Three‐Dimensional Study of the Facial Canal Using Microcomputed Tomography for Improved Anatomical Comprehension

Shin, Kang‐Jae; Gil, Young-Chun; Lee, Juyoung; Kim, Jeong‐Nam; Song, Wu‐Chul; Koh, Ki Seok

doi:10.1002/ar.22977

Cited by 19 publications

(16 citation statements)

References 25 publications

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“…The compression of an inflamed facial nerve has previously been explained on the basis of irregularity between the lumen size of the un-yielding facial canal and the neve width [11,12]. However the sporadic reports on the variation of size and shape of the stylomastoid foramen [13,14], which can also have clinical implications in unexplained cases of facial nerve palsy, have never been discussed with regards to compression of the nerve. Hence the present study was conducted with an objective to study the variations in size and shape of the stylomastoid foramen in dry adult human skulls.…”

Section: Introductionmentioning

confidence: 99%

Variations in the morphology of stylomastoid foramen: a possible solution to the conundrum of unexplained cases of Bell’s palsy

Ghosh

Narayan

2021

Folia Morphol

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Background: Stylomastoid foramen is the terminal part of facial canal and is the exit gateway for facial nerve from skull base. We hypothesized that anatomical variations of this foramen could be a risk factor for the injury of facial nerve resulting in unilateral facial nerve paralysis or Bell's palsy. Hence the present study was conducted to study the variations in size and shape of stylomastoid foramen in dry adult human skulls. Materials and methods: The study was conducted on 37 dry adult human skulls of unknown age and sex. High resolution images of the skulls under study were processed by ImageJ software and observations were undertaken. Results: Total 8 variations of stylomastoid foramen were observed in terms of shape. The common variants were round, oval and square (present in 83.79% skulls on right side and 81.07% skulls on left side), whereas the rare variants were triangular, rectangular, serrated, bean and irregular. It was noted that stylomastoid foramen were associated with extensions (45.95% skulls) and also adjacent foramen (18.92% skulls). Exclusively unilateral observations included bifurcation of foramen (16.22% skulls), foramen situated deep inside skull groove (5.41% skulls) and foramen interrupted by bony spur (2.7% skulls). No significant differences were observed between the mean diameters (antero-posterior and transverse) of the stylomastoid foramen. Conclusions: The unilateral variations along with rare variations in terms of shape such as serrated, bean and irregular foramen (which were also unilateral findings) could be potential risk factors towards injury of facial nerve at the point of exit from skull base leading to Bell's palsy.

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Section: Introductionmentioning

confidence: 99%

Variations in the morphology of stylomastoid foramen: a possible solution to the conundrum of unexplained cases of Bell’s palsy

Ghosh

Narayan

2021

Folia Morphol

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“…Therefore, we applied microtomography to obtain reconstructed objects with a resolution of 18 µm, which appeared accurate enough to visualize the facial canal morphology and its course in a three-dimensional manner. This imaging modality was used in only a few studies to present the overall course and morphology of the facial canal but not its structural defects [16, 17]. Although micro-CT is excellent for visualizing morphological aspects of the osseous defects of the facial canal, computed tomography still remains the fundamental technique for imaging facial canal anatomy in preoperative practice [8].…”

Section: Discussionmentioning

confidence: 99%

Micro-CT study of the dehiscences of the tympanic segment of the facial canal

et al. 2016

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PurposeTo depict the anatomy of the tympanic segment of the facial canal using a 3D visualization technique, to detect dehiscences, and to evaluate their frequency, location, shape, and size.MethodsResearch included 36 human temporal bones (18 infant and 18 adult samples) which were scanned using a Nanotom 180N device. The final resolution of the reconstructed object was 18 µm. Obtained micro-CT data were subsequently processed by the volume rendering software.ResultsThe micro-CT study allowed for the 3D visualization of the tympanic segment of the facial canal and detects dehiscences in the studied material in both infants and adults. Most of the dehiscences (66.7 %) involved the inferior wall of the tympanic segment in infants as well as in adults, and were located above and backward to the oval window. The most frequent dehiscence shape was elliptic (66.7 % in infants; 50 % in adults). Furthermore, we observed dehiscences of fusiform and trapezoidal shape in infants. Length of the dehiscences in most cases ranged from 0.5 to 1.4 mm (50 % in infants; 75 % in adults).ConclusionsVolumetric reconstructions demonstrated the course of the tympanic segment of the facial canal and its relationship with the tympanic cavity. Knowledge about the size and location of any dehiscence within the tympanic segment of the facial canal is necessary due to the surgical significance of this region. If a dehiscence occurs, there is an increased risk of injury to the facial nerve during the operations or spread of inflammation from the middle ear.

