The Repercussions of Concussions

Concussion effects on the brain might remain long after symptoms have ceased

(RxWiki News) BOOM! Athletes from football to gymnastics to soccer are familiar with the dizzying effects of a concussion. But how do they know when it's safe to put their heads back in the game?

This question plagues trainers, coaches and the athletes themselves, and it turns out that relying on the two most common methods of measuring a concussions' symptoms may not be sufficient to provide good answers.

"Get a thorough medical evaluation before playing again after a concussion."

Scott Livingston, assistant professor in the Department of Rehabilitation Sciences and director of the Concussion Assessment Research Lab at the University of Kentucky, used a different method than typically used to measure the effects of a concussion in a group of athletes.

Concussions are generally diagnosed by one or both of two different methods. One method relies on what a patient reports, and symptoms include headache, dizziness, confusion, disorientation, memory loss and difficulty concentrating.

Alternatively, doctors can diagnose a concussion based on a patient's performance on computerized neuropsychological testing programs that measure the patient's brain functions. The skills tested include concentration, memory, learning, verbal fluency and overall cognitive processing.

Livingston used a different kind of electricophysiological measurement that provides more information about changes in cognitive function and looked for problems in the way the brain physically worked after a concussions symptoms appeared to be gone.

The test he used is called an MEP, which stands for "motor-evoked potentials," and it uses electrodes on a person's hand or foot to measure the reaction time it takes electric signals sent from a device on the patient's head to reach the limb.

For his study, 18 college athletes, half of whom had been diagnosed with a concussion in the previous 24 hours, were evaluated daily for 10 days using all three methods of concussion symptoms: self-reported, the neurocognitive tests, and the MEPs.

Each athlete with a concussion was compared to a participating athlete without a concussion who had similar characteristics, including age, gender, sport, position played, history of concussions and any history of learning disabilities or attention deficit disorders.

Both the self-reported symptoms and the concussed athletes' neurocognitive performance showed the most severe effects of the concussion during the first three days after it occurred and then decreased gradually over the next week and a half.

But the MEP test told a different story. The MEPs revealed slower reaction times over the full 10 days as well as physiological changes increasing over those 10 days - even though the athlete's symptoms and cognitive function appeared to get better.

These results mean that the athletes may not be fully recovered from the concussion after 10 days - even if their clinical symptoms and standard methods of measuring a concussion's effects appear to say so.

Livingston cautions that more research of MEPs and the significance of these findings is needed before they can draw any conclusions about what they mean for treating concussed athletes.

"In the meantime, sports medicine personnel caring for concussed athletes should be cautious about relying solely on self-reported symptoms and neurocognitive test performances when making return-to-play decisions," Livingston said.

The study appears in the February issue of the Journal of Clinical Neurophysiology. The research was funded by the National Operating Committee on the Standards of Athletic Equipment and the National Athletic Trainers' Association Research and Education Foundation. No information was provided regarding potential competing interests.

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Review Date: 
March 6, 2012