CINCINNATI -- Mark DeRosa wants to learn the source of the lingering numbness in his left hand before he considers undergoing surgery on the damaged tendon in his wrist.
DeRosa, who has left his Minor League injury rehabilitation assignment with Triple-A Fresno to be examined, will undergo a vascular test Thursday, which will include an ultrasound examination that could reveal what's causing the numbness. On Friday, DeRosa will be examined in San Francisco by a neurologist.
DeRosa, who signed a two-year, $12 million contract last offseason, began complaining of the numbness in the pinky and ring fingers of his left hand when he was placed on the disabled list in mid-May.
"We need to find out what's causing the numbness," head athletic trainer Dave Groeschner said Wednesday. "You can't say we're done until we know what's going on. It's hard to fix something until you know how it's broken."
Groeschner said that DeRosa's numbness has subsided somewhat but hasn't vanished, prompting skepticism that the infielder-outfielder's tendon issue is the cause.
"We don't want to have surgery on his tendon and [then] he has numbness in his hand every six months," Groeschner said.