RESUMO
BACKGROUND: Orbital complications may be occured by means of surgical injury to lamina papyracea during endoscopic sinus surgery or intranasal ethmoidectomy. The frequency of orbital complications increases when the natural dehiscence of lamina papyracea(NDLP) with or without prolapse of orbital content into ethmoid sinus is present. OBJECTIVES: The aim of this study is to evaluate the incidence and radiologic characteristics of NDLP, and to evaluate association NDLP with anatomical variations of nasal cavity and paranasal sinuses. MATERIALS AND METHOD: The axial and coronal paranasal sinus CT scans of 183 patients with chronic paranasal sinusitis(366 sides) who had undergone endoscopic sinus surgery were retrospectively reviewed and analyzed. The incidence and radiologic features of NDLP, and the association NDLP with anatomical variations of paranasal sinus and nasal cavity were analyzed. RESULTS: The NDLP was found in 18 patients(9.8%, n=183 patients) or 22 sides(6.0%, n=366 sides). The most common site of NDLP was superior portion(45.5%) in coronal image of paranasal sinus CT scans and anterior ethmoid sinus area(68.2%) in axial image. Grade 1 of NDLP(86.4%) was observed most commonly. NDLP was not associated with anatomical variations of paranasal sinus. CONCLUSION: The incidence of NDLP with prolapse of orbital content is far beyond general expectation, and close preoperative evaluation of paranasal sinus CT scans is important to avoid possible orbital complications.