Diagnostic value of S-100 protein and neuron-specific enolase as serum markers for cerebral deficiency after general anaesthesia.: Study in patients with hip or knee replacement

S-100 protein and neuron-specific enolase (NSE) serum concentrations serve as markers of cerebral damage in cardiac surgery, neurology, or after head injury. In these circumstances, S-100 and NSE levels correspond with the results of neuropsychological tests. The present study investigated the diagnostic value in orthopaedic patients after joint replacement. Methods. Forty patients scheduled for elective hip or knee arthroplasty were investigated. Serum values of NSE and S-100 were determined preoperatively and 30 min and 4, 18, and 36 h postoperatively. Neuropsychological tests (syndrome short test, SKT, delirium assessment according to DSM IV) were performed preoperatively and two, three,and four days following surgery. General anaesthesia was induced with fentanyl and etomidate and maintained with isoflurane in oxygen/air Findings. The S-100 increased from a median of 0.04 ng/ml (range 0.004-0.19 ng/ml) preoperatively to 1.03 ng/ml (range 0.18-3.65 ng/ml) at 30 minutes postoperatively (P<0.0001). These levels returned to normal in the course of the following 2 days. NSE values were 8.55 ng/ml (range 4.6-14.9 ng/ml) preoperatively and 7.07 ng/ml (range 4-16.4 ng/ml) postoperatively (P=0.167). There were no differences in serum concentrations of S-100 and NSE between normal patients and those with postoperative cognitive deficit. Furthermore, no correlation was found between the serum marker and neuropsychological tests. Interpretation. Obviously,increased NSE levels seem to indicate cerebral damage only in more severe cases. S-100 does not seem to be brain-specific in patients undergoing orthopaedic surgery. Therefore, the value of S-100 in the assessment of brain disorders is limited.