The team said Polamalu had a "blow to the head" and did not return.
The 6-foot-6, 290-pound Maneri had lined up in the backfield as an eligible receiver and hauled in a short pass from Tyler Palko. Polamalu came up to make the tackle and dove at Maneri's legs, his head banging into the big offensive tackle's knee.
Polamalu, who had been dealing with some sore ribs, looked a bit wobbly as he got up. He was helped to the sideline by trainers and did not return on the Steelers' next defensive series.
Polamalu wasn't the only Steeler to be sent to the locker room early. Pro Bowl center Maurkice Pouncey left the game in the second quarter of Sunday's game with an illness.
Polamalu, Pittsburgh's defensive leader, was a bit wobbly when he stood up and Tomlin said after the game that he was experiencing "concussion-like symptoms."
Polamalu was seen on the team's sideline during the second quarter but he was wearing sweat pants and was not seen near his helmet.
A nine-year veteran, Polamalu has a history of concussions and left the Oct. 16 game against Jacksonville with a head injury. The 2010 Defensive Player of the Year is standing on the sideline with his helmet on, an indication that he wants to return to the game.
Information from ESPN.com writer Jamison Hensley and The Associated Press was used in this report.