Detroit Lions tight end Dorin Dickerson is the latest NFL player to stay in a game with a concussion.
He joined a list that is likely long.
Buffalo Bills safety Jim Leonhard and Tennessee Titans safety George Wilson both acknowledged this week they have played with concussions in the past.
San Diego Chargers safety Eric Weddle said, "of course it happens," because players don't want to come out of games for fear of losing their jobs or roles.
Dickerson didn't tell the Lions' medical staff immediately about his concussion, which he recalled getting on a kickoff during the second half.
He later dropped a pass and was called for holding in overtime of Sunday's 23-20 loss to the New York Giants.
"I just got knocked out," Dickerson told reporters after the game. "I just got a little concussion. I should have reported it. I thought I could get through it."
Four days later, the 25-year-old journeyman was put on injured reserve.
Dickerson, who has caught 11 passes in 23 games over three years with three NFL teams, may have simply been trying to make the most of his opportunity to play even if he was putting his health at risk.
For players and the league, there's a lot at stake.
Millions can be made by men who can thrive and survive in what Lions receiver Nate Burleson called "a gladiator sport," by shaking off hits that are so hard brains collide with skulls. And, hundreds of millions of dollars - perhaps billions in the future - can be lost by the league.
The NFL agreed a week before this season started to pay $765 million to settle lawsuits from thousands of former players who developed dementia or other concussion-related health problems they claimed were caused by the same on-field violence that boosted the game's popularity and profit.
Former Lions and Washington Redskins athletic trainer Al Bellamy, who worked for NFL teams from 1988-2012, said there's only so much medical professionals can do to protect players from themselves.
"I don't think there's anything you can do if a player isn't being forthright about his health," said Bellamy, now the director of athletic training at Temple.
"Athletic trainers and team doctors are trying to see what they can from the sideline and the NFL puts an athletic trainer in the press box to point out possible concerns.
"Ultimately, though, it's up to the players to be forthcoming about their health when there's any doubt."
Sometimes, that simply doesn't happen.
Dr. Stanley A. Herring, a Seattle Seahawks team physician for 20-plus years and chairman of the NFL head, heck and spine committee subcommittee, said a key component of diagnosing concussions is a good relationship with players.
"The clinical diagnosis is aided if you know what the player is like - how he thought, acted and talked - before he was injured," Herring said in a telephone interview Thursday night.
"You can't understand if a player is acting differently if you don't know him very well."
Leonhard said he continued playing "an important" game for the New York Jets three or four years ago with a concussion. Looking back, he said it was a "terrible decision" because of what he has learned about head injuries.
"But sometimes it's hard - you're a competitor," he said.
In a series of interviews in 2011 about head injuries with The Associated Press, 23 of 44 NFL players said they would try to conceal a possible concussion rather than pull themselves out of a game.
Wilson said it's just the nature of the game to stay on the field even with a head injury.