An Evaluation of the Surgical Trauma to Intracochlear Structures After Insertion of Cochlear Implant Electrode Arrays: A Comparison by Round Window and Antero-Inferior Cochleostomy Techniques

  • Kapil SikkaEmail author
  • Arvind Kairo
  • Chirom Amit Singh
  • T. S. Roy
  • Sanjeev Lalwani
  • Rakesh Kumar
  • Alok Thakar
  • Suresh C. Sharma
Original Article


To evaluate the extent of intracochlear damage by histologic assessment of cadaveric temporal bones after insertion of cochlear implants by: round window approach and cochleostomy approach. Cochlear implantation was performed by transmastoid facial recess approach in 10 human cadaveric temporal bones. In 5 temporal bones, electrode insertion was acheieved by round window approach and in the remaining 5 bones, by cochleostomy approach. The bones were fixed, decalcified, sectioned and studied histologically. Grading of insertion trauma was assessed. In the round window insertion group, 2 bones had to be excluded from the study: one was damaged during handling with electrode extrusion and another bone did not show any demonstrable identifiable cochlear structure. Out of the 3 temporal bones, a total of 35 sections were examined: 24 demonstrated normal cochlea, 4 had basilar membrane bulging and 7 had fracture of bony spiral lamina. In the cochleostomy group, histology of 2 bones had to be discarded due to lack of any identifiable inner ear structures. Out of the 3 bones studied, 18 sections were examined: only 3 were normal, 4 sections had some bulge in spiral lamina and 11 had fracture of bony spiral lamina. The fracture of spiral lamina and bulge of basement membrane proportion is relatively higher if we perform cochleostomy as compared to round window approach. Therefore, round window insertion is relatively less traumatic as compared to cochleostomy. However, our sample size was very small and a study with a larger sample is required to further validate these findings.


Cochlear implants Round window Electrodes 



Authors sincerely acknowledge the funding received from Research section, AIIMS (Code: A-171) and thank Director, AIIMS, Dean and Subdean, research section, AIIMS.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical Approval

All procedures performed in studies involving cadavers were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.


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Copyright information

© Association of Otolaryngologists of India 2017

Authors and Affiliations

  • Kapil Sikka
    • 1
    Email author
  • Arvind Kairo
    • 1
  • Chirom Amit Singh
    • 1
  • T. S. Roy
    • 2
  • Sanjeev Lalwani
    • 3
  • Rakesh Kumar
    • 1
  • Alok Thakar
    • 1
  • Suresh C. Sharma
    • 1
  1. 1.Department of Otolaryngology, Head and Neck SurgeryAll India Institute of Medical SciencesNew DelhiIndia
  2. 2.Department of AnatomyAll India Institute of Medical SciencesNew DelhiIndia
  3. 3.Department of Forensic MedicineAll India Institute of Medical SciencesNew DelhiIndia

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