Skip to main content
Log in

Surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation based on three-dimensional reconstructed temporal bone CT images

  • Original Article
  • Published:
Surgical and Radiologic Anatomy Aims and scope Submit manuscript



In this study, we evaluated the surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation (CI).

Materials and methods

Twenty computed tomography (CT) images of the temporal bone from patients aged between 20 and 60 years were selected. The inclusion criterion was a radiologically normal temporal bone CT scan. Three-dimensional (3D) reconstructed images were obtained using high-resolution axial temporal bone CT scans. Eight points were used to evaluate the surgical anatomy of the posterior tympanotomy and cochleostomy. The length of lines between the points and the angles between the lines were measured.


The mean length of line AB (superior-inferior length of the posterior tympanotomy for CI) was 6.48 ± 0.26 mm, while line AC (width of the chorda tympani and facial nerves) was 3.60 ± 0.2 mm. The mean angle of ABC (angle at which the chorda tympani nerve branched from the facial nerve) was 18.40° ± 1.05°. The mean length of line AD (distance from the facial ridge to the point of cochleostomy) was 9.58 ± 0.47 mm.


3D imaging of the facial recess and round window can be used to identify the facial recess before surgery. This may help to avoid injury to the chorda tympani nerve during posterior tympanotomy, and make it easier to insert the electrode array during CI by creating a large enough posterior tympanotomy to avoid injury to the facial nerve, which can cause immediate or delayed facial palsy.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4

Similar content being viewed by others


  1. Adunka OF, Radeloff A, Gstoettner WK, Pillsbury HC, Buchman CA (2007) Scala tympani cochleostomy II: topography and histology. Laryngoscope 117:2195–2200

    Article  PubMed  Google Scholar 

  2. Banfai P, Hortmann G, Kubik S, Wustrow F (1979) Projection of the spiral cochlear canal on the medial wall of the tympanic cavity with regard to the cochlear implant. Scand Audiol Suppl 11:157–170

    PubMed  CAS  Google Scholar 

  3. Briggs RJ, Tykocinski M, Stidham K, Roberson JB (2005) Cochleostomy site: implications for electrode placement and hearing preservation. Acta Otolaryngol 125:870–876

    Article  PubMed  Google Scholar 

  4. Calli C, Pinar E, Oncel S, Tatar B, Tuncbilek MA (2010) Measurements of the facial recess anatomy: implications for sparing the facial nerve and chorda tympani during posterior tympanotomy. Ear Nose Throat J 89:490–494

    PubMed  Google Scholar 

  5. Eby TL (1996) Development of the facial recess: Implications for cochlear implantation. Laryngoscope 106(5[2] suppl. 80):1–7

    Article  PubMed  CAS  Google Scholar 

  6. Fayad JN, Wanna GB, Micheletto JN, Parisier SC (2003) Facial nerve paralysis following cochlear implant surgery. Laryngoscope 113:1344–1346

    Article  PubMed  Google Scholar 

  7. Gibson D, Gluth MB, Whyte A (2012) Rotation of the osseous spiral laminar from the hook region along the basal turn of the cochlea: results of a magnetic resonance image anatomical study using high-resolution DRIVE sequences. Surg Radiol Anat 34:781–785

    Article  PubMed  Google Scholar 

  8. Hamamoto M, Murakami G, Kataura A (2000) Topographical relationships among the facial nerve, chorda tympani nerve and round window with special reference to the approach route for cochlear implant surgery. Clin Anat 13(4):251–256

    Article  PubMed  CAS  Google Scholar 

  9. Hara M, Takahashi H, Kanda Y (2012) The usefulness of reconstructed 3D images in surgical planning for cochlear implantation in a malformed ear with an abnormal course of the facial nerve. Clin Exp Otolaryngol 5(Supp 5):S48–S52

    Google Scholar 

  10. Li PM, Wang H, Northrop C, Merchant SN, Nadol JB Jr (2007) Anatomy of the round window and hook region of the cochlear with implications for cochlear implantation and other endocochlear surgical procedures. Otol Neurotol 28(5):641–648

    Article  PubMed  CAS  Google Scholar 

  11. Mcmanus LJ, Dawes PJD, Stringer MD (2011) Clinical anatomy of the chorda tympani: a systematic review. J Laryngol Otol 125:1101–1108

    Article  PubMed  CAS  Google Scholar 

  12. Ulla MB, Vazquez F, Pumar JM, Rio M, Romero G (2009) Oblique multiplanar reformation in multislice temporal bone CT. Surg Radiol Anat 31:475–479

    Article  Google Scholar 

Download references

Conflict of interest

The authors declare that they have no conflict of interest.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Beomcho Jun.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Jeon, EJ., Jun, B., Song, JN. et al. Surgical and radiologic anatomy of a cochleostomy produced via posterior tympanotomy for cochlear implantation based on three-dimensional reconstructed temporal bone CT images. Surg Radiol Anat 35, 471–475 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: