![]() The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements. The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). This is particularly important when the recommended agent is a new and/or infrequently employed drug. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. Usage and distribution for commercial purposes as well as any distribution of modified material requires written permission. This article is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND). Our patient had a radiologically normal middle ear with intact ossicles and had no rhinorrhea upon presentation. Congenital perilymphatic fistulas, however, are predominantly associated with middle-ear anomalies or CSF otorrhea. The finding of profound sensorineural hearing loss with erosion of the otic capsule in a 14-month-old patient raised concerns for a congenital perilymphatic fistula. Genicular and tympanic segments of the facial nerve were also poorly delineated. The posteromedian surface contains the porus acousticus (opening of the internal auditory canal for the. Marked dilation of the IAC with thinning of the otic capsule and erosion, and a lack of bone covering between the cochlea and the IAC was visualized on CT. The petrous pyramid contains the inner ear. In our case, MRI demonstrated an ill-defined cystic lesion centered in the left IAC and petrous apex isointense on T1 and T2 sequences without any significant enhancement. MRI is the imaging modality of choice for defining lesions in the cerebellopontine angle and IAC. Familiarity with these structures can prevent confusion with, or misinterpretation as, a fracture line, and further study such as MR imaging may be required when any enlargement or erosion of these nerve canals is present.Imaging is therefore critical for distinguishing between the type of lesions in the IAC prior to any intervention. The canal for the saccular branch of the inferior vestibular nerve was located just below the canal for the superior vestibular nerve, and that for the posterior ampullary nerve, the so-called singular canal, ran laterally or posteolaterally from the posteroinferior aspect of the canal for the saccular branch.ĬONCLUSION: Five bony nerve canals in the fundus of the internal auditory canal were detected by high-frequency on high-resolution temporal bone CT. The canal for the cochlear nerve was located just below that for the labyrinthine segment of the facial nerve, while that canal for the superior vestibular nerve was seen at the posterior aspect of these two canals. In all detectable cases, the canal for the labyrinthine segment of the facial nerve was revealed as one which traversed anterolaterally, from the anterosuperior portion of the fundus of the internal auditory canal. On coronal CT images, canals for the labyrinthine segment of the facial and superior vestibular nerve were seen in 100% of cases, but those for the cochlear nerve, the saccular branch of the inferior vestibular nerve, and the singular canal were seen in 90.1%, 87.4% and 78% of cases, respectively. ![]() Four canals were identified on axial CT images in 100% of cases the so-called singular canal was identified in only 68%. RESULTS: Five bony canals in the fundus of the internal auditory canal were identified as nerve canals. Three radiologists determined the detectability and location of canals for the labyrinthine segment of the facial, superior vestibular and cochlear nerve, and the saccular branch and posterior ampullary nerve of the inferior vestibular nerve. Those with a history of uncomplicated inflammatory disease were included, but those with symptoms of vertigo, sensorineural hearing loss, or facial nerve palsy were excluded. MATERIALS AND METHODS: We retrospectively reviewed high-resolution (1 mm thickness and interval contiguous scan) temporal bone CT images of 253 ears in 150 patients who had not suffered trauma or undergone surgery. PURPOSE: To identify and evaluate the normal anatomy of nerve canals in the fundus of the internal auditory canal which can be visualized on high-resolution temporal bone CT. ![]()
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