This feature is part of our bi-weekly look at the NHL, which appears every other Sunday on Page 2 of the print edition.

Flyers captain Chris Pronger will miss the remainder of the season and playoffs due to “severe” post-concussion syndrome. (Matt Slocum/AP)

Right now, they’re also all sidelined with concussions.

Over the past week, my Twitter timeline has been besieged by news of one concussion after another, beginning with Giroux.

*Last Saturday, Giroux, the 23-year-old Flyers’ center and NHL’s leading scorer, was accidentally kneed in the head in a collision with a teammate. It was later confirmed what everyone has suspected when he left the game: He had suffered a concussion and would be out indefinitely.

*Monday, Crosby, the face of the NHL and arguably its best player, acknowledged he had suffered a setback in his return from a concussion that had already cost him 11 months. His career is also on hold, again.

*Tuesday, Ottawa’s Michalek suffered a concussion in a collision with teammate Erik Karlsson. Michalek was in the midst of a career season, tied for the league lead in goals with 19. His brother, Zybnek, has also missed time in Pittsburgh with a concussion (though he had hoped to return Friday).

*Wednesday, Carolina announced that Jeff Skinner, the reigning rookie of the year, and key defenseman Joni Pitkanen are out indefinitely with concussions.

*Thursday, Philadelphia announced that Pronger, their captain and best defenseman, will miss the remainder of the season and playoffs due to “severe” post-concussion syndrome.

Concussions, of course, are not new in the NHL. And, in fact, the league says recorded incidences are actually down year over last.

Asked why it seems that there are more concussions this season, Flyers General Manager Paul Holmgren said, “I would like to believe it’s more awareness.”

But when so many stars are sidelined simultaneously, the issues need to be re-examined and serious questions must be considered.

Last year, the league introduced Rule 48, banning blindside hits to the head, and this season Brendan Shanahan, the league’s senior vice president of player safety, has been diligent in doling out fines and suspensions to perpetrators.

But what about Giroux and Milan Michalek? They were injured by bumping into teammates. Rule 48 wouldn’t have protected them.

Player agent Allan Walsh took aim at the NHL this week in an interview with the Canadian Press, describing the recent rash of concussions to star players as an “epidemic” and a “crisis” and calling on league officials to take a long look at the game’s increased speed, size of equipment, rule changes, helmet safety standards, use of mouthguards, staged fights and headshots.

He’s right about all of that, from helmets to fighting. But the word that grabbed my attention was “speed.”

In sports, speed kills. In hockey, though, is it possible that too much speed concusses?

I’ve often wondered if the rule changes implemented in 2005 — the removal of the red line, the introduction of the trapezoid and stricter enforcement of obstruction fouls — have made the game too fast.

The objective of the tweaks coming out of the lockout was to increase flow and scoring. The result has been a more exciting game for fans, but a more dangerous work environment for players that, in Walsh’s words, features “increased collision.”

Whether there are more collisions today can be argued. So can the suggestion that they are more violent.

What can’t be debated, though, is that players are bigger and stronger and moving at higher rate of speed than ever before.

Would re-introducing the red line – and, thus, the two-line pass – apply the brakes? What about relaxing rules against clutching and grabbing, even if the end result is a reduction in offense? How about switching to Olympic size rinks?

Despite an increase in speed, the size of the playing surface has remained 200’ x 85’. Would expanding the rink to the international size of 210’ x 98’ make a tangible difference? Would owners sacrifice a few hundred prime seats to make it happen?

I’m not sure how feasible any of those suggestions are, or whether they would be seriously considered by the game’s stakeholders. But when $50 million in player salaries are sidelined, it’s time to have a serious discussion.

View Photo Gallery: Tarik El-Bashir assesses the top teams in the National Hockey League this week (Dec. 16). Records are through Thursday’s games.