Given how much emphasis there is on player safety and concussions nowadays, it's rare that players are able to come back within a week of suffering a head injury. It still happens, but for the Detroit Lions this season, players have usually missed at least one game after suffering a concussion.
Perhaps the exception to this could be defensive end Cliff Avril. He suffered a concussion on Sunday against the Minnesota Vikings and was obviously forced to leave the game. While it remains to be seen what his status will be for this week's game against the Green Bay Packers, Jim Schwartz said on Monday that Avril is already doing much better. From MLive:
"He was much improved after the game, probably more so than with a lot of the other concussions that we've had," Schwartz said. "He'll have to go through a protocol to return, but he presented different after the game than some of the other guys have."
That's good to hear, as it's an indication that it wasn't a severe concussion. Obviously any concussion at all is a serious matter, but if Avril can get cleared this week and return on Sunday, it would be a good sign going forward.