St. Louis Cardinals pitcher Chris Carpenter underwent nerve surgery on Thursday in Dallas, and the team said he faces a rehabilitation time of two to three months.

Carpenter has been unable to pitch this season because of a nerve problem affecting the strength of the muscles in his pitching shoulder. The operation Thursday, called neurogenic thoracic outlet surgery, was performed by Dallas specialist Dr. Greg Pearl.

"We are pleased with today's results and Chris will soon return to St. Louis to begin his rehab," said Cardinals General Manager John Mozeliak. "We look forward to seeing Chris around the ballpark during his recovery."

Carpenter, 37, is expected to return to St. Louis in several days to begin his rehab..

"Carpenter should be fully able to have a normal off-season in preparation for the 2013 season," the team said in announcing the procedure.