DeRosa will see a specialist in San Francisco on Thursday. He's been sidelined since May 9. He was on a minor-league rehabilitation stint when he began feeling numbness in the left hand again.
The Giants signed DeRosa to a $12 million, two-year deal last winter. He had wrist surgery after last season with St. Louis. The 35-year-old DeRosa said last month he might require more surgery if the problem doesn't go away.
Giants trainer Dave Groeschner provided an update on DeRosa before San Francisco's game at Cincinnati on Wednesday night.