A team that has been hammered by head injuries like few others in the NHL the last several seasons, the Bruins now are dealing with another concussion to a key player.

General manager Peter Chiarelli revealed yesterday that center Patrice Bergeron suffered what's been classified as a mild concussion as a result of a hit by Claude Giroux in the third period of Game 4 of the Eastern Conference semifinal series with Philadelphia on Friday night.

Now Chiarelli, whose team has had to survive without Bergeron in the past and lost star center Marc Savard for most of this season, is planning on the Bruins potentially being without Bergeron for the start of their Eastern Conference final series with Tampa Bay. That series' start date has yet to be determined.

"I guess anything can happen, but that's the assumption I'm operating under," Chiarelli said during a press conference at Ristuccia Arena yesterday.

Chiarelli said that when Bergeron left the Bruins' series-clinching 5-1 victory, he was held in the quiet room as part of the new NHL protocol on head injuries. He then took a modified Sport Concussion Assessment Tool 2 test. Doctors did not clear Bergeron for a return to the game, and he didn't play the rest of the night.

NHL concussion protocol now calls for Bergeron to be symptom-free before he can be tested again and then possibly cleared for activity.

This is Bergeron's third publicized NHL concussion. His first came as a result of a hit from behind by Philadelphia's Randy Jones in October 2007. Bergeron missed the rest of the season. In December 2008, he collided with then-Carolina defenseman Dennis Seidenberg and missed more than a month of game action with a concussion.

Chiarelli spoke with Bergeron after the game Friday but had not been in touch with the player yesterday before he addressed the media.