Philadelphia general manager Paul Holmgren made the announcement through a team spokesman early in the first period of the Flyers' game against Montreal on Thursday night.
Some are even wondering if the injuries could end Pronger's career.
Pronger has been sidelined since Nov. 19.
"After consultation with respected concussion specialists Dr. Joseph Maroon and Dr. Micky Collins, it is the opinion of both doctors that Chris is suffering from severe post-concussion syndrome," Holmgren said. "It is the recommendation of doctors Maroon and Collins that Chris not return for the remainder of the 2011-12 season or playoffs. Chris will continue to receive treatment and therapy with the hope that he can get better."
Pronger visited Maroon and Collins on Wednesday in Pittsburgh after complaining about a fairly persistent headache and sluggish feeling. The 37-year-old defenseman also missed six games this season because of an eye injury, and had surgery on his left knee last month.
In 13 games this season, he had a goal and 11 assists. He has 157 goals and 541 assists in 1,167 career regular-season games in 18 seasons with Hartford, St. Louis, Edmonton, Anaheim and Philadelphia.
The 6-foot-6 player led Anaheim to the 2007 Stanley Cup title and won Olympic gold medals with Canada in 2002 and 2010. He signed a seven-year contract with Philadelphia in 2009.
Flyers star forward Claude Giroux, the NHL scoring leader with 39 points, also is out indefinitely with a concussion. He took an inadvertent knee to the head from teammate Wayne Simmonds in a game Saturday.
"Claude's status remains the same," Holmgren said "He is out indefinitely."