Neuron loss after coronary artery bypass detected by SPECT estimation of benzodiazepine receptors.

Abstract

Cerebral dysfunction is common after cardiac surgery and probably related to embolic phenomena, but the etiological mechanisms have not been elucidated. The aim of this study was to assess whether a possible neuron loss could be detected by single photon emission computer tomography (SPECT) estimation of benzodiazepine receptor density. In addition, we correlated the findings with neuropsychological test results. We included 15 elderly patients undergoing coronary artery bypass surgery. Neuropsychological testing was performed before surgery and postoperatively at discharge from hospital and after 3 months using a neuropsychological test battery. SPECT was performed before surgery and after 3 months using the iomazenil bolus/infusion technique, and the benzodiazepine receptor density was calculated for the frontal, parietal, temporal, and occipital cortex. Cognitive dysfunction was found in 46.7% at discharge from hospital and in 6.7% after 3 months. A significant decrease in the estimated density of neurons was found in the frontal cortex, but no significant correlation was found between cognitive dysfunction and SPECT findings. Neuron loss was detectable in the frontal cortex, but the decrease did not correlate with neuropsychological test results.