Coach Marvin Lewis said in his postgame news conference that Burfict had a "cervical strain."
The play came just inside the final two minutes of the opening period, when Burfict was chasing Colts quarterback Andrew Luck out of the pocket deep in the red zone. As Luck ran inside the 10, Burfict made contact with him with what appeared to be the crown of his helmet.
Replays showed that no other part of Burfict had hit the quarterback before his helmet struck Luck's chest. Just after the play ended, Burfict was down on the ground for a few moments before trainers rushed out to evaluate him.
Burfict got up under his own power and headed to the sideline before being taken into the locker room for observation.
After the game, Burfict was seen in the locker room talking with the player who took over his play-calling duties, Vincent Rey. The two were at their lockers discussing defensive strategy and assignments following a game that saw Rey collect 16 tackles.
Burfict's neck injury comes after he has already dealt with concussion problems most of this season. He has only finished one game this year -- last week's -- after missing parts of four others with head injuries.
Burfict experienced a concussion in Week 1 and came back from it to play in Week 2, when he was diagnosed with another. After that game, he took the next three weeks off before coming back last Sunday against the Panthers.
He left briefly last week after suffering what was called a "hit to the head."
"You always are worried when your teammate gets a couple of concussions and then a stinger [like Sunday]," cornerback Terence Newman said. "You don't know if that's related or whatnot, but he's a great football player so anytime you lose him, it's definitely heartbreaking. But he's got a long career ahead of him and he has to just be smart."
Burfict's concussion issues were among topics of conversation all week in Cincinnati and abroad. They led a reporter earlier in the week to ask head coach Marvin Lewis about his concern over Burfict's frequency of head-related injuries. Lewis was asked at what point he becomes concerned about Burfict not only as a player, but also as a human being, given the number of concussions.
"He had a concussion [Week 2] against Atlanta," Lewis replied. "That's the biggest concern. You don't want him to have ... again, I coached defense and linebackers for a long time and concussions didn't linger. Now we've found that because of the media and things they seem to linger longer. There's a lot of attention paid to it. I don't know why they linger longer, but I don't remember them lingering like they do now."
Lewis' comments set off a firestorm of criticism, including comments from NFL Players Association president Eric Winston, who tweeted his disapproval.
The NFL in recent years has intensified its approach regarding concussions and renewed its policies related to the level of medical scrutiny players must go through before getting cleared to play again after a concussion. Many of the league's concerns stem from long-term health issues retired players have experienced, and recent research that has made some connections between former player deaths and head trauma.
Lewis was asked hours after his news conference if he wanted to clarify his comments. He declined, acknowledging he probably shouldn't have broached the topic in the first place.
On Sunday, Burfict was replaced by a combination of safety Taylor Mays and rookie Marquis Flowers. Reserve linebackers Jayson DiManche and Rey also got starts for injured starters Emmanuel Lamur and Rey Maualuga.
"Obviously you're with a rookie and basically another rookie, so things change a little bit," Lewis said of the backups. "So things changed a little bit. Your plan changes and things like that and obviously, it becomes critical, particularly when you have third downs and some things like that, and you don't play things exactly the way you should. You give up plays and then everybody starts doubting a little bit."
Burfict had four tackles before leaving the game.
The Bengals also lost veteran cornerback Leon Hall in the first half after he received a lower back strain. Lewis didn't provide an update on Hall's condition.
Hall had four tackles and a pass break-up before his departure. The pass break-up came in the first quarter when he dropped a sure interception near the Bengals' goal line. With few Colts near him, Hall might have returned that interception 97 yards for a touchdown.