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INTRODUCTION. Anesthesia with xenon is characterized by stable hemodynamic parameters, cardio- and neuroprotection preferable in elderly. Assessment of the depth of hypnosis remains challenging. The Kugler classification based on electroencephalogram has been suggested for such assessment. OBJECTIVES. To assess the feasibility of Kugler scale for objective assessment of the depth of hypnosis induced by xenon alone or in combination with narcotics and regional anesthesia during knee arthroplasty in elderly. MATERIALS AND METHODS. The study included 57 patients divided into 2 groups. In group 1, general anesthesia with xenon was performed, fentanyl and femoral nerve block were used for pain control. In group 2, xenon anesthesia was performed in combination with femoral and sciatic nerve block. The depth of hypnosis was monitored using EEG and matched with the Kugler scale. Also, the bispectral index (BIS) was recorded. RESULTS. At xenon concentration of 40 %, the depth of hypnosis reached D2 stage in group 1 and D1 in group 2 patients, while at 55 % and above it was D2 in both groups. Fentanyl increased the δ-rhythm by 19.08 %, which corresponded to reduction in the effective xenon concentration by 20 %. A correlation between δ-rhythm decrease and BIS was seen in groups 1 (r = –0.78; R2 = 60 %) and 2 (r = –0.61; R2 = 37 %). The differences could be related to the use of fentanyl in group 1. The intergroup difference between the reduction of BIS was not significant. CONCLUSIONS. In elderly patients undergoing knee arthroplasty under combined anesthesia, stage D2 according to Kugler scale (proportion of δ-rhythm more than 50 %) is achieved at xenon concentration of 55 % without narcotics and at concentration of 40 % with fentanyl. The diminished correlation between δ-rhythm and BIS in group 2 and no difference in decrease of BIS suggests that BIS is less accurate for determining the depth of hypnosis during xenon monoanesthesia.

Correlations between the impairments of higher cortical functions (assessed by clinical scores and neuropsychological tests) and multichannel EEG spectra were analyzed in elderly patients with mild dementia and children with cognitive problems. A decrease in the regional cerebral blood flow, an imbalance between neocortical and limbic structures, and a lack of inhibitory influences from the frontal cortex are discussed as probable causes of these brain functional disorders associated with a “slow sensorimotor rhythm.”

EEG topography correlates of severity and type of Alzheimer type dementia (DAT) have been studied in 21 senile dementia (SD), and in 18 Alzheimer disease (AD) patients, as well as in 15 mentally normal elderly persons. EEG maps in SD and AD patients differed from that in normals by increase of theta-delta EEG spectral power, and by suppression of alpha band power, more pronounced in AD than in SD patients, especially, in the left hemisphere. AD and SD patients also showed different EEG topography dynamics with increase in degree of cognitive functions impairment assessed by MMSE. Results obtained are in good concordance with data on metabolism and local cerebral blood flow decrease, and on cognitive deficiencies in different clinical forms of DAT.

The high-resolution EEG was taken from 35 healthy subjects (16 males, 19 females) in the task of identification of cardinal (horizontal, vertical) and oblique (45°, 135°) orientations. The integrated approach was developed and used for the ERPs analysis. It includes the modeling of the distributed intracranial dipole sources of the ERPs' components by the weighted Minimum Norm Estimates (wMNE) method, the combination of distributed intracranial dipole sources with the M RI data and the statistical analysis of the current density. It was shown that a multiple network of brain structures was active during the early stage of analysis of line orientation. It includes not only primary striate visual area, but also the parietal, temporal and prefrontal corticies. The new data was obtained about the participation of structures, responsible for navigation (parahippocampal gyrus and entorhinal area) in the line orientation detection. For the first time the gender-related differences in the organization ofthe line detection network were described. The obtained data provides a significant supplement to the knowledge of the mechanisms of the orientation sensitivity and assumes that orientation sensitivity plays an important role in the navigation.