Patient management
Medical records and follow-up data of each patient, including the medical history, neurologic examination, operative reports, pathology reports. The SAS was determined from the patient’s intraoperative anesthesia chart where blood pressures and heart rates were recorded every 5 minutes, and three intraoperative parameters including estimated blood loss (EBL), lowest mean arterial pressure (LMAP), and lowest heart rate (LHR) were obtained. Follow-up of patients were conducted by contacting patients using telephone or by outpatient clinics26-29. Preoperative management, anesthetic, and surgical techniques for all patients were standardized and have been previously reported.