PMC6422875_01
Distribution of the power relations between analyzed frequency bands, marked in gray scale, in both examinations for all EEG channels. In the first examination, spectral power with a statistically different distribution is found for the T6 channel (caused by high delta disturbances) and in the O1-02 channels (where the alpha activity is higher than in other locations). The second examination has a completely different spectral structure in all locations with the exception of Fz and Cz.
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F1
We found no hemispherical asymmetry (p < 0.05) (Figures 1, 2A,C). This is due to a change in the relative spectral power calculated for the 3.5-7 Hz band and (to a lesser extent) the 18-24 Hz band in the signal recorded 26 months after CPR in comparison to the EEG measured 17 months earlier (Figure 1).
Mapping of the relative spectral power of EEG signals registered unipolar in reference to a frontal midline (Fp1/Fp2) relative spectral power of EEG signals registered during initial (left) and control (right) hospitalization. Spectra were obtained using FFT, and ratios were calculated for the theta (3.5-7.5 Hz) band (A,B) and beta-2 (18-24 Hz) band (C,D) as the power of EEG in a specific band divided by the level obtained for all bands (1-24 Hz). The high ration value obtained for theta activity in the first examination and the central location (A) is caused by the slow-frequency artifacts in the Cz channel. Theta activity dominates in posterior channels and is much stronger in both absolute and relative values in the second examination (B). Fast beta activity is stronger in the frontal area; yet its relative power is much smaller in the second examination (D), where its distribution has a predominance in the left hemisphere; however, the differences visible at (C,D) are not statistically significant.
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F2
We found no hemispherical asymmetry (p < 0.05) (Figures 1, 2A,C). The spectral maps prepared for EEG recorded 9 and 26 months after CPR presented some changes in this distribution (Figure 2).
MR examination, axial T2-weighted images. The initial MR showed diffuse, mild cortico-subcortical atrophy of the brain (A). The follow-up image (B) revealed an increased rate of brain atrophy after 2 years.
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F3
MR images showed diffuse, mild cortico-subcortical brain atrophy (Figure 3A). MR spectroscopy revealed a decreased NAA/Cr ratio in the PCG region, as well as within the parietal white matter (Figure 4A); the NAA/Cr ratios were 1.25 and 1.28, respectively.
MRS examination within the left parietal white matter area performed at 9 months after cardiorespiratory arrest revealed decreased NAA/Cr ratios (A). The control MRS examination (18 months after cardiorespiratory arrest) demonstrated a moderate improvement of NAA/Cr ratios within white matter; however, the NAA/Cr ratio still remained decreased (B).
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F4
MR images showed diffuse, mild cortico-subcortical brain atrophy (Figure 3A). MR spectroscopy revealed a decreased NAA/Cr ratio in the PCG region, as well as within the parietal white matter (Figure 4A); the NAA/Cr ratios were 1.25 and 1.28, respectively.