Korean J Radiol.  2019 May;20(5):823-829. 10.3348/kjr.2018.0065.

Duplicated Internal Auditory Canal: High-Resolution CT and MRI Findings

Affiliations
  • 1Imaging Center, the Affiliated Hospital of Jining Medical University, Jining, China.
  • 2Department of Radiology, the First People's Hospital of Jining City, Jining, China. zlh968968@163.com

Abstract


OBJECTIVE
To summarize the high-resolution computed tomography (HRCT) and magnetic resonance imaging (HRMRI) features of duplicated internal auditory canals (DIACs).
MATERIALS AND METHODS
Ear HRCT data of 64813 patients with sensorineural hearing loss (SNHL), obtained between August 2009 and November 2017, were reviewed. Among these patients, 12 (13 ears) were found to have DIACs, 9 of whom underwent HRMRI. Their images were evaluated by two otoradiologists.
RESULTS
The rate of occurrence of DIAC among SNHL patients was 0.019% (12/64813). The internal auditory canals of 13 ears were divided into double canals by complete (n = 6) and incomplete (n = 7) bony septa, with varied orientations ranging from horizontal to approximately vertical. All of the anterosuperior canals extended into the facial nerve (FN) canal, except for 1, which also extended to the vestibule. The posteroinferior canals ended in the cochlea and vestibule, except for 2, which also connected to the FN canals. Magnetic resonance images revealed that 77.8% (7/9) and 22.2% (2/9) of vestibulocochlear nerves (VCNs) were aplastic and hypoplastic, respectively. Furthermore, 88.9% (8/9) of FNs were normal, except for 1, which was hypoplastic. All of the affected ears also had other ear anomalies: a narrow, bony cochlear nerve canal was the most common other anomaly, accounting for 92.3% (12/13). Malformations of other systems were not found.
CONCLUSION
Double-canal appearance is a characteristic finding of DIAC on HRCT, and it is usually accompanied by other ear anomalies. The VCN usually appears aplastic, with a normal FN, on HRMRI.

Keyword

Internal auditory canal; Duplication; Computed tomography; Magnetic resonance imaging

MeSH Terms

Cochlea
Cochlear Nerve
Ear
Facial Nerve
Hearing Loss, Sensorineural
Humans
Magnetic Resonance Imaging*
Vestibulocochlear Nerve
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