"Heath Miller is experiencing the discomfort that goes along with concussions," coach Mike Tomlin said Tuesday. "We'll see if it picks up as the week goes along. Of course, if we're going to err, we're going to err on the side of caution when it comes to players' health."
McClain was not penalized, but was fined $40,000 by the NFL on Monday for an illegal hit to the head of a defenseless receiver.
Tight end Matt Spaeth (concussion) has been cleared by doctors to return to practice Wednesday. While Spaeth is returning, right tackle Flozell Adams (high ankle sprain) is unlikely to play against Cincinnati (2-10).
Quarterback Ben Roethlisberger, who had surgery Monday to repair a broken nose, will wear a face shield during practice for the Steelers (9-3).
"I'm sure there's going to be some level of discomfort," Tomlin said. "I don't think it's going to keep him out of football in any form or fashion."
Defensive end Aaron Smith (torn triceps tendon) has resumed lifting weights but won't be evaluated again for two weeks. He was hurt Oct. 24. The Steelers chose not to put him on the injured reserve list in case he healed in time for the playoffs.