Distribution of Elastic and Collagen Fiber in Uvular Tissue of Patients with Obstructive Sleep Apnea and Snorers / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Sleep related obstructive breathing disorders are frequently observed in adults. Despite extensive work of recent years, the essential pathophysiologic mechanism that mediates this process is still unclear. This study was conducted to determine whether distribution of connective tissue in the uvula is different among apneics, snorers and normal controls. MATERIALS & METHODS: Uvula was obtained by uvulopalatopharyngoplasty in 8 apneics, 6 snorers (mean apnea index 17.1, 2.43 respectively) and by autopsy in 5 individuals not known to have snoring. The surgical specimen of uvula was fixed in 10% formalin and subsequently embedded in paraffin. Each specimen was cut into 5 micrometer-thick section and stained with hematoxylin-eosin for general appearance, Masson-Trichrome stain for collagen fiber, and Verhoeff stain for elastic fiber. Microscopic examination was performed by two pathologists who were blinded to the polysomnographic data. RESULTS: Infiltration of inflammatory cells and edema were significantly increased in the snorer and apneic groups compared with the control group (p<0.0001, p<0.05 respectively). Compared with the normal group, the density of elastic fibers and collagen fibers were significantly decreased in snorers and apneics (elastic fiber p<0.0005, collagen fiber <0.01). The distribution of elastic and collagen fiber showed significantly heterogeneous patterns in the snorer and apneic group compared to the control group (elastic fiber p<0.001, collagen fiber p<0.0005). CONCLUSION: Since connective tissue fibers have the supportive function in the body, this condition may result in increased collapsibility of upper airway and contributes to the development of obstructive sleep apnea.