Studies of the histomorphology and function of the uvula

Abstract

Alternations in pharyngeal structure and function are considered fundamental in the pathogenesis of snoring or obstructive sleep apnea (OSA). The physiological function of the uvula as a dynamic sealing of the nasopharynx prevents a "craniocaudal aspiration" during deglutition. The oropharyngeal soft tissues and the uvula are known to play an important role in affecting the oropharyngeal airflow resistance but studies about alterations in the histomorphological uvula structure are controversial. We studied the histomorphological tissue composition of the uvula (midsagittal and transversal sections) in 142 patients who underwent uvulopalatopharyngoplasty (UPPP) or uvulopalatoplasty (UPP) for snoring and by autopsy in 30 normal subjects not known to have been snoring. Statistical comparisons were controlled for differences caused by age and body mass index. The uvula was found to be significantly longer in patients with snoring than in control subjects. Patients with snoring had a significantly greater percentage of fat content and connective tissue in combination with a muscle atrophy in the uvula than did normal subjects. The disturbance of the specific muscular composition and formation causes a reduction of muscular tonus and a loss of muscular contraction. The uvula is destabilized on the basis of a missing skeletal and cartilaginous brace. The uvula destabilization causes a narrowing of the pharyngeal airway that could lead to an increased oropharyngeal airflow resistance with an intensified passive uvula movement and vibration during mouth breathing.