Expert Concussion Advice


 Dr. James Moriarity, Sports Medicine Consultant
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 Dr. David Darby, Behavioral Neurologist & Medical Consultant
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Why do we measure thinking to help measure a concussion?
Dr. Moriarity: “When an Athlete suffers a head injury it is possible that the result is an injury to the brain. Injury to the brain can be indicated by symptoms such as headaches, nausea, fainting and can be seen through changes in the ability of the Athlete to think quickly and accurately. While it is possible that the Athlete, the coaching and athletic training staff or family can notice the presence of some symptoms, changes in thinking ability are generally not obvious. It is important to note that changes in thinking ability can still be present even when other symptoms have gone. Most importantly, changes in thinking ability indicate that the brain has not recovered from the injury, and therefore the Athlete is not ready to return to play and may also be hindered in his/her classroom ability. A combination of Cogstate' Baseline and After Injury test results is a helpful tool for Doctors to use in managing sports-related concussions as it indicates any change in cognition.” 

My son has taken the Cogstate Baseline test twice, but hasn’t earned an acceptable result. Now what do I do?
Dr. Moriarity: “Best effort Baseline test results are acceptable for future comparisons. These are indicated by a green checkmark at the top right of a report. In my experience, some Athletes (perhaps 10 percent) will not get an acceptable Baseline result the first time they use the Cogstate CCAT—even after they’ve taken a Practice test. I have found these Athletes usually only need a little encouragement to complete the test faster or more accurately the next time. Often, Athletes are too focused on “getting all the answers right” and end up sacrificing speed for accuracy. Since a successful test takes into account both accuracy and speed, I suggest your son take the test in a quiet room and focus on both speed and accuracy: in other words, “go fast carefully.”

You may also refer to the Baseline Test Report for guidance on which tasks need improvement (look again for green checkmarks or red Xs under Test Results. Note: Athletes can repeat the test (without an additional charge) until they get an acceptable Baseline result. See Tips for Successful Test Taking for guidance.

Why is it recommended that an Athlete complete an acceptable Baseline test every year?
Dr. Moriarity: “Young brains, like bodies, develop and mature and do so at different rates, and each year some improvement in cognition may occur. We find children mature and improve in both speed and accuracy performance on the Cogstate CCAT to the ages of at least 15 years. That's why completing an annual Baseline test ensures an accurate and current record of the Athlete's true ability and aids detection of subtle declines in thinking ability that can occur after a concussion. In addition, having an annual Baseline test result can help detect changes from a prior Baseline (perhaps indicating a head injury during the off-season—a fall off a bike or snowboard, for instance) and ensure an accurate record of the Athlete's cognitive performance before any sporting contact occurs. For young Athletes annual Baselines are especially important as developing brains may be more vulnerable to concussions than Athletes who have reached the collegiate or professional levels.”

Also see “Age-Related Differences in Neuropsychological Testing Among High School Athletes,” by Tamerah N. Hunt, PhD, ATC, and Michael S. Ferrara, PhD, ATC; where the authors conclude, “Although scores appear to remain stable after 10th grade, we still recommend testing annually until additional research is conducted to confirm these findings.”

I’ve heard that once you’ve had a concussion, the likelihood of having a second is significantly greater. Is this true?  What is Second Impact Syndrome?
Dr. Moriarity: “Generally speaking, it is true that Athletes who have suffered a concussion are at a statistically greater risk for developing a future concussion than those who have never suffered a concussive head injury. This was first noted in a study published in 1986 by Gerberich looking at injury rates in Minnesota high school Athletes, and subsequent investigations have supported this observation. However, like most generalities, the devil is in the details.  What is not clear is if this increased risk is due to:

  1. Genetic pre-disposition to concussive injury,
  2. A lowered threshold for concussion as a result of damage from the initial concussion, or
  3. Patient awareness of concussive symptoms as a result of sustaining a concussive head injury that make them more likely to report concussive symptoms in the future.

One should be aware that the above observation applies only to the long-term statistical risk of suffering a concussion as a result of participation in athletic activity. It has nothing to do with the short-term risks associated with returning to activity too soon after sustaining a concussive head injury. In the short-term setting, the risk of experiencing prolonged post-injury symptoms and delayed recovery, or the development of further concussive injury, is far greater in those who return to activity and competition prematurely when the recovering brain is still in a vulnerable state. The combination of attentive, knowledgeable medical care, cognitive testing (utilizing the Axon Sport Computerized Cognitive Assessment Tool) and a graded return to activity and competition is currently the best defense we have of preventing prolonged and recurrent concussion injury.

Second Impact Syndrome (SIS) is a very rare medical catastrophe. It is classified as a secondary brain injury which means that even though the injury was caused by an initial head trauma, the trauma was not sufficient to cause immediate and severe disability. It is only later when another seemingly minor head injury occurs (hence, “second impact”) that the catastrophic process begins. In short, SIS is characterized by a sudden, massive swelling of fluid (not blood) inside the brain with nowhere for the fluid to expand because of the confines of the bony skull. The pressure in the brain rises very quickly and in a short time stops all blood circulation and oxygen delivery. Death follows rapidly unless the pressure is released. No one really knows what causes SIS although it has been associated with relatively minor head trauma (including concussion) causing brain bruising or small subdural hematomas (TADD syndrome). Sudden death due to SIS differs from sudden death caused from the acute head trauma of epidural and subdural hematomas. In those injuries, large amounts of bleeding in the brain displace and compress brain tissue resulting in cell death, abnormally high pressures, and circulation loss.

As stated earlier, SIS is exceedingly rare in comparison to the number of concussions sustained yearly by Athletes, and it should not be invoked as a cause of death in cases of acute epidural and subdural hematomas.  Nevertheless, it is a serious cause for concern in the management of sports-related head injury and reinforces the concept that ‘there is no such thing as a minor head injury.’”

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