ABSTRACT
BACKGROUND AND OBJECTIVES: Pathogenesis, definition, and treatment of sinonasal polyps remain uncertain. To elucidate them, many studies on polyps have been made. However, recently reported studies on polyps using animal models seldom provided comparative data on polyp formation in various conditions. The aim of this study is to develop an animal model of polyps which is more suitable for further polyp studies. We attempted a semiquantitative analysis on the effects of mechnical trauma to the sinus mucosa on formation of polyps and polypoid mucosa in duction of rabbit maxillary sinusitis by Streptococcus pneumoniae and compared the prevalences of polyps under the different conditions. MATERIALS AND METHODS: The natural ostia of both sinuses were occluded in 10 Pasturella-free New Zealand white rabbits. Both sinuses were inoculated with S. pneumoniae, without brushing the mucosa in the left maxillary sinuses (control group) and with brushing in the right sinuses (experimental group). After four weeks, all sinuses were re-opened. Macroscopic polyp and light microscopic polyps and/or polypoid mucosa were semiquantitatively analyzed and each prevalence was compared between the two groups. RESULTS: The number of macroscopic polyps per sinus was significantly larger in the experimental group (1.1 polyps) than that in the control group (0.1 polyps). Microscopic examination revealed significantly more polyps and/or polypoid mucosa in the experimental group than in the control group. CONCLUSIONS: Our results suggest that mechanically traumatizing the sinus mucosa, such as brushing, is more helpful to polyp formation when a rabbit model of polyps is to be induced by S. pneumoniae.