Skip to main content
Advertisement

Main menu

  • Home
  • Content
    • Current Issue
    • Publication Preview--Ahead of Print
    • Past Issue Archive
    • Case of the Week Archive
    • Classic Case Archive
    • Case of the Month Archive
  • For Authors
  • About Us
    • About AJNR
    • Editors
    • American Society of Neuroradiology
  • Submit a Manuscript
  • Podcasts
    • Subscribe on iTunes
    • Subscribe on Stitcher
  • More
    • Subscribers
    • Permissions
    • Advertisers
    • Alerts
    • Feedback
  • Other Publications
    • ajnr

User menu

  • Subscribe
  • Alerts
  • Log in

Search

  • Advanced search
American Journal of Neuroradiology
American Journal of Neuroradiology

American Journal of Neuroradiology

  • Subscribe
  • Alerts
  • Log in

Advanced Search

  • Home
  • Content
    • Current Issue
    • Publication Preview--Ahead of Print
    • Past Issue Archive
    • Case of the Week Archive
    • Classic Case Archive
    • Case of the Month Archive
  • For Authors
  • About Us
    • About AJNR
    • Editors
    • American Society of Neuroradiology
  • Submit a Manuscript
  • Podcasts
    • Subscribe on iTunes
    • Subscribe on Stitcher
  • More
    • Subscribers
    • Permissions
    • Advertisers
    • Alerts
    • Feedback
  • Follow AJNR on Twitter
  • Visit AJNR on Facebook
  • Follow AJNR on Instagram
  • Join AJNR on LinkedIn
  • RSS Feeds
Case ReportCase Report

A Venous Cause for Facial Canal Enlargement: Multidetector Row CT Findings and Histopathologic Correlation

G. Moonis, K. Mani, J. O'Malley, S. Merchant and H.D. Curtin
American Journal of Neuroradiology May 2011, 32 (5) E83-E84; DOI: https://doi.org/10.3174/ajnr.A2094
G. Moonis
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
K. Mani
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
J. O'Malley
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
S. Merchant
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
H.D. Curtin
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Data
  • Info & Metrics
  • References
  • PDF
Loading

Abstract

SUMMARY: An enlarged facial nerve canal can be a seen in both pathologic and nonpathologic processes. The purposes of this report are the following: 1) to present a rare cause of bony facial nerve canal enlargement, due to an enlarged vein, with high-resolution MDCT and histopathologic correlation; and 2) to discuss the vascular anatomy that gives rise to this variant.

Abbreviations

A
artery
AICA
anterior inferior cerebellar artery
GSPN
greater superficial petrosal nerve
MDCT
multidetector row CT

The facial nerve runs a tortuous course in the fallopian canal through the temporal bone and is well evaluated on MDCT. The caliber of the fallopian canal on MDCT is relatively fixed, particularly proximally; the diameter of the intratemporal facial canal ranges from approximately 0.9 to 2 mm on histopathology.1,2 Deviations in its size may be related to anatomic variants or pathologic processes. Herein, we describe a case of fallopian canal enlargement due to a prominent vein running alongside the facial nerve.

Case Report

The temporal bone specimen came from a 79-year-old man who had bilateral gradually progressive hearing loss and tinnitus throughout his life. There was no history of trauma or surgery to the temporal bone. He joined the National Temporal Bone Bank Program, and after his death from unrelated causes, his temporal bone was evaluated in the Temporal Bone Laboratory at our institution.

Temporal bone histopathologic specimens were stained and examined by light microscopy. We performed CT scanning of the specimen in the axial plane on a 4-channel CT scanner (Somatom Plus 4 Volume Zoom; Siemens, Erlangen, Germany) with 0.5-mm collimation, 0.5-mm thickness, 320 mAs, and 120 kV(peak). The axial data were transferred to a separate workstation for postprocessing, with a commercially available 3D reformatting software (Voxar 3D; Barco, Edinburgh, Scotland).

