Surgical approach to the facial recess influences the acceptable trajectory of cochlear implantation electrodes



To provide practical guidance to the operative surgeon by mapping the location, where acceptable straight-line virtual cochlear implant electrode trajectories intersect the facial recess. In addition, to investigate the influence of facial recess preparation, virtual electrode width and surgical approach to the cochlea on these available trajectories.


The study was performed on imaging data from eight cadaveric temporal bones within the University of Melbourne Virtual Reality (VR) Temporal Bone Surgery Simulator. The facial recess was opened to varying degrees, and acceptable trajectory vectors with varying diameters were calculated for electrode insertions via cochleostomy or round window membrane (RWM). The percentage of acceptable insertion vectors through each location of the facial recess was visually represented using heatmaps.


Seven of the eight bones allowed for acceptable vector trajectories via both cochleostomy and RWM approaches. These acceptable trajectories were more likely to lie superiorly within the facial recess for insertion via the round window, and inferiorly for insertion via cochleostomy. Cochleostomy insertions required a greater degree of preparation and skeletonisation of the junction of the facial nerve and chorda tympani within the facial recess. The width of the virtual electrode had only marginal impact on the availability of acceptable trajectories. Heatmaps emphasised the intimate relationship the acceptable trajectories have with the facial nerve and chorda tympani.


These findings highlight the differences in the acceptable straight-line trajectories for electrodes when implanted via the round window or cochleostomy. There were notable exceptions to both surgical approaches, likely explained by the variation of hook region anatomy. The methodology used in this study holds promise for translation to patient specific surgical planning.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5

Availability of data and material

On contact of corresponding author.

Code availability

On contact of corresponding author.


  1. 1.

    Santa Maria PL, Gluth MB, Yuan Y, Atlas MD, Blevins NH (2014) Hearing preservation surgery for cochlear implantation: a meta-analysis. Otol Neurotol 35(10):e256–e269

    Article  Google Scholar 

  2. 2.

    Adunka OF, Radeloff A, Gstoettner WK, Pillsbury HC, Buchman CA (2007) Scala tympani cochleostomy II: topography and histology. Laryngoscope 117(12):2195–2200

    Article  Google Scholar 

  3. 3.

    Adunka O, Gstoettner W, Hambek M, Unkelbach MH, Radeloff A, Kiefer J (2005) Preservation of basal inner ear structures in cochlear implantation. ORL 66(6):306–312

    Article  Google Scholar 

  4. 4.

    Gstoettner W, Kiefer J, Baumgartner W-D, Pok S, Peters S, Adunka O (2004) Hearing preservation in cochlear implantation for electric acoustic stimulation. Acta Otolaryngol 124(4):348–352

    Article  Google Scholar 

  5. 5.

    Meshik X, Holden TA, Chole RA, Hullar TE (2010) Optimal cochlear implant insertion vectors. Otol Neurotol 31(1):58

    Article  Google Scholar 

  6. 6.

    Breinbauer HA, Praetorius M (2015) Variability of an ideal insertion vector for cochlear implantation. Otol Neurotol 36(4):610–617

    Article  Google Scholar 

  7. 7.

    Deshpande AS, Todd NW (2016) Implanting straight into cochlea risks the facial nerve: a Cartesian coordinate study. Surg Radiol Anat 38(10):1153–1159

    Article  Google Scholar 

  8. 8.

    Shapira Y, Eshraghi AA, Balkany TJ (2011) The perceived angle of the round window affects electrode insertion trauma in round window insertion–an anatomical study. Acta Otolaryngol 131(3):284–289

    Article  Google Scholar 

  9. 9.

    Zhou L, Friedmann DR, Treaba C, Peng R, Roland JT (2015) Does cochleostomy location influence electrode trajectory and intracochlear trauma? Laryngoscope 125(4):966–971

    Article  Google Scholar 

  10. 10.

