Following approval from the Research Ethics Committee of the Medical Faculty of Uludağ University, (the date and protocol number assigned by this ethics committee were March 4, 2008 and 5/30, respectively),written informed consent was obtained from patients undergoing elective scheduled operations involving craniotomy during anaesthesia consultations. Ninety American Society of Anesthesiologists (ASA) Physical Status classification system I or II patients of either sex between 18-85 years of age were allocated to this randomised, prospective, placebo-controlled, double-blind study. The patients were randomly divided into three groups using a sealed-enveloped technique to receive either 20 ml of 0.5% bupivacaine (Group B (n=30)), 20 ml of 0.5% levobupivacaine (Group L (n=30)) or saline as a placebo (Group C (n=30)). Twenty-millilitre syringes for the block were prepared and numbered by a blinded assistant.
