Pronger late last month had knee surgery, which was expected to keep him out about four weeks. But now his return has no fixed date.
"While Chris' knee is improving, he has struggled with other issues that are concussion-like symptoms," Flyers general manager Paul Holmgren said in a statement released by the team Friday. "Chris will see Dr. Joe Maroon and Dr. Mickey Collins on Wednesday, December 14th in Pittsburgh for further evaluation. Chris will be out indefinetly."
Holmgren also announced that rookie forward Brayden Schenn is out indefinitely.
"Brayden reported not feeling himself on December 5th," Holmgren said in the statement. "Our doctors believe he has a mild concussion. Brayden will be out indefinitely."
Pierre LeBrun covers the NHL for ESPN.com.