Study reveals microstructural brain damage in hockey players with concussions

Martinos Center researchers observed acute microstructural changes in the brains of hockey players who had recently had concussions. They published the findings last week in the Journal of Neurosurgery.

A number of imaging-based studies have looked at subjects post-concussion, but interpreting the results from these studies can be challenging because the state of the brain prior to the injury isn't known. "Add to this the fact that imaging is often performed weeks after the injury," said the Martinos Center's Karl Helmer, one of the authors of the present report, "and it becomes very difficult to interpret the results that are obtained through imaging and to be able to say something about the progression of the effects after mild traumatic brain injury, or mTBI."

Helmer and colleagues, in contrast, obtained MRI imaging data before, during and after a season, giving them a better sense of the effects of concussion. They performed scans on 45 male and female Canadian university hockey players. Eleven of the players had concussions during the season. Each was given additional scans within 72 hours, two weeks and two months after the injury.

The latter scans revealed microscopic changes in the brains of those who were clinically diagnosed with concussion during the season. This gave the researchers important insights into mild traumatic brain injury and how it might be detected.

"The study proposes a biomarker, which we call the “hypointensity burden” (HIB), to detect damage from mTBI that is smaller than the size (~5 mm) normally used in the visual identification of cerebral microbleeds," Helmer said. "This biomarker increases after concussion and decreases over time. We also detected a difference in the average baseline value of the HIB between men and women (that for men was higher). This larger value was consistent with the cohort of men having had more previous concussions than the women."

The researchers are now applying this method to data from patients with persistent post-concussive symptoms. In the Journal of Neurology study, both the elevation of mean HIB and the symptoms resolved by the end of the season. In this new cohort, the symptoms have persisted over a longer period of time. The researchers are hoping to determine whether they can detect evidence of damage in these patients not seen by other methods.

The Journal of Neurosurgery study has already received a good deal of attention in the media. It has been covered by The New York Times and The Globe and Mail among others.