Morphometric analysis of the uvula in patients with sleep-related breathing disorders

The upper-airway mucosa in obstructive sleep apnea (OSA) patients and snore rs is often described as edematous and hyperplastic. The morphologic aspect s of the pharyngeal mucosa, and in particular the mucosa of the uvula and s oft palate, in OSA patients are, however, not well described. The aim of th e present retrospective study therefore was to perform histologic examinati on of the pharyngeal mucosa obtained from patients with various forms of sl eep-related breathing disorders, including primary snoring. A midsagittal s ection of uvulas obtained by uvulopalatopharyngoplasty (UPPP) was investiga ted in 34 OSA patients and 9 non-apneic snorers. Control tissues were taken by autopsy in 19 patients not known to have OSA or snoring. A morphometric point counting technique was used to determine the tissue composition. The data showed that OSA patients and non-apneic snorers had a significantly g reater percentage of intercellular space than controls (65.7% vs 54.0%; P = 0.006). Control uvulas contained more muscle than OSA and snorers (14.0% v s 7.8%; P = 0.006). Moreover, the covering epithelium was significantly thi cker in OSA and snorers than in controls (variance ratio = 7.64; P = 0.008) . When taking body mass index (BMI) into account, no correlation was found between fat deposition and BMI. Findings showed that an increased clinical severity of OSA did not affect the tissue composition. Indeed, uvula morpho logy was similar in OSA patients with respect to non-apneic snorers. Since the increased amount of intercellular space is the expression of edema, we hypothesize that these mucosal changes together with hyperplasia of the cov ering epithelium are secondary effects to snoring. They presumably play a m inor role in the etiopathogenesis of OSA, but may increase the severity of OSA by further narrowing the pharyngeal lumen.