SAN FRANCISCO — San Francisco Giants lefty Noah Lowry will be shut down for a "significant" amount of time as he struggles to heal from a nerve injury in his forearm.

Lowry is still feeling the tingling in his left forearm that forced him to undergo surgery to repair his nerves in March. Tests conducted Tuesday by hand specialist Dr. Gordon Brody showed signs of improvement in Lowry's nerves, but he will get a second opinion Monday from Dr. James Andrews because he still is feeling symptoms.

"We're probably going to have to shut him down for a significant amount of time," Giants athletic trainer Dave Groeschner said. "It could be three weeks or it could be a little bit longer. Nerves are slow to heal. I think the fact that the nerve conduction study was normal was a good sign. But the fact of the matter is he's still having these symptoms. The doctors think they will go away with time, but it is going to be time."

Lowry originally hoped to be back in mid-April after undergoing surgery on his left forearm March 7. Lowry was supposed to throw off a mound last week but that plan was scrapped when the arm still didn't feel normal.

The Giants have no definitive timetable for Lowry's return.

"Right now he's going to be shut down until this thing is right, when the pins and needles and numbness goes away," Groeschner said. "Otherwise we're going to keep spinning our wheels."

Lowry led the Giants with 14 wins last season and was being counted on again as a key part of the rotation. He has a 40-31 record with a 4.03 ERA in 106 career games.

With Lowry and Kevin Correia (left oblique strain) sidelined with injuries, the Giants are short-handed in their rotation. Pat Misch was called up to replace Correia, but opening day starter Barry Zito has been relegated to the bullpen after an 0-6 start.

The Giants don't need a fifth starter again until May 10, so manager Bruce Bochy has time to decide whether to return Zito to the rotation.

In other injury news, shortstop Omar Vizquel is making progress in his recovery from surgery on his left knee and could play a few innings in an extended spring training game in Arizona later this week. Vizquel, who underwent arthroscopic surgery on his left knee Feb. 27, has been running, fielding grounders and taking batting practice this week.