Statistical analysis
The PASS 15 software (NCSS, LLC, USA) was used to calculate the sample size based on the primary endpoint. According to a previous study, the proportion of satisfactory brain relaxation was about 80% in the TIVA group [The statistical analysis was performed on a modified intention-to-treat basis (ITT). For the primary outcome, analysis was also performed in the per-protocol (PP) population, excluding those who received rescue treatment before dura opening. Absolute standardized difference (ASD) was determined to identify any imbalance in baseline characteristics.Categorical variables (including the primary outcome) were presented as counts (percentages) and analyzed using χA two-sided 