CT showed smooth enlargement of the bony facial nerve canal from the geniculate ganglion to the stylomastoid foramen without osseous erosion (Fig 1). There was a V-shaped branching pattern at the level of the first genu with 2 channels extending anteriorly. The foramen spinosum was present. The contralateral facial canal was normal in size.

Fig 1.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 1.

A, Axial MDCT scan through the right temporal bone at the level of the cochlea demonstrates smooth enlargement of the tympanic segment of the facial canal (white arrows) with a V-shaped continuation anteriorly at the level of the first genu (black arrow and white arrowhead). B, Axial image at a more inferior level demonstrates an enlarged mastoid segment of the facial nerve (black arrow).

Histopathologically, the facial canal contained a normal-sized facial nerve with a similar-sized vein running parallel to it (Fig 2B). At the first genu, there was a V-shaped branching pattern of the venous structures replicating the CT appearance (Fig 2A).

Fig 2.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 2.

Photomicrographs of axial histopathologic specimens through the right temporal bone. A, Prominent veins (white arrow, black arrowhead) enter the facial canal anteriorly. The asterisk indicates the genu of the facial nerve. B, An enlarged vein (small black arrow) accompanies the mastoid segment of the facial nerve (long black arrow). The asterisk indicates the cochlea; the small black arrowheads, the tympanic membrane (hematoxylin-eosin stain, 1.5× magnification).

Discussion

Arterial supply to the facial nerve is segmental. The intracanalicular facial nerve is supplied by the AICA.3 The internal auditory artery, a branch of AICA, supplies the labyrinthine segment of the facial nerve.3

The petrosal artery (also referred to as the superficial petrosal artery) branches off from the middle meningeal artery immediately after it enters the skull through the foramen spinosum.4 It enters the hiatus of the GSPN accompanying that nerve and provides arterial arborization to the geniculate ganglion and the tympanic segment (Fig 3). There is occasionally a second branch of the middle meningeal artery; the superior tympanic artery, which either anastomoses with the petrosal artery or itself extends into the facial canal (sometimes accompanying the lesser petrosal nerve) (Fig 3).4,5

Fig 3.
  • Download figure
  • Open in new tab
  • Download powerpoint
Fig 3.

Schematic illustrates the tortuous course of the intratemporal facial canal, from proximal to distal ends: 1) labyrinthine segment 2) geniculate ganglion 3) tympanic segment, and 4) mastoid segment. The petrosal artery arises from the middle meningeal artery and enters the fallopian canal via the hiatus for the GSPN (5). The superior tympanic artery arises from the middle meningeal artery and supplies the facial nerve through a separate bony canal.

The stylomastoid artery from the posterior auricular artery ascends via the stylomastoid foramen to supply the mastoid segment.5 It anastomoses with the petrosal artery in the tympanic segment of the facial nerve.4

Venous drainage of the facial nerve generally accompanies the named arteries within the nerve sheath.4 Ultimately the venous drainage from the geniculate ganglion and tympanic segment is into the middle meningeal vein.4 In our case, the V-shaped configuration of the venous channels suggests that these represent prominent petrosal and superior tympanic veins.

Causes of facial canal enlargement are numerous. Congenital/developmental variants include a persistent stapedial artery (associated with absent foramen spinosum),6 congenital cholesteatoma,7 and meningocele with or without a CSF fistula involving the facial canal.8,9 Primary facial nerve neoplasms include schwannomas, neurofibromas, hemangiomas, meningiomas, epidermoids, and paragangliomas.10–12 Also, perineural spread of parotid (and other) malignancies via this route,13 leukemic infiltration,14 and metastatic disease affecting the facial nerve15 have been described.

