"[Robinson] is in the concussion protocol right now ... so that's kind of out of our hands," Nagy said on a Zoom call.
Robinson caught a 6-yard pass over the middle and was immediately tackled from behind by Los Angeles Rams safety Nick Scott with 4:11 remaining in the Bears' 24-10 loss on Monday night. Officials signaled for Robinson to leave the field after he stood up, and he did not return for Chicago's final 11 plays on offense.
He would be a key loss for the Bears (5-2), who host the New Orleans Saints (4-2) on Sunday.
Robinson leads Chicago with 44 receptions for 544 yards. Last year, he had a career-high 98 catches for 1,147 yards and seven touchdowns for one of the league's worst offenses.
He is in the final season of a three-year contract signed with Chicago in March 2018. The two sides have yet to come to terms on a contract extension.
The Bears are also bracing for the possibility of not having center Cody Whitehair in Week 8.
Whitehair, who has started 71 straight games since he entered the league in 2016, is day-to-day after suffering a calf injury vs. the Rams. Former undrafted free agent Sam Mustipher played the final 26 snaps at center on Monday and would start in place of Whitehair against the Saints.
Nagy said Whitehair's calf injury is not believed to be severe or season-ending.