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A narrow internal auditory canal with duplication in a patient with congenital sensorineural hearing loss.

Baik HW, Yu H, Kim KS, Kim GH - Korean J Radiol (2008)

Bottom Line: A narrow internal auditory canal (IAC) with duplication is a rare anomaly of the temporal bone.Aplasia or hypoplasia of the vestibulocochlear nerve may cause the hearing loss.In this case, the IAC was divided by a bony septum into an empty stenotic inferoposterior portion and a large anterosuperior portion containing the facial nerve that was clearly delineated on MRI.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Chung-Ang University Hospital, College of Medicine, Chung-Ang University, Seoul, Korea.

ABSTRACT
A narrow internal auditory canal (IAC) with duplication is a rare anomaly of the temporal bone. It is associated with congenital sensorineural hearing loss. Aplasia or hypoplasia of the vestibulocochlear nerve may cause the hearing loss. We present an unusual case of an isolated narrow IAC with duplication that was detected by a CT scan. In this case, the IAC was divided by a bony septum into an empty stenotic inferoposterior portion and a large anterosuperior portion containing the facial nerve that was clearly delineated on MRI.

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Narrow internal auditory canal with duplication in 6-year-old girl.A. Coronal CT image shows narrow internal auditory canal with duplication divided by bony septum into relatively large anterosuperior (arrow) and stenotic inferoposterior portions.B. Axial CT image shows same findings. Inferoposterior portion (arrow) of internal auditory canal is smaller than anterosuperior portion.C. Axial CT image shows normal contralateral internal auditory canal (arrow).D. 3D-DRIVE T2-weighted axial image of right temporal bone shows narrow internal auditory canal with duplication.E. T2-weighted fast spin echo parasagittal image of right internal auditory canal demonstrates facial nerve that fills upper canal (arrow), but vestibulocochlear nerve is not seen in lower canal (arrowhead).F. T2-weighted fast spin echo parasagittal image of left internal auditory canal demonstrates normal facial nerve (arrow), common vestibular nerve (small arrowhead), and cochlear nerve (large arrowhead).
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Figure 1: Narrow internal auditory canal with duplication in 6-year-old girl.A. Coronal CT image shows narrow internal auditory canal with duplication divided by bony septum into relatively large anterosuperior (arrow) and stenotic inferoposterior portions.B. Axial CT image shows same findings. Inferoposterior portion (arrow) of internal auditory canal is smaller than anterosuperior portion.C. Axial CT image shows normal contralateral internal auditory canal (arrow).D. 3D-DRIVE T2-weighted axial image of right temporal bone shows narrow internal auditory canal with duplication.E. T2-weighted fast spin echo parasagittal image of right internal auditory canal demonstrates facial nerve that fills upper canal (arrow), but vestibulocochlear nerve is not seen in lower canal (arrowhead).F. T2-weighted fast spin echo parasagittal image of left internal auditory canal demonstrates normal facial nerve (arrow), common vestibular nerve (small arrowhead), and cochlear nerve (large arrowhead).

Mentions: As seen on temporal bone HRCT, there were two narrow bony canals in the IAC of the right temporal bone. The IAC was divided by a bony septum into a relatively large anterosuperior portion (1.6 mm) and a stenotic inferoposterior portion (0.8 mm) (Figs. 1A-C). The anterosuperior portion ended in a wide connection in the facial canal and a narrow connection to the vestibule. The inferoposterior portion ended in narrow connections to the cochlea and vestibule. The two canaliculi partially joined at the lateral end of the right IAC. The facial nerve canal was intact along its course, except for a slightly widened labyrinthine segment. There were no abnormalities in the cochlea, vestibule, and semicircular canals as seen on HRCT.


A narrow internal auditory canal with duplication in a patient with congenital sensorineural hearing loss.

Baik HW, Yu H, Kim KS, Kim GH - Korean J Radiol (2008)

Narrow internal auditory canal with duplication in 6-year-old girl.A. Coronal CT image shows narrow internal auditory canal with duplication divided by bony septum into relatively large anterosuperior (arrow) and stenotic inferoposterior portions.B. Axial CT image shows same findings. Inferoposterior portion (arrow) of internal auditory canal is smaller than anterosuperior portion.C. Axial CT image shows normal contralateral internal auditory canal (arrow).D. 3D-DRIVE T2-weighted axial image of right temporal bone shows narrow internal auditory canal with duplication.E. T2-weighted fast spin echo parasagittal image of right internal auditory canal demonstrates facial nerve that fills upper canal (arrow), but vestibulocochlear nerve is not seen in lower canal (arrowhead).F. T2-weighted fast spin echo parasagittal image of left internal auditory canal demonstrates normal facial nerve (arrow), common vestibular nerve (small arrowhead), and cochlear nerve (large arrowhead).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
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Figure 1: Narrow internal auditory canal with duplication in 6-year-old girl.A. Coronal CT image shows narrow internal auditory canal with duplication divided by bony septum into relatively large anterosuperior (arrow) and stenotic inferoposterior portions.B. Axial CT image shows same findings. Inferoposterior portion (arrow) of internal auditory canal is smaller than anterosuperior portion.C. Axial CT image shows normal contralateral internal auditory canal (arrow).D. 3D-DRIVE T2-weighted axial image of right temporal bone shows narrow internal auditory canal with duplication.E. T2-weighted fast spin echo parasagittal image of right internal auditory canal demonstrates facial nerve that fills upper canal (arrow), but vestibulocochlear nerve is not seen in lower canal (arrowhead).F. T2-weighted fast spin echo parasagittal image of left internal auditory canal demonstrates normal facial nerve (arrow), common vestibular nerve (small arrowhead), and cochlear nerve (large arrowhead).
Mentions: As seen on temporal bone HRCT, there were two narrow bony canals in the IAC of the right temporal bone. The IAC was divided by a bony septum into a relatively large anterosuperior portion (1.6 mm) and a stenotic inferoposterior portion (0.8 mm) (Figs. 1A-C). The anterosuperior portion ended in a wide connection in the facial canal and a narrow connection to the vestibule. The inferoposterior portion ended in narrow connections to the cochlea and vestibule. The two canaliculi partially joined at the lateral end of the right IAC. The facial nerve canal was intact along its course, except for a slightly widened labyrinthine segment. There were no abnormalities in the cochlea, vestibule, and semicircular canals as seen on HRCT.

Bottom Line: A narrow internal auditory canal (IAC) with duplication is a rare anomaly of the temporal bone.Aplasia or hypoplasia of the vestibulocochlear nerve may cause the hearing loss.In this case, the IAC was divided by a bony septum into an empty stenotic inferoposterior portion and a large anterosuperior portion containing the facial nerve that was clearly delineated on MRI.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Chung-Ang University Hospital, College of Medicine, Chung-Ang University, Seoul, Korea.

ABSTRACT
A narrow internal auditory canal (IAC) with duplication is a rare anomaly of the temporal bone. It is associated with congenital sensorineural hearing loss. Aplasia or hypoplasia of the vestibulocochlear nerve may cause the hearing loss. We present an unusual case of an isolated narrow IAC with duplication that was detected by a CT scan. In this case, the IAC was divided by a bony septum into an empty stenotic inferoposterior portion and a large anterosuperior portion containing the facial nerve that was clearly delineated on MRI.

Show MeSH
Related in: MedlinePlus