Radiological Investigation of the Variance of Ossicular Position in Microtic Ears

OBJECTIVE: To radiologically investigate the malformations in microtic ears so as to provide assistance for canaloplasty of the external auditory meatus and tympanoplasty operation. MATERIALS and METHODS: High-resolution computed tomography (HRCT) data of 48 patients with unilateral congenital microtia and aural atresia were studied. Multi-planar reconstruction (MPR) was performed to investigate the anatomic anomaly. The oblique axial and coronal planes were evaluated, on which the tympanic bone remnant was shown and the ossicular mass appeared with the largest size. The angles between the oblique axial/coronal planes and standard axial/coronal planes were measured and named α and β. The thickness of the atresia plate was measured on the oblique planes. The measurements in the microtic ears were compared with data from the normal side and 40 ears in 20 control individuals without ear malformations as well. RESULTS: In most of the microtia patients, the α angle in the affected side (19.78°±7.42°) was larger than the α angle in the normal side (15.30°±4.60°), while the β angle in the affected side (16.77°±13.43°) was smaller than the β angle in the normal side (27.46°±6.87°). The thickness of the atresia plate was less than the thickness of the cribriform area in the normal side. A significant correlation was found between the Marx classification and the thickness of the atresia plate. CONLUSION: HRCT evaluation using MPR is an important complement for the Jahrsdoerfer scoring system. The investigation is of great realistic significance. Preoperative measures for individual patients can provide guidance for canaloplasty and tympanoplasty operation.