Phil Hughes' dead arm remains a mystery.
Test results on the Yankees' right-hander came back negative for all circulatory and vascular issues.
Last week the team thought he may have thoracic outlet syndrome and was sent to a specialist in St. Louis.
At the time, general manager Brian Cashman said Hughes would be out "a while." With the cause of his dead arm unknown, there's no reason to believe that will change.
In three starts this season, Hughes was 0-1 with a 13.94 ERA, allowing 16 earned runs in 10 1/3 innings. Last season the 24-year-old was 18-8 with a 4.19 ERA.For more baseball news, rumors and analysis, follow @cbssportsmlb on Twitter or subscribe to the RSS feed.