Carson Palmer was placed in the NFL's concussion protocol following a hit in the fourth quarter of Week 4.
On the play, a sack was split by Rams defensive tackle Aaron Donald and defensive end Eugene Sims, and Palmer's head appeared to hit the turf. He was wobbly after being helped up by teammates and was met by team doctors and trainers at the sideline as he came off the field. They evaluated him on the sideline and then escorted him to the locker room, where he underwent further evaluation.
The Cardinals play at the 49ers in Week 5 on Thursday.
"Probably not, probably not," Bruce Arians said. "We'll be very, very careful with this injury. It is not like a sore wrist or a sore shoulder."