Marchand left the game and didn't return after getting elbowed in the head by Devils defenseman Anton Volchenkov with 4:49 left in the second period. He needed help off the ice from Andrew Ference and Jaromir Jagr and headed straight for the dressing room.
Volchenkov was issued a five-minute major for elbowing and a game misconduct.
"After the second period our trainer said he wasn't going to be back," Julien said of Marchand. "Whether that's being cautious or not, I don't know. I'll let our doctors give me the verdict before I say anything, but I haven't talked to anybody about him since the game finished."
The Bruins are already playing without center Patrice Bergeron, who missed his fourth straight game Wednesday with a concussion. Bergeron has resumed working out on his own.