Measuring brain electrical activity to track recovery from sport-related concussion

Barr WB, Prichep LS, Chabot R, Powell MR, McCrea M. Brain Injury. 2011 Oct; ahead of print.

Several prospective studies have illustrated that most concussions achieve complete recovery from signs and symptoms, neurocognitive dysfunction, and balance issues within 7 to 10 days. However, some studies utilizing advanced technologies like quantitative electroencephalography (EEG; measure of electrical brain activity) and neuroimaging techniques (e.g., magnetic resonance spectroscopy) have demonstrated that functional brain abnormalities may linger even after signs and symptoms are alleviated but it remains unclear how long this may last. The purpose of this study was to follow recovery from a concussion within athletes using an index based on changes in quantitative electroencephalographic (EEG; brain activity) that was previously developed among an independent Emergency Department sample of head-injured subjects with traumatic brain injuries. The study included 59 concussed football players and 31 non-injured football players from a larger cohort of athletes from eight high schools and two colleges in Milwaukee, Wisconsin (823 player season; 3 years). All concussed athletes were subject to a battery of sideline concussion tests at the time of the injury, 8, and 45 days post injury. The controls were subject to the same concussion assessment and EEG protocol. Authors measured Concussion Symptoms Inventory (CSI; assesses symptoms and severity of symptoms), Standardized Assessment of Concussion (SAC; cognitive screening tool), Balance Error Scoring System (BESS; assess postural stability), Automated Neuropsychological Assessment Metrics (ANAM; a computerized neuropsychological test), and 10 minutes of eyes-closed, resting EEG recording. The EEG results were used to calculate an index value (MTBI-DS Index) that could range from 0 to 100. The concussed group obtained significantly worse scores on the CSI and SAC the day of the injury compared to controls, but there were no differences between groups at days 8 and 45. There were no significant differences found within the BESS test between groups. The MTBI-DS index was significantly greater in the concussed group compared to control group on the day of the injury and on day 8, but not at day 45. Further analyses within the concussed population determined that there was no difference between the MTBI-DS index at the day of the injury and day 8, but there was a significant difference between the day of the injury and day 45. The MTBI-DS index did not differ across time in the control group.

It is imperative that physiological recovery from a concussion be assessed so that we can determine how long the brain is vulnerable following a concussion. This insight could help us better inform clinicians and patients as well as improve concussion management policies. This study revealed that there are significant abnormalities at the day of injury between concussed and control patients. However, at day 8, when common clinical assessments were not different between concussed athletes and control athletes, there were still abnormalities on the EEG. In addition, even though there was no statistical significance reached at day 45 between the 2 groups the mean MTBI-DS scores for the concussed group were much higher than control group (58, 41, respectively), which could suggest that some athletes were still recovering from the concussion. It would be interesting if future studies further evaluated why some patients had elevated scores at 45 days after the injury. More reference time points could also allow for a more systematic study of when patients’ EEG recovers. The authors suggest that the brain is still healing after clinical recovery from signs and symptoms, cognitive dysfunction, and other functional impairments. Therefore, prolonged observation after clinical recovery should be implemented. The researchers indicated that there should be an intermediate assessment point around 15-days post injury, but that the tests clinicians utilize may not be sensitive enough to detect this window of vulnerability. Does anyone re-evaluate a concussed athlete around 15-days post injury? If so what methods did you use and did you ever have to pull an athlete after return to play?

Written by: Jane McDevitt MS, ATC, CSCS
Reviewed by: Jeffrey Driban

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Barr WB, Prichep LS, Chabot R, Powell MR, & McCrea M (2012). Measuring brain electrical activity to track recovery from sport-related concussion. Brain Injury, 26 (1), 58-66 PMID: 22107157