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Restless legs syndrome (RLS) is a common sleep disorder characterized by dysesthesias and paresthesias in the legs, occurring at rest, worsening at evening and night and alleviated by movements. Apart from idiopathic cases, RLS and psychiatric diseases share a common association and recent studies have shown a strong association between RLS and antidepressants. The effects of antidepressants such as selective serotonin reuptake inhibitors and venlafaxine on worsening RLS have been widely studied and their use should be avoided. The clinical spectrum of RLS and the physiopathological link with antidepressant will be discussed in this review in order to provide new preventive strategy in clinical practice to improve diagnosis, orientating therapeutic decision and evaluating efficacy of treatment.

This study describes the technical steps for the making of a mandibular advancement device for sleep disordered patients (apnea index < 10). In a second part of the study, a group of 21 patients with sleep disordered breathing treated successfully with a mandibular advancement device is compared to a homologous control group. The experimental group showed cephalometric characteristics approaching those seen in patients with sleep apnea syndrome. The mandibular advancement device moved the mandibule forward (SNB angle increases by 1.7 degrees) and downward (mandibular plane angle increases by 3 degrees, which can be related to the 7.4 mm anterior vertical height increase). The hyoid bone adopted a more distant position from the cervical vertebrae. Important individual variations were seen among the patients for the optimal repositioning of the mandible.

The upper airway can be described as a collapsible segment (the pharynx) interposed between two rigid bony (the cavum) or cartilaginous (the trachea) segments. Due to this structure, the pharynx behaves as a collapsible tube, in which airflow does not depend on the downstream pressure, but is limited to a maximum value which depends only on the upstream pressure and on the pressure surrounding the collapsible segment; this behavior, known as a Starling resistor can be modeled by the waterfall effect. Thus, the upper airways can be in three different conditions: an occluded condition, in which no flow is possible, a patent condition, in which flow depends on the difference between upstream and downstream pressures (according to Poiseuille's law), and a situation in which flow is limited. The behavior of the upper airway is largely dependent on its anatomic structure, but functional factors play a critical role. Among these sleep state is both a determinant of the collapsibility of the pharynx, and determined by the simulation of upper airway mechanoreceptors whose activity depends on the activity of respiratory muscles. Thus the interplay of three factors: ventilatory drive, upper airway collapsibility, and arousal threshold can predict most of the situations of stable and unstable ventilatory behavior during sleep. The level of the arousal threshold governs the stability of the ventilatory pattern, as it determines whether a combination of slow, respiratory effort, and blood gases can be maintained or is interrupted by an arousal.

CLINIC AND HISTORY: Expression of hypersomnia can take on several forms: long period of nocturnal sleep, excessive diurnal somnolence or both. History taking is essential. Useful tools include standardized questionnaires and a diary of sleeping habits. Not only do they provide evidence of the hypersomnia, but also information on possible eccentric origin(s). A pathological hypothesis can then be put forward: sleep apnea syndrome, narcolepsy, idiopathic hypersomnia, or periodic movements during sleep. POLYGRAPHY: Different recording protocols have been designed to determine sleep patterns, often depending on the clinical setting. The goal is to obtain an objective confirmation of hypersomnia and demonstrate a cause. The type of recording (hour and duration of the recording, parameters monitored) depends on the information desired. Because captors themselves sometimes perturb sleep, polygraphic explorations must be adapted to each individual situation.

Obstructive sleep apnea (OSA) patients have increased diuresis and natriuresis during sleep. In order to investigate the possible mechanisms of these changes in renal function, 35 consecutively diagnosed OSA patients were studied during sleep before and during nasal continuous positive airway pressure (CPAP) treatment, and were compared with 23 non-snoring controls. The excretion of urine and of electrolytes was increased before treatment and normalized with nasal CPAP treatment. The mechanism involved seems to be decreased sodium reabsorption at the level of the ascending limb of the loop of Henle. The observed increase in cyclic guanosine monophosphate excretion supports the hypothesis of increased atrial natriuretic peptide release during sleep in OSA patients.