Dissection and Exposure of the Whole Course of Deep Nerves in Human Head Specimens after Decalcification

Imaging plays a critical role in the evaluation of a number of facial nerve disorders. The facial nerve has a complex anatomical course; thus, a thorough understanding of the course of the facial nerve is essential to localize the sites of pathology. Facial nerve dysfunction can occur from a variety of causes, which can often be identified on imaging. Computed tomography and magnetic resonance imaging are helpful for identifying bony facial canal and soft tissue abnormalities, respectively. Ultrasound of the facial nerve has been used to predict functional outcomes in patients with Bell's palsy. More recently, diffusion tensor tractography has appeared as a new modality which allows three-dimensional display of facial nerve fibers.

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“… Diagram of the course of the intratemporal facial nerve from the fundus of the IAC to the stylomastoid foramen [10]. …”

Section: Figurementioning

confidence: 99%

Imaging the Facial Nerve: A Contemporary Review

Gupta

Mends

Hagiwara

et al. 2013

Radiology Research and Practice

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“…Măru et al (19) found the CF-SM length went from 0.2 to 9.7 mm with a mean of 7.2 mm. On the other hand, CF-SM length ranged from 5.93 to 21.63 mm with a mean of 13.32 in the study of Liu et al (20) The CF-SM length ranged from 2.06 to 5.5 mm with a mean of 4.08 ± 0.8 mm in the study of Jain et al (21) on 35 temporal bones.…”

Section: Discussionmentioning

confidence: 94%

The Impact of the Location of Chorda Tymapni Nerve Origin on the Round Window Accessibility During Pediatric Cochlear Implantation: A Radioclinical Assessment

et al. 2022

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Objectives: This study assessed the impact of the location of the chorda tympani nerve (CTN) origin on the round window (RW) accessibility during pediatric cochlear implantation (CI). We also tried to validate the radiologic method to measure the length between the origin of the CTN from the facial nerve to the stylomastoid foramen (CF-SM). Study Design: It was a prospective observational case-series study. Settings: The included CI surgeries were performed at tertiary referral institutions from November 2018 to August 2021. Subjects: We included 146 pediatric patients who were candidates for CI. Intervention: We measured the CF-SM length in the parasagittal cut of the preoperative high-resolution computed tomography. We also classified the intraoperative RW according to the accessibility through the ordinary posterior tympanotomy approach into accessible or inaccessible. Main Outcome Measure: We correlated the preoperative radiologic CF-SM length with the intraoperative RW accessibility. Results:The radiologic CF-SM length ranged from 2.9 to 7.4 mm with a mean of 4.9 ± 1.03 mm. The RW was accessible in 107 patients and inaccessible in 39 patients. Spearman's correlation coefficient revealed a significant relationship between the location of CTN origin and the RW accessibility as the p value was less than 0.0001. Conclusions: We found a precise method to measure the CF-SM length in the parasagittal cut of the high-resolution computed tomography. We also found a significant impact of the location of the CTN origin on intraoperative RW accessibility. The radiologic CF-SM length of more than 5.4 mm had a powerful prediction capability of the RW inaccessibility.

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“…14 Liu et al described chorda tympani as a very fine nerve (0.44 mm in diameter within the tympanic cavity), and the distance between the chorda tympani and stylomastoid foramen as ranging from 5.93 mm to 21.63 mm, with the average distance being 13.32 mm. 13 Zou et al found the distance from the crotch of the CTN to the stylomastoid foramen to be 2.67 +/− 0.51 mm. 24…”

Section: Discussionmentioning

confidence: 99%

“…There is lot of variability in the origin of the chorda tympani above stylomastoid foramen. 13 14 15 Hence, the CTN is potentially vulnerable in all CI surgeries. Unfavorable anatomy of the FN also places the FN at risk.…”

Section: Introductionmentioning

confidence: 99%

Anatomical Study of the Facial Recess with Implications in Round Window Visibility for Cochlear Implantation: Personal Observations and Review of the Literature

Jain

Deshmukh

Lakhotia

et al. 2019

Int Arch Otorhinolaryngol

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Introduction Posterior tympanotomy through facial recess (FR) is the conventional and most preferred approach to facilitate cochlear implantation, especially when the electrode is inserted through the round window. The complications of the FR approach can be minimized by proper understanding of the anatomy of the FR. Objective The present study was undertaken to assess the various parameters of FR and round window visibility, which may be of relevance for cochlear implant surgery. Methods Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of FR and posterior tympanum. Photographs were taken with an 18 megapixels digital camera, which were then imported to a computer to determine various parameters. Results The mean distance from the take-off point/crotch of the chorda tympani nerve (CTN) to the stylomastoid foramen was 4.08 ± 0.8 mm (range of 2.06 - 5.5 mm). The variations in the course of the CTN included origin at the level of the lateral semicircular canal. The mean chorda-facial angle in our study was 26.91° ± 1.19°, with a range of 25° to 28.69°. The mean FR length ranged between 9.4 mm and 18.56 mm (mean of 12.41 ± 2.91mm) and varied with the origin of the CTN and pneumatization of temporal bone. The average maximum width of the FR was 2.93 ± 0.4 mm (range 2.24–3.45 mm) and the mean width of the FR at the level of the round window was 2.65 ± 0.41 mm. Conclusion The FR approach provides good access to the round window membrane in all cases. In some cases, table adjustment is required.

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Dissection and Exposure of the Whole Course of Deep Nerves in Human Head Specimens after Decalcification

Cited by 9 publications

References 14 publications

Imaging the Facial Nerve: A Contemporary Review

Imaging the Facial Nerve: A Contemporary Review

The Impact of the Location of Chorda Tymapni Nerve Origin on the Round Window Accessibility During Pediatric Cochlear Implantation: A Radioclinical Assessment

Anatomical Study of the Facial Recess with Implications in Round Window Visibility for Cochlear Implantation: Personal Observations and Review of the Literature

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