sleep apnea syndrome and the upper airway muscles
B, Hausser-Hauw C, Chabolle F.
Unite Respiration-Sommeil, Hopital Saint-Antoine, 184, rue du faubourg
Saint-Antoine 75012 Paris.
muscles are prone to distorsion during inspiratory negative pressure.
Some pharyngeal muscles, called pharyngeal dilatators, exhibit tonic
and/or phasic inspiratory activity. At the velar level, tensor palatini,
glossopharyngeus, palatopharyngeus and musculus uvula drive the airflow
towards nasal or buccal breathing. Genioglossus and geniohyoid muscles
exert a forward propulsion to the tongue. The contraction of the dilatators
muscles precedes the diaphram contraction. These muscles show a poor
endurance. In obstructive sleep apnea syndrome, they contract during
unfavorable metabolic (hypoxia and hypercapnia) as well as mechanical
(excentrical contraction) conditions. Histological changes occur in
upper airway dilator muscles: muscle volume and proportion of type Ila
fibers are increased. These changes, considered as compensatory mechanisms,
are variable within the different studied pharyngeal muscles. The initial
pharyngeal obstructive site, and its further extension, could be determined
by the different strength and endurance properties of these muscles.
Neurol (Paris) 2001 Nov;157(11 Pt 2):S72-7