Concussions

Concussions are the most common injury in all of sports, both contact and non-contact, from intramural college teams to professional sports. Not only are athletes more likely to suffer from concussions than the average person, but they are also at a greater risk to develop future brain damage as a direct result. Athletes must decide when they are able to come back to play. If one returns too early to play, one risks developing another concussion or potentially dealing with Second Impact Syndrome (SIS). SIS does not need to stem from a large impact, but any impact following a concussion has the potential to trigger the condition, which has only a 25% survival rate. Several tests are used to decide whether or not an athlete is able to safely return to the playing field. However, these tests are measuring psychomotor speed (time to think of something and then perform a task) as opposed to visuomotor speed (time to see something and react) which is far more game relevant. This results in some athletes returning to play before they have fully recovered. Studies show that upper extremity and oculormotor functions deficiencies can still be present a year after a concussion, long after other symptoms have faded. This had led to a call for more intensive testing for athletes returning from concussion. An obvious way to do this would be to implement some sort of test to measure visuomotor speed. Along with being relevant to the environment, incorporating visuomotor tests may increase the sensitivity of current post-concussion testing methods.

The Departments of Psychology and Kinesiology at the University of Waterloo in Ontario, Canada has recently conducted an experiment to see if including visuomotor tests will significantly increase the sensitivity of post-concussion testing. The experiment contained 40 participants, 20 athletes and 20 non-athletes (NA). The 20 athletes were further split into two groups of 10, concussive athletes (CA) who have previously suffered a concussion (CA) and non-concussive athletes (NCA). None of the participants has any known conditions that could complicate the data. All three groups were tested for visuomotor reaction time though a motor tasks test. The athletes were further tested using CogSports testing (a commonly used computer-administered neuro-psychological test battery). The motor tasks test required participants to place their finger in the bottom corner of a touchscreen. After a random delay, a target of sizes 4, 8, 15, and 29 mm would appear at the top center of the touchscreen. The participant must move to touch the target as soon as possible. The test was done 40 times (ten times each size). The test was then repeated for the participants other hand. The test employs Fitt’s law that states any psychomotor (or visuomotor) act has a speed-accuracy trade off.

The CogSports data is highly sensitive to post-concussion changes in motor reflexes. It did not detect any significant difference between the reaction times of those who had and had not suffered concussions. The motor tasks test showed significance between speed and accuracy, validating Fitt’s law. Other post hoc exploration on the CogSports data showed though that while not at a level of high significance, CAs responded slower than both NCAs and NAs. The motor tasks test, unlike the CogSports test, found a significant difference in simple reaction times in half of the CAs. Therefore, the motor tasks test, which incorporates visuomotor testing, was more sensitive to post-concussion decencies. Because the motor tasks tests utilized Fitt’s law, the data shows that the decline in results from concussion suffered was not due to impairment in the speed-accuracy trade-off but rather just an overall decline in speed. Performance on the CogSports and motor tasks tests were uncorrelated.

1. testing can be improved by a larger sample size and a more difficult visuomotor task

Locklin, Jason, Lindsey Bunn, Eric Roy, and James Danckert. "Measuring Deficits in Visually Guided Action Post-Concussion." Sports Medicine 40.3 (2012): 183-187. Web. 12 Sep 2010
http://ehis.ebscohost.com/ehost/pdfviewer/pdfviewer?vid=5&hid=114&sid=44ce9306-cf0f-4cd0-a024-3ecd4215e555%40sessionmgr113