There are approximately three million sports-related concussions reported each year in the U. S., and the rate of diagnosed concussions continues to rise. Concussions can have lasting impacts on injured athletes, including compromised nerve function weeks after the initial trauma, according to a recent Penn State study.
Semyon Slobounov, professor of kinesiology and director of the Penn State Center for Sport Concussion Research and Service, and his colleagues are studying brain functional integrity in concussed athletes post-injury. Their work was recently published in Neurology.
In the study, concussed athletes were tested 30 days post-injury alongside healthy volunteers of the same age and gender at Penn State’s Social, Life, and Engineering Science Center (SLEIC). Slobounov’s previous functional magnetic resonance imaging (fMRI) research focused on concussed athletes seven days after injury and was published in Brain Imaging and Behavior.
“In both studies, subjects faced a battery of tests to measure oculomotor nerve deficits while using an fMRI,” Slobounov explained. “The oculomotor nerve is the nerve in the brain that controls the muscles that enable eye movement. Oculomotor nerve function is becoming a valuable source of brain function information for clinicians and neuroscientists in diagnosing neural injuries and diseases.”
According to Slobounov, both behavioral and fMRI data revealed discrepancies between the concussed and healthy volunteer groups. “Concussed subjects showed significant differences in three of the seven oculomotor tasks 30 days post-injury, including voluntary eye movement away from a stimuli and memory-guided movements of the eye,” he said. Researchers discovered that while these three tasks did show significant improvement from the acute phase of injury, there was not complete resolution.
The findings are significant, as there are no universally accepted assessments for concussion diagnosis. “It’s exciting, oculomotor testing is showing promise as a potential diagnostic and management tool,” said Slobounov. “With this new knowledge we are closer to understanding the reasons for disrupted performance with the aide of advanced neuroimaging tools.”
Despite the brain’s capability to perform basic oculomotor tasks following concussion, there is evidence that concussion may disrupt its underlying neurophysiology. “It may also lead us to be able to pinpoint changes and nuances in brain morphology, physiology, and function caused by concussion that may be of clinical importance,” Slobounov said.
Other members of the research team were Brian Johnson, Ph.D., postdoctoral fellow with the Penn State Center for Sport Concussion Research and Service, and Mark Hallett, M.D., senior investigator at the National Institute of Neurological Disorders and Stroke.
Funding: The project was supported by the National Institutes of Health’s National Institute of Neurological Disorders and Stroke. Other funding was provided by Penn State’s Office of Vice President for Research, College of Health and Human Development, Departments of Kinesiology and Athletics, the Social Science Research Institute, and SLEIC.
Source: Kristie Auman-Bauer – Penn State University
Image Source: The image is credited to the researchers/Penn State
Original Research: Abstract for “Follow-up evaluation of oculomotor performance with fMRI in the subacute phase of concussion” by Brian Johnson, Mark Hallett, and Semyon Slobounov in Neurology. Published online August 28 2015 doi:10.1212/WNL.0000000000001968
Abstract
Follow-up evaluation of oculomotor performance with fMRI in the subacute phase of concussion
Objective: To expand on our previous study by performing a follow-up testing session in the subacute phase of injury for participants recently diagnosed with a concussion.
Methods: A battery of oculomotor tests were administered to participants 30 days postconcussion while simultaneous fMRI was performed.
Results: Three of the 7 oculomotor tasks (antisaccade, self-paced saccade, and memory-guided saccade) administered showed significant differences between the recently concussed group compared with normal volunteers. However, performance in these 3 tasks did show improvement from the acute phase of injury. The fMRI analysis revealed significant differences in brain activation patterns compared with normal volunteers, with the concussed group still demonstrating increased and larger areas of activation. Similar to the oculomotor performance, the fMRI analysis showed that at 30 days postinjury, the concussed group more closely mirrored that of the normal volunteer group compared with at 7 days following insult.
Conclusions: Even at 30 days postinjury, and despite being clinically asymptomatic, advanced techniques are able to detect subtle lingering alterations in the concussed brain. Therefore, progressive neuroimaging techniques such as fMRI in conjunction with assessment of oculomotor performance may be beneficial in clinical management of concussion.
“Follow-up evaluation of oculomotor performance with fMRI in the subacute phase of concussion” by Brian Johnson, Mark Hallett, and Semyon Slobounov in Neurology. Published online August 28 2015 doi:10.1212/WNL.0000000000001968
