Johnson wouldn't confirm if he's still experiencing symptoms, but he acknowledged "it's a long season."
Detroit's star receiver hasn't been himself this season. He leads the Lions with 48 receptions, but his 16 touchdowns from a year ago are a distant memory. Johnson has only one touchdown this season, and it wasn't even thrown by starter Matthew Stafford. He caught it with backup quarterback Shaun Hill in the game.
The Lions have shown promise in recent weeks because they've discovered balance on offense. Detroit is running the ball more and taking heat off the passing game. Johnson sees constant double teams. He's the focal point of every opponent's game plan, making his production in 2011 even more impressive. He's struggling with more than just double coverage in 2012.
Follow Marc Sessler on Twitter @MarcSesslerNFL.