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“…Bell's palsy (BP) is the commonest cause of facial paralysis. While it is currently idiopathic by definition, virally mediated inflammation is widely accepted as the foremost etiological factor 1,2 . It has also been suggested that the anatomy of the facial nerve canal might play an important causative role.…”

Section: Introductionmentioning

confidence: 99%

“…It has also been suggested that the anatomy of the facial nerve canal might play an important causative role. In particular, neural inflammation within the narrow portions of the facial nerve canal is presumed to result in neural impingement 1‐4 . This is most relevant at the labyrinthine portion and its meatal foramen, where the facial nerve canal is at its narrowest 2,4 .…”

Section: Introductionmentioning

confidence: 99%

“…While it is currently idiopathic by definition, virally mediated inflammation is widely accepted as the foremost etiological factor. 1 , 2 It has also been suggested that the anatomy of the facial nerve canal might play an important causative role. In particular, neural inflammation within the narrow portions of the facial nerve canal is presumed to result in neural impingement.…”

Section: Introductionmentioning

confidence: 99%

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Computed tomographic features of the proximal petrous facial nerve canal in recurrent Bell's palsy

Touska

Dudau

Patel

et al. 2021

Laryngoscope Investig Oto

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Objectives The primary objective was to determine whether the narrowest dimensions of the labyrinthine facial nerve (LFN) canal on the symptomatic side in patients with unilateral recurrent Bell's palsy (BP) differ from those on the contralateral side or in asymptomatic, age‐ and gender‐matched controls on computed tomography (CT). The secondary objectives were to assess the extent of bony covering at the geniculate ganglion and to record inter‐observer reliability of the CT measurements. Methods The dimensions of the LFN canal at its narrowest point perpendicular to the long axis and the extent of bony covering at the geniculate ganglion were assessed by two radiologists. Statistical analysis was performed using the Wilcoxon signed‐rank and Mann‐Whitney U tests (LFN canal dimensions) and the Chi‐squared test (bony covering at the geniculate ganglion). Inter‐observer reliability was evaluated using Intra‐Class Correlation (ICC) and Cohen's kappa. Results The study included 21 patients with unilateral recurrent BP and 21 asymptomatic controls. There was no significant difference in the narrowest dimensions of the ipsilateral LFN canal when compared to the contralateral side or controls (P = .43‐.94). Similarly, there was no significant difference in the extent of bony covering at the geniculate ganglion when compared to either group (P = .19‐.8). Good inter‐observer reliability was observed for LFN measurements (ICC = 0.75‐0.88) but not for the bony covering at the geniculate ganglion (Cohen's kappa = 0.53). Conclusion The narrowest dimensions of the LFN canal and the extent of bony covering at the geniculate ganglion do not differ in unilateral recurrent BP, casting doubt over their etiological significance. Level of Evidence Level IV.

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Three‐Dimensional Study of the Facial Canal Using Microcomputed Tomography for Improved Anatomical Comprehension

Cited by 19 publications

References 25 publications

Variations in the morphology of stylomastoid foramen: a possible solution to the conundrum of unexplained cases of Bell’s palsy

Variations in the morphology of stylomastoid foramen: a possible solution to the conundrum of unexplained cases of Bell’s palsy

Micro-CT study of the dehiscences of the tympanic segment of the facial canal

Computed tomographic features of the proximal petrous facial nerve canal in recurrent Bell's palsy

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