Even though the clinical signs of concussion are not present, some high school football players may suffer an alteration in brain function, and continue playing because nobody knows anything is wrong, report researchers from Purdue University Weldon School of Biomedical Engineering in an article published in the Journal of Neurotrama. According to post-mortem evidence, repeated head blows may eventually damage the brain, even though individual blows might not provide any clinical symptoms of concussion, the researchers write. In order to minimize future injury risk, the detection and characterization of head trauma needs to be improved, the authors add.

Concussion, or mild traumatic brain injury (MTBI) is a head injury with temporary loss of brain function. The sufferer can experience cognitive, physical and emotional symptoms. It is an injury to the brain, usually caused by a blow to the head or a jolt – in most cases the individual does not lose consciousness. There were 351,992 sports-related head injuries that were treated in hospital emergency rooms in America in 2008, according to the Consumer Product Safety Commission.

Thomas Talavage, a functional neuroimaging expert, associate professor of biomedical engineering and electrical and computer engineering and co-director of the Purdue MRI Facility, said:

Our key finding is a previously undiscovered category of cognitive impairment.

A significant number of high school football players may be unaware of their brain injuries, because they are difficult to diagnose.

Larry Leverenz, an athletic training expert, clinical professor of health and kinesiology at Purdue, said:

The problem is that the usual clinical signs of a head injury are not present. There is no sign or symptom that would indicate a need to pull these players out of a practice or game, so they just keep getting hit.

Twenty-one football players were screened and monitored at Jefferson High School, Lafayette, Ind. They wore special helmets equipped with six accelerometers – special sensors. These accelerometers transmit data, such as impact information wirelessly to equipment placed by the side of the pitch.

Each participant underwent an imaging scan of the brain, as well as cognitive tests before and after each sports season. Football games and practice sessions were videoed so that sustained impacts could be visually recorded.

The researchers compared the imaging scans with impact data they had gathered. Unlike previous studies which only included players who had had concussion, this one monitored every player.

Cognitive impairment was detected among players who had not been diagnosed with concussion, the researchers wrote. They added that this discovery surprised them.

11 players were identified who had either..:

  • ..been diagnosed with concussion by a doctor
  • ..received an abnormally high number of head blows
  • ..received one very hard blow

Three of them were diagnosed with concussions during the football season, four showed no changes, while the other four displayed alterations in brain function, the writers reveal.

Leverenz said:

So, half of the players who appeared to be uninjured still showed changes in brain function. These four players showed significant brain deficits. Technically, we aren’t calling the impairment concussions because that term implies very specific clinical symptoms, such as losing consciousness or having trouble walking and speaking. At the same time, our data clearly indicate significant impairment.

Anecdotal evidence of players suffering cognitive impairment even though no concussion was diagnosed seems to be backed up by this study.

The study, which is still ongoing, could eventually determine how many impacts are needed to cause impairment, which would help formulate guidelines on how many blows a player should be limited to each week.

Eric Nauman, Associate Professor at Purdue University College of Engineering, said:

We’re not yet sure exactly how many hits this is, but it’s probably around 50 or 60 per week, which is not uncommon. We’ve had kids who took 1,600 impacts during a season.

“Functionally-Detected Cognitive Impairment in High School Football Players Without Clinically-Diagnosed Concussion”
Thomas M. Talavage, Eric Nauman, Evan L. Breedlove, Umit Yoruk, Anne E Dye, Katie Morigaki, Henry Feuer, Larry J. Leverenz.
Journal of Neurotrauma. doi:10.1089/neu.2010.1512.

Written by Christian Nordqvist