General anesthesia induction was performed by administering fentanyl 1-2 mcg/kg, propofol 1-2 mg/kg, and rocuronium 0.6 mg/kg. Subsequently, scalp nerve block was performed with 0.5% ropivacaine.

During surgery, a sudden rise of heart rate and blood pressure higher than 20% from baseline was considered as pain, and a bolus of fentanyl was administered as rescue analgesia.

General anesthesia induction was performed by administering fentanyl 1-2 mcg/kg, propofol 1-2 mg/kg, and rocuronium 0.6 mg/kg. Then, continuous fentanyl infusion as analgesia maintenance as the standard treatment. During surgery, a sudden rise of heart rate and blood pressure higher than 20% from baseline was considered as pain, and a bolus of fentanyl was administered as rescue analgesia.

Compared to active comparator arm, the experimental arm received the same procedure except in the analgesia maintenance which was performed by nerve block of the scalp using 0.5% ropivacaine. However, during craniotomy surgery, pain may occur in patients in any arms. This was defined as a sudden rise of heart rate and blood pressure higher than 20% from baseline. In that case, a bolus of fentanyl was administered as rescue analgesia.

Opioid used was fentanyl, and it was administered during and post surgery which was measured μg/kg.

Pain scale was assessed using the Critical-care Pain Observational Tool (CPOT) every 4 hours

Laboratory markers measured were Interleukin (IL)-6 (pg/mL), Tumor Necrosis Factor (TNF)-α (pg/mL), prostaglandin E2 (PGE2) (pg/mL), cortisol level (μg/dL), blood glucose level (mg/dL), neutrophil count (cells/μL), lymphocyte count (cells/μL) and neutrophil-to-lymphocyte ratio (NLR).