Brain Tumor Surgery and Postoperative Delirium

1. To explore whether the combined administration of dexmedetomidine during and after surgery in patients undergoing brain tumor resection is an effective and safe modality to prevent postoperative delirium and improve sleep quality than giving it alone after surgery. 2. To explore whether intraoperative and postoperative administration of dexmedetomidine to patients undergoing brain tumor surgery can reduce postoperative acute pain and prevent chronic pain. 3. To explore whether intraoperative and postoperative administration of dexmedetomidine to patients undergoing brain tumor surgery can provide stable anesthesia depth, hemodynamics and reduce the dose of anesthetics, thereby accelerating patient recovery.