NONTRAUMATIC PROLAPSE OF THE ORBITAL CONTENTS INTO THE ETHMOID SINUS - EVALUATION WITH SCREENING SINUS CT

Purpose: The purpose of this study is to evaluate the incidence and CT features of nontraumatic prolapse of the orbital content into the eth moid sinus, which may be a cause of orbital complication of ethmoidect omy. Materials and Methods: CT of 1,024 consecutive patients with subj ective sinonasal symptoms who underwent screening sinus CT were review ed and analyzed. The 573 men and 451 women were between the ages of 5 and 79 years old. The patients with a history of sinus surgery or faci al trauma were excluded from this study. The incidence and CT features of dehiscence and/or bowing of the lamina papyracea with prolapse of the orbital content in each age group and differences between the age groups were analyzed. Results: Ethmoidal prolapse of the orbital conte nt was found in 67 patients (6.5%). There was a tendency of increasing incidence with increasing age. The incidence in the juvenile age grou p was significantly low (1.9%) as compared with that of adult. Four pa tients (0.4%) had bilateral lesions. Twenty-nine lesions showed prolap se of moderate to severe degree, and deformity of the medial rectus mu scle on coronal CT image was associated in 21 lesions. Inflammatory ch ange of adjacent ethmoid sinus was indicated in 19 lesions, and there was no statistical difference in incidence from that of the opposite s ide. Conclusion: The incidence of nontraumatic prolapse of the orbital content is far beyond general expectations, and detailed structural i nformation with CT for this anatomic alteration may be important befor e endoscopic sinus surgery to avoid possible complication. The higher incidence in adult may suggest age-related acquired etiologic factors besides congenital dehiscence or weakness of the lamina papyracea. Cop yright (C) 1996 by W.B. Saunders Company.