Imaging assessment of profound sensorineural deafness with inner ear anatomical abnormalities

Abstract

Objective: To explore the value of a combined computed tomography (CT) and magnetic resonance imaging (MRI) in evaluating profound sensorineural deafness patients before cochlear implant (CI) surgery.

Methods: A retrospective analysis of 1012 cases of profound sensorineural deafness that received CI was performed.

Results: A total of 96 cases were diagnosed with inner ear abnormalities including large vestibular aqueduct syndrome (LVAS, n = 61), Michel deformity (n = 3), cochlear incomplete partition I (n = 2), cochlear incomplete partition II (n = 6), cochlear hypoplasia with vestibular malformation (n = 3), cochlear ossification (n = 3), bilateral internal auditory canal obstruction (n = 5) and internal auditory canal stenosis (n = 2).

Conclusion: High resolution CT (HRCT) can display bony structures while MRI can image the membranous labyrinth in preoperative evaluation for cochlear implantation. The combination of these two modalities provides reliable anatomical information regarding the bony and membranous labyrinths, as well as the auditory nerve.

Keywords: Cochlea; Hearing loss; Multimodal imaging.

Fig. 1

Imaging analysis of cochlear translocation malformation. A: The angle between cochlear basal turn plane and head midsagittal plane (red lines). B: The angle between a connection line from facial nerve vertical section midpoint to the upper edge of the round window niche and head midsagittal plane (green lines). C: Vertical distance A from the surface of facial nerve vertical section to the external canal wall in a round window plane.

Fig. 2

Imaging findings of large vestibular aqueduct syndrome. A: CT scan images with a white arrow pointing to enlarged vestibular aqueduct. B: MRI images showing enlarged endolymphatic canal and sac.

Fig. 3

Imaging findings of Michel deformity. A: CT; B: MRI.

Fig. 4

Imaging findings of cochlear incomplete partition I. A: CT; B: MRI.

Fig. 5

Imaging findings of Mondini dysplasia. A: CT; B: MRI.

Fig. 6

Cochlear hypoplasia combined vestibular malformation. A: HRCT showing undeveloped cochlea, vestibular deformity combined with internal auditory canal. B: MRI showing the vestibule connected with internal auditory canal, and absence of cochlear perilymphatic space.

Fig. 7

CT images of cochlear ossification. A: Axial view; B: Coronal view.

Fig. 8

Image findings of internal auditory canal obstruction associated with cochlear nerve dysplasia. A: CT scans showing internal auditory canal stenosis. B: axial section MRI images of internal auditory canal showing cochlear nerve aplasia.

Fig. 9

α and β angles comparison between normal and cochlear translocation malformation patients. A: Cochlear translocation malformation. B: Normal cochlea.