Phil Hughes had cortisone injection

DETROIT -- The Yankees will be without Phil Hughes for another six to eight weeks as team doctors continue to search for the cause of his mysterious loss of velocity.

General manager Brian Cashman on Wednesday revealed on a conference call that Hughes, who has been on the disabled list since April 15 with a dislocated fastball, was treated with a cortisone injection on April 28 that has relieved some of the inflammation detected in his right shoulder.

But he acknowledged the Yankees do not know why Hughes, who won 18 games last year, suddenly saw his fastball plummet from 93-94 mph last year to between 89-91 mph this season, which resulted in his ERA soaring to 13.94 after three ineffective starts.

"He feels significantly better," Cashman said of Hughes, who was in New York meeting with team doctor Chris Ahmad after returning from St. Louis, where he was tested for thoracic outlet syndrome, a serious and potentially career-threatening condition.

"I think he feels much better mentally about bigger concerns being ruled out," Cashman said, referring to the TOS test, which came back negative. "Hopefully, this was just a bump in the road, so to speak."

Cashman said Ahmad recommended that Hughes not throw for another two more weeks before beginning a still unspecified rehab program.

"I think we're realistically looking at six to eight weeks before he can pitch again," said Cashman, who cautioned, "There is no guarantee that this is the issue."

All along, Hughes has said he felt no real pain in his shoulder, just numbness and a lack of life on his pitches. The Yankees originally classified his problem as a dead arm and later, as right shoulder inflammation. Hughes underwent at least two MRIs, both of which the Yankees say came back negative, as well as several doppler vascular tests to map the blood flow to his pitching arm.

"I can't tell you we're through the woods yet," Cashman said. "But my understanding is he believes the shot will do the trick, or has done the trick, and it will just be another two weeks of rest before we can turn him loose."

Bartolo Colon has stepped in and pitched well in Hughes' absence, an arrangement manager Joe Girardi said he is satisfied with.

"We've been fortunate with Bartolo," Girardi said. "But there was a black cloud [over Hughes] before and now there's reason for optimism that he will be back. We'll keep our fingers crossed."

Wallace Matthews covers the Yankees for ESPNNewYork.com.