Abstract:

Introduction: Incomplete partition (IP) type and accompanying cochlear nerve (CN) anomalies affect the patient’s management. We revealed the cochlear nerve area (CNA), cochlear nerve canal width (CNCW), and inner auditory canal width (IACW) of IP types. Methods: We retrospectively scanned patients with IP. There were 88 IP ears (26 IP type 1, 54 IP type 2, 8 IP type 3) and 54 controls. The CNCW and IACW were measured in axial temporal computed tomography sections. The CNA and facial nerve area (FNA) were measured in the distal IAC on the sagittal-oblique plane of 3D constructive interference steady-state T2-weighted magnetic resonance images. Results: CNA and CNA/FNA values for each IP type differed significantly compared with the control group. However, the CNCW and IACW values did not differ significantly. The CNA was the least in IP 1 cases. Five CN aplasia were detected, and all were associated with IP type 1 anomaly (3.5% of all, 5.6% of IP types, and 19.2% of IP type 1 cases). CN hypoplasia was observed in 10 IP type 1 (38.5% of IP 1), 6 IP type 2 (6.8% of IP type 2), and 1 IP type 3 (12.5% of IP type 3) ears. None of the CN hypoplasia had a CNC hypoplasia. Conclusion: CN aplasia and hypoplasia most frequently accompanied with IP type 1 in our study. Therefore, they need an extra interest in CN evaluation. CNCW and IACW are not very useful in predicting CN dysplasia in IP cases.

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