Before induction, ketamine 0.5mg/kg, dexamethasone 8mg or normal saline of same volume will be administrated intravenously according to the study group allocated. Induction of anaesthesia will be achieved according to a standard protocol. Regional block with 2% lignocaine with 1 in 80000 adrenaline will be performed by surgeon before start of the procedure. The surgery will be started once the anaesthesia is effective.