    Briggs RJ, Tykocinski M, Lazsig R, Aschendorff A, Lenarz T, Stöver T et al (2011) Development and evaluation of the modiolar research array–multi-centre collaborative study in human temporal bones. Cochlear Implants Int 12(3):129–139

    Article  Google Scholar 

  11. 11.

    Risi F (2018) Considerations and rationale for cochlear implant electrode design-past, present and future. J Int Adv Otol 14(3):382

    Article  Google Scholar 

  12. 12.

    Caversaccio M, Gavaghan K, Wimmer W, Williamson T, Ansò J, Mantokoudis G et al (2017) Robotic cochlear implantation: surgical procedure and first clinical experience. Acta Otolaryngol 137(4):447–454

    Article  Google Scholar 

  13. 13.

    Wang Z, Li J, Wu Y, Zhu R, Wang B, Zhao K (2020) Optimal path generation in scala tympani and path planning for robotic cochlear implant of perimodiolar electrode. Proc Inst Mech Eng H J Eng Med 0954411920908969

  14. 14.

    Rau TS, Kreul D, Lexow J, Hügl S, Zuniga MG, Lenarz T et al (2019) Characterizing the size of the target region for atraumatic opening of the cochlea through the facial recess. Comput Med Imaging Graph 77:101655

    Article  Google Scholar 

  15. 15.

    Wimmer W, Venail F, Williamson T, Akkari M, Gerber N, Weber S et al (2014) Semiautomatic cochleostomy target and insertion trajectory planning for minimally invasive cochlear implantation. BioMed Res Int 2014:596498

  16. 16.

    Labadie RF, Balachandran R, Noble JH, Blachon GS, Mitchell JE, Reda FA et al (2014) Minimally invasive image-guided cochlear implantation surgery: first report of clinical implementation. Laryngoscope 124(8):1915–1922

    Article  Google Scholar 

  17. 17.

    Torres R, Kazmitcheff G, Bernardeschi D, De Seta D, Bensimon JL, Ferrary E et al (2015) Variability of the mental representation of the cochlear anatomy during cochlear implantation. Eur Arch Oto-Rhino-Laryngol 273:2009–2018

    Article  Google Scholar 

  18. 18.

    Lovato A, de Filippis C (2019) Utility of OTOPLAN reconstructed images for surgical planning of cochlear implantation in a case of post-meningitis ossification. Otol Neurotol 40(1):e60–e61

    Article  Google Scholar 

  19. 19.

    Pirlich M, Tittmann M, Franz D, Dietz A, Hofer M (2017) An observational, prospective study to evaluate the preoperative planning tool “CI-Wizard” for cochlear implant surgery. Eur Arch Otorhinolaryngol 274(2):685–694

    Article  Google Scholar 

  20. 20.

    Finley CC, Skinner MW (2008) Role of electrode placement as a contributor to variability in cochlear implant outcomes. Otol Neurotol 29(7):920

    Article  Google Scholar 

  21. 21.

    Briggs RJ, Tykocinski M, Stidham K, Roberson JB (2005) Cochleostomy site: implications for electrode placement and hearing preservation. Acta Otolaryngol 125(8):870–876

    Article  Google Scholar 

  22. 22.

    Adunka OF, Buchman CA (2007) Scala tympani cochleostomy I: results of a survey. Laryngoscope 117(12):2187–2194

    Article  Google Scholar 

  23. 23.

    Barhoum F, Hoppe U, Liebscher T, Iro H, Hornung J (2019) Hearing preservation and speech perception–experiences with the slim modiolar array CI532 (Cochlear®). Laryngo-Rhino-Otol 98(S02):10980

    Google Scholar 

  24. 24.

    Gomez Serrano M, Patel S, Harris R, Selvadurai D (2019) Initial surgical and clinical experience with the nucleus CI532 slim modiolar electrode in the UK. Cochlear Implants Int 20(4):207–216

    Article  Google Scholar 

  25. 25.

