In a press conference Thursday morning at Scotiabank Place, Murray said Spezza, the club's No. 1 center, will undergo surgery Friday in Toronto to address a herniated disc.
"I can't give you a time frame simply because until the surgery and rehab starts we won't know the total extent," Murray said. "We are hoping that he gets back at the later part of the season and, if we're in the [Stanley Cup] Playoffs, [he] will be able to participate at that time."
The usual recovery time for surgery on a herniated disc is six to eight weeks, which means Spezza could miss at least 30 games.
Spezza had a previous disc surgery in 2006.
"You can't replace high-end skill very easily. I don't think there is another team that will call me and offer help when I go back to my office. That's not how we work in our business. It's a big loss." -- Senators GM Bryan Murray
Monday, Spezza consulted with team doctors and visited a specialist in Toronto, then decided to have surgery.
"He had opinion with our doctors and went for a second opinion," Murray said. "[Surgery is] probably the best thing to do right now."
After the surgery Friday, Spezza will rest a week then begin the rehabilitation process.
In five games this season, Spezza had two goals and three assists. In 2011-12, he scored 34 goals and 84 points in 80 games.
Murray said the Senators would try to replace Spezza with somebody from inside the organization before exploring potential trades.
"You can't replace high-end skill very easily," Murray said. "I don't think there is another team that will call me and offer help when I go back to my office. That's not how we work in our business. It's a big loss."