Anatomical features of the mastoid segment of the facial canal
, 2, 1, 1, 3, 4, 4, 4, 4
Abstract
Background: Considering the tortuous course of the facial canal that houses the facial nerve, the stylomastoid artery and the homonymous vein, its morphological features are of great clinical significance in otologic, maxillofacial, oncologic, reconstructive and plastic surgery of the head and neck. The aim of this paper was to determine the individual specific features of the mastoid segment of facial canal and of the stylomastoid foramen.
Material and methods: The study was carried out on 82 temporal bones (41 right/41 left), at the Department of anatomy and clinical anatomy of Nicolae Testemitanu State University of Medicine and Pharmacy of the Republic of Moldova. The morphometry of the mastoid segment of the facial canal and of the stylomastoid foramen was performed. The morphometric parameters were statistically analyzed by descriptive and inferential statistics methods.
Results: The mastoid segment exited the facial canal by an obtuse, right and sharp angles, with a mean value of 113.1 ± 21.80° (right/left – 112.1 ± 23.85°/114.1 ± 19.76°), p = 0.701. The mean length of the mastoid segment was 15.1 ± 3.78 mm (right/left – 15.7 ± 3.66 mm/14.5 ± 3.84 mm), p = 0.153. The longitudinal diameter of the stylomastoid foramen had a mean of 3.0 ± 0.93 mm (right/left – 3.3 ± 0.96 mm/2.7 ± 0.81 mm), p = 0.007. The transverse diameter had a mean of 2.6 ± 0.74 mm (right/left – 2.9 ± 0.80 mm/2.4 ± 0.60 mm), p = 0.012.
Conclusions: In otologic surgery and particularly in mastoidectomy, it should be taken into consideration that the mastoid segment of the facial canal could exit the temporal bone by a sharp, right and obtuse angles that along with high morphological variability of the stylomastoid foramen might be a predisposal factor for Bell's palsy.
Keywords: facial canalfacial nerveanatomical variationsmorphometry
References
- Babuci A, Catereniuc I, Zorina Z, et al. Morphology and variability of the facial nerve trunk depending on the branching pattern, gender, anthropometric type and side of the head in Moldovan population. Folia Morphol. 2023; 82(4): 791–797.
- Gavriliuc M. Examenul neurologic. Universitatea De Stat De Medicină Şi Farmacie „Nicolae Testemiţanu”, Chișinău 2012.
- Ghosh SK, Narayan RK. Variations in the morphology of stylomastoid foramen: a possible solution to the conundrum of unexplained cases of Bell's palsy. Folia Morphol. 2021; 80(1): 97–105.
- Glastonbury CM, Fischbein NJ, Harnsberger HR, et al. Congenital bifurcation of the intratemporal facial nerve. AJNR Am J Neuroradiol. 2003; 24(7): 1334–1337.
- Gong Li, Feng Y, Tang X, et al. Variation of the stapes and its surrounding anatomical structures based on micro-computed tomography. Folia Morphol. 2023 [Epub ahead of print].
- Gulotta G, Pace A, Iannella G, et al. Facial nerve dehiscence and cholesteatoma: a comparison between decades. J Int Adv Otol. 2020; 16(3): 367–372.
- Gülüstan F, Aslan H, Songu M, et al. Relationships between facial canal dehiscence and other intraoperative findings in chronic otitis media with cholesteatoma. Am J Otolaryngol. 2014; 35(6): 791–795.
- Hafez M, Ghonim M, Razek AA, et al. Congenital duplication of mastoid segment of facial nerve in child candidate for Cochlear Implantation Surgery: a rare case report. Minia J Med Res. 2020; 31(2): 313–316.
- Hervochon R, Madelain V, Seiller I, et al. CT and clinical prognostic factors in Bell's palsy: a study of 56 cases. Clin Otolaryngol. 2019; 44(5): 861–864.
- Ho ML, Juliano A, Eisenberg RL, et al. Anatomy and pathology of the facial nerve. AJR Am J Roentgenol. 2015; 204(6): W612–W619.
- Hohman MH, Bhama PK, Hadlock TA. Epidemiology of iatrogenic facial nerve injury: a decade of experience. Laryngoscope. 2014; 124(1): 260–265.
- Jakkani RK, Ki R, Karnawat A, et al. Congenital duplication of mastoid segment of facial nerve: a rare case report. Indian J Radiol Imaging. 2013; 23(1): 35–37.
- Jatale SP, Chintale SG, Kirdak VR, et al. Our experience of anatomical variations of facial nerve in cadaveric temporal bone dissection. Indian J Otolaryngol Head Neck Surg. 2021; 73(3): 271–275.
- Juliano AF, Ginat DT, Moonis G. Imaging review of the temporal bone: part I. Anatomy and inflammatory and neoplastic processes. Radiology. 2013; 269(1): 17–33.
