Concerning the importance of pharyngeal muscles in the maintenance of upper airway patency during sleep. An opinion.

918 Pharyngeal Muscles during Sleep (Strohl, Olson) W hile it is known that neural activation of pharyngeal muscle exhibits respiratory periodicity and is an integral part of the respiratory control system,’ the mechanical consequences of neuromuscular activity in upper airway muscles are not well understood. Clinical and physiologic studies of Remmers et al,2 Brouillete and Thach,3 and others4 are evidence to presume a relationship between pharyngeal muscle activation and upper airway obstruction during sleep. In these studies, reduction in upper airway muscle activity-genioglossus, geniohyoid, etc-was associated with the onset of upper airway obstruction. Comments on the cause-effect relationship of this association acknowledged that basic mechanical properties ofthe airways and on the link(s) between upper airway muscle activity and airway patency were not well understood. Yet, the usual interpretation of these studies involves an implicit assumption of a direct relationship between muscle activity and airway patency. This interpretation has led to theories concerning a central pathogenesis for obstructive apneas and too often unsuccessful therapeutic attempts to treat these apneas by altering respiratory drive.5 We have evolved a different theory of the maintenance of pharyngeal patency and will argue for the relative unimportance of muscle activation in the initiation ofobstructive apneas during sleep.