Does Cochlear Nerve Size Differ Among Societies?

Abstract

Objective: Cochlear nerve size is a prognostic factor for successful cochlear implantation. Reports about the cochlear nerve size in normal-hearing patients and differences among societies in the cochlear nerve size are not satisfactory. The purpose of this study was to determine the average cochlear nerve size in normal-hearing adults and to investigate whether there is a difference among societies on the basis of literature data. Materials and Methods: This retrospective study included 21 patients (38 ears) who underwent Magnetic Resonance Imaging (MRI) because of either vertigo and/or tinnitus complaints. Measurements were conducted on parasagittal constructive interfer- ence in steady state (CISS) sequence MRI. Vertical and horizontal diameters and cross-sectional area (CSA) were evaluated at the fundus of the internal auditory canal. Differences in the cochlear nerve size between the right and left ears and gender were evaluated. The difference in the cochlear nerve size among societies was compared with a z-test using data from literature. Results: The average vertical diameter, horizontal diameter, and CSA were 1.11 mm, 1.10 mm, and 0.96 mm2, respectively. No difference was found between the right and left ears and gender and among societies. Conclusion: This study shows that the mean normal size of the cochlear nerve does not change between right and left ears and gender and among societies.