Although the presence of veins and arteries in the facial canal is well known,16,17 venous causes of facial canal enlargement have not been previously described. Being aware of a venous etiology of facial canal enlargement can help prevent unnecessary work-up and intervention in asymptomatic patients. The otologist can be alerted to the presence of this vascular variant if middle cranial fossa surgical procedures entailing elevation of the dura are planned to decrease intraoperative bleeding risk.

References

  1. 1.↵
    1. Eicher SA,
    2. Coker NJ,
    3. Alford BR,
    4. et al
    . A comparative study of the fallopian canal at the meatal foramen and labyrinthine segment in young children and adults. Arch Otolaryngol Head Neck Surg 1990; 116: 1030–35
    CrossRefPubMed
  2. 2.↵
    1. Nakashima S,
    2. Sando I,
    3. Takahashi H,
    4. et al
    . Computer-aided 3-D reconstruction and measurement of the facial canal and facial nerve. I. Cross-sectional area and diameter: preliminary report. Laryngoscope 1993; 103: 1150–56
    PubMed
  3. 3.↵
    1. Mercier P,
    2. Cronier P,
    3. Mayer B,
    4. et al
    . Microanatomical study of the arterial blood supply of the facial nerve in the ponto-cerebellar angle. Clin Anat 1982; 3: 263–70
    CrossRef
  4. 4.↵
    1. Minatogawa T,
    2. Kumoi T,
    3. Hosomi H,
    4. et al
    . The blood supply of the facial nerve in the human temporal bone. Auris Nasus Larynx 1980; 7: 7–18
    CrossRefPubMed
  5. 5.↵
    1. Nager GT,
    2. Nager N
    . The arteries of the human middle ear, with particular regard to the blood supply of the auditory ossicles. Ann Otol Rhinol Laryngol 1953; 62: 23–49
  6. 6.↵
    1. Silbergleit R,
    2. Quint DJ,
    3. Mehta BA,
    4. et al
    . The persistent stapedial artery. AJNR Am J Neuroradiol 2000; 21: 572–77
    Abstract/FREE Full Text
  7. 7.↵
    1. Robert Y,
    2. Carcasset S,
    3. Rocourt N,
    4. et al
    . Congenital cholesteatoma of the temporal bone: MR findings and comparison with CT. AJNR Am J Neuroradiol 1995; 16: 755–61
    Abstract
  8. 8.↵
    1. Gray BG,
    2. Willinsky RA,
    3. Rutka JA,
    4. et al
    . Spontaneous meningocele, a rare middle ear mass. AJNR Am J Neuroradiol 1995; 16: 203–07
    Abstract
  9. 9.↵
    1. Petrus LV,
    2. Lo WW
    . Spontaneous CSF otorrhea caused by abnormal development of the facial nerve canal. AJNR Am J Neuroradiol 1999; 20: 275–57
    Abstract/FREE Full Text
  10. 10.↵
    1. Falcioni M,
    2. Russo A,
    3. Taibah A,
    4. et al
    . Facial nerve tumors. Otol Neurotol 2003; 24: 942–47
    CrossRefPubMed
  11. 11.↵
    1. Lo WW,
    2. Shelton C,
    3. Waluch V,
    4. et al
    . Intratemporal vascular tumors: detection with CT and MR imaging. Radiology 1989; 171: 445–48
    PubMed
  12. 12.↵
    1. Petrus LV,
    2. Lo WM
    . Primary paraganglioma of the facial nerve canal. AJNR Am J Neuroradiol 1996; 17: 171–74
    Abstract
  13. 13.↵
    1. Ginsberg LE,
    2. De Monte F,
    3. Gillenwater AM
    . Greater superficial petrosal nerve: anatomy and MR findings in perineural tumor spread. AJNR Am J Neuroradiol 1996; 17: 389–93
    Abstract
  14. 14.↵
    1. Effat KG,
    2. Naguib AW
    . Simultaneous leukaemic infiltrate and cholesteatoma in the same temporal bone. J Laryngol Otol 1998; 112: 867–69
    PubMed
  15. 15.↵
    1. Suryanarayanan R,
    2. Dezso A,
    3. Ramsden RT,
    4. et al
    . Metastatic carcinoma mimicking a facial nerve schwannoma: the role of computerized tomography in diagnosis. J Laryngol Otol 2005; 119: 1010–12
    PubMed
  16. 16.↵
    1. Nager GT,
    2. Proctor B
    . The facial canal: normal anatomy, variations and anomalies. II. Anatomical variations and anomalies involving the facial canal. Ann Otol Rhinol Laryngol Suppl 1982; 97: 45–61
    PubMed
  17. 17.↵
    1. Ogawa A,
    2. Sando I
    . Spatial occupancy of vessels and facial nerve in the facial canal. Ann Otol Rhinol Laryngol 1982; 91 (1 pt 1): 14–19
    PubMed
  • Received December 28, 2009.
  • Accepted after revision February 5, 2010.
  • Copyright © American Society of Neuroradiology
View Abstract
PreviousNext
Back to top

