Blood biomarkers for brain injury in concussed professional ice hockey players
Shahim P., Tegner Y., Wilson DH., Randall J., Skillback T., Pazooki D., Kallberg B., Blennow K., Zetterberg H. JAMA Neurol. 2014; E1-E9.
Take Home Message: Biochemical markers in the blood, like T-tau, are elevated after a concussion and are associated with recovery time. These markers may eventually be developed into clinical tools to determine diagnosis and prognosis after concussions as well as to devise improved return-to-play decisions.
Most concussions heal within days to weeks, but up to 20% of patients have a prolonged recovery. The danger of developing chronic or progressive concussion symptoms may be linked to repeated concussions before the brain completely heals. Tools to detect and monitor the brain during the recovery process, such as biochemical markers (biomarkers) in the blood, could help us make objective decisions on whether returning an athlete to play is safe. As a first step in finding a potential biomarker, the authors compared preseason concentrations (47 players) of 3 biomarkers (total tau [T-tau], S-100b, neuron-specific enolase NSE]) to postconcussion concentrations (27 players) among professional Swedish ice hockey players. Team physicians collected preseason blood samples from two out of 12 teams in Sweden’s top professional ice hockey league. Players from one of these teams also provided blood samples immediately after a friendly game that had no concussions. Any athlete in the league who sustained a concussion had consecutive blood samples drawn 1, 12, 36, and 48 hours as well as 144 hours after the injury, or the date on which the athlete returned to unrestricted activity. T-tau levels were significantly higher at all time points compared with preseason levels. Players had similar T-tau concentrations after a friendly game compared with preseason concentrations. In contrast, NSE and S100B were elevated after a friendly game and S-100b was only elevated immediately after an injury while NSE concentrations were unaffected by concussions. Levels of S-100b were higher in players that had loss of consciousness as well as those that took more than 10 days to return to play. T-tau concentrations 1 hour after a concussion correlated with the number of days it took for concussion symptoms to resolve. Additionally, T-tau levels 144 hours after concussion remained significantly elevated in players with persistent concussive symptoms of 6 or more days compared with those whose symptoms resolved within 6 days. The authors found that T-tau concentrations 1 hour after a concussion had the highest diagnostic accuracy for detecting players who developed persistent symptoms for more than 6 days.
This study demonstrated that there are biochemical changes following a concussive event that could have diagnostic and prognostic benefits. Future research may help us determine if biomarkers like T-tau can also serve as an objective measure to diagnose a concussion. The major finding was that plasma levels of T-tau increased in ice hockey players that were diagnosed with a concussion. T-tau may be a better biomarker to continue to investigate since S-100b and NSE may not be sensitive enough to detect a concussion. This was apparent since both were elevated after a game with no incidence of concussion, where T-tau did not show higher levels when a concussion did not occur. Also, T-tau levels measured at 1 hour after concussion was related with the number of days it took for symptoms to resolve as well as had the highest diagnostic accuracy when comparing it to concentration 1 hour after a friendly game. It’ll be interesting to see how T-tau performs when we compare preseason, post-concussion, and post-friendly game concentrations from the same athlete. Furthermore, we need to learn if a concussion injury from several repetitive blows would also change the T-tau concentration. While more research is required to establish if T-tau concentrations could help us diagnose a concussion and establish safe return to play criteria this study shows that this might be feasible.
Questions for Discussion: Do you think you would be able to get a blood sample 1 hour after the concussive injury? Do you think your athletes would allow you to take baseline blood samples if they knew it could help with concussion diagnosis?
Written by: Jane McDevitt, PhD
Reviewed by: Jeffrey Driban