Background and objectiveS100B protein is a serum marker of cerebral damage. The objective was to evaluate the brain damage caused by general anesthesia, by determining the concentration of serum S100B protein before and after of general anesthesia. Patients and methodPatients with chronic adenotonsillar hypertrophy and indications for tonsillectomy were included. A venous blood sample was taken from the patients before general anesthesia (basal sample). The patients were anaesthetized using the following intravenous anesthetic drugs: midazolam, fentanyl and propofol; and inhaled sevoflurane. A second venous blood sample (postoperative sample) was taken from patients after the surgery, in the operating room. The concentration of serum S100B protein was determined in the basal sample (S100Bb) and postoperative sample (S100Bp) by immunoassay electro-chemiluminescence in MODULAR E-170 (Roche Diagnostics). ResultsSeventy-six patients were included, 46 males and 30 females, aged between 3 and 14 (median 5 years). In all the patients, serum S100B protein levels increased after general anesthesia. The values of S100Bp (median 164.0ng/l) were significantly higher than the values of S100Bb (median 94.5ng/l). The median of the difference between S100Bp and S100Bb was 58.0ng/l. There were statistically significant differences between S100Bb and S100Bp using the Wilcoxon test (p<0.0001). ConclusionsThe concentration of serum S100B protein increased significantly after general anesthesia. This indicates that general anesthesia may cause brain damage.