open access

Vol 76, No 2 (2017)
Original article
Submitted: 2016-05-08
Accepted: 2016-07-09
Published online: 2016-09-23
Get Citation

The relationship between the dimensions of the internal auditory canal and the anomalies of the vestibulocochlear nerve

A. O. El Sadik1, M. H. Shaaban1
·
Pubmed: 27665959
·
Folia Morphol 2017;76(2):178-185.
Affiliations
  1. Anatomy and Embryology Department, Faculty of Medicine, Cairo University, Cairo, Egypt

open access

Vol 76, No 2 (2017)
ORIGINAL ARTICLES
Submitted: 2016-05-08
Accepted: 2016-07-09
Published online: 2016-09-23

Abstract

Background: Internal auditory canal (IAC) stenosis and vestibulocochlear nerve (VCN) abnormalities have been reported to be associated with sensorineural hearing loss. Previous studies classified the normal dimensions of the IAC and its anomalies with no consideration of the VCN. Other studies categorised the VCN development in only stenotic canals. In the present study, an anatomical classification of the normal dimensions of the IAC and its anomalies and their association with malformations of the VCN and its subdivisions were described.

Materials and methods: Retrospective review was undertaken for children ranged from 1 to 10 years. A total of 764 canals were investigated for pre-operative assessment of cochlear implantation. Other 100 canals of normal hearing ears were included as the control group. The maximum anteroposterior diameter, considered the width of the canal, was measured in axial plane and the length of the canal was identified in coronal plane. The canals were categorised normal: if they are from 3 to 8 mm, patulous: if they are more than 8 mm, stenotic: if they are less than 3 mm and atretic if absent, using multislice computed tomography. The VCN trunks and their subdivisions were investigated using magnetic resonance imaging.

Results: Internal auditory canals were found normal in 66% with a mean width: 5.27 ± ± 0.68, patulous in 17% with a mean width 113% more than that of the control group (p = 0.000), stenotic in 13% with a mean width 73% less as compared to that of the control group (p = 0.000) and atretic in 4% of the experimental canals. The VCN trunks were found normal with well-developed subdivisions in 77.8% of the normal canals, 98.4% of the patulous canals, and 19.2% of the stenotic canals. The VCN trunks were normal with hypoplastic subdivisions in 11.3% of the normal canals, 1.6% in the patulous canals, and 61.6% in the stenotic canals with a mean width 52% less than that of the normal trunk with developed subdivisions. Hypoplastic VCN trunks with absent subdivisions were reported in 7.3% of the normal canals, 11.1% of the stenotic canals and in 3.2% of the atretic canals. The VCN trunks were not found in 3.6% of the normal canals, in 8.1% of the stenotic canals and in 96.8% of the atretic canals.

Conclusions: Internal auditory canal formation was dependent on the process of development and growth of the eighth cranial nerve and its subdivisions that greatly affected the completion of IAC canalisation. This paper could serve as a reference providing a quantitative classification of the relationship between the dimensions of the IAC and the development of the VCN trunk and its subdivisions.

Abstract

Background: Internal auditory canal (IAC) stenosis and vestibulocochlear nerve (VCN) abnormalities have been reported to be associated with sensorineural hearing loss. Previous studies classified the normal dimensions of the IAC and its anomalies with no consideration of the VCN. Other studies categorised the VCN development in only stenotic canals. In the present study, an anatomical classification of the normal dimensions of the IAC and its anomalies and their association with malformations of the VCN and its subdivisions were described.

Materials and methods: Retrospective review was undertaken for children ranged from 1 to 10 years. A total of 764 canals were investigated for pre-operative assessment of cochlear implantation. Other 100 canals of normal hearing ears were included as the control group. The maximum anteroposterior diameter, considered the width of the canal, was measured in axial plane and the length of the canal was identified in coronal plane. The canals were categorised normal: if they are from 3 to 8 mm, patulous: if they are more than 8 mm, stenotic: if they are less than 3 mm and atretic if absent, using multislice computed tomography. The VCN trunks and their subdivisions were investigated using magnetic resonance imaging.

Results: Internal auditory canals were found normal in 66% with a mean width: 5.27 ± ± 0.68, patulous in 17% with a mean width 113% more than that of the control group (p = 0.000), stenotic in 13% with a mean width 73% less as compared to that of the control group (p = 0.000) and atretic in 4% of the experimental canals. The VCN trunks were found normal with well-developed subdivisions in 77.8% of the normal canals, 98.4% of the patulous canals, and 19.2% of the stenotic canals. The VCN trunks were normal with hypoplastic subdivisions in 11.3% of the normal canals, 1.6% in the patulous canals, and 61.6% in the stenotic canals with a mean width 52% less than that of the normal trunk with developed subdivisions. Hypoplastic VCN trunks with absent subdivisions were reported in 7.3% of the normal canals, 11.1% of the stenotic canals and in 3.2% of the atretic canals. The VCN trunks were not found in 3.6% of the normal canals, in 8.1% of the stenotic canals and in 96.8% of the atretic canals.

Conclusions: Internal auditory canal formation was dependent on the process of development and growth of the eighth cranial nerve and its subdivisions that greatly affected the completion of IAC canalisation. This paper could serve as a reference providing a quantitative classification of the relationship between the dimensions of the IAC and the development of the VCN trunk and its subdivisions.

Get Citation

Keywords

vestibulocochlear nerve, internal auditory canal, multislice computed tomography, magnetic resonance imaging

About this article
Title

The relationship between the dimensions of the internal auditory canal and the anomalies of the vestibulocochlear nerve

Journal

Folia Morphologica

Issue

Vol 76, No 2 (2017)

Article type

Original article

Pages

178-185

Published online

2016-09-23

Page views

1926

Article views/downloads

2382

DOI

10.5603/FM.a2016.0052

Pubmed

27665959

Bibliographic record

Folia Morphol 2017;76(2):178-185.

