The ketamine group will receive intrathecal bupivacaine (7.5 mg) in 1.5 ml (Marcaine, Astra Zeneca, France, 0.5%) and ketamine (25mg) in 0.5 ml (Ketam, EIPICO, Egypt, 50 mg/mL),. Total volume is 2 ml will injected. The control group will receive only intrathecal bupivacaine (7.5 mg) in 1.5 ml plus 0.5ml normal saline to achieve total volume of 2 ml.