- Kalaiarasi R, Kiran AS, Vijayakumar C, et al. Anatomical features of intratemporal course of facial nerve and its variations. Cureus. 2018; 10(8): e3085.
- Karaca H, Soydan L, Yildiz S, et al. Measurement of the depth of facial nerve at the level of stylomastoid foramen using MR imaging in Bell's palsy. Clin Imaging. 2019; 58: 34–38.
- Kim J, Jung GH, Park SY, et al. Anatomical consideration of the temporal bone as a pathogenesis of Bell's palsy. Med Hypotheses. 2011; 77(5): 705–707.
- Li T, Lai ZC, Wang XuD, et al. Measurement and analysis of facial nerve on fully displayed multislice computed tomographic multiplanar reconstruction image. J Craniofac Surg. 2013; 24(4): 1411–1413.
- Liston SL, Kleid MS. Histopathology of Bell's palsy. Laryngoscope. 1989; 99(1): 23–26.
- Meng FH, Song Yu, Qiao Bo, et al. Image-guided, surgical robot-assisted percutaneous puncture of the foramen ovale and foramina stylomastoideum: a cadaveric study. Chin Med J (Engl). 2021; 134(19): 2362–2364.
- Moonis G, Mani K, O'Malley J, et al. A venous cause for facial canal enlargement: multidetector row CT findings and histopathologic correlation. AJNR Am J Neuroradiol. 2011; 32(5): E83–E84.
- Moreano EH, Paparella MM, Zelterman D, et al. Prevalence of facial canal dehiscence and of persistent stapedial artery in the human middle ear: a report of 1000 temporal bones. Laryngoscope. 1994; 104(3 Pt 1): 309–320.
- Nager GT, Proctor B. Anatomic variations and anomalies involving the facial canal. Otolaryngol Clin North Am. 1991; 24(3): 531–553.
- Nitek S, Wysocki J, Niemczyk K, et al. The anatomy of the tympanic sinus. Folia Morphol. 2006; 65(3): 195–199.
- Ottaiano AC, Gomez GD, Freddi Td. The Facial Nerve: Anatomy and Pathology. Semin Ultrasound CT MR. 2023; 44(2): 71–80.
- Przewoźny TT, Kosiński A, Markiet K, et al. Körner's septum (petrosquamosal lamina): the anatomical variant or clinical problem? Folia Morphol. 2020; 79(2): 205–210.
- Qin Yi, Liu J, Zhang X, et al. To explore the pathogenesis of Bell's palsy using diffusion tensor image. Sci Rep. 2023; 13(1): 15298.
- Somayaji K, Rajeshwary A, Goutham MK. Dehiscent mastoid segment of the facial nerve. Arch Med Health Sci. 2018; 6(1): 187.
- Rana A, Khan M, Parab S. A rare case of aberrant facial nerve course in the mastoid segment. Pol Otorhino Rev. 2021; 10(2): 30–33.
- Sharma N, Varshney R. Morphometry of stylomastoid foramen and its clinical application in facial nerve block. Saudi J Anaesth. 2015; 9(1): 60–63.
- Singh R. Morphological Study of Stylomastoid Foramen at the Base of Skull and its Role in Facial Nerve Palsy. J Craniofac Surg. 2023; 34(5): 1584–1586.
- Skrzat J, Kozerska M, Zarzecki M, et al. A micro-computed tomography study of the sinus tympani variation in humans. Folia Morphol. 2023; 82(4): 898–908.
- TanrivermiŞ Sayit A, Gunbey HP, Sağlam D, et al. Association between facial nerve second genu angle and facial canal dehiscence in patients with cholesteatoma: evaluation with temporal multidetector computed tomography and surgical findings. Braz J Otorhinolaryngol. 2019; 85(3): 365–370.
- Tewari S, Gupta C, Palimar V. A morphometric study of stylomastoid foramen with its clinical applications. J Neurol Surg B Skull Base. 2022; 83(1): 33–36.
- Topaloglu I, Yaslikaya S, Berkiten G. Facial canal dehiscence in patients undergoing surgery for chronic otitis media: analysis of 850 patients. Otolaryngol Pol. 2022; 77(1): 1–5.
- Vaishali B, Mohanraj K. Morphological and morphometric analysis of stylomastoid foramen in dry human skulls and its clinical implications. J Pharm Res Int. 2021; 33(60B): 1659–1664.
- Vianna M, Adams M, Schachern P, et al. Differences in the diameter of facial nerve and facial canal in bell's palsy — a 3-dimensional temporal bone study. Otol Neurotol. 2014; 35(3): 514–518.
- Yetiser S. The dehiscent facial nerve canal. Int J Otolaryngol. 2012; 2012: 679708.
