Blood biomarkers for brain
injury in concussed professional ice hockey players

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.

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.

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?

by: Jane McDevitt, PhD
by: Jeffrey Driban

Shahim, P., Tegner, Y., Wilson, D., Randall, J., Skillbäck, T., Pazooki, D., Kallberg, B., Blennow, K., & Zetterberg, H. (2014). Blood Biomarkers for Brain Injury in Concussed Professional Ice Hockey Players JAMA Neurology DOI: 10.1001/jamaneurol.2014.367