Evaluation of Impact of Bruxism Related Arousals on Cardiovascular Risk in Co-morbid Insomnia and Sleep Apnea (COMISA)

I. Introduction

Sleep disordered breathing is a common and serious health problem. According to epidemiological data, it may affect about 20% of the adult population, the majority is not aware of the disease. The most common sleep disorder is obstructive sleep apnea (OSA). The essence of OSA are the episodes of airway obstruction repeated many times during sleep, as a result of which the level of partial oxygen in the blood decreases. Apnea episodes end up with arousal, causing sleep fragmentation, deep sleep and REM deficiency. The consequence of episodes of OSA and fragmentation of sleep is ineffective, non-restful sleep, pathological daytime sleepiness, shortness of breath or choking. Fragmentation of sleep and repeated episodes of hypoxia result in a deterioration of the quality of life, chronic fatigue, and an increased risk of road accidents. The immediate consequences of apnea are hypoxia, awakening, increased heart rate, and an increase in blood pressure. Common complications of OSA include high blood pressure, stroke, arrhythmias, coronary artery disease, pulmonary hypertension, and heart failure. Untreated OSA increases the risk of premature death, especially in men under 50, contributing to the development of vascular endothelial dysfunction and increasing cardiovascular risk.

Comorbid Insomnia and Sleep Apnea (COMISA) is a highly prevalent and debilitating disorder that causes additional disturbances in sleep, daytime functioning, and quality of life for patients, and is a significant diagnostic and therapeutic problem for clinicians. Although the presence of COMISA was first noticed by Christian Guilleminault and his colleagues in 1973, it received very little research attention for almost three decades. There is still lack ofclinical trials concerning this topic.

An additional problem in OSA patients is the increased incidence of bruxism. Bruxism is associated with increased masticatory muscle activity during sleep, which may be phasic or tonic. It is estimated that the incidence of bruxism in the adult population is 13%. The most common symptoms of bruxism include: pathological wear and tooth sensitivity, damage to the periodontium and oral mucosa, muscle pain, headaches and damage to prosthetic restorations. However, the symptoms of bruxism can go unnoticed for a long time, leaving patients often unaware of the problem. There are two different types of bruxism: sleep bruxism (SB) and awake bruxism (AB). The etiology of bruxism is multifactorial and not fully understood, it is believed that it may be modulated by biological, psychological and exogenous factors. Bruxism may also be a protective factor in patients with disordered breathing during sleep. A key aspect of this relationship is likely related to arousals.

So far, it has not been possible to clearly define the exact cause-and-effect relationship between obstructive sleep apnea, insomnia and sleep bruxism. The relationship with cardiovascular risk is also unclear.More research is needed to clarify the relationship between these phenomena.