Radiological Evaluation of Cochlear Orientation and Its Implications in Cochlear Implantation

  • Avvaru Satya Kiran
  • Ajoy Mathew Varghese
  • Aparna Irodi
  • Anjali Lepcha
  • John Mathew
  • Visalakshi Jeyaseelan
Original Article


To test whether there are variations in cochlear orientation with respect to age and sex, and its relevance in cochlear implant surgery. Implant otologists rely upon the anatomic landmarks including the facial recess and round window niche and round window membrane for accessibility and placement of electrode array into scala tympani of basal turn of cochlea. Anecdotally, surgeons note variations in cochlear orientation with respect to age. Cochlear orientation studied radiologically by pre-operative CT scan of temporal bone can guide a Surgeon’s approach to cochlear implantation. To investigate the changes in cochlear orientation with respect to age and sex; and its relevance in cochlear implantation. A retrospective analytical study was performed on CT scans of temporal bones in patients (of our hospital from July 2013 to January 2015 i.e. for a period of 18 months) with no congenital or radiological abnormalities of cochlea. The basal turn angulations of cochlea varied with age and majority of change occurred during early age. The basal turn angulations of cochlea in difficult situations during cochlear implantation were correlated with the data. There is a significant variation in cochlear orientation as measured radiologically by basal turn angulations relative to midsagittal plane. The more obtuse and acute basal turn angulations have implications like difficulty in cochleostomy and electrode placement during cochlear implantation.


Cochlear orientation Basal turn angulations Radiological orientation of cochlea Cochlear implant surgery Cochleostomy and Round window insertion 



The authors thank the subjects and the staff in the department of Radiology and ENT at Christian Medical College, for all their assistance and support. This article was derived during Post doctoral fellowship in Implant Otology at Christian Medical College, Vellore, India.

Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical Approval

The above study was approved by Institutional Review Board (IRB) of Christian Medical College and the consent was waived because the High Resolution CT scans of the temporal bones were done for various reasons (not just for study purpose and did not financially impact the study population), from which the necessary data was extracted from radiology department.


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Copyright information

© Association of Otolaryngologists of India 2017

Authors and Affiliations

  1. 1.HyderabadIndia
  2. 2.Department of E.N.T.Christian Medical College and HospitalVelloreIndia
  3. 3.Department of RadiologyChristian Medical College and HospitalVelloreIndia
  4. 4.Department of BiostatisticsChristian Medical College and HospitalVelloreIndia

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