Neurobehavioral outcome prediction after cardiac surgery: role of neurobiochemical markers of damage to neuronal and glial brain tissue.

BACKGROUND AND PURPOSE

The goal of the present study was to investigate the predictive value of neurobiochemical markers of brain damage (protein S-100B and neuron-specific enolase [NSE]) with respect to the short- and long-term neuropsychological outcomes after cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

We investigated 74 patients who underwent elective CABG or valve replacement surgery and who showed no severe neurological deficits after surgery. Patients were investigated with a standardized neurological examination and a comprehensive neuropsychological and neuropsychiatric assessment 1 to 2 days before surgery, 3 and 8 days after surgery, and 6 months later. Serial venous blood samples were taken preoperatively and 1, 6, 20, and 30 hours after skin closure. Protein S-100B and NSE were analyzed with immunoluminometric assays.

RESULTS

Patients with severe postoperative neuropsychological disorders showed a significantly higher and longer release of neurobiochemical markers of brain damage. Patients who presented with a delirium according to DSM-III-R criteria 3 days after surgery had significantly higher postoperative S-100B serum concentrations. Multivariate analysis (based on postoperative NSE and S-100B concentrations and age of patients, type of operation, length of cross-clamp and perfusion time, and intraoperative and postoperative oxygenation) identified NSE and S-100B concentrations 6 to 30 hours after skin closure as the only variables that contributed significantly to a predictive model of the neuropsychological outcome. NSE, but not S-100B, release was significantly higher in patients undergoing valve replacement surgery.

CONCLUSIONS

Postoperative serum concentrations and kinetics of S-100B and NSE have a high predictive value with respect to the early neuropsychological and neuropsychiatric outcome after cardiac surgery. The analysis of NSE and S-100B release might allow insight into the underlying pathophysiology of brain dysfunction, thus providing a valuable tool to monitor and evaluate measures to improve cardiac surgery with CPB.