Keywords

vestibulocochlear nerve
internal auditory canal
multislice computed tomography
magnetic resonance imaging

Authors

A. O. El Sadik
M. H. Shaaban

References (25)
  1. Adunka OF, Roush PA, Teagle HFB, et al. Internal auditory canal morphology in children with cochlear nerve deficiency. Otol Neurotol. 2006; 27(6): 793–801.
  2. Baek SK, Chae SW, Jung HH. Congenital internal auditory canal stenosis. J Laryngol Otol. 2003; 117(10): 784–787.
  3. Casselman JW, Offeciers FE, Govaerts PJ, et al. Aplasia and hypoplasia of the vestibulocochlear nerve: diagnosis with MR imaging. Radiology. 1997; 202(3): 773–781.
  4. Casselman JW, Offeciers EF, De Foer B, et al. CT and MR imaging of congential abnormalities of the inner ear and internal auditory canal. Eur J Radiol. 2001; 40(2): 94–104.
  5. Djalilian HR, Thakkar KH, Hamidi S, et al. A study of middle cranial fossa anatomy and anatomic variations. Ear Nose Throat J. 2007; 86(8): 474, 476–81.
  6. Erkoç MF, Ímamoglu H, Okur A, et al. Normative size evaluation of internal auditory canal with magnetic resonance imaging: review of 3786 patients Folia Morphol. 2012; 71(4): 217–220.
  7. Farahani R, Nooranipour M, Nikakhtar K. Anthropometry of Internal Acoustic Meatus. Int J Morphol. 2007; 25(4).
  8. Fujita S, Sando I. Postnatal development of the vestibular aqueduct in relation to the internal auditory canal. Computer-aided three-dimensional reconstruction and measurement study. Ann Otol Rhinol Laryngol. 1994; 103(9): 719–722.
  9. Giesemann AM, Neuburger J, Lanfermann H, et al. Aberrant course of the intracranial facial nerve in cases of atresia of the internal auditory canal (IAC). Neuroradiology. 2011; 53(9): 681–687.
  10. Huang BY, Roche JP, Buchman CA, et al. Brain stem and inner ear abnormalities in children with auditory neuropathy spectrum disorder and cochlear nerve deficiency. AJNR Am J Neuroradiol. 2010; 31(10): 1972–1979.
  11. Ito K, Suzuki S, Murofushi T, et al. Neuro-otologic findings in unilateral isolated narrow internal auditory meatus. Otol Neurotol. 2005; 26(4): 767–772.
  12. Lang J. Clinical anatomy of the cerebellopontine angle and internal acoustic meatus. Adv Otorhinolaryngol. 1984; 34: 8–24.
  13. Li Y, Yang J, Liu J, et al. Restudy of malformations of the internal auditory meatus, cochlear nerve canal and cochlear nerve. Eur Arch Otorhinolaryngol. 2015; 272(7): 1587–1596.
  14. Marques SR, Smith RL, Isotani S, et al. Morphological analysis of the vestibular aqueduct by computerized tomography images. Eur J Radiol. 2007; 61(1): 79–83.
  15. Marques SR, Ajzen S, D Ippolito G, et al. Morphometric analysis of the internal auditory canal by computed tomography imaging. Iran J Radiol. 2012; 9(2): 71–78.
  16. Masuda S, Usui S, Matsunaga T. High prevalence of inner-ear and/or internal auditory canal malformations in children with unilateral sensorineural hearing loss. Int J Pediatr Otorhinolaryngol. 2013; 77(2): 228–232.
  17. Polat C, Baykara M, Ergen B. Evaluation of internal auditory canal structures in tinnitus of unknown origin. Clin Exp Otorhinolaryngol. 2014; 7(3): 160–164.
  18. Roche JP, Huang BY, Castillo M, et al. Imaging characteristics of children with auditory neuropathy spectrum disorder. Otol Neurotol. 2010; 31(5): 780–788.
  19. Rothschild MA, Wackym PA, Silvers AR, et al. Isolated primary unilateral stenosis of the internal auditory canal. Int J Pediatr Otorhinolaryngol. 1999; 50(3): 219–224.
  20. Rubinstein D, Sandberg EJ, Cajade-Law AG. Anatomy of the facial and vestibulocochlear nerves in the internal auditory canal. AJNR Am J Neuroradiol. 1996; 17(6): 1099–1105.
  21. Sennaroglu L, Saatci I. A new classification for cochleovestibular malformations. Laryngoscope. 2002; 112(12): 2230–2241.
  22. Sheth S, Branstetter BF, Escott EJ. Appearance of normal cranial nerves on steady-state free precession MR images. Radiographics. 2009; 29(4): 1045–1055.
  23. Sildiroglu O, Cincik H, Sonmez G, et al. Evaluation of cochlear nerve size by magnetic resonance imaging in elderly patients with sensorineural hearing loss. Radiol Med. 2010; 115(3): 483–487.
  24. Thomsen J, Reiter S, Borum P, et al. Tomography of the internal acoustic meatus. A critical evaluation of the radiological appearance in normals and in patients with acoustic neuromas. J Laryngol Otol. 1981; 95(12): 1191–1204.
  25. Verbist BM. Imaging of sensorineural hearing loss: a pattern-based approach to diseases of the inner ear and cerebellopontine angle. Insights Imaging. 2012; 3(2): 139–153.

Regulations

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By VM Media Group sp. z o.o., Grupa Via Medica, Świętokrzyska 73, 80–180 Gdańsk, Poland

tel.: +48 58 320 94 94, faks: +48 58 320 94 60, e-mail: viamedica@viamedica.pl