Abstract:
OBJECTIVES : This study aimed to qualitatively evaluate the variations in nerve bundles
between patients with normal anatomy and those with inner-ear anomalies.
METHODS : Magnetic resonance imaging (MRI) scans of the temporal bones of candidates
for cochlear implants (CIs) enrolled at a tertiary center were retrospectively
reviewed from the clinical database. The 3.0-Tesla MRI scans were analyzed using a
three-dimensional slicer to visualize the nerve bundles in the internal auditory canal.
RESULTS : A total of 49 ears were analyzed. Twenty ears exhibited normal inner ear
anatomy, whereas 29 ears had various inner-ear malformations. The cochlear nerve
(CN) was visible on all 20 scans with normal inner-ear anatomy. In addition, the CN
was visualized in 18 scans with inner ear malformations. Furthermore, the CN was
identified in six of the eight scans with IP type I, whereas in two scans, the CN and
vestibular nerve were unclear. Three scans with a common cavity showed only two
nerve bundles.
CONCLUSION : The findings of this study show that the CN can be visualized in most
inner-ear anatomical types. Even in severely malformed inner ears, the common
nerve bundle that represents the cochlear and vestibular nerves can be visualized.
The MRI is highly recommended for CN assessment before CI surgery.
LEVEL OF EVIDENCE : Level IV.
