For the first time,
researchers have documented irregular brain activity within the first 24 hours
of a concussive injury, as well as an increased level of brain activity weeks
later—suggesting that the brain may compensate for the injury during the recovery
time. The findings are published in the September issue of the Journal of the
International Neuropsychological Society. Dr Thomas Hammeke of the Medical
College of Wisconsin, is the lead author. To study the natural recovery from
sports concussion, 12 concussed high school American football athletes and 12
uninjured teammates were evaluated at 13 hours and again at seven weeks
following concussive injury. The concussed athletes showed the expected
post-concussive symptoms, including decreased reaction time and lowered
cognitive abilities. Imaging via fMRI (functional magnetic resonance imaging)
showed decreased activity in select regions of the right hemisphere of the
brain, which suggests that the poor cognitive performance of concussion
patients is related to underactivation of attentional brain circuits. Seven
weeks post-injury, the concussed athletes showed improvement of cognitive
abilities and normal reaction time. However, imaging at that time showed the
post-concussed athletes had more activation in the brain’s attentional circuits
than did the control athletes. “This hyperactivation may represent a
compensatory brain response that mediates recovery,” said Dr. Hammeke. “This is
the first study to demonstrate that reversal in activation patterns, and that
reversal matches the progression of symptoms from the time of the injury
through clinical recovery.” “Deciding when a concussed player should return to
the playing field is currently an inexact science,” said Dr. Stephen Rao,
director of the Schey Center for Cognitive Neuroimaging at the Cleveland Clinic
and a senior author. “Measuring changes in brain activity during the acute
recovery period can provide a scientific basis for making this critical
decision.”
