Hughes has featured 36 times for Norwich since joining in summer 2009
Norwich City midfielder Stephen Hughes will undergo surgery to try to establish the problem behind an ongoing ankle injury.
The 27-year-old has only featured twice this term after having his pre-season hampered by the complaint.
Manager Paul Lambert told BBC Radio Norfolk: "He's going for an operation on his ankle. That's another one that will be out for a bit of time."
Meanwhile left-back Adam Drury is expected to be out for several weeks.
Drury, 32, hobbled out of Saturday's goalless draw at QPR with a calf injury and is likely to be unavailable for "a few weeks" according to Lambert.
I'm not going to make excuses, that's what we've got and that's what we'll go with
Norwich boss Paul Lambert
City were forced into two changes for Tuesday's home defeat by Crystal Palace, with Steven Smith replacing Drury and Jens Berthel Askou stepping into central defence for the suspended Elliot Ward.
The Canaries are already missing defender Michael Nelson with an ankle injury while fellow centre-half Zak Whitbread has only just returned from a long lay-off.
Lambert is also without long-term casualty Andrew Surman in midfield, but is refusing to blame the Palace defeat on a lack of numbers.
"I'm not going to make excuses, that's what we've got and that's what we'll go with," he said
"We can only do what we can do, I've never moaned about it and I'm not going to tart now."
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