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Comparative evaluation of round window niche accessibility pre-operatively on high-resolution computed tomography of the temporal bone with intra-operative findings

  • R Sharma (a1), R Meher (a1), J C Passey (a1), J Kumar (a2), A Gupta (a1) and S Kharbanda (a3)...



To compare round window niche visibility as seen endoscopically during cochlear implant surgery with pre-operative high-resolution computed tomography of the temporal bone.


Nineteen patients scheduled for cochlear implantation, aged 2–20 years, were referred for computed tomography from October 2016 to March 2018. Angles were measured between the lines passing through the mid-sagittal plane and cochlear basal turn on the scans. Endoscopic round window niche visibility during posterior tympanotomy was categorised as: type I = 100 per cent, type IIa = more than 50 per cent, type IIb = less than 50 per cent or type III = 0 per cent. Pre-operative computed tomography measurements were used to predict round window niche visibility before surgery and correlated with intra-operative findings.


The mean (range) of pre-operative angles on computed tomography for endoscopic visibility types I, IIa and IIb, were 64.06° (61.16–69.37°), 63.81° (58.61–71.35°) and 56.48° (50.37–59.05°), respectively, a statistically significant finding (one-way analysis of variance test, p = 0.016).


Pre-operative high-resolution temporal bone computed tomography measurements are useful in predicting round window niche visualisation as viewed endoscopically during posterior tympanotomy. The angle was more acute in type IIb compared to type I.


Corresponding author

Author for correspondence: Dr Raman Sharma, Department of Otorhinolaryngology, Maulana Azad Medical College and Associated Lok Nayak Hospital, Govind Ballabh Pant Institute of Postgraduate Medical Education and Research (‘GIPMER’) Hospitals and Guru Nanak Eye Centre, University of Delhi, New Delhi, India 110002 E-mail:


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Dr R Sharma takes responsibility for the integrity of the content of the paper



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1Jeffery, N, Spoor, F. Prenatal growth and development of the modern human labyrinth. J Anat 2004;204:7192
2Li, PM, Wang, H, Northrop, C. 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
3Pendem, SK, Rangasami, R, Arunachalam, RK. HRCT correlation with round window identification during cochlear implantation in children. J Clin Imaging Sci 2014;4:70
4Leong, AC, Jiang, D. Evaluation of round window accessibility to cochlear implant insertion. Eur Arch Otorhinolaryngol 2013;270:1237–42
5Karatas, E, Aud, MD, Baglam, T. Intraoperative electrically evoked stapedius reflex thresholds in children undergone cochlear implantation: round window and cochleostomy approaches. Int J Pediatr Otorhinolaryngol 2011;75:1123–6
6Roland, PS, Wright, CG, Isaacson, B. Cochlear implant electrode insertion: the round window revisited. Laryngoscope 2007;117:1397–402
7Francis, HW, Niparko, JK. Cochlear implantation update. Pediatr Clin North Am 2003;50:341–61
8Takahashi, H, Sando, I. Computer-aided 3-D temporal bone anatomy for cochlear implant surgery. Laryngoscope 1990;100:417–21
9Shapira, Y, Eshraghi, AA, Balkany, TJ. The perceived angle of the round window affects electrode insertion trauma in round window insertion – an anatomical study. Acta Otolaryngol 2011;131:284–9
10Pau, HW, Just, T. Noise exposure of the inner ear during drilling a cochleostomy for cochlear implantation. Laryngoscope 2007;117:535–40
11Briggs, RJ, Tycocinski, M, Stidham, K. Cochleostomy site: implications for electrode placement and hearing preservation. Acta Otolaryngol 2005;125:870–6
12Paprocki, A, Biskup, B, Kozłowska, K. The topographical anatomy of round window and related structures for the purpose of cochlear implant surgery. Folia Morphol (Warsz) 2004;63:309–12
13Lloyd, SK, Kasbekar, AV, Kenway, B. Developmental changes in cochlear orientation – implications for cochlear implantation. Otol Neurotol 2010;31:902–7
14Chen, K, Lyu, H, Xie, Y, Yang, L, Zhang, T, Dai, P. Morphological characteristics of round window niche in congenital aural atresia and stenosis patients. J Comput Assist Tomogr 2015;39:547–51
15Bettman, RH, Appelman, AM, van Olphen, AF. Cochlear orientation and dimensions of the facial recess in cochlear implantation. J Otorhinolaryngol Relat Spec 2003;65:353–8
16Adunka, O, Unkelbach, MH, Mack, M. Cochlear implantation via the round window membrane minimizes trauma to cochlear structures: a histologically controlled insertion study. Acta Otolaryngol 2004;124:807–12


Comparative evaluation of round window niche accessibility pre-operatively on high-resolution computed tomography of the temporal bone with intra-operative findings

  • R Sharma (a1), R Meher (a1), J C Passey (a1), J Kumar (a2), A Gupta (a1) and S Kharbanda (a3)...


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