    Riemann N, Ludwig S, Hans S, Arnolds J, Lang S, Arweiler-Harbeck D (2019) Residual hearing in cochlea implant patients with CI532 electrode from Cochlear®. Laryngorhinootologie 98(S02):10853

    Google Scholar 

  26. 26.

    Zhao YC, Kennedy G, Hall R, O’Leary S (2010) Differentiating levels of surgical experience on a virtual reality temporal bone simulator. Otolaryngol Head Neck Surg 143(5):S30–S35

    Article  Google Scholar 

  27. 27.

    Zhao YC, Kennedy G, Yukawa K, Pyman B, O’Leary S (2011) Can virtual reality simulator be used as a training aid to improve cadaver temporal bone dissection? Results of a randomized blinded control trial. Laryngoscope 121(4):831–837

    Article  Google Scholar 

  28. 28.

    Wijewickrema S, Ioannou I, Kennedy G (eds) (2013) Adaptation of marching cubes for the simulation of material removal from segmented volume data. Computer-Based Medical Systems (CBMS), 2013 IEEE 26th International Symposium on. IEEE

  29. 29.

    Briggs RJ, Tykocinski M, Xu J, Risi F, Svehla M, Cowan R et al (2006) Comparison of round window and cochleostomy approaches with a prototype hearing preservation electrode. Audiol Neurotol 11(Suppl. 1):42–48

    Article  Google Scholar 

  30. 30.

    Haralick RM, Sternberg SR, Zhuang X (1987) Image analysis using mathematical morphology. IEEE Trans Pattern Anal Mach Intell 4:532–550

    Article  Google Scholar 

  31. 31.

    Martinez-Monedero R, Niparko JK, Aygun N (2011) Cochlear coiling pattern and orientation differences in cochlear implant candidates. Otol Neurotol 32(7):1086–1093

    Article  Google Scholar 

  32. 32.

    Ma X, Wijewickrema S, Zhou Y, Copson B, Bailey J, Kennedy G et al (2017) Simulation for training cochlear implant electrode insertion. Computer-Based Medical Systems (CBMS), 2017 IEEE 30th International Symposium

  33. 33.

    Leong AC, Jiang D, Agger A, Fitzgerald-O’Connor A (2013) Evaluation of round window accessibility to cochlear implant insertion. Eur Arch Oto-Rhino-Laryngol 270(4):1237–1242

    Article  Google Scholar 

  34. 34.

    Adunka OF, Dillon MT, Adunka MC, King ER, Pillsbury HC, Buchman CA (2014) Cochleostomy versus round window insertions: influence on functional outcomes in electric-acoustic stimulation of the auditory system. Otol Neurotol 35(4):613–618

    Article  Google Scholar 

  35. 35.

    Atturo F, Barbara M, Rask-Andersen H (2014) On the anatomy of the ‘hook’’ region of the human cochlea and how it relates to cochlear implantation.’ Audiol Neurotol 19(6):378–385

    Article  Google Scholar 

  36. 36.

    Iseli C, Adunka OF, Buchman CA (2014) Scala tympani cochleostomy survey: a follow-up study. Laryngoscope 124(8):1928–1931

    Article  Google Scholar 

  37. 37.

    Roland JT (2005) Cochlear implant electrode insertion. Oper Tech Otolaryngol Head Neck Surg 16(2):86–92

    Article  Google Scholar 

  38. 38.

    Atturo F, Barbara M, Rask-Andersen H (2014) On the anatomy of the “hook” region of the human cochlea and how it relates to cochlear implantation. Audiol Neurootol 19(6):378–385

    Article  Google Scholar 

  39. 39.

    Erixon E, Högstorp H, Wadin K, Rask-Andersen H (2009) Variational anatomy of the human cochlea: implications for cochlear implantation. Otol Neurotol 30(1):14–22

    Article  Google Scholar 

  40. 40.

