Rolston leaves game with concussion

And the league's most frightening problem just seems to get worse by the day.

This time it was Islanders' veteran forward Brian Rolston who left the game during the first period of the Islanders' 3-2 loss to Dallas with a concussion.

Rolston, who has three goals and four assists, is the fourth Islander this season to miss time with a concussion. Rick DiPietro missed the first three weeks of the season with the head injury, rookie forward Nino Niedereiter hasn't played since suffering one from Mark Fistric's suspension-worthy hit Dec. 3, and Steve Staios is also believed to be out with a concussion.

Rolston's injury happened shortly after the Philadelphia Flyers announced captain Chris Pronger will miss the rest of the season with severe post-concussion syndrome. Philadelphia's Claude Giroux is also out with a concussion, as are Rangers defensemen Marc Staal and Mike Sauer, Carolina's Jeff Skinner and Joni Pitkanen, Pittsburgh's Kris Letang and Zbynek Michalek and Ottawa's Milan Michalek. Pittsburgh's Sidney Crosby is also sidelined with concussion-like symptoms less than a month removed from his triumphant return from a 10-month absence from the game.