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Miami Dolphins quarterback Tua Tagovailoa suffered a concussion at the conclusion of a fourth-and-4 run in the third quarter of the Week 2 "Thursday Night Football" matchup against the Buffalo Bills. Tagovailoa lowered his head attempting to gain the first down when he collided with Bills safety Damar Hamlin in the red zone. The Dolphins quickly ruled him out for the remainder of the contest. 

After crumpling to the field, Tagovailoa appeared to go into the "fencing response," which he similarly showed after suffering a frightening concussion during a 2022 "Thursday Night Football" matchup against the Cincinnati Bengals. 

Tagovailoa remained on the turf as trainers evaluated him while teammates on the field took a knee. He soon got up and walked off the field under his own power with trainers by his side. Dolphins backup Skylar Thompson replaced Tagovailoa under center as the Dolphins went on to lose 31-10.

In July, Miami signed Tagovailoa to a four-year, $212.4 million extension with $167 million in guarantees following a career season in 2023. He led the league with 4,624 yards passing to go along with 29 touchdowns and 14 interceptions.

There were legitimate concerns about the former No. 5 overall pick's long-term health following the 2022 season as he missed four starts due to concussions. However, Tagovailoa made a concerted effort that offseason to avoid concussions. He bulked up, trained in martial arts and started wearing a new helmet. As a result, Tagovailoa started every game for Miami in 2023 for the first time in his career. 

Unfortunately, this newest incident and the resulting fencing response drag up a long-running story that has not been addressed in over a year. 

NFL concussion history

In Week 3 of the 2022 season, during a matchup in Miami against the Bills, Tagovailoa took a hit where he was knocked backward and hit his head on the field. The quarterback got up and appeared to be woozy, even dropping down to the ground again before teammates helped him up. He exited the game and apparently passed concussion protocol, with the Dolphins classifying his injury as a back issue. The NFLPA even said afterward it would investigate the situation. 

Just four days later, the Dolphins travelled to Cincinnati to take on the Bengals. In the second quarter, Tagovailoa was sacked and violently hit the back of his head against the playing surface. He went into a fencing response, where he raised his hands eerily as a neurological response to head trauma. Tagovailoa was stretchered off the field and transported to the University of Cincinnati Medical Center via ambulance. However, he was discharged from the hospital and flew home with the team.

Dr. Rahul Shah, a board-certified orthopedic spine and neck surgeon, gave CBS Sports some insight into what the fencing response is:

"So what happens is when the head gets a hit, it basically snaps backwards," Dr. Shah said. "So when you have this type of scenario, this whole structure basically gets affected and what will happen is the person gets knocked out and they basically have this decorticate response. Basically, think of it as a short-circuiting that's occurring that's going all the way to the fingertips. And that's what it's showing -- it gives you insight that the base of the neck or that brain area is still fairly fragile, particularly after the fact that he's had his prior injury." 

Tagovailoa would miss the next two games, but return for a Week 7 matchup against the Pittsburgh Steelers. However, his concussion issues were not over. In a Christmas Day matchup against the Green Bay Packers, Tagovailoa had a terrible second half in which he threw three interceptions. The following day, it was announced that he had entered concussion protocol. Tagovailoa would miss the final two regular-season starts, and Miami's Super Wild Card Weekend matchup against Buffalo. 

Tagovailoa's injury Thursday night marks what is officially his third concussion in his NFL career. The quarterback even admitted that he considered retirement after being stretchered off the field in Cincinnati. 

"Yeah, I think I considered it for a time having sat down with my family, having sat down with my wife and having those conversations," Tagovailoa said in April 2023. "But really, it would be hard for me to walk away from this game with how old I am, with my son. I always dreamed of playing as long as I could to where my son knew exactly what he was watching his dad do. I mean, it's my health, it's my body, I feel like this is what's best for me and my family."

What's next

Dolphins head coach Mike McDaniel told reporters after the 31-10 loss to the Bills that he spoke with Tagovailoa on the field and in the locker room before he went home, saying he "was in good spirits." 

"My thought was concern," McDaniel responded when asked what he immediately thought after Tagovailoa's injury. "I was just worried about my guy. Not something that you ever want to be a part of, you know? You hope not to." 

McDaniel offered no insight about a potential trip to injured reserve, saying only that Tagovailoa will be evaluated on Friday. 

Some, including Pro Football Hall of Famer Tony Gonzalez, are already calling for Tagovailoa to retire for the sake of his long-term health. Apart from taking time to recover, the next step for Tagovailoa in the process of returning to the field would be clearing concussion protocol. Concussions are different for everyone, and not every player will clear protocol as quickly as others. But if the concussion proves as "extreme" as it appeared on Thursday, Tagovailoa could be sidelined a minimum of eight to 12 weeks, according to CBS Sports HQ injury expert Marty Jaramillo. He adds the quarterback's history of head trauma suggests "retirement has to at least be in play."

Ultimately it's up to Tagovailoa and the doctors. We now await results from Friday's evaluations.