The incident occurred at 2:22 of the second period during the Blackhawks' 4-2 loss on Wednesday. Seabrook's head struck the glass with such force that it left him with a dazed expression a couple of seconds before he fell to the ice. Wisniewski received a minor penalty for charging.
Neither coach Joel Quenneville nor assistant general manager of hockey operations Stan Bowman would elaborate on the severity of Seabrook's condition, or what tests he has undergone to check for a possible concussion.
The Blackhawks face the Los Angeles Kings on Thursday night.
"He's got an upper-body injury right now. We'll say day to day right now, but we don't know more than that," Quenneville said Thursday.
After Wednesday's game, Quenneville called Wisniewski's hit as bad as they come.
"You hit a guy without the puck, you could kill a guy," Quenneville said. "It's the most dangerous hit in the history of the game, all right.
" ... He tried to hurt him," Quenneville added. "If that's not intent, that's as bad a hit as you could ever have in the game."
In a conference call Thursday, Ducks general manager Bob Murray took offense to Quenneville's assertion.
"I played in Chicago for a long time, I lived in the city of Chicago, it used to be a black-and-blue town, it didn't have whiners," Murray said. "I strongly suggest Joel worries about his goaltending and stops trying to run the National Hockey League. He should worry about coaching."
Wednesday was the second game in a row that the Blackhawks lost a valuable member of their defense to a big hit.
Campbell will miss seven to eight weeks because of the fractured collar bone and broken rib he sustained. Ovechkin received a two-game suspension for the play.
"I'm not comparing the two and the quantity of games. That's not for me to decide," Quenneville said. "I'm not so worried about that. I'm worried about Seebs. That's what I'm worried about. We don't have him tonight."
Bowman also had little to say about the length of Wisniewski's suspension compared to Ovechkin's, saying: "The league's job is to weigh all the factors, and they have a lot more experience in that stuff than I do. So you have to assume they did their homework and they came to that decision for the right reason.
"The league obviously looked at it and they think that's the right number. But we're just going to move forward. We're not going to focus on that anymore. We're more worried about Seabrook than Wisniewski."
Wisniewski, who began his career with the Blackhawks before getting traded to the Ducks in March 2009, also was suspended for two games Oct. 31, 2009, and is considered a repeat offender under the terms of the Collective Bargaining Agreement. He will forfeit $268,292 in salary.
"Mr. Wisniewski delivered a retaliatory hit to the head of an opponent who never had possession of the puck," said Colin Campbell, NHL Senior Executive Vice President of Hockey Operations. "The fact that Mr. Wisniewski is a repeat offender also entered into this decision."
Wisniewski will be eligible to return April 3 at Los Angeles.
"I am truly sorry that my friend Brent Seabrook was hurt on the play. I certainly wish him the best," he said in a statement. "I am, however, very disappointed in the length of the suspension. Eight games is incredibly hard to swallow, especially in comparison to other recent hits that have resulted in lesser punishment."
Commissioner Gary Bettman explained the reason for the suspension on his weekly radio show.
Speaking on the "NHL Hour With Gary Bettman," the commissioner said Wisniewski's hit on Seabrook during Wednesday night's game was "completely different" from the one delivered by Pittsburgh forward Matt Cooke earlier this month that left Boston forward Marc Savard with a Grade 2 concussion.
"In that case, unlike some of these others, there was no puck possession, the hitting involved rising up to make contact with the head, and so the circumstances gave rise to being able to punish what we have previously defined -- long before this season -- as illegal acts on the ice," Bettman said.
"And that's why the eight-game suspension."
Murray backed up the NHL's decision to levy such a lengthy punishment against his defenseman, although he questioned the league's consistency in disciplinary matters.
"He crossed the line, he's got to get whacked, I have no problem with that, I support [Colin Campbell]," said Murray. "But let's make it equal across the board. Whether it's a fourth-line player or first-line player, whether the player plays on the East Coast or the West Coast. Don't forget, what's the last suspension of eight games or more here guys? Chris Pronger here in Anaheim. Let's just get it all across the board and make sure it's even."
No matter how the league handles these incidents, Bowman said that the players have to police themselves so that they don't occur with as much frequency as they have this season.
"There's been a lot of talk about what the league going to do about it, but I think we have to start talking a little bit about the players," Bowman said. "It would be one thing if the things that happened were legal plays. But as you see, these guys are getting suspended because they're illegal plays.
"I mean, it seems like there's been a lack of respect for each other. And that's probably the bigger thing," Bowman added. "Ultimately, the players are the ones who control these events. The league is here to deal with them once they happen. But in terms of stopping it, I think we've got to get a little bit of respect back in the game from player to player."
ESPN.com's Jesse Rogers, ESPN.com's Pierre LeBrun and The Associated Press contributed to this report.