When neurosurgeon Tina Duhaime, MD, of the Mass General Youth Sports Concussion Clinic, talks with families about concussion, she takes time to explain what is known, and just as importantly, what isn’t known, about this common injury. “There is disagreement about what a concussion actually is, and how reliable current guidelines are,” she says. “A lot of the concepts about this injury are probably oversimplified.”It is Dr. Duhaime’s goal, and the goal of the Clinic as a whole, to help families make the best decisions for their child in the face of these uncertainties. And to improve that decision-making process in the future, the Clinic pursues research to gain a deeper understanding of just what concussions are, and what risks they hold for young athletes.

“In most concussion clinics, there is one point of view, one specialty,” that drives decision-making and discussions with the family, she says. In helping to found the Clinic, Dr. Duhaime wanted to broaden the field of opinion, to make it a truly multidisciplinary group, which would bring a variety of perspectives about concussions. “When there is a difference of opinion, that tends to be where you find the most fruitful area of research.”

 In a study in which Dr. Duhaime, who is Program Director of the Pediatric Brain Trauma Lab at Mass General, was an investigator, over 400 college athletes wore helmets outfitted with impact sensors over several seasons. The average football player sustained about 400 helmet contacts over 10 g’s. To better understand what that feels like, she donned a helmet and tried, unsuccessfully, to recreate a 10-g hit. “These are substantial contacts, not light taps,” she said. Among the tens of thousands of impacts the athletes sustained, there were 48 diagnosed concussions. But there was less correlation between the severity of the impact and the risk for concussion than the investigators expected. The average concussion-inducing hit was 86 g’s, but ranged from 16 g to 180 g. There was no single concussion threshold, and many high-impact hits didn’t cause concussion. “Unlike hypertension or diabetes,” Dr. Duhaime says, “There’s no one number to indicate risk, and the specific consequences of head impact appear to vary from one individual to another, even apart from the specific symptoms experienced.” Genetic factors and developmental history are likely influencing risk as well.

Just as there is no one number, there is no single message to parents and young athletes in the clinic. When she counsels families whose son or daughter has sustained an injury, “We don’t say, ‘Here’s what the answers are.’ Instead we say, ‘There is a lot we don’t know. We are going to try to keep you safe, and to get you back to your activities. Those are our goals. We may also ask you participate in research to answer some of the unanswered questions. We are going to periodically review what’s new from around the world, to continuously incorporate new findings into how we approach management.’”

Keeping the athlete safe means, above all, avoiding the risks of an undiagnosed subdural hemorrhage. “The catastrophic injuries are not just concussions. They are most often bleeds that mimic concussions,” with headaches and malaise. In most cases of athletes who have died from so-called second-impact syndrome, the impact usually caused a subdural hemorrhage.

“So our recommendation are, you can’t play if you have a headache,” in part to prevent a serious injury if a player’s headache may indicate an unhealed bleed.

Other guidelines in post-injury care and returning to play are much less cut and dried. Many schools require baseline testing of reaction time, but Dr. Duhaime notes that returning to baseline may not mean as much as some parents believe. “The assumption is that this means your brain is all better, but there have been no prospective studies to fully test that assumption. My contention is that we still don’t fully understand whether there is any reliable correlation between your score on that test and the vulnerability of your brain to further injury.” That, she notes, is an urgent area for future research.

In the clinic, Dr. Duhaime talks with families at length about the decision to return to play, but ultimately doesn’t “clear” an athlete. “That should be the family’s decision,” she says. But not, she emphasizes, the student’s decision alone. “They often feel a great obligation to the team, are focused on the short term, and don’t always have the maturity or the long-term perspective to make that choice by themselves.”

“The message I try to convey is that there is still a lot of work to do to understand this problem. We don’t have all the information. As new pronouncements come out, physicians often feel they have to give a single answer to the family. But we have to be more humble. It’s OK to tell them we don’t know.”