    Pelosi S, Noble JH, Dawant BM, Labadie RF (2013) Analysis of inter-subject variations in intracochlear and middle ear surface anatomy for cochlear implantation. Otol Neurotol 34(9):1675–1680

    Article  Google Scholar 

  41. 41.

    Gibson D, Gluth MB, Whyte A, Atlas MD (2012) Rotation of the osseous spiral lamina 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(8):781–785

    Article  Google Scholar 

  42. 42.

    Tang J, Tang X, Li Z, Liu Y, Tan S, Li H et al (2018) Anatomical variations of the human cochlea determined from micro-CT and high-resolution CT imaging and reconstruction. Anatomical Rec 301(6):1086–1095

    Article  Google Scholar 

  43. 43.

    Torres R, Drouillard M, De Seta D, Bensimon J-L, Ferrary E, Sterkers O et al (2018) Cochlear implant insertion axis into the basal turn: a critical factor in electrode array translocation. Otol Neurotol 39(2):168–176

    Article  Google Scholar 

  44. 44.

    Roland PS, Wright CG (2006) Surgical aspects of cochlear implantation: mechanisms of insertional trauma. Cochlear Brainstem Implants 64:11–30

  45. 45.

    Schneider D, Stenin I, Ansó J, Hermann J, Mueller F, Braga GPB et al (2019) Robotic cochlear implantation: feasibility of a multiport approach in an ex vivo model. Eur Arch Otorhinolaryngol 276(5):1283–1289

    Article  Google Scholar 

  46. 46.

    Goury O, Nguyen Y, Torres R, Dequidt J, Duriez C (eds) (2016) Numerical simulation of cochlear-implant surgery: towards patient-specific planning. In: International conference on medical image computing and computer-assisted intervention, Springer

Download references


No funding was received to assist with the preparation of this manuscript. The authors have no relevant financial or non-financial interests to disclose.

Author information




All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Bridget Copson, Sudanthi Wijewickrema, Xingjun Ma, Yun Zhou, Jean-Marc Gerard and Stephen O’Leary. The first draft of the manuscript was written by Bridget Copson and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Bridget Copson.

Ethics declarations

Conflicts of interest

The authors have no conflicts of interest to disclose.

Ethical approval

Ethical approval was given by the Royal Victorian Eye and Ear Hospital Ethics Committee (17-1313H).

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary Information

Below is the link to the electronic supplementary material.

Supplementary file1 Percentage of available trajectories via cochleostomy in various stages of facial recess preparation, as compared to anatomic facial recess preparation. The diameter of the virtual electrode is 0.8mm. (TIFF 98467 KB)

Supplementary file2 Three dimensional rendered segmentations of Bones 2, 4, 6, 8 in orthogonal views showing the variation in hook region anatomy. Cochlear = magenta, RWM = teal, OSL/basilar membrane/spiral ligament = blue, facial nerve = green, chorda tympani = blue, semicircular canals and vestibule = cream, incus = yellow, malleus = aqua, stapes = blue, stapedius tendon = orange, dura = sand, sigmoid = light teal. (TIFF 2446 KB)

Supplementary file3 (TIFF 2003 KB)

Supplementary file4 (TIFF 1833 KB)

Supplementary file5 (TIFF 1927 KB)

Supplementary file6 (TIFF 2228 KB)

Supplementary file7 (TIFF 1800 KB)

Supplementary file8 (TIFF 1732 KB)

Supplementary file9 (TIFF 1526 KB)

Supplementary file10 Bone 5 stage 1 of facial recess exposure. Light grey area shows the facial recess region which is the anatomic region of the facial recess. (TIFF 747 KB)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Copson, B., Wijewickrema, S., Ma, X. et al. Surgical approach to the facial recess influences the acceptable trajectory of cochlear implantation electrodes. Eur Arch Otorhinolaryngol (2021).

Download citation


  • Cochlear implant
  • Electrode insertion vector
  • Electrode insertion trajectory
  • Optimal facial recess
  • Optimal insertion vector
  • Temporal bone surgery
  • Surgical training