SAN DIEGO — St. Louis Cardinals starting pitcher Kyle Lohse is suffering from a rare condition that either requires surgery or necessitates a permanent role change, say sources familiar with the diagnosis given Lohse on Wednesday by an Anaheim, Calif., specialist.

Hand and wrist specialist Dr. Steven S. Shin met with Lohse for less than an hour at the Kerlan-Jobe Orthopedic Clinic about 90 minutes north of San Diego. Shin found Lohse to be suffering from extreme compartment syndrome, a condition in which the sheath covering a muscle in the pitcher's forearm fails to allow it to expand.

The condition is more closely associated with distance runners and motocross riders.

No known precedent exists for the condition in Lohse's line of work, according to the pitcher.

"They don't know of any major-league pitcher who has dealt with this before," he said. "We're kind of in uncharted territory here."

The lack of precedent complicates any estimate for Lohse's return.

Shin and Cardinals medical supervisor Dr. George Paletta have undertaken a search for an American surgeon experienced in addressing the condition, which is most common with European motocross riders. The Cardinals have yet to place Lohse on the disabled list but may do so Thursday in conjunction with a further announcement.

Recovery time for motocross athletes who require surgery to alleviate the condition is typically around seven weeks; however, such a prognosis is considered very optimistic for a major-league pitcher, according to a medical source.

Should Lohse eventually consent to surgery he would probably miss at least two months and quite possibly be out for the remainder of the season, sources confirmed.

Cardinals assistant athletic trainer Greg Hauck and a representative from agent Scott Boras' company accompanied Lohse to Wednesday's evaluation. Though Boras suggested Lohse consult Shin for a second opinion, the process is described as a cooperative one between the club and the player's agent.

The Cardinals released a brief statement after Wednesday's exam that read, in part, "The team will evaluate and make a decision on today's finding in 24 hours. A statement by the team will be made at that time."

Lohse expressed relief Wednesday over the consistency of his diagnoses but remains concerned about what the finding means for a career stalled since late last May by forearm issues.

Lohse confirmed last weekend he suffered discomfort for much of spring training and early this season but had come to believe "that's just the way it was going to be." The condition has left his right forearm swollen and his right hand at times cold to touch.

"We're going to have to do something," Lohse said. "I've tried to pitch with it. But the way it is now, there's no way."

MRI studies administered Monday in St. Louis found that muscle in the forearm becomes irritated when exerted.

With the muscle's covering, or fascia, unable to expand, a cramping sensation develops that prevents Lohse from properly flexing his right wrist. The inability prevents Lohse from imparting sink on his two-seam fastball, which instead "cuts" on a flatter plane. Well aware there is little case history among pitchers for his condition, Lohse senses that some may remain skeptical about its severity. "It's not something I want," he said. "I want to pitch. But what happened last weekend told me I can't."

There is no known treatment for the condition short of surgery. Since swelling and cramping in the forearm intensifies with effort, Lohse's options are confined to continuing his career as a relief specialist or submitting to surgery.

Lohse left last Saturday's start against the Los Angeles Angels after 31/3 innings. He has averaged less than five innings in his last five starts.

The Cardinals appear increasingly likely to examine trade and free agent options should Lohse indeed be lost for a significant portion of the season. Rookie P.J. Walters is scheduled to make Thursday afternoon's start against the San Diego Padres in place of Brad Penny, who is on the disabled list with a strained muscle in his upper back.

Manager Tony La Russa insisted before Wednesday night's game that no decision had been made on who will inherit Saturday's start against the Chicago Cubs. Adam Ottavino could be promoted from Class AAA Memphis to make his major-league debut, or Blake Hawksworth or Kyle McClellan could be assigned a spot start.

La Russa acknowledged a decision to start one of the relievers would be heavily scrutinized because of the potential disruption of what has been one of the team's most dependable strengths.

The Cardinals remain hopeful that Penny's loss will be confined to no more than three weeks. However, promoting Ottavino would inject a third rookie into a rotation that opened the season with 30 quality starts in the first 36 games. The club fears such exposure eventually would compromise the bullpen as well.

"It's something we're still talking about," La Russa said. "There's a lot to consider."