Characterization of quantitative EEG in patients with postoperative cognitive dysfunction / 医学研究生学报

ABSTRACT

Objective Very few studies have been reported on the application of quantitative electroencephalogram (qEEG) in patients with postoperative cognitive dysfunction (POCD). This study was to investigate the qEEG features of POCD and provide some help for the early detection and diagnosis of the condition. Methods We enrolled 31 postoperative patients treated in our Department of Critical Care Medicine from January 2018 to October 2018. Based on the pre- and post-operative scores on the Mini-Mental State Examination (MMSE), we divided the patients into a POCD (MMSE score >2, n = 11) and a non-POCD control group (MMSE score ≤2, n = 20). Using the brain function instrument, the electrode set according to the standard international 10-20 system and with bipolar longitudinal F3-P3 and F4-P4 four channels, we conducted bedside monitoring for all the patients and calculated the average value of the consecutive clips of 10-min qEEG. Then, we analyzed the amplitude-integrated EEG (aEEG), relative frequency band energy, relative α variability and spectrum entropy, and the correlation of relative frequency band energy and relative α variability with the MMSE scores. Results Compared with the non-POCD controls, the POCD patients showed significant decreases in the total MMSE scores (28.35 ± 1.27 vs 18.91 ± 2.34, P < 0.05), orientation score (9.75 ± 0.44 vs 6.82 ± 1.47, P < 0.05) and memory score (2.90 ± 0.31 vs 2.09 ± 1.04, P < 0.05) as well as in the concentration, calculation, recalling and language scores (all P < 0.05); and the POCD patients also exhibited marked reduction in the left α variability ([22.59 ± 10.98]% vs [14.39 ± 8.25]%, P < 0.05), right α variability ([24.07 ± 9.73]% vs [15.70 ± 9.59]%, P < 0.05), left α frequency band energy ([7.17 ± 4.73] vs [3.83 ± 2.62] μV2, P < 0.05) and right α frequency band energy ([6.94 ± 4.53] vs [3.82 ± 2.51] μV2, P < 0.05). The MMSE scores were found to be negatively correlated with left α variability (r = -0.793, P = 0.004), right α variability (r = -0.835, P = 0.001), left α frequency band energy (r = -0.633, P = 0.037) and right α frequency band energy (r = -0.682, P = 0.021). Conclusion Quantitative EEG of POCD patients is characterized by significantly decreased α variability and α frequency band energy, which may contribute to the early detection and diagnosis of POCD.