S100B Protein and Postoperative Cognitive Dysfunction

The neurocognitive assessment protocol will design to evaluate general cognitive function and identify patients with cognitive dysfunction. Neuropsychological tests of all patients will conduct on the one day prior to surgery, the seventh day after surgery, and the 3rd month after surgery, respectively. According to a consensus statement, cognitive function will assess using a battery of seven neuropsychological tests: Rey Auditory Verbal Learning Test (delayed recall), Trail Making Test (Parts A and B), Digit Span Test (forward and backward), and Grooved Pegboard Test (dominant and non-dominant hands). To determine a normal reference value of cognitive functions, a group of 20 healthy individuals appropriately selected with respect to sex, age and education level without any significant mental or somatic disorders and without operation were recruited as a control group. To determine the cognitive dysfunction, baseline score or time measurement were subtracted from test score and the difference was divided by the standard deviation of the score in the control group. The result was called the Z score. Z score was calculated for each test and, POCD was defined as a Z score greater than 1.96 in at least two of the seven tests, and/or a combined Z score greater than 1.96.

Serum levels of S100B protein will obtain from venous blood samples collected before surgery, after anesthesia induction, at 30 min and 24 h after surgery.

Inclusion criteria

• over 50 years old
• scheduled for robotic-assisted laparoscopic radical prostatectomy
• the body mass index ranged from 18 kg/m2 to 25 kg/m2
• American Society of Anesthesiologists class I, II or III

Exclusion criteria

• Patients with previous neurological deficit (symptomatic stroke, hemorrhage, transient ischemic attack)
• other neurologic disorders (epilepsy, trauma, intra- or extracranial malignancy)
• psychiatric diseases (schizophrenia, or depressive disorder)
• alcoholism or any other drug dependence
• serious hearing or visual impairment