It’s actually tricky to categorize concussions by the severity of symptoms. The widely used American Academy of Neurology’s clinical guidelines for sports concussions previously assigned one of three grades to concussions based on symptoms. Similar scales had been developed by the Colorado Medical Society and by Cantu, but these classification systems fell out of favor over the past decade as research revealed the grades did not correlate with recovery times. Also, using symptoms to determine severity can be misleading, says Daniel Clearfield, assistant professor of orthopedic surgery at the University of North Texas Health Science Center. For this reason and others, the American Academy of Neurology updated its guidelines in March (pdf).
Counterintuitive secondary findings
Two other findings in Eisenberg’s study reveal how little is still known about concussions. Kids younger than 13 recovered a little sooner (median 11 instead of 15 days) than kids older than 13—contradicting past animal studies’ findings—and youths who lost consciousness recovered a little faster (median 11 instead of 14 days) than those who did not lose consciousness. Younger players may recover faster because their parents may be more likely to bring them in for milder concussions, Nowinski says, or younger kids may be sustaining less severe injuries because the hits are not as hard as with older, bigger, stronger kids, Clearfield and Eisenberg suggest.
The loss of consciousness surprised Eisenberg but not Nowinski or Clearfield. Nowinski notes that kids who lose consciousness are more likely to go to the ER because the concussions are immediately recognized. “Most concussions that do not involve loss of consciousness are not immediately diagnosed,” Nowinski says. “Therefore, the athletes often finish the game, causing additional injury to the brain prior to beginning physical and cognitive rest.”
Eisenberg also suggested other possibilities for the finding about loss of consciousness, such as study bias: it could be that more kids with mild concussions involving brief loss of consciousness visited the ER, whereas kids who did not lose consciousness came in only if the concussion was particularly severe. It is also possible that those who lose consciousness may have better adherence to treatment plans and time off for recovery. Or, Eisenberg says, as in mice, “it may be that the mechanism that led you to lose consciousness may be different than the mechanism that causes you to experience the other symptoms of the concussion, but we can’t say based on our results alone.”
Second study muddies the waters
More research on youth concussions is clearly needed, Eisenberg and the other experts say. Yet, the Journal of Pediatrics study by Kontos was not helpful, Cantu says. The study recorded the number of concussions diagnosed among 468 western Pennsylvanian youth football players, aged eight to 12, during the 2011 season. Among more than 8,415 practices and 2,923 games, a total of 20 “medically diagnosed” concussions were reported, nearly all during games.
The authors concluded concussions are less common during practices than during games because the incidence rate of concussions was 25 times greater during games. But that’s the wrong conclusion, Nowinski and Cantu say. Both pointed out that the occurrence of only 20 concussions in more than 11,000 games and practices indicates “gross” underreporting, especially at practices where medical personnel and spectators are not present to watch the kids and only the worst injuries are likely to end up diagnosed.