DODGERS NOTEBOOK: GAGNE MAY NEED BACK SURGERY.

Byline: VINCENT BONSIGNORE Staff Writer

Dodger closer Eric Gagne is facing the possibility of yet another surgery, only this time it has nothing to do with his right elbow.

An MRI on Thursday revealed Gagne is suffering from a herniation of the L-4 and L-5 disks in his lower back. The first course of treatment was a nerve block and epidural injection Thursday, but doctors will move quickly if the condition doesn't improve in the next day or so.

``He could be facing surgery if the injections do not work,'' Dodger trainer Stan Johnston said.

Gagne, admitted to St. Vincent Medical Center after waking up Tuesday in servere pain, remained hospitalized as doctors continued to monitor his condition. Johnston, who described Gagne's mood as ``very down,'' said the injury was not the result of any one incident.

``It's the type of thing you can do bending over to tie your shoes,'' Johnston said.

For Gagne, the back injury is the latest in a series of physical problems since the beginning of the 2005 season. His past problems have all been related to his pitching elbow, which has required three surgeries since last season and has kept him sidelined for all but two innings this year.

Gagne, on the disabled list since suffering an injured ulnar nerve June 6, was inching closer to a return. Johnston gave no indication when Gagne might return, with or without surgery.

``It's up to Mother Nature,'' Dodgers general manager Ned Colletti said.

Playing it safe: Jeff Kent was out of the lineup for the third straight game with a slight strain of the oblique muscle, although he did his best to talk his way into the lineup after taking some swings in the batting cage before Thursday's game against San Francisco.

``But I talked him out of it,'' Johnston said.

Kent said he'll test the muscle again today, and he quickly shot down any notion of shutting things down until after the All-Star break.

``That just means I'd have to sit and wa tch three more baseball games,'' Kent joked. ``And I don't like watching baseball.''

In the booth: The Dodgers will use former players Todd Zeile on Saturday and Robin Ventura on Sunday as radio partners for Charley Steiner this weekend as Rick Monday has time off.