After undergoing a bevy of tests in St. Louis this week, the Cardinals have determined that starting pitcher Chris Carpenter has nerve irritation, leading to weakness in his right shoulder.

The cervical disc injury which Carpenter suffered earlier in spring training is a non-issue.

The right-hander experienced renewed discomfort in his shoulder/neck during a session of catch on Monday. He has yet to pitch in a spring training game this season.

The Cardinals expect Carpenter to return to spring training camp by Monday, but a time-table for his return to the mound is undetermined.

In 34 starts last season, Carpenter was 11-9 with a 3.45 ERA. He also went 4-0 with a 3.25 ERA in six playoff starts.