After six months’ rest, two additional players had increased proportions of brain with decreased fractional anisotropy. One player who had had decreased fractional anisotropy at the end of the season returned to normal after six months’ rest. Another player with decreased fractional anisotropy at the end of the season was unchanged after six months’ rest. A third player seemed to be recovering after six months’ rest, but was still not back to baseline.
“These data allow us to draw some thresholds above which you start to see white matter damage,” said Dr. Bazarian. “The one that stood out was players who had had head hits resulting in rotational acceleration greater than 4,500 radians/s2. Once you got above 40 or 45 hits, the amount of your white matter that has changes went up above what controls’ levels were. What those changes mean over the long term is not clear.”
—Erik Greb
Senior Associate Editor
Suggested Reading
Bazarian JJ, Zhu T, Blyth B, et al. Subject-specific changes in brain white matter on diffusion tensor imaging after sports-related concussion. Magn Reson Imaging. 2012;30(2):171-180.
Henry LC, Tremblay J, Tremblay S, et al. Acute and chronic changes in diffusivity measures after sports concussion. J Neurotrauma. 2011;28(10):2049-2059.
Marchi N, Bazarian JJ, Puvenna V, et al. Consequences of repeated blood-brain barrier disruption in football players. PLoS One. 2013;8(3):e56805