Two years ago, Mr Garry Douglas Tan went for an operation at Tan Tock Seng Hospital to remove a brain tumour.
Three days after the first phase of the procedure, which removed 60 per cent of the tumour, he was conscious and could speak and eat normally.
But his condition suddenly deteriorated and he is now in a coma.
His family now questions the level of care he received. But the hospital, in consultation with independent experts, said investigations showed proper care was given.