Measuring cochlear duct length in North Indian population: a detailed study

Authors

  • Sumit Maheshwari Department of ENT, Mehrotra ENT Hospital, Kanpur, Uttar Pradesh, India
  • Neeraj Sainy Department of ENT, Mehrotra ENT Hospital, Kanpur, Uttar Pradesh, India
  • Neha Gupta Department of ENT, Mehrotra ENT Hospital, Kanpur, Uttar Pradesh, India
  • Rohit Mehrotra Department of ENT, Mehrotra ENT Hospital, Kanpur, Uttar Pradesh, India
  • Monika Mehrotra Department of Radiology, Mehrotra ENT Hospital, Kanpur, Uttar Pradesh, India
  • Ujjwal Mehrotra Department of ENT, Mehrotra ENT Hospital, Kanpur, Uttar Pradesh, India

DOI:

https://doi.org/10.18203/issn.2454-5929.ijohns20232521

Keywords:

Cochlear duct length, Cochlear implantation, High-resolution computed tomography

Abstract

Background: The cochlea is a shell-like structure of the inner ear which is comprised of two canals (the Scala vestibule and the Scala tympani) and the Organ of Corti. Cochlear duct length is defined as the length of the scala media as measured from the middle of the round window to the helicotrema. Preoperative measurement of CDL is significantly important if the desired intracochlear electrode array placement is required.

Methods: This retrospective study was done in Mehrotra ENT Hospital, Kanpur, India, which is a tertiary care hospital and referral centre for cochlear implants. We included 800 patients (400 males and 400 females) in the study with bilateral hearing loss who were evaluated for cochlear implantation. HRCT temporal bone of these patients were analyzed and a variable A was measured.

Results: Our study included 800 patients, Mean of distance A value for male children is 7.94mm (range 7.0-9.2mm). Mean of distance A value for female children is 7.72mm (range 6.95-8.8mm). So the overall average is 7.83mm. We calculated cochlear duct length using the formula, CDL=4.16A-3.98. The mean cochlear duct length was 28.6mm with a range from 24.9-34.3mm.

Conclusions: Our study is one of the most detailed large (800 cases) study of cochlear duct length in the North Indian population. Our results suggest that an average smaller cochlear duct length in our geographical area is a significant finding in the understanding of cochlear anatomy and physiology. It will have great importance on the insertion depth in cochlear implantation.

References

Alexiades G, Dhanasingh A, Jolly C. Method to estimate the complete and Two-turn cochlear duct length. Otol Neurotol. 2014;36:904-7.

Escudé B, James C, Deguine O, Cochard N, Eter E, Fraysse B. The size of the cochlea and predictions of insertion depth angles for cochlear implant electrodes. Audiol Neurotol. 2006;11(1):27-33.

Blake S. Wilson, Michael F. Dorman, The design of cochlear implants. In: John K.Niparko, Editor. Cochlear Implants: Principles & Practices. 2nd ed. Philadelphia: Lippincott Williams & Wilkins; 2009:97.

Takagi A, Sando I. Computer-aided three-dimensional reconstruction: a method of measuring temporal bone structures including the length of the cochlea. Ann Otol Rhinol Laryngol. 1989;98(7):515-22.

Würfel W, Lanfermann H, Lenarz T, Majdani O. Cochlear length determination using Cone Beam Computed Tomography in a clinical setting. Hear Res. 2014;316:65-72.

Greenwood DD. A cochlear frequency-position function for several species 29 years later. J Acous Soc Am. 1990;87(6):2592-605.

Von Bekesy G. Experiments in hearing. USA: Mc Graw Hill; 1960.

Hardy M. The length of the organ of Corti in man. Am J Anat. 1938;62:291-311.

Bredberg G. Cellular pattern and nerve supply of the human organ of Corti. Acta Otolaryngol. 1968;236:1.

Finley CC, HoldenTA, Holden LK. Role of electrode placement as a contributor to variability in cochlear implant outcomes. Otol Neurotol. 2008;29(07):920-8.

Meng J, Li S, Zhang F, Li Q, Qin Z. Cochlear size and shape variability and implications in cochlear implantation surgery. Otol Neurotol. 2016;37(9): 1307-13.

Ulehlová L, Voldrich L, Janisch R. Correlative study of sensory cell density and cochlear length in humans. Hear Res. 1987;28(2):149-51.

Sato H, Sando I, Takahashi H. Sexual dimorphism and development of the human cochlea. Computer 3-D measurement. Acta Otolaryngol. 1991;111(6):1037-40.

Ketten DR, Skinner MW, Wang G, Vannier MW, Gates GA, Elly JN. In vivo measures of cochlear length and insertion depth of nucleus cochlear implant electrode arrays. Ann Otol Rhinol Laryngol. 1998; 107:1-16.

Pelliccia P, Venail F, Bonafé A. Cochlea size variability and implications in clinical practice. Acta Otorhinolaryngol Ital. 2014;34(1):42-9.

Grover M, Sharma S, Singh SN, Kataria T, Lakhawat RS, Sharma MP. Measuring cochlear duct length in Asian population: worth giving a thought!. Eur Arch Otorhinolaryngol. 2018;275(03):725-8.

Mori MC, Chang KW. CT analysis demonstrates that cochlear height does not change with age. AJNR Am J Neuroradiol. 2012; 33(1):119-23.

Thong JF, Low D, Tham A, Liew C, Tan TY, Yuen HW. Cochlear duct length-one size fits all? Am J Otolaryngol. 2017;38(02): 218-21.

Downloads

Published

2023-08-24

Issue

Section

Original Research Articles