Bartrum phoned Eagles trainer Rick Burkholder on Monday afternoon complaining of a severely stiff neck, and subsequent tests revealed a small chip on a vertebra, a bulging disk and a herniated disk. Burkholder said the chip is incidental and that the bulging disk is "not a big problem" but acknowledged the herniated disk is a concern.
"[It's] lying against his spinal cord," Burkholder told the Philadelphia media. "We're not going to let him play the rest of the season, and at the end of the season, we'll re-evaluate and see what needs to be done."
Philadelphia on Wednesday signed free-agent long snapper Jon Dorenbos, who has played in 39 games with Buffalo (2003-04) and Tennessee (2005-06), to replace Bartrum.
In Sunday's loss at Indianapolis, Bartrum made an early third-quarter tackle of Terrence Wilkins on a punt return, which may have exacerbated the injuries. But it is believed the problems revealed by the MRI on Monday were a pre-existing condition perhaps aggravated by Sunday's game.
"We think it's old stuff in his neck," Burkholder said. "That's what made us disqualify him from playing. Any time there's a disk that close to the spinal cord, there's a chance for a catastrophic outcome."
Bartrum, 36, has long been regarded as one of the NFL's premier long snappers, and his mastery of the esoteric art earned him a Pro Bowl berth last season. He has also lined up occasionally as a tight end in goal-line and short-yardage situations and has 11 career receptions for 65 yards and six touchdowns.
He has appeared in 171 games and been with the Eagles since 2000. Before that, he played in Kansas City (1993-94), Green Bay (1995) and New England (1996-99). There has been some speculation this year that Bartrum might retire at the end of the season.
Len Pasquarelli is a senior NFL writer for ESPN.com.