[Upper airways and sleep apnea syndrome].

The imaging techniques of the upper airway (UA) now permit a description of the characteristics of pharyngeal collapse during the course of obstructive apnoea. The start is oropharyngeal with active movements anterior and posterior of the soft palate and a falling back of the tongue. The extension occurs almost systematically towards the hypopharynx. A displacement of the hyoid bone and of the cervical spine is noted synchronously with thoracoabdominal movements. These imaging techniques of UA show the occurrence of passive pharyngeal collapse during certain types of central apnoea. In snorers and in apnoeics, there is a reduction of the calibre of the pharynx. However, these abnormalities are not specific and do not enable the diagnosis to be confirmed nor an estimate of the severity of the sleep apnoea syndrome. Cephalometry and computed tomography of the pharynx should be carried out particularly when a uvulopalatopharyngoplasty (UPPP) is envisaged. For practical purposes, the existence on cephalometry of retrognathism with an MP-H > 24 mm and a PAS distance of < 5 mm is associated with a poor result for UPPP. The same thing applies when macroglossia or a reduction of the surface of the hypopharynx is found on computed tomography.