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Background and Objectives It is necessary to understand the variations of the paranasal sinuses (PNS) and other anatomical structures during an endoscopic sinus surgery (ESS). The purpose of this study was to investigate any association between the degree of frontal sinus (FS) pneumatization and the development of the PNS structures. Subjects and Method We analyzed 311 PNS computed tomography (CT) scans (622 sinuses, including the left and right sides). We classified FS into type I (aplasia), type II (hypoplasia), and type III (control). We assessed and compared the middle turbinate pneumatization (MTP), superior turbinate pneumatization (STP), agger nasi cell (ANC), infraorbital cell (IOC), optic nerve (ON) type, and vidian nerve (VN) type with the pneumatization of the FS. We further studied for any association between the degree of pneumatization of the FS, maxillary sinus (MS), and sphenoid sinus (SS) and the lateral lamella length (LLL). Results MTP, ANC, and IOC rates according to the FS types were not significant (p>0.05). Both type II and III showed more frequent occurrences of STP than type I (p=0.005). The ON type III and IV were significantly frequent in the FS type III (p<0.001). The occurrence of VN type III in the FS type I was significant (p<0.001). When comparing the pneumatizations of FS with MS or SS, there were no significant correlations between them (p>0.05). In the FS type II and III, the LLL was significantly greater than in type I (p<0.001). Conclusion Increased FS pneumatization shows greater indentation of ON and VN into the SS, as well as increased LLL. During ESS, it is important to recognize the possibility of structural damage of ON, VN, and LLL according to FS pneumatization.

keratinous substances. A choristoma is a normal tissue located away from its original location.Surgical excision is the recommended treatment for a hairy polyp. To the best of our knowledge, this study is the first case of a hairy polyp arising from the nasal vestibule.

Background and Objectives It is important to identify variations of paranasal sinuses during sinus surgery. The Onodi cell (OC), a variant of the paranasal sinuses, is the most posterior ethmoid cell with a close relationship with the optic nerve (ON). The purpose of this study is to evaluate the prevalence of OCs and analyze the relationship of OCs with ON in Koreans.Subjects and Method This retrospective study utilized CT images of 526 slides from 263 Korean adults. The prevalence of the OCs and the degree of indentation of the ON within the OC was determined using binary logistic regression analysis.Results The OCs were observed in 37.3% of 263 subjects and in 27.6% of 526 slides. The OCs are found more frequently in males than in females (<i>p</i>=0.01), and also more frequently in the right side than in the left side (<i>p</i>=0.001). Binary logistic regression analysis revealed that the ON protrusion in female was 0.339 times lower than in male and 1.052 times higher with the increased age. The ON protrusion within the OC in the postsellar type was 10.214 times higher than that in the presellar.Conclusion The OCs were observed in 37.3% of the Koreans. The protrusion of the ON within the OCs increased in male and in the postsellar type of the sphenoid sinus.

Background and Objectives: The olfactory fossa is an important anatomical structure to prevent surgical complications such as skull base injury and meningitis. The purpose of this study is to determine if there is a difference in lateral lamella length (LLL) between the left and right sides, a topic that has been studied rarely in Korea. Subjects and Method: We analyzed 592 left and right sides of 296 PNS CTs. We measured LLL as the distance between the fovea ethmoidalis and the horizontal cribriform plate in the olfactory fossa of the coronal surface where the crista galli was observed. Results: The average LLL on the left side was significantly longer than that on the right. Age and LLL showed a negative correlation. Multiple regression analysis revealed younger age and left side as independent variables for predicting increasing LLL. Conclusion: There was a significant difference between the two sides of LLL on sinus CT in Koreans. Before sinus surgery, the asymmetry of the ethmoid roof must be assessed, even by skilled doctors. If the height of the ethmoid roof is asymmetric, extra care is required during sinus surgery.