Obstructive Sleep Apnea Syndrome and Features of the Neurophysiological Sleep Pattern

The high prevalence of obstructive sleep apnea syndrome (OSA) causes a steady interest in this pathology. In recent years, one of the urgent problems in modern somnology is the assessment of the main mechanisms of neuronal dysfunction during the day and at night in OSA, the ideas about which, to a large extent, remain contradictory and not fully understood. One of the modern methods for assessing neuronal dysfunction during sleep is the study of the sleep microstructure, and for its assessment, the method of analysis of cyclic alternating pattern (CAP), an EEG marker of unstable sleep, is used. The cyclic alternating pattern is found both in the sleep of adults and children with various sleep disorders and, in particular, with OSAS, therefore, it is a sensitive tool for studying sleep disorders throughout life. With the elimination of night hypoxia against the background of CPAP therapy, the sleep microstructure is restored, the spectral characteristics of the EEG change, and a decrease in the number of EEG arousals after treatment leads to the restoration of daytime functioning. Understanding the role of short-term EEG activations of the brain during sleep can provide significant data on sleep functions in health and disease. Despite the improving diagnosis of sleep disorders using machine algorithms, assessing the relationship of structures and functions of the brain during sleep, neurophysiological data are not entirely clear, which requires further research. In this review, we tried to analyze the results of the main studies of the neurophysiological sleep pattern in OSA against the background of respiratory support during sleep. 

[Evaluation of the structural organization of sleep in obstructive apnea syndrome from the perspective of modern pathophysiology]

OBJECTIVE

To evaluate the features of structural organization of sleep in men 35-55 years of age with varying degrees of severity and duration of clinical manifestations of obstructive sleep apnea syndrome (OSAS) from the perspective of modern pathophysiology.

MATERIAL AND METHODS

The study included 49 male patients, aged 35-55 years (average age was 43.4±9.2 years), with a body mass index (BMI) of 33.64±1.2 kg/m² with complaints of snoring of varying degrees of intensity, daytime sleepiness, arrest of breathing during sleep (according to others). The control group consisted of 15 healthy men who did not have complaints of sleep disorders and clinical manifestations of OSAS. The Pittsburgh sleep quality index (PSQI) questionnaire and polysomnographic monitoring study (PSG) were used. According to the results of the polysomnographic study, all patients were divided into 2 subgroups: 12 men of group 1with moderate OSAS (duration of clinical manifestations 4.5±1.0 years) and 37 men of group 2 with severe OSAS (duration 1.5±1.5 years).

RESULTS

A decrease in the sleep quality was detected in 61.9% of patients in the group 1 and 89.2% of patients in the group 2. Significantly higher scores for the components of «sleep disturbance» and «daytime dysfunction» in patients with a longer duration of clinical manifestations were detected. Changes in the structure of sleep were identified in patients compared with controls. A statistically significant increase in WASO led to the reduction of sleep efficiency. In patients of group 2, a deficiency of the deep stages and REM-sleep was determined. There was a significant increase in the number of arousals in patients of both groups relative to the controls. Moreover, significant between-group differences were found.

CONCLUSION

The short duration of OSAS symptoms causes a restructuring of the physiological system of sleep homeostasis to a different level of functioning with compensatory hyperfunction of the structures responsible for REM sleep and a decrease (economization) in the activity of anabolic processes during sleep due to a decrease in SWS, which is a characteristic feature of long-term adaptation. Severe course of OSAS leads to the appearance of specific phenomena of gross structural disorganization of sleep - «alpha-delta sleep» and disruption of its segmental organization, which shows the depletion and disruption of compensatory-adaptive mechanisms in the system of sleep homeostasis, disintegration and transformation of functional physiological system in the pathological condition.

[A scientometric analysis of materials of 10 All-Russian conferences 'Modern problems of somnology' (1998-2016)]

AIM

To analyze proceedings of the I-X Conferences 'Modern problems of somnology'.

MATERIAL AND METHODS

The authors have analyzed 888 abstracts from the abstract books of the conferences held from 1998 to 2016 in Moscow and Saint-Petersburg. The territorial, sectoral and scientific indicators of the activity of participants as well as longitudinal research trends were analyzed. Mathematical and statistical data analysis was carried out using the methods of descriptive statistics (95% confidence intervals) and χ² tests.

RESULTS

On average, 300 researchers from 6 countries and 14 regions of Russia participated in each conference, most from higher education (19), research (16) and medical (12) institutions. The highest number of publications were related to clinical somnology and sleep medicine (50% to different neurological conditions), the numeral material was included in 83% and statistical analysis was performed in 32.5%. A trend towards more active participation of research and medical institutions from all the country and involvement of new regions was observed. The interest to the clinical subjects, including treatment choices in sleep disorders as well as organizing aspects of sleep medicine, has been increasing. The number of studies on different aspects of sleep apnea has increased significantly as well.

CONCLUSION

The features of scientific and clinical activity in the field of somnology presented in the materials of conferences are stable in terms of the institutional and territorial representation. It complies to international trends of research and clinical development. This allows better planning of the structure and main issues of the further conferences.

[Anxiety and sleep in experiment and clinic]

High anxiety is a genetically determined personal trait. It is produced by limbic system and other cerebral structures involved in maintenance of wakefulness and development of sleep. Analysis of experiments on the animals and clinic observations showed that animals and individuals with high personal anxiety have a high risk of anxiety disorders. Inhibition of GABA-benzodiazepine system which is typical for high anxiety dramatically influences sleep duration and sleep quality. Phenazepamum due to its anxiolytic properties deactivates the excitation focus in the brain, jugulates anxiety and normalize sleep.