"After being examined by the Bruins medical staff today, Marc has been diagnosed with a moderate concussion," Chiarelli said Monday night. "There is no timetable on his return and no further updates at this time."
Savard is expected to be re-evaluated after this weekend's All-Star break. This is the fourth concussion of his career.
Savard crashed head-first into the end boards early in the second period in Saturday's game against the Colorado Avalanche and did not return. He left the team and went home to Boston on Sunday to be examined by team doctors Monday.
Savard missed the first 23 games of this season due to post-concussion syndrome from a Grade 2 concussion suffered last March on a hit to the head by the Penguins' Matt Cooke. He was deemed 100 percent healthy and returned to the lineup Dec. 2.
Savard played 25 games, posting two goals and eight assists for 10 points with a minus-7 rating.
He suffered a minor head injury Jan. 15 at TD Garden. With 12:50 remaining in the third period, Savard was on the receiving end of a clean hit by Engelland. Savard's head hit the boards and he fell to the ice.
Savard remained on the ice, holding his helmet, and was tended to by a team trainer. Savard made it to the bench on his own and continued to play in Boston's 3-2 loss.
He was examined after the game by the team's medical staff, who determined that there were no issues and that further testing was not needed.
"I'm a little dazed. I haven't got a headache or anything like that, yet," Savard said after that game. "I'm just a little dazed after getting my bell rung a bit. I don't think it's anything to worry about right now."
Savard played the next four games before his setback last Saturday in Denver. Colorado defenseman, and former Bruins teammate, Matt Hunwick made a clean body check, but Savard's head slammed against the bottom of the glass and he fell to the ice. He needed to be helped off the ice and was in obvious pain.
He did not return to the game, and when -- or if -- he will return is unclear.
When Chiarelli announced at the start of training camp that Savard would be out indefinitely because of post-concussion syndrome, ESPNBoston.com spoke with Dr. Mark Lovell, who is considered a concussion expert internationally and is the founding director of the University of Pittsburgh Medical Sports Medicine Concussion Program.
Lovell, who had no knowledge of Savard's case, said the number of brain injuries and the effect they can have on athletes differs from case to case.
"The tolerance of players is hugely variable," Lovell said. "First of all, there's no magic number. It would be really easy if there were, if you knew that once you've had three concussions you needed to retire. But it doesn't work that way.
"I've seen athletes who have had multiple concussions that were spaced out over time, who we can't find anything wrong with. And I've seen players who have had one concussion who had to retire. So it really is that variable. There are a lot of factors we don't understand."
Before Savard was deemed healthy to return to game action in late November, the Bruins' medical staff wanted a completely separate, independent opinion on whether it was safe for Savard to play again.
Savard was sent to the University of Pittsburgh to be examined by Lovell's colleague, Dr. Michael Collins, who is an expert at interpreting impact testing results. Savard was put through a battery of tests and given medical clearance.
Joe McDonald covers the Bruins and Red Sox for ESPNBoston.com.