How do you solve a problem like concussions in sports? Fears over the short- and long-term health effects of head impacts in collision sports have already led to rule changes, lawsuits, and decreased youth participation in football and hockey. Last month, a scientific study turned the spotlight onto baseball, concluding that major league players returning to action after having suffered a concussion performed statistically worse at the plate. But can science or technology also find a way to fix this?
According to that baseball research, which was published in The American Journal of Sports Medicine, several batting metrics dropped significantly following a concussion-enforced break, including batting average (.249 to .227), on-base percentage (.315 to .287), and slugging percentage (.393 to .347). Those results made national news and were picked up by The New York Times, Reuters and Fox News. But reading between the numbers raises perhaps the biggest issue with concussions: We don’t know enough.
"I think it was a well-intentioned study,” says Uzma Samadani, an assistant professor of neurosurgery at NYU’s Langone Medical Center, and co-director of NYU’s Steven and Alexandra Cohen Veterans Center, “[but] I’m not convinced that the conclusions are sound. I think they’re overstated.”
The study compares two groups of hitters that are substantially different. One is made up of players who take time off due to known or suspected concussions, the other of players who take breaks due to either bereavement or paternity leave. Both the types of players and the average length of time off were substantially different between the two groups—catchers made up 39% of the concussed group, but just 16% of the paternity/bereavement group, and the average time off for the concussed players was 10.9 days compared to 4.8—and no indication is given as to whether the concussed players could have suffered other injuries at the same time. When the data was corrected for position, number of days missed, and pre-event batting metrics, only one statistic, on-base percentage immediately following return to play, showed a statistically significant difference.
However, inconclusive or not, this research paper raises an interesting question: Could the secret to fixing the concussion problem be to focus more on its negative competitive side effects than on its medical impact? While the health fears of concussion and chronic traumatic encephalopathy (CTE), a degenerative disease linked to repeated head trauma, are well publicized, athletes are still suspected of playing down the severity of injuries fearing they might get dropped from their teams. Perhaps, knowing more about how concussion affects their abilities could make those athletes think twice about hiding these injuries. Because, if a player’s batting metrics drop due to the lingering effects of concussions, that might be enough to lose a tight game, and risk a bubble team not making the postseason.
Before contemplating that, though, we still need to know more about concussions. We still don’t know what the long term impact of big hits is, what the danger of repeated low-level collisions is, or why recovery times for seemingly identical concussions can vary from six days to six months. Or the real scale of the problem: how many concussions go undetected. More data and better on-field diagnosis might be a first step towards answering those questions.
Could the secret to fixing the concussion problem be to focus more on its negative competitive side effects than on its medical impact?
A huge range of companies are vying for the emerging concussion-tracking market, monitoring impact forces and warning players, coaches, and parents about significant head impacts. Some make helmet-mountable sensors, others make devices that fit into headbands or skullcaps, or incorporate sensors into mouth guards. All essentially work the same way, using accelerometers and gyroscopes to measure linear and rotational acceleration, and thus to work out the size of impact forces on the head. None can actually diagnose concussions, because only a doctor can do that, but all are instead designed to give information on the sizes of impact forces, either as raw numbers or using color-coded risk levels.
One of the problems with diagnosis is that no player is the same. Identical impact forces can have very different effects in different athletes, and while knowing the sizes of the external forces can be useful, they don’t always translate the same way to what is happening inside. “It’s about that Jell-O within that cranium,” says Dennis Cardone, an associate professor of orthopedic surgery at Langone Medical Center, and co-director of NYU’s Concussion Center. “How it moves around, and how it collides with the cranium itself.”
According to Cardone, even MRI scans of the brain are not good enough to decide whether a player might be suffering from a concussion. Instead, diagnosis is made by looking at the symptoms a patient is suffering. Because a significant proportion of our brains is used to process visual information, many of the symptoms that can be used to diagnose concussions affect vision.
Cardone uses a screening test called the King-Devick test, which was developed in 1976 to measure deficiencies in eye movement during reading. The system uses a series of three cards with sets of numbers written on them, and measures the time taken to read these numbers aloud without making errors. In 2011, a research study published in Journal of Neurology used King-Devick to identify concussions, and found that boxers and mixed martial artists performed significantly worse after a fight in which they received significant hits to the head.
Samadani is also working on a portable eye-tracking system to diagnose concussions on the sideline. Based on research she has published on eye movement differences in patients with head trauma, this system assesses the function of the three nerves that move the eyes, looking for restrictions that could indicate nearby swelling in the brain.
Though impact sensors may be able to warn of concussion risks, eye movement tests such as the King-Devick and Samadani’s also offer the potential to monitor recovery from concussion, and for teams to make return-to-play decisions on injured players. Perhaps measuring eye tracking could even become standard pre- and post-game procedure, simply another tool to analyze a player’s fitness to play.
Most of these force-monitoring or concussion-diagnosis systems could be used in professional leagues, but the primary focus is on youth sports, from elementary school through college. Professional teams usually have sideline doctors and better injury-tracking protocols. Assuming companies are willing to share the information their devices record with researchers, this data could be used to improve existing concussion models and better understand the physical mechanism of concussion. For example, says Jesse Harper, CEO of i1 Biometrics, which makes the Vector Mouthguard, when considering repeated low-level head impacts, “the challenge there is we don’t know what is a healthy dose of those, and what is an unhealthy dose.”
According to Samadani, though, there is a potential that the use of these devices may have a negative effect on youth sports. Simply seeing the size of the impact forces their children are exposed to, even if those forces are not dangerous, might make parents more reluctant to allow their children to play contact sports. And Samadani believes the social and fitness benefits of organized sports still far outweigh the injury risks. Besides, “if you tell them they can’t play football, they’re going to skateboard off the roof,” she says. “This is what kids do.”