Changes in event-related synchronization/desynchronization of brain electric activity in cardiosurgical patients with postoperative cognitive dysfunction

Aim of the study was to analyze the event-related synchronization/desynchronization of brain electrical activity during visual selection task in patients underwent on-pump coronary artery bypass grafting (CABG) with and without postoperative cognitive dysfunction (POCD). Material and methods. The study included 32 men who underwent on-pump CABG, mean age 57,2 ± 6,08 years. All patients carried out extended neuropsychological testing, a multi-channel computer electroencephalography (EEG) 3-5 days before CABG and on the 7-10th day after the surgery. The POCD was determined according to the criterion: 20 % decrease in the cognitive indicator compared to that at baseline on 20 % of the tests included in the neuropsychological battery. Monopolar EEGs were recorded in 62 sites of 10-20 system with NEUVO encephalograph (Compumedics, USA) during cognitive task performing in patients with and without POCD. Statistical processing was performed using the STATISTICA 10.0. Results. It was found that the POCD patients had less pronounced theta desynchronization in the left frontal-central regions during the stage of 200-400 ms at the 7-10 days after CABG in comparison to patients without cognitive decline. Moreover, in the left parietal leads POCD patients had decreased theta desynchronization during the stage of 200-400 ms even before the surgery. At the 7-10 days after CABG, only the patients without POCD had a decrease of event-related theta activity in the left parietal leads compared with baseline. During the stage of 600-800 ms, the POCD patients had a lower degree of theta-desynchronization of both frontal-central and parietal regions of right hemisphere compared to patients without cognitive decline. Conclusion. The cognitive decline in patients after CABG determined according to neuropsychological testing is accompanied by pathological changes in the event-related theta activity. An analysis of event-related synchronization/desynchronization can be used both as predictor of postoperative cognitive impairment and as objective marker of POCD.