Helmet sensor data indicate impact forces to the head range from 20 to more than 100 Gs.
"To give you some perspective, a roller coaster subjects you to about 5 Gs and soccer players may experience up to 20 G accelerations from heading the ball," Nauman said.
Head impacts cause the brain to bounce back and forth inside the skull, damaging neurons or surrounding tissue. The trauma can either break nerve fibers called axons or impair signaling junctions between neurons called synapses.
The findings suggest the undiagnosed players suffer a different kind of brain injury than players who are diagnosed with a concussion.
"To be taken out of a game you have to show symptoms of neurological deficits - unsteady balance, blurred vision, ringing in the ears, headaches and slurred speech," Leverenz said. "Unlike the diagnosed concussions, however, these injuries don't affect how you talk, whether you can walk a straight line or whether you know what day it is."
The fMRI reveals information about brain metabolism and blood flow, showing which parts of the brain are most active during specific tasks, Talavage said.
"One of the most challenging aspects of treating concussions is diagnosing the part of the brain that has been damaged," he said.
The fMRI data from before, during and after the season were compared to see whether there was any difference in brain activity that indicated impairment. The players also were studied using a standard cognitive test to show how well they were able to remember specific letters, words and patterns of lines.
The work may enable researchers to learn whether high school players accumulate damage over several seasons or whether they recover fully from season to season. The researchers have found that players diagnosed with con
|Contact: Emil Venere|