Postoperative delirium (POD) is a common complication, and the incidence of POD ranges from 10% to 60%. Previous studies suggested that frontal approach and tumor located at the temporal lobe were independent risk factors for POD after supratentorial tumor resections. Therefore, patients undergoing awake craniotomies are high-risk populations for POD. A lot of trials show that dexmedetomidine might help to reduce the incidence of delirium in patients undergoing non-cardiac surgery. However, the impact of dexmedetomidine (DEX) on POD for patients undergoing awake craniotomies remains unclear. The purpose of this study was to investigate the effect of DEX on POD in patients undergoing awake craniotomies.

Inclusion Criteria:

• Patients undergoing selective awake craniotomies.
• Age ≥18 years.
• Obtain written informed consent.

Exclusion Criteria:

• 1.Preoperative moderate and severe cognitive impairment (Montreal Cognitive Assessment, MoCA< 18).
• 2.Preoperative psychotropic medication within one year.
• 3.BMI≤18 or ≥30 Kg/ m2
• 4.Pregnant or lactating women.
• 5.History of traumatic brain injury or neurosurgery.
• 6.Severe bradycardia (heart rate less than 40 beats per minute), sick sinus syndrome or second-to-third degree atrioventricular block.
• 7.Severe hepatic or renal dysfunction.