Cardinals starting pitcher Chris Carpenter has left spring camp, seeking a second opinion on his "neck discomfort," according to the St. Louis Post-Dispatch.

The right-hander will fly back to St. Louis to be evaluated.

As the Post-Dispatch report notes, Carpenter was on a modified throwing program this spring anyway, due to his 273 regular and postseason workload in 2011. And this portion of the report may be a bit troubling:
The club has remained intentionally vague about Carpenter's timetable after initially suggesting he would miss one Grapefruit League start. Carpenter said Thursday that he had experienced neck discomfort for 5-6 days but neither he nor the club disclosed whether the matter is thought to be muscle- or nerve-related.
UPDATE: Derrick Gould of the Post-Dispatch tweets that Cardinals general manager John Mozeliak said Carpenter's neck is indeed being checked for nerve damage.

Obviously, if Carpenter misses much more time he won't be ready to join the Cardinals rotation in time for opening day. If that happens, they do have ace Adam Wainwright ready to front the rotation, but he's recovering from Tommy John surgery.

Carpenter, 36, was 11-9 with a 3.45 ERA, 1.26 WHIP and 191 strikeouts in 237 1/3 innings last season. He made six postseason starts, including three in the World Series, where he went 2-0 with a 2.84 ERA and won the decisive Game 7.