Gisele revealed the news in an interview with Charlie Rose on CBS This Morning:
Brady didn't miss any games due to injury last season.
The NFL would release a statement regarding Gisele's comments, via NFL.com:
"We have reviewed all reports relating to Tom Brady from the unaffiliated neurotrauma consultants and certified athletic trainer spotters who worked at Patriots' home and away 2016 season games as well as club injury reports that were sent to the league office.
"There are no records that indicate that Mr. Brady suffered a head injury or concussion, or exhibited or complained of concussion symptoms. Today we have been in contact with the NFLPA and will work together to gather more information from the club's medical staff and Mr. Brady. The health and safety of our players is our foremost priority and we want to ensure that all our players have and continue to receive the best care possible."
According to David P. Woods of The Score, the Patriots have not listed Brady on the injury report with a concussion over the past four seasons.
ESPN's Bomani Jones offered some perspective with regard to Gisele labeling whatever Brady was dealing with as a concussion:
The 12-time Pro Bowler sat out the first four games of 2016 due to a suspension stemming from Deflategate before going on to post an 11-1 regular-season record and lead the Pats to a win over the Atlanta Falcons in the Super Bowl.
Despite the concussion, Gisele told Rose that Brady's transition to a plant-based diet has made him feel better physically, per CBS News:
The 39-year-old veteran showed no signs of slowing down last season, throwing for 3,554 yards, 28 touchdowns and just two interceptions during the regular season.
Brady has not missed a game due to injury since 2008, when he was forced to sit out 15 contests after tearing his ACL and MCL in the season opener.