Concussion has been in the sports news a lot in recent years, especially in high impact sports such as rugby and American football.
And it is also very much on Dr Melanie Bussey’s mind. She is Director of the Motion Analysis Research Lab University of Otago, where she is currently testing the theory that a rugby player with a history of concussion might be more prone to concussion in future.
University of Otago researchers are studying rugby players who have experienced multiple bouts of concussion. Photo: 123RF
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Concussion is a form of mild traumatic brain injury. It can be caused by a direct blow to the head, or by sudden indirect force such as whiplash.
Brain damage is caused when the head comes to a sudden halt, but the brain keeps moving and collides with the skull. A collision can also cause the brain to rotate or twist within the skull.
Melanie Bussey says that “the injury we call concussion comes from strains in the brain due to the rotational acceleration of the head during impact. And that’s what causes the neurological symptoms that we … call concussion, so fuzzy thinking, lack of co-ordination and those sorts of things.”
Repeated bouts of concussion in rugby players have been associated with small to moderate neurocognitive effects affecting memory, reaction time, processing speed and the ability to pay attention to complex tasks.
In the worst cases, cumulative damage from a number of concussions can result in a condition known as chronic traumatic encephalopathy, or CTE. It leads to speech and memory problems, and shares features with Alzheimer’s disease. CTE in American footballers has been linked to a number of suicides.
Melanie Bussey, Jayden Pinfold and Lorenz Kissling next to the machine they use to deliver a precise impact to a volunteer's chest. Photo: RNZ / Alison Ballance
Previous research in the Motion Analysis Lab has shown that rugby players who had experienced a number of concussion events “had higher head acceleration during rugby-type impacts than those who had no history of concussion.”
“This tells us that something has changed neurologically,” says Melanie, “to cause them to have potentially less control of their head during the impacts.”
This lack of head control increases the chance that an impact will cause further concussion.
She says that the relationship between the number of concussion events and how fast their head moved during an impact was a very strong one, and suggests that people with a history of concussion are more likely to suffer concussion in the future.
Melanie says the effect lasts much longer than expected.
“Some [participants in the study] had a fair amount of time since their last concussion, one or even two years, and they still had higher rotation… So the cumulative neurological effects that we see seem to be more long-lasting than we would expect.”
Jayden Pinfold attaches electrodes to volunteer Lorenz Kissling's neck, in an experiment to measure how quickly neck muscles stiffen to prevent the head from moving following a rugby-type impact. Photo: RNZ / Alison Ballance
In the current study, Masters student Jayden Pinfold is looking specifically at the neck muscles and how they are controlling the head.
He is testing rugby players with and without a history of concussion to measure how quickly their neck muscles stiffen following an impact to their chest.
