Magnesium Sulphate Versus Fentanyl Sedation During Burr-hole Surgery

a loading of 50 mg/kg in 15 minutes of Magnesium sulphate, and will be followed by continuous infusion at 1 ml/kg/h of 15 mg/ml solution

loading of 1 mcg/kg in over 15 minutes of fentanyl then will receive continuous infusion starting at 1 ml /kg/h. of 0.5 mcg/ml solution

0.5-1.5 mg/kg bolus of propofol over 10 minutes to achieve target Ramsay sedation scale (RSS) of 3 (respond to command), if RSS afterwards does not reach 3 a supplementary bolus dose of 0.2 mg/kg propofol will be given to the patients, and will be followed by 1-2.5 mg/kg/hr infusion to maintain Intraoperative BIS readings between 60 - 80