Skip to main content Accessibility help

Cochlear orientation: pre-operative evaluation and intra-operative significance

  • S Sharma (a1), M Grover (a1), S N Singh (a1), T Kataria (a1) and R S Lakhawat (a1)...



The study primarily aimed to calculate the orientation of the cochlea pre-operatively, using high-resolution computed tomography of the temporal bone, and predict the ease of electrode insertion.


Pre-operatively, high-resolution computed tomography scans were conducted on children scheduled for cochlear implantation, and two angles, α and β, were calculated. The values of α and β were then correlated with intra-operative difficulty in insertion of the electrode array.


Ninety-six children were included in the study. Of the seven patients who had an α angle of less than 50 degrees, the surgeon experienced difficulties in electrode insertion. However, there were four patients with an α angle of more than 50 degrees for whom the surgeon also experienced difficulties in electrode insertion. In all these patients, the β angle was more than 20 degrees.


Calculation of cochlear orientation and its angle with the surgical axis (α and β) can aid the planning of surgery, particularly with regard to the cochleostomy site and preservation of residual hearing.


Corresponding author

Address for correspondence: Dr Mohnish Grover, Department of Otorhinolaryngology and Head Neck Surgery, SMS Medical College and Hospital, Jaipur – 302004, Rajasthan, India E-mail:


Hide All

Dr M Grover takes responsibility for the integrity of the content of the paper



Hide All
1Spoor, CF. The Comparative Morphology and Phylogeny of the Human Bony Labyrinth. Utrecht: Utrecht University, 1993
2Jeffery, N, Spoor, F. Prenatal growth and development of the modern human labyrinth. J Anat 2004;204:7192
3Lloyd, SK, Kasbekar, AV, Kenway, B, Prevost, T, Hockman, M, Beale, T et al. Developmental changes in cochlear orientation – implications for cochlear implantation. Otol Neurotol 2010;31:902–7
4Kennedy, DW. Multichannel intracochlear electrodes: mechanism of insertion trauma. Laryngoscope 1987;97:42–9
5Li, PM, Wang, H, Northrop, C, Merchant, SN, Nadol, JB Jr. Anatomy of the round window and hook region of the cochlea with implications for cochlear implantation and other endocochlear surgical procedures. Otol Neurotol 2007;28:641–8
6Briggs, RJ, Tykocinski, M, Stidham, K, Roberson, JB. Cochleostomy site: implications for electrode placement and hearing preservation. Acta Otolaryngol 2005;125:870–6
7Adunka, O, Unkelbach, MH, Mack, M, Hambek, M, Gstoettner, W, Kiefer, J. Cochlear implantation via the round window membrane minimizes trauma to cochlear structures: a histologically controlled insertion study. Acta Otolaryngol 2004;124:807–12
8Balkany, TJ, Cohen, NL, Gantz, BJ. Surgical technique for the CLARION cochlear implant. Ann Otol Rhinol Laryngol Suppl 1999;177:2730


Related content

Powered by UNSILO

Cochlear orientation: pre-operative evaluation and intra-operative significance

  • S Sharma (a1), M Grover (a1), S N Singh (a1), T Kataria (a1) and R S Lakhawat (a1)...


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.