Do blood levels of neuron-specific enolase and S-100 protein reflect cognitive dysfunction after coronary artery bypass?

Background: Neuron-specific enolase (NSE) and S-100 protein have been used as markers for major brain damage. Cognitive dysfunction after cardiac surgery represents subtle brain damage that is detected by neuropsychological testing. We hypothesised that blood levels of NSE and S-100 protein would increase after coronary artery bypass surgery and that the change in blood level would correlate with the change in cognitive function. Methods: We included 35 elderly patients undergoing coronary artery bypass surgery. Neuropsychological testing was per formed before surgery and postoperatively at discharge from hospital and after 3 months using a neuropsychological test battery. Serum levels of NSE and S-100 protein were measured before surgery and postoperatively after 24 h and 48 h. Results: Serum level of both NSE and S-100 protein increased significantly 24 and 48 h after coronary artery bypass. Only the increase in NSE after 24 h was found to correlate with the degree of cognitive dysfunction at discharge from hospital. The increase in S-100 protein after 24 h correlated significantly with the duration of cardiopulmonary bypass. Conclusion: NSE seems to be a useful blood marker for early cognitive dysfunction after coronary artery bypass surgery.