Oct. 9, 2010— -- Some high school football players can have neurological impairment without suffering a concussion, researchers found.
That group of players had a significantly greater rate of hits to the head compared with players who were concussed or who did not have any neurological impairment, Thomas Talavage of Purdue University in West Lafayette, Ind., and colleagues reported online in the Journal of Neurotrauma.
Because players without concussion symptoms will continue to participate in practices and games, those players may be at risk for long-term neurodegeneration from repeated impacts to the head -- even if no individual blow causes a concussion -- the researchers noted.
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"Consequently, high priority should be given to the development of procedures that may lead to identification of these at-risk individuals," they wrote.
Talavage and his colleagues performed neurocognitive testing with the ImPACT concussion screening tool and functional MRI scans on 21 high school football players before the start of the 2009 season. Throughout the season, all players wore sensors in their helmets that indicated the direction and intensity of any collisions to the head during practices or games.
The researchers selected 11 of the players for further in-season and post-season assessments because they either suffered a concussion, had an unusually high number of hits to the head, or had a particularly strong hit to the head. Three had a concussion and eight did not.
As expected, the three concussed players had significantly lower neurocognitive performance after their injuries compared with baseline values. They also had impairments observed on fMRI, particularly in the regions of the brain known as the posterior middle and the superior temporal gyri.
Among the eight players who did not suffer a concussion during the season -- who were meant to act as controls -- four did not have impairments on neurocognitive testing and fMRI scans.
The other four, however, unexpectedly had significant reductions in their ImPACT scores, as well as decreased fMRI activation levels in the areas of the brain known as the dorsolateral prefrontal cortex and the cerebellum, which are associated with working memory. The impairments were at least as severe as those in the players who suffered concussions, according to the researchers.
Those four non-concussed but impaired players, compared with the other seven who underwent in-season assessments, had a significantly greater number of impacts to head throughout the season, particularly to the top-front of the head directly above the dorsolateral prefrontal cortex.
The finding of neurological impairment without a concussion diagnosis is consistent with previous studies that found chronic traumatic encephalopathy in professional football players who did not have a history of concussions, Talavage and his colleagues noted.
"Given the dire outcomes observed as a consequence of chronic traumatic encephalopathy, and given that such a functional observation suggests that present clinical practice does not succeed in detecting the neurological deficits in these individuals, it is important that we develop a means to detect when such injury occurs or, perhaps more importantly, to predict and prevent injuries of this nature," they wrote.