Bilateral Bispectral Index, Asymmetries and Post-operative Delirium

Values of the study variables will be extract in these specific moments (considering a delay of thirty seconds between the in vivo phenomenon and the instrument): (t1) BIS probe application (t2) 60" before GA administration (t3) 60" after myoresolution (t4) intubation (t5) surgical incision (t6) end of ipnosis (t7) 10 minutes after extubation. Daily follow-up for the first five post-operative days is performed in order to verify the onset of POD and a telephone follow-up at thirty and ninety post-operative days in order to verify the onset of POD / POCD.

CAM scale will be used for the diagnosis of POD; while for the diagnosis of POCD, 6-CIT test will be used, the EQ50 test in the case of tracheostomized patients.

Inclusion criteria

-Patients, undergoing head&neck surgery, who have at least 3 of the following criteria (to establish "a priori" increased risk of POD):

• Age> 70;
• Male sex; or ASA III;
• Smoker;
• High blood pressure;

Exclusion criteria

• ASA IV, V or ASA IE, IIE, IIIE (patients with anesthetic risk ASA>III and those undergoing urgent-emergency surgery will be excluded from the study);
• Past positive medical history for:

• Stroke;
• Dementia;
• Cerebral aneurysm;
• Intracranial mass;
• Head trauma;
• Epilepsy;
• Diabetes mellitus;
• Previous neurosurgical intervention;
• Psychiatric illnesses requiring chronic treatment;
• Patients undergoing surgery in the previous two weeks;
• Patients whose hospitalization duration is estimated to be less than five days;
• Lack of understanding of the Italian language or English;
• Age <18 years.