Under the NFL's new medical timeout rule, Patriots wide receiver Julian Edelman might not have been on the field with New England trying to score the go-ahead touchdown in the Super Bowl.

Edelman appeared dazed after a fourth-quarter hit by Seahawks safety Kam Chancellor. The trainer stationed in the press box to watch for potential head injuries noticed and let the staff on the sideline know. But with the Patriots in an up-tempo offense, Edelman remained in the game through the end of the drive.

Only then was he tested for a concussion, and the results were negative -- but that doesn't necessarily mean he wasn't concussed.

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Dr. Richard Ellenbogen, co-chair of the NFL's Head, Neck and Spine Committee, noted Wednesday that in 90 percent of concussions, the symptoms can clear within minutes.

"It is very possible for a person to play, come out and then test normal," he said. "We're trying to get ahead of that."

Under the new rule, the trainer in the press box can immediately notify the referee to call a medical timeout. The game and play clock stop until the player can leave the field, and his team isn't charged for a timeout. The player must then sit out at least one snap.

"The issue is at the time of the injury," said Ellenbogen, the department chair for neurological surgery at the University of Washington. "That's a place where we think we have an opportunity to do better."

Ellenbogen insisted that no one play prompted the NFL to institute the new rule. But league officials made clear at a presentation about its health and safety procedures Wednesday that the Edelman hit was exactly the kind of scenario the medical timeout is designed to address.

"It was a hurry-up offense. There was no incomplete pass; there's no huddle," said Jeff Miller, the NFL's senior vice president of health and safety policy. "There was no obvious time in which somebody could intervene."

Edelman went on to catch what would be the winning touchdown pass on New England's next possession.

Miller predicted the medical timeouts would not be used often because of other mechanisms already in place: Referees, teammates and coaches have been instructed to notice when a player is in distress and ensure he leaves the field. But still there were some cases where none of them were aware of the apparent head injury.

"It's designed to be a fail-safe," NFL vice president of officiating Dean Blandino said of the new rule.

Team physicians on the sideline will be able to watch replays this year to figure out how someone was hurt. The trainer in the press box has replay access and can send the clip down to the field to help the doctors make a diagnosis if they didn't see the hit.

Dr. Robert Heyer, the Panthers' team physician and the president of the NFL Physicians Society, showed video Wednesday of a play where a Carolina player was kneed in the head -- and Heyer didn't see it from 10 yards away because of all the other players swarming around the ball.

If the trainer in the press box isn't able to notify the referee before the next snap or doesn't see the apparent injury until watching replays, the medical timeout can still be called later in the drive, Blandino said.

The NFL said Wednesday that there were 112 concussions in regular-season games in 2014, down 24 percent from the 148 in 2013 and 35 percent from the 173 in 2012