The boss conceded that the big defender 'has to be a doubt' for next week's penultimate Premiership fixture at Middlesbrough after picking up an ankle injury just 30 minutes into the 2-0 defeat.
Just back from a back problem, Dean was left clutching his ankle after landing awkwardly going for a ball in the United penalty area.
"It's Deano's ankle and we're not sure of the degree of the damage yet," said Glenn.
"He's not one who would want to come off so he must of turned it quite badly. He has to be doubtful for next week and it's all change again.
"It's very, very annoying because we had to make another change straight away.
"It puts you on the back foot, someone else has to come on and adjust to the pace of the game, Ledley has another defensive partner and it's the story of our defensive unit for the past two years. It's frustrating and annoying."
Glenn Hoddle couldn't hide his disappointment after Dean Richards limped out of Sunday's clash against Manchester United.