Analysis of sleep patterns in patients with chronic disorders of consciousness attracts attention from the perspective of the diagnosis and prognosis of the disease as well as the treatment. Yet, the very existence of normal sleep in patients in a vegetative or minimally conscious state is still a matter of debate. This paper presents a retrospective analysis of overnight polysomnographic records of 40 patients with chronic disorders of consciousness aimed at the possibility of establishing the connection between the degree of impaired consciousness and the presence and organization of polysomnographic graphical elements, associated with stages of sleep in normal individuals. Specialized software based on expert system artificial intelligence was developed to calculate indices and parameters that characterize sleep. It was shown that a remarkably low percentage of patients have a rhythmic change in sleep patterns, what indicates the prevalence of violations of the Sleep–Wake cycle in a vegetative state and minimally conscious state. Sleep spindles were not found in records, however, the absence can originate from the limitations of polysomnographic method applied to patients with severe brain damage. A positive correlation between the rhythmic change of sleep patterns, better outcome and CRS-R scores was confirmed.

ABSTRACT. An increase in the number of patients with severe brain damage of various etiologies determines the need to improve neuroprotection technologies. The review is devoted to modern views on the mechanisms of brain protection, as well as the basic processes underlying damage to neurons. The article discusses the results of the most important experimental studies in this area using inert xenon gas. The authors analyzed a number of works highlighting neurotective properties of the xenon inhalation anesthetic in studies performed in vitro and in vivo. The main mechanisms of neuronal death depending on the type of damage are shown, the points of application of the protective effect of xenon on the brain and the prospects for further research in this area are demonstrated in the article.

Relevance. The increase in the number of severe brain injuries due to stroke and traumatic brain injury determines the need to study and develop effective strategies for neuroprotection. The article highlights new mechanisms of the neuroprotective action of the inhalation anesthetic xenon based on the data of our own experimental studies.Aim of study. To assess the effect of anesthesia with xenon at a concentration of 0.5 MAC (minimum alveolar concentration) on the phosphorylation of glycogen synthase kinase 3β (GSK-3β) and the content of antioxidant defense enzymes in the rat brain.Material and methods. The effect of inhalation anesthesia with xenon on the phosphorylation of the GSK-3β enzyme in comparison with lithium chloride, as well as on the content of heme oxygenase, catalase, and Mn-superoxide dismutase in rat brain homogenates was studied by immunoblotting.Results. The use of xenon at a concentration of 0.5 MAA causes an almost twofold increase in the content of the phosphorylated form of the GSK-3β enzyme in comparison with the control (p<0.05) and significantly increases the pool of antioxidant defense enzymes: heme oxygenase by 50% (p <0.05) and Mn-superoxide dismutase by 60% (p<0.05).Conclusion. The conducted experimental study revealed new molecular mechanisms of action of the inhalation anesthetic xenon. The effect of xenon on the pool of enzymes involved in the protection of the brain from oxidative distress was found. The data obtained indicate the prospects for using xenon and require further research in this direction. The use of xenon at a concentration of 50 vol.% (0.5 MAA) for 30 minutes does not affect the content of the glycogen synthase-3β enzyme, at the same time causing an almost twofold increase in its phosphorylated form, the glycogen synthase-3β enzyme, and is accompanied by a significant increase the content of heme oxygenase, Mn-superoxide dismutase and a slight increase in the content of catalase in rat brain homogenates. Thus, the results of the study suggest that one of the possible mechanisms of the neuroprotective effect of xenon is the phosphorylation of glycogen synthase-3β, which prevents the opening of the mitochondrial pore, inhibiting the death of mitochondria-mediated apoptosis of neurons and increasing the level of antioxidant protection in them.

In addition to high mortality, craniocerebral injuries have another danger, a long rehabilitation period and a high percentage of disability with the development of cognitive impairment. This is primarily associated with the processes of neuroinflammation, which development, according to recent data, leads to a long-term impairment of consciousness. The anti-inflammatory effects of xenon inhalation anesthetic, which have been repeatedly shown in previous studies, have the potential to beneficially affect the level of consciousness in these patients by targeting key links of neuroinflammation.AIM OF STUDY To evaluate the effect of oxygen-xenon mixture inhalation on the level of consciousness recovery and the severity of spastic activity in patients after traumatic brain injury.MATERIAL AND METHODS A prospective randomized clinical trial of the effect of inhaled xenon sedation on the level of consciousness and spastic activity in patients with post-coma long-term impairment of consciousness was conducted. Patients were randomized into two equal groups. In group I (comparisons, n=15) (in addition to the standard treatment after a traumatic brain injury), each patient included in the study underwent 7 sessions of inhalation of an air-oxygen mixture with an oxygen content of at least 30 vol% for 30 minutes. In group II (study, n=15) (in addition to standard treatment), each patient included in the study inhaled an oxygen-xenon gas mixture (xenon content 30 vol%) for 7 days 1 time per day. Before and after the course of treatment (on the 7th day), patients were assessed using the CRS-R scale and the modified Ashworth scale.RESULTS The final evaluation included 12 patients from the comparison group and 12 patients from the study group. Three patients were excluded from each group as a result of critical incidents not related to the type of the therapy. In the comparison group on the 7th day, the level of consciousness was score 9 [7; 11] and did not differ statistically significantly from the baseline (p>0.05), which was score 8 [6; 10]. Spastic activity also did not change statistically significantly. In group II, the initial level of consciousness was 9 [7; 10], and on the 7th day — score 15 [12; 17], which was statistically significantly higher both in relation to the level of consciousness by the 1st day (p=0.021) within the group, and in relation to it on the 7th day in group I (p=0.038). When comparing spastic activity on the 1st and 7th days, we did not obtain a statistically significant difference in any of the groups.CONCLUSION Our method of xenon inhalation made it possible to have a beneficial effect on the level of consciousness of patients after traumatic brain injury, but this did not affect the final level of spastic activity in any way.