The number of concussions in the NHL is down slightly from this point last season, but it’s the type of players who are suffering them that has everybody in the league on high alert.

The game’s best player, Pittsburgh’s Sidney Crosby, is out indefinitely again after suffering recurring symptoms only eight games into his return.

The best defenseman of his generation, Philadelphia’s Chris Pronger, already has been declared out through the rest of the regular season and Stanley Cup playoffs. The league’s leading point-scorer, Philadelphia’s Claude Giroux, and leading goal-scorer, Ottawa’s Milan Michalek, are out indefinitely.

Last season’s Calder Trophy winner (top rookie), Carolina’s Jeff Skinner, is out indefinitely.

“It’s an epidemic,” Blue Jackets general manager Scott Howson said. “There’s no question we’re paying closer attention to head injuries than we used to, but I don’t buy that it’s only that. There’s more to it than that to me.”

But nobody, including Howson, is quite sure what to blame.

Players are bigger, faster and stronger now than they were even 15 years ago, and the equipment they wear is significantly lighter. That, combined with rules adaptations — no clutching and grabbing, legal two-line passes — has sped up the game considerably.

But it doesn’t entirely explain the current epidemic.

Michalek and Giroux were hurt in collisions with teammates. Crosby’s initial concussion was suffered after an inadvertent collision with David Steckel, then playing for Washington, in last year’s Winter Classic.

“There are no easy answers yet,” said NHL commissioner Gary Bettman at the Board of Governors meeting earlier this month.

Each day, though, it seems another unnerving report surfaces.

On Thursday, Pronger’s agent, Pat Morris, detailed to The Hockey News how Pronger has been feeling in recent weeks. THN’s Ken Campbell reported that Pronger has been “stumbling around, regularly forgetting very simple things, and constantly feeling severe nausea.”

Keep in mind, Pronger is one of the biggest, baddest players the league has seen the past 20 years.

“It’s been very difficult to see the state he’s in,” Morris told The Hockey News. “He has always been a player who has answered the bell through all of his injuries, but this is the one time where he can’t answer the bell. So he’s listening to two renowned doctors who are telling him that he’s in trouble.”

The NHL and other leagues have used the ImPACT concussion grading scale to determine if a player has returned to his “baseline” cognitive skills. If not, he’s not allowed to return to play.

But in the case of Crosby and Pronger, both players passed the test, but are still suffering symptoms.

The Blue Jackets have not been hit as hard as some clubs with concussions, but defenseman Radek Martinek has been out since the fifth game of the season, and he won’t be back before Christmas. He suffered his second concussion in five months and third in his career when he collided with Detroit’s Brad Stuart, snapping Martinek’s head forward.

The Blue Jackets, under medical director Joseph Ruane, have been “very diligent” with Martinek for weeks now.

“It’s something we meet to discuss and get updated on almost daily,” Howson said.

Slap shots

The Blue Jackets have talked with Phoenix regarding forward Kyle Turris, but the two clubs don’t seem like a match for a deal. … Tampa Bay defenseman Mattias Ohlund might be done for the season without playing a game. The 35-year-old had surgery on both knees on Oct. 11, but the recovery has gone poorly — so poorly that retirement might come sooner than Ohlund expected. … Ohio State assistant coach John Exter will be an assistant coach for Team USA at the World Junior Championships in Calgary and Edmonton beginning Dec. 26. … Raleigh’s RBC Center will change its name to PNC Arena in March. … Ryan Nugent-Hopkins could be the first Oilers player to win the Calder Trophy. That’s right, Wayne Gretzky didn’t win it. He had 137 points in 1979-80 but wasn’t considered a rookie because he had already played a season in the World Hockey Association.

Slap shots II

Blue Jackets fans wonder if wily veteran Vinny Prospal will sign a contract extension. At Prospal’s age (36), it seems likely he’ll be dealt to a contender at the trade deadline. Why stick around here? … Calgary’s Jarome Iginla has 496 goals. It could be a historic night when the Flames play in Nationwide Arena on Dec. 27. … Wonder if the success former Blue Jackets coach Ken Hitchcock has had in St. Louis — the Blues were 12-2-3 entering the weekend since his hire on Nov. 6 — will prompt more clubs to hire “old-guard” coaches after a three-year trend toward young, first-time coaches. … The Kings are expected to name Darryl Sutter coach this week. It won’t be long before Randy Carlisle gets snapped up, either. … Russian-born right winger Nail Yakupov is seen by many as the early favorite to go No. 1 overall in the draft next June. He’s playing for Sarnia of the Ontario Hockey League, where former Blue Jacket Trevor Letowski is an assistant coach.

aportzline@dispatch.com