Former NHL star Keith Primeau says the violent hit by Vancouver Canucks forward Raffi Torres on Chicago Blackhawks defenceman Brent Seabrook exposes a "grey area" in the league rule designed to limit concussions.

"It was 100 per cent my definition of a blindside hit," Primeau said in a telephone interview with CBC News. "Not a blindside hit to the head but still a blindside hit to a player in a very vulnerable position."

The collision occurred in the second period of Sunday night's 3-2 Canucks' win over the Blackhawks in Chicago.

Seabrook was skating behind his own net and looking back for the puck when Torres slammed into him. Torres received a two-minute minor penalty for interference.

Under the NHL's Rule 48, had it been ruled an illegal blindside hit to the head, Torres would have been assessed a five-minute major penalty and a game misconduct.

And there's the rub.

Seabrook was clearly dazed by the body check, lying face down on the ice momentarily before getting up and skating to the bench. 

Primeau thinks Seabrook suffered a head injury on the play.

"In my opinion he [Seabrook] suffered a concussion."

And that, Primeau says, exposes a second grey area in the league rules.

"He should not have returned to play. It's extremely dangerous. He's going to need time to recover."

The NHL's revised Protocol for Concussions Evaluation, which went into effect in March, states: "a player who is suspected of having a concussion will be removed from the game and sent to a quiet place free of distraction so they can be examined by an on-site physician."

Seabrook spoke briefly with the trainer on the bench but returned to the ice and was then hit into the boards again by Torres. Seabrook went to the dressing room after the second hit.

Primeau — whose own career ended after multiple concussions and who is still suffering from post-concussion syndrome five years later — says it was difficult to watch.

"I was watching the highlights and I saw the hit and my head just dropped because it was so upsetting.  And then to see him get hit again … it was just so frustrating," he says.

"You can't trust the player to say he's OK. He's not OK, trust me. It was the same as [NHL superstar Sidney] Crosby, the same as [Toronto forward Mikhail] Grabovski. It takes far less contact to get hurt the second time."

Crosby hasn't played since suffering a concussion when he was slammed into the boards by Tampa Bay's Victor Hedman in January. Some suspect Crosby was actually hurt prior to that hit when he was knocked off his skates by Washington's David Steckel during the Winter Classic on New Year's Day. 

Grabovski was hit twice during a game with Boston in February and appeared to be dazed and disoriented but remained in the game, eventually returning to score the winning goal.

Primeau says it can take days to notice the symptoms of a concussion.  

"With my numbers three and four [concussions] I didn't feel the true effects until 48 hours after the hit.  Extreme headaches, head pressure, dizziness and disorientation, sensitivity to light."

Primeau also says the Seabrook situation makes it harder for him to sell his message of the dangers of blindside hits and subsequent concussions.

Primeau has been an outspoken advocate for more awareness of head injuries.

"Don't get me wrong, I don't want to see hitting removed from the game," he says. "I don't want to see the nature of the game changed."

"I just want to see the rules clearly defined and enforced."

It's not known if Seabrook, who reportedly suffered two concussions last year, will miss any time.

The Canucks lead the best of seven series 3-0.