data, the authors performed free-water imaging, which reflects an increase in specificity
over other dMRI analysis methods by identifying alterations that occur in the extracellular space compared with those that occur
in proximity to cellular tissue in the white matter. They used an individualized approach to identify alterations that are spatially
heterogeneous, as is expected in concussions.
Paired comparison of the concussed players before and after injury revealed a statistically significant (p < 0.05) com
mon pattern of reduced free-water volume and reduced axial and radial diffusivities following elimination of free-water. These
free-water?corrected measures are less affected by partial volumes containing extracellular water and are therefore more specific
to processes that occur within the brain tissue. Fractional anisotropy was significantly increased, but this change was no longer
significant following the free-water elimination.
Concussion during ice hockey games results in microstructural alterations that are detectable using dMRI. The
alterations that the authors found suggest decreased extracellular space and decreased diffusivities in white matter tissue. This find
ing might be explained by swelling and/or by increased cellularity of glia cells. Even though these findings in and of themselves
cannot determine whether the observed microstructural alterations are related to long-term pathology or persistent symptoms, they
are important nonetheless because they establish a clearer picture of how the brain responds to concussion.
Pasternak O, Koerte IK, Bouix S, Fredman E, Sasaki T, Mayinger M, , Helmer KG, Johnson AM, Holmes JD, Forwell LA, Skopelja EN, , Shenton ME, Echlin PS. Hockey concussion education project, part 2. microstructural white matter alterations in acutely concussed ice hockey players: A longitudinal free-water mri study. J Neurosurg 2014;.