Dvorak left the game in the first period after getting hit by defenceman Jared Spurgeon. A replay showed Spurgeon catching Dvorak with a hit to the head.
No penalty was called on the play. Jake Evans was moved up to play with Mike Hoffman and Laurent Dauphin.
After the game, head coach Dominique Ducharme confirmed that Dvorak had been pulled from the game by a concussion spotter and that he had failed his test.
"It happened quickly. I'd imagine if there's something, the league will look at it," Ducharme said. "He was pulled by the spotter and he didn't pass his tests. We'll see what's up in a few days."
In his first season with the Canadiens, Dvorak has seven goals and 16 points in 33 games.