La balance sympatho-vagale et le bruxisme du sommeil.

摘要

Sleep is a period of physiological and psychological recuperation which is different from other quiescent status because a certain level of contact with the environment is maintained. Some sleep disorders can have an intrinsic origin like sleep bruxism, a movement disorder.; Rythmic masticatory muscle activity (RMMA) can be accompanied by teeth grinding during sleep in subjects with sleep bruxism. Sleep bruxism's etiology is still not fully understood, but there are many possible avenues that can be explored, like its association with the autonomic nervous system which will be explored in this thesis.; Recently, it was showed that a sequence of events seems to precede each episode of sleep bruxism: an electroencephalographic activation and an acceleration of the heart rate. The first study evaluated and characterized sleep bruxism episodes with regard to static (ex.: sleep stages) and dynamic activity (ex.: autonomic nervous system modulation) during sleep in sleep bruxers and control subjects. The second study consisted of a randomized double-blind crossover, placebo controlled clinical study with propranolol (120 mg), a non-selective beta-blocker, and clonidine (0.3 mg), a alpha2 agonist. These two medications inhibit sympathetic activity through different pathways but being liposoluble, they can both cross the blood-brain barrier to reach the central nervous system.; For these two studies, polygraphic sleep recordings were done in a sleep laboratory for all subjects included in the studies. Sleep and sleep bruxism were scored according to validated research criteria. To determine the sympatho-vagal dominance, a spectral analysis of the heart rate variability was used because it is widely used, non-invasive method.; In the first study, it was observed that sleep bruxers have a similar sleep quality and architecture than the control subjects, but a strong association between sleep bruxism episodes and micro-arousals. These sleep bruxism episodes are preceded, starting at -8 minutes, by an increase in sympathetic activity. In the second study, propranolol does not have any effect on sleep while clonidine suppressed rapid eye movements (REM) sleep resulting in an increase of sleep stage 2 duration. Propranolol did not influence the sleep bruxism index. On the other hand, clonidine decreased the sleep bruxism index (61%) by inhibiting the increased sympathetic activity which precedes a sleep bruxism episode. These results show the influence of the sympathetic nervous system on the sequence of events preceding most sleep bruxism episodes.; In conclusion, these two studies give us an overview on sleep bruxism physiopathology and etiology which can suggest which treatments should be explored in futur large sample and long term clinical trials.; Keywords. sleep bruxism, autonomic nervous system, heart rate variability, propranolol, clonidine