Objective: The aim of this study was to determine differences in diameter of cochlear nerves (CN) among three measurement points at the midpoint of the internal auditory canal (IAC), IAC fundus and cochlear aperture, and to evaluate whether nerve size varies with age.
Methods: A total of 336 normal-hearing ears of 201 children were assessed, who were underwent 3D-Fiesta sequence scanning of inner ear. All subjects were divided into 12 groups at one year interval. The diameter measurements of CN were obtained in the midpoint of the IAC, IAC fundus and cochlear aperture respectively on the axial and oblique sagittal images of 3.0-T MRI. SPSS 18.0 statistics software was applied for data analysis, and all of the data showed a normal distribution and expressed in x ± s.
Results: The diameters of normal-hearing children's CN at the midpoint of the IAC, IAC fundus and cochlear aperture were respectively: 1.12 ± 0.08 mm, 1.05 ± 0.06 mm, 0.87 ± 0.14 mm, and there were significant differences among the three measuring points (F = 527.57, p < 0.05). The diameters of the CN had no significant difference (p > 0.05) in age groups, gender and sides (p > 0.05), and there was no correlation between the diameters of normal children's CN and age (r is -0.129, 0.128 and -0.113, respectively).
Conclusion: The diameters of normal-hearing children's CN change with different points of the internal auditory canal, of which the maximum value is in the midpoint of the IAC, followed by the IAC fundus, and the cochlear aperture is at the minimum; moreover the normal size doesn't change with age.
Keywords: Cochlear nerve; Internal auditory canal; Magnetic resonance imaging.
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