Harrison was to be part of a trade with the Detroit Lions that would have brought him to Philly in exchange for Ronnie Brown.
ESPN's Adam Schefter cites sources as saying Harrison is not expected to play again this season, but his long-term prognosis both for life and his football career appear to be good.
The trade might have actually saved Harrison's life, the sources said.
The Eagles announced Tuesday they dealt Brown to Detroit for Harrison and an undisclosed pick in the 2013 draft.
However, on Wednesday, news came that the deal had been voided.
Detroit wouldn't confirm the move because the franchise doesn't until deals are done.
Harrison played eight games for the Eagles last season.
The Lions were looking forward to adding Brown to a backfield that might be without starting running back Jahvid Best for a while. He had his third concussion Sunday in a loss to San Francisco.
With Best out, the Lions (5-1) were sounded as if they were ready to plug Brown into the lineup Sunday against the Falcons (3-3) despite not being able to put him on the practice field Wednesday.