# Effect of Carotid Stenosis Severity on Patterns of Brain Activity in Patients after Cardiac Surgery
## 3 Results
#### 3.1.2 EEG Data  
For the next stage of the analysis, a repeated-measures ANOVA with a between-subjects factor of GROUP (two levels: with CA stenoses of less than 50%/without stenoses), and within-subjects factors of EXAMINATION TIME (two levels: before/after surgery), AREA (five levels: frontal, central, parietal, occipital and temporal), and LATERALITY (two levels: left/right hemisphere) was conducted. The significant factors and interactions associated with the GROUP factor are found in the theta2, alpha1 and alpha2 EEG ranges.  
The statistically significant interactions of the factors GROUP \(\times\) EXAMINATION TIME (F\({}_{1.84}\) = 4.95, \(p\) = 0.03) and GROUP \(\times\) EXAMINATION TIME \(\times\) AREA \(\times\) LATERALITY (F\({}_{4.336}\) = 3.54, \(p\) = 0.02) were found in the theta2 range of EEG resting state with eyes closed. The patients with CA stenoses had higher values of the theta2-rhythm power at 7-10 days after CABG in comparison to the patients without stenoses (Figure 2). In addition, the CA stenoses group had higher values of rhythm power in the left hemisphere in the frontal and centroparietal cortical regions and in the right hemisphere in all sites, except for the occipital regions.  
The significance of the GROUP factor was obtained in the theta2, alpha1 and alpha2 frequency ranges of EEG resting state with eyes open (F\({}_{1,84}\) = 4.68, \(p\) = 0.034; F\({}_{1,84}\) = 3.88, \(p\) = 0.05 and F\({}_{1,84}\) = 4.96, \(p\) = 0.029, respectively). The patients with CA stenoses had higher power values of these rhythms compared to patients without stenoses before and after cardiac surgery.  
Figure 2: Differences in the theta2-rhythm power of EEG resting state with eyes closed in patients who underwent on-pump CABG, depending on the presence of CA stenoses less than 50%: dark columns—the patients with CA stenoses, light columns—the patients without CA stenoses, error bars denote SE, *—_p_ < 0.05 Newman–Keuls multiple comparison test.  
Additionally, the analysis of EEG resting state with open eyes revealed a statistically significant interaction of the factors GROUP \(\times\) EXAMINATION TIME \(\times\) AREA \(\times\) LATER-ALITY (F\({}_{4,336}\) = 2.77, \(p\) = 0.04) in the alpha2 frequency range. Before surgery, the power of rhythm was higher in the right frontal (\(p\) = 0.04) and central (\(p\) = 0.025) areas in patients with CA stenoses compared to patients without stenoses. There were no between-group differences in the left hemisphere. After CABG, the patients with CA stenoses had higher power values in the frontal (\(p\) = 0.03 and \(p\) = 0.036, respectively), central (\(p\) = 0.007 and \(p\) = 0.01, respectively) and parietal (\(p\) = 0.02 and \(p\) = 0.019, respectively) regions of the left and right hemispheres (Figure 3).  
Thus, the presence of CA stenoses of less than 50% in patients who underwent on-pump CABG was associated with more pronounced signs of EEG of brain dysfunction. Both before and after CABG, the patients with CA stenoses demonstrated higher values of theta2- and alpha-rhythm power compared to the patients without CA stenoses.  
The Postoperative Neurophysiological Status Changes in the Patients after Combined On-Pump CABG and CEA