"Claude reported not feeling very good today," Flyers General Manager Paul Holmgren said. "Over the past few days, his symptoms have gradually gotten worse. He will be out indefinitely."
Giroux was injured late in the second period of Saturday's game against the Tampa Bay Lightning when he was accidentally kneed in the head by teammate Wayne Simmonds. Giroux had gone to his knees to make a defensively play in the neutral zone. Simmonds was trailing the play and tried to jump over Giroux, but didn't get high enough, and his knee collided with the right side of Giroux's head.
Giroux leads the League with 39 points, and tops the Flyers with 16 goals and 23 assists. He also leads the team's forwards in average ice time per game at 21:28, and plays on the team's top power-play and penalty-killing units.
"He's our best player," linemate Scott Hartnell said Saturday. "He's a big catalyst for us. He's so strong on pucks, he's great defensively. Obviously we know what he can do offensively. If he's out we're going to miss him big-time."
Rookie Sean Couturier, who had been centering an all-rookie fourth line, likely will slide into Giroux's spot on the top line between Hartnell and Jaromir Jagr when the Flyers play Tuesday in Washington.
"I'll try to use my size and my creativity in the offensive zone," Couturier said following Tuesday's morning skate. "They're two great guys so it should be easy to adapt for me … just have to work hard and get to the net and good things should happen."
Giroux is the third member of the team out with a head injury. Team captain Chris Pronger will visit noted concussion specialists Dr. Micky Collins and Dr. Joseph Maroon in Pittsburgh on Wednesday to assess with his concussion-like symptoms, and rookie forward Brayden Schenn is out with a mild concussion.
Contact Adam Kimelman at firstname.lastname@example.org. Follow him on Twitter: @NHLAdamK