Patricia said there "is a medical plan in place" for Stafford, but he didn't want to divulge what that was.
A source told ESPN's Adam Schefter that Stafford's injury involves fractured bones in his back.
Initially, Patricia said he didn't anticipate Stafford playing Sunday, but then said he doesn't see any scenario in which the quarterback would play this weekend.
Stafford, after playing 136 straight games, will now miss his second straight start. He didn't practice at all this week but was in attendance at least during the media portion of practice, often standing in the back, near the coaches, while watching quarterbacks Jeff Driskel and David Blough work.
He would occasionally talk with Driskel or Blough, appearing to offer pointers.
Driskel went 27 for 46 for 269 yards, one touchdown and one interception last week against Chicago, when he was told the morning of the game he would be the team's starter. Now he has had a week to prepare to start against Dallas.
On Wednesday, Driskel said Stafford has been a help to him as he has prepared to once again take over for him.
"He's just a great teammate, great professional. He's been doing it for a long time," Driskel said. "He's played a lot of ball, seen a lot of different things. But I think the biggest thing I take away from him is just go out there and play.
"I thought he did a great job, helped me out a lot on Sunday. But it just goes down to him being a great teammate, a great guy and a great competitor, so I'm glad that he's on our side."
Patricia and Lions offensive coordinator Darrell Bevell said there are some things they may do differently to use Driskel's skill set -- he has more capability as a runner -- but much of their offense can fit either Stafford or Driskel.
"There are things that are core fundamental foundations to what we do, and those don't change," Patricia said. "With that in mind, then there are a couple of nuances that you can include in those things when you have different people in the lineup."
Driskel started five games for the Bengals last season in place of Andy Dalton, going 1-4 while throwing for 1,003 yards, six touchdowns and two interceptions.
Stafford has completed 64.3% of his passes for 2,499 yards, 19 touchdowns and five interceptions this season. Earlier this year, he became the fastest quarterback in NFL history to surpass 40,000 passing yards.