In this issue

American Journal of Neuroradiology: 32 (5)
American Journal of Neuroradiology
Vol. 32, Issue 5
1 May 2011
  • Table of Contents
  • Index by author
Advertisement
Print
Download PDF
Email Article

Thank you for your interest in spreading the word on American Journal of Neuroradiology.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
A Venous Cause for Facial Canal Enlargement: Multidetector Row CT Findings and Histopathologic Correlation
(Your Name) has sent you a message from American Journal of Neuroradiology
(Your Name) thought you would like to see the American Journal of Neuroradiology web site.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Citation Tools
A Venous Cause for Facial Canal Enlargement: Multidetector Row CT Findings and Histopathologic Correlation
G. Moonis, K. Mani, J. O'Malley, S. Merchant, H.D. Curtin
American Journal of Neuroradiology May 2011, 32 (5) E83-E84; DOI: 10.3174/ajnr.A2094

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Share
A Venous Cause for Facial Canal Enlargement: Multidetector Row CT Findings and Histopathologic Correlation
G. Moonis, K. Mani, J. O'Malley, S. Merchant, H.D. Curtin
American Journal of Neuroradiology May 2011, 32 (5) E83-E84; DOI: 10.3174/ajnr.A2094
del.icio.us logo Digg logo Reddit logo Twitter logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One
Purchase

Jump to section

  • Article
    • Abstract
    • Abbreviations
    • Case Report
    • Discussion
    • References
  • Figures & Data
  • Info & Metrics
  • References
  • PDF

Related Articles

  • No related articles found.
  • PubMed
  • Google Scholar

Cited By...

  • No citing articles found.
  • Crossref
  • Google Scholar

This article has not yet been cited by articles in journals that are participating in Crossref Cited-by Linking.

More in this TOC Section

  • Atypical Diffusion-Restricted Lesion in 5-Fluorouracil Encephalopathy
  • Multimodal Imaging of Spike Propagation: A Technical Case Report
  • Dural Infantile Hemangioma Masquerading as a Skull Vault Lesion
Show more Case Reports

Similar Articles

Advertisement

News and Updates

  • Lucien Levy Best Research Article Award
  • Thanks to our 2021 Distinguished Reviewers
  • Press Releases

Resources

  • Evidence-Based Medicine Level Guide
  • How to Participate in a Tweet Chat
  • AJNR Podcast Archive
  • Ideas for Publicizing Your Research
  • Librarian Resources
  • Terms and Conditions

Opportunities

  • Share Your Art in Perspectives
  • Get Peer Review Credit from Publons
  • Moderate a Tweet Chat

American Society of Neuroradiology

  • Neurographics
  • ASNR Annual Meeting
  • Fellowship Portal
  • Position Statements

© 2022 by the American Society of Neuroradiology | Print ISSN: 0195-6108 Online ISSN: 1936-959X

Powered by HighWire