New markers of delayed cerebral ischemia resulting from non-traumatic subarachnoid hemorrhage in the lower delta range of electroencephalograms

The paper analyzes electroencephalographic (EEG) data in 14 patients treated in the intensive care unit of the Sklifosovsky Research Institute for Emergency Medicine for non-traumatic subarachnoid hemorrhage. During the treatment, delayed cerebral ischemia in the postoperative period was diagnosed in 4 patients. Delayed ischemia did not develop in 10 patients. Comparison of EEG data in these patients using the wave train electrical activity analysis method revealed differences in EEG of patients with delayed cerebral ischemia in the frequency range of 0.1-1.5 Hz in wavelet spectrograms. It was found that the EEG of patients with delayed ischemia contains wave trains in the lower delta range of wavelet spectrograms, which are not typical for patients without delayed ischemia (AUC=0.92). In addition, it was shown that wave trains in the lower delta range with certain parameters typical for patients without delayed ischemia are not characteristic of patients with delayed ischemia (AUC=0.11). Thus, two markers of delayed ischemia after subarachnoid hemorrhage were detected. A negative correlation was found between the number of wave trains characteristic of patients with delayed ischemia and the number of wave trains characteristic of patients without delayed ischemia (Spearman test, p-value < 0.0001).