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
  • 41 Downloads

Abstract

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.

Keywords

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

Notes

Acknowledgements

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.

References

  1. 1.
    Jeffery N, Spoor F (2004) Prenatal growth and development of the modern human labyrinth. J Anat 204(2):71–92CrossRefPubMedPubMedCentralGoogle Scholar
  2. 2.
    Erixon E, Hogstorp H, Wadin K, Rask-Andersen H (2009) Variational anatomy of the human cochlea: implications for cochlear implantation. Otol Neurotol 30(1):14–22CrossRefPubMedGoogle Scholar
  3. 3.
    Lloyd SKW, Kasbekar AV, Kenway B et al (2010) Developmental changes in cochlear orientation—implications for cochlear implantation. Otol Neurotol 31:902–907CrossRefPubMedGoogle Scholar
  4. 4.
    Theodore R, Rackan Mc, Fitsum A et al (2012) Comparision of cochlear implant relevant anatomy in children versus adults. Otol Neurotol 33:328–334CrossRefGoogle Scholar
  5. 5.
    Bast TH (1942) Development of the otic capsule. VI. Histological changes and variations in the growing bony capsule of the vestibule and cochlea. Ann Otol Rhinol Laryngol 51:343–357CrossRefGoogle Scholar
  6. 6.
    Siebenmann F (1890) Die Korosions-Anatomie Des Knochernan Labyrinthes Des Menschlichen Ohres. Bergmann, J.F, WiesbadenGoogle Scholar
  7. 7.
    Schonemann A (1906) Schlafenbein und Schadelbasis, eine anatomischotiatrische Studie. N Denkschr algem Schweizer Gesellsch gesamt Naturwiss 40:95–160Google Scholar
  8. 8.
    Hyrtl J (1845) Vergleichend-Anatomische Untersuchungen Uber das Innere Gehororgan Des Menschen und der Saugethiere. Prague, Ehrlich, F.Google Scholar
  9. 9.
    Sercer A, Krmpotic J (1958) Further contributions to the development of the labyrinthine capsule. J Laryngol Otol 72:688–698CrossRefPubMedGoogle Scholar
  10. 10.
    Zehnder AF, Kristiansen AG, Adams JC et al (2006) Osteoprotegrin knockout mice demonstrate abnormal remodeling of the otic capsule and progressive hearing loss. Laryngoscope 116:201–206CrossRefPubMedPubMedCentralGoogle Scholar
  11. 11.
    Farkas LG, Posnick JC, Hreczko TM (1992) Anthropometric growth study of the head. Cleft Palate Craniofac J 29:303–308CrossRefPubMedGoogle Scholar
  12. 12.
    Richtsmeier JT, Cheverud JM (1986) Finite element scaling analysis of human craniofacial growth. J Craniofac Genet Dev Biol 6:289–323PubMedGoogle Scholar
  13. 13.
    Eby TL, Nadol JB Jr (1986) Postnatal growth of the human temporal bone. Implications for cochlear implants in children. Ann Otol Rhinol Laryngol 95:356–364CrossRefPubMedGoogle Scholar
  14. 14.
    Paprocki A, Biskup B, Kozlowska K et al (2004) The topographical anatomy of the round window and related structures for the purpose of cochlear implant surgery. Folia Morphol (Warsz) 63(3):309–312Google Scholar
  15. 15.
    Stjernholm C (2003) Aspects of temporal bone anatomy and pathology in conjunction with cochlear implant surgery. Acta Radiol 44(Suppl 430):2–15CrossRefGoogle Scholar
  16. 16.
    Seicshnaydre MA, Johnson MH, Hasenstab MS, Williams GH (1992) Cochlear implants in children: reliability of computed tomography. Otolaryngol Head Neck Surg 107(3):410–417CrossRefPubMedGoogle Scholar
  17. 17.
    Nikolopoulos TP, O’Donoghue GM, Robinson KL et al (1997) Preoperative radiologic evaluation in cochlear implantation. Am J Otol 18(6 Suppl):S73–S74PubMedGoogle Scholar
  18. 18.
    Verbist BM, Joemai RM, Briaire JJ et al (2010) Cochlear coordinates in regard to cochlear implantation: a clinically individually applicable 3 dimensional CT-based method. Otol Neurotol 31(5):738–744CrossRefPubMedGoogle Scholar
  19. 19.
    Martinez-Monedero R, Niparko JK et al (2011) Cochlear coiling pattern and orientation differences in cochlear implant candidates. Otol Neurotol 32(7):1086–1093CrossRefPubMedGoogle Scholar
  20. 20.
    Escude B, James C, Deguine O et al (2006) The size of the cochlea and predictions of insertion depth angles for cochlear implant electrodes. Audiol Neurotol 11(1 Suppl):27–33CrossRefGoogle Scholar

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

Personalised recommendations