Rolle was first diagnosed with an injured right shoulder after intercepting a pass against the Cleveland Browns in the final two minutes of a 28-10 victory on Sept. 21, and predicted he would recover quickly.
However, more extensive exams determined that the pain was stemming from the neck due to a stinger and bulging disc. Rolle was held out of the Ravens' 23-20 overtime loss Monday night to the Pittsburgh Steelers. The best-case scenario would be for him to return Nov. 2 against the Browns.
"We have a time frame on him, and it's maybe a month-plus," Harbaugh said. "That's where it's at right now. He had a surgery this week on his neck, just to kind of clean things up in there a little bit. It will be multiple weeks.
"We just don't know how long right now. It was all kind of related, from a stinger perspective. That's what he felt, the tingling, and then it felt it through the shoulder, too. It was all part of the same deal."
With Rolle out for an extended period, Fabian Washington will continue to start in his place. Washington has a bulging disc, too, but is choosing to wait until after the season to determine if he'll need surgery.
Rolle, who was diagnosed with epilepsy last season and missed the majority of training camp this year while grieving his father's death, is hoping to return later this season.
Acquired via a trade from the Oakland Raiders this spring, Washington made his debut with the Ravens against the Steelers and allowed a 38-yard touchdown pass to wide receiver Santonio Holmes.
A former first-round draft pick, Washington started for the Raiders until losing his job last season to Stanford Routt.
"That's what they brought me here to do, I expect nothing less of myself," Washington said. "I've been a starter in this league before, so that's nothing new to me. Just go out there and play football. You've got to build on what you're doing. If you're not getting better, you're getting worse."
Listed at 5-foot-11, 180 pounds, Washington will be at a disadvantage in terms of size against the Titans' imposing wide receivers. Justin Gage and Justin McCareins are listed at 6-4, 212 pounds and 6-2, 215 pounds, respectively.
"It's always going to be a challenge for a guy of my stature, I'm only 5-10," Washington said. "Luckily, I can jump through the roof."
Meanwhile, the team is still awaiting word on the outlook of nose guard Kelly Gregg. Gregg has yet to play this year after undergoing arthroscopic surgery on his left knee in early August.
The Ravens have sent magnetic resonance imaging pictures of Gregg's knee to outside doctors for a second opinion.
Gregg has been experiencing pain and discomfort due to a hole in the cartilage in his knee.
"We're hopeful that he'll play this year," Harbaugh said. "There's no guarantee right now. We're up in the air. We'll have to see what we find out."
Ravens' Rolle out for at least a month
Ravens Insider Top Stories
2017 Baltimore Ravens Team OutlookSenior Fantasy Football Expert Shawn Childs goes in-depth covering every Fantasy aspect of the 2017 Baltimore Ravens!
State of the Broncos: Running BacksMile High Huddle brings you State of the 2017 Broncos — a position by position evaluation of the roster. Today's edition focuses on running backs. Publisher Chad Jensen examines.
Mile High HuddleYesterday at 10:25 AM
Friday Five: Best transfers of SEC eraHawgsDaily ranks the top five Arkansas transfers since the Razorbacks joined the SEC in 1992.
Hawgs DailyFriday at 3:13 PM
Can Denver Avoid Oakland's QB Trappings?The Raiders made Derek Carr the highest-paid player in NFL history on Thursday, but now they must change their financial approach to roster building, while the Broncos are getting…
Mile High HuddleFriday at 5:11 AM