Introduction: There has been many therapeutic attempts in eustachian tube(ET) dysfunction. Until today, it has been numerous treatment such as laser, micro-debrider and balloon catheter dilatation therapy. Also injection of various materials in ET and intratubal catheter insertion were performed as treatment of patulous ET. Therefore It is important to figure out the location between internal carotid artery (ICA) and ET for safe ET surgery. This study is aimed to evaluate anatomical relationships between ET & ICA using Computed Tomography (CT) via calculating the depth and angle of structures located surrounding at E-tube & ICA and to investigate difference of the parameters according to age and gender

Subjects and Method: Retrospective review of contrast enhanced CT scan of the paranasal sinus performed at our institution between January 2005 and December 2010. 216 patients (432 ears) were enrolled in this study. Distance from anterior cushion of torus tubaris to ICA (AC-ICA), distance from posterior cushion of torus tubaris to ICA (PC-ICA), distance from Rosenmuller fossa to ICA (RF-ICA), shortest distance from ET lumen to ICA (ET-ICA), angle between the imaginary line from orifice of ET to posterior end point of nasal septum and the imaginary line from posterior end point of nasal septum to ICA (∠ET-NS-ICA) were measured each patients, and all patients were divided by age and sex as 10 groups.

Results: In all factors, p-value was found to be a value less than 0.05, and this showed that the differences according to gender and age were statistically significant. And it was verified that in a group of female patients aged more than 65 years old AC-ICA, PC-ICA were the closest from nasopharynx. This is expected to be affected by atrophy of organ with increasing age. It was also verified that for female groups ∠ET-NS-ICA is of medialization in groups aged more than 65 years old. AC-ICA (p<0.05), PC-ICA (p<0.05) and ET-ICA (p<0.05) had negative correlation with increasing age in female groups, while ∠ET-NS-ICA (p<0.05) had positive one in female.

Conclusion: Distance and correlation between ET and ICA represents a variety of distribution according to sex and age. When performing a surgery for nasopharyngeal portion of E-tube, surgeon should be careful of the ICA location during ET surgery and should be aware of preoperative radiologic findings.