The NHL Players Association filed an appeal on his behalf to NHL commissioner Gary Bettman on Wednesday evening. Wideman can then appeal further to a neutral arbitrator if the suspension is still six or more games after Bettman rules.
"We strongly disagree with the League's decision to suspend Dennis Wideman," the union said in a statement announcing the appeal. "Dennis has played in 11 NHL seasons and almost 800 games without incident. The facts, including the medical evidence presented at the hearing, clearly demonstrate that Dennis had no intention to make contact with the linesman."
If the suspension stands, Wideman, 32, will forfeit $564,516.20, money that will go to the Players' Emergency Assistance Fund.
In a video explaining the suspension, the NHL said Wideman was diagnosed with a concussion after that game, but said being disoriented as a result of a hit was no excuse for "the nature and severity of the offense he committed on the ice.''
"Wideman did not merely bump into or collide with the linesman,'' the NHL said in the video. "He delivered a forceful blow that was no accident.''
A source told ESPN.com that a spotter -- as mandated by the league's concussion policy -- alerted the Flames that Wideman was exhibiting signs of a concussion, but that Wideman did not want to leave the game. The NHL's video alluded to this, saying, "by (Wideman's) own admission, he repeatedly refused immediate medical attention and returned to the game."
Wideman, who had been suspended indefinitely before the All-Star break, met with NHL officials in Toronto on Tuesday at an appeal hearing that lasted 90 minutes. Henderson was also in the hearing, a source confirmed.
Also present at the hearing for the Flames were team president Brian Burke, general manager Brad Treliving and assistant GM Craig Conroy.
"We disagree with the severity of today's suspension ruling and maintain that Dennis' collision with the linesman was unintentional and accidental," Burke said in a statement Wednesday. "We agree that our officials' safety and well-being is of extreme importance in order to allow them to perform their duties. They perform an invaluable but underappreciated role in our game. We support sanctions against players who make deliberate contact with any official. However, unintentional and accidental contact does occur at times in our game."
In October 2008, Mike Peca's 10-game suspension for grabbing the arm of referee Greg Kimmerly while protesting an opposing goal was reduced to five games by Bettman.
But Wideman's hit was certainly different.
In the game against the Predators on Jan. 27, Wideman had just taken a hit from Nashville winger Miikka Salomaki and was skating toward the Flames' bench when he leveled Henderson from behind, sending Henderson to the ice and against the boards. Wideman said the hit was unintentional. He was not penalized.
Wideman said after the game that he was distracted after the Salomaki hit and unintentionally collided with Henderson.
"At the last second, I looked up and saw [Henderson] and couldn't avoid it," he said after the game. "I went up to Donnie and apologized to him on the ice. I didn't see him. I didn't know where to go and how to get out of the way.
"I've been around for a few years, and I think I've treated every official with the utmost respect, and I would never intentionally try to hit a linesman or a ref. It was completely unintentional, and I already apologized to him."
At the next stoppage, Wideman skated over to where the officials were gathered and apologized.
Wideman, who is in his fourth season with the Flames, is second on the team in penalty minutes with 30 and has two goals and 19 points this season.
Before Wideman's suspension was announced, the Flames recalled defenseman Jakub Nakladal from their AHL affiliate, the Stockton Heat.
Most physical contact between players and officials has occurred when officials have been trying to break up fights among players.
In the 2014 Eastern Conference finals, the New York Rangers' Dan Carcillo elbowed linesman Steve Driscoll, who was trying to keep the left wing away from Montreal Canadiens forward Brandon Prust. Carcillo was assessed a game misconduct penalty and suspended 10 games.
Information from The Associated Press was used in this report.