A predictive parameter in patients with brain related complications after cardiac surgery?

The prognostic estimation of cerebral complications after cardiac surgery is a major problem in the early postoperative period. Neuron specific enolase (NSE) is an enzyme involved in glycolysis, which is localized in neurons and axonal processes. It escapes into the blood and cerebrospinal fluid at the time of neural injury. Therefore we focused the study on the question of how far serum levels of neuron specific enolase can predict the neurological and neuropsychological outcome after cardiac surgery.

We determined, with a prospective study design of NSE serum levels in 200 patients undergoing cardiac surgery preoperatively, right after the operation and 48 h later. The NSE was measured with a solid phase enzyme immuno assay which utilized a highly specific monoclonal antibody to NSE. We evaluated the neurological and neuropsychological status before and 72 h after surgical intervention. As a control group we recruited 50 patients undergoing general surgical treatment.

The preoperative serum levels of NSE are constantly low in all patients with a mean value of 11.1 ng/ml (8.3-13.6) and a mean +/- S.D. of 3.12 in the main group and a mean value of 9.6 ng/ml (7.8-10.3) and a mean +/- S.D. of 1.84 in the control group. The early postoperative measurements indicated a significant increase to a mean value of 19.7 ng/ml (8.7-70.9) with a mean +/- S.D. of 2.89 in the main group. In contrast there is no increase of NSE serum levels after general surgery. The 48 h postoperative mean levels declined to 14.2 ng/ml (9.9-26.2), S.D. of 3.23. In 17 out of the 200 patients a neurological complication occurred. Elevated NSE levels were found in 16 of these 17 patients. The highest concentrations of NSE were measured in 7 patients with the most severe neurological complications being transient ischemic attack and stroke.

The early serum levels of NSE after cardiopulmonary bypass, in those patients with severe neurological deficits, indicate that NSE is a suitable marker for the detection and quantification of cerebral injury after open heart surgery. Therefore, in addition NSE seems to be of predictive value for the clinical outcome and gives implications for the treatment and prognosis of patients with brain related complications in cardiac surgery.