A Retrospective Study to Identify the Relationship Between the Dimension of Osseous External Auditory Canal and Chronic Otitis Media.

Whether the dimension of the osseous external auditory canal (OEAC) is related to chronic otitis media (COM) remains an important but unresolved issue. In the literature, routine canaloplasty has been suggested to help elucidate this problem. In this study, we intended to investigate the relationship between the diameter or shape of OEAC and COM. We retrospectively reviewed the high-resolution computed tomography (HRCT) images of the temporal bones of 62 patients with unilateral COM who underwent tympanoplasty from January 1, 2011, to December 31, 2013. For comparison, the HRCT images of another 62 patients with normal ears were collected to be the control group. The shape of OEAC was categorized into 5 groups according to Mahboubi's classification, and the dimension of each patient's OEAC was measured at 2 defined sections (annular section and isthmus/midcanal section). The most prevalent shape of OEAC for the lesion sides of the ears was cylindrical, followed by conical, and hourglass in both the COM and the control groups. As to the dimension of OEAC, there were no significant differences between lesion ears and normal ears among patients in the COM group as well as between lesion ears in the COM group and normal ears in the control group. We concluded that the bony dimension of the external ear canal was not related to COM. This suggested that chronic inflammation or infection of middle ear may not cause bony thickening of OEAC, despite the kind of OEAC shape involved.