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How to predict cochlear length before cochlear implantation surgery
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Otolaryngology and Head and Neck Surgery.
2013 (English)In: Acta Oto-Laryngologica, ISSN 0001-6489, Vol. 133, no 12, 1258-1265 p.Article in journal (Refereed) Published
Abstract [en]

Conclusions: The basal turn diameter of the human cochlea predicts the outer wall length of the basal and two first turns relatively well but there was less correlation for the total cochlear length. The linear regression graph defines the length of the basal turn within an error of +/- 1 mm and could be used clinically to distinguish small and large cochleae. Objective: The human cochlea varies in size. The preoperative assessment of cochlear length can be crucial for non-traumatic electrode insertion and hearing preservation. In this study, we estimated the external cochlear wall length by assessing the basal turn diameter. Methods: A total of 51 non-selected, human inner ear moulds were analysed. A line was drawn from the midpoint of the round window through the cochlear mid-portion to the opposite side (A) and correlated to the cochlear turn lengths. Linear regression analyses were carried out. Results: Mean diameter A was 9.3 mm. The mean basal turn length was 22.8 mm, the two first turns were 35.1 mm and the total length was 41.2 mm. Linear regression analyses indicated a coefficient of determination (R-2) of 0.74 for diameter A and the basal turn length, R-2 = 0.70 for the two-turn length and R-2 = 0.39 for the total length.

Place, publisher, year, edition, pages
2013. Vol. 133, no 12, 1258-1265 p.
Keyword [en]
Human cochlea, electro-acoustic-stimulation, EAS, partial deafness, cochlear implant, hearing preservation
National Category
Medical and Health Sciences
URN: urn:nbn:se:uu:diva-213453DOI: 10.3109/00016489.2013.831475ISI: 000327419700004OAI: oai:DiVA.org:uu-213453DiVA: diva2:682720
Available from: 2013-12-30 Created: 2013-12-23 Last updated: 2014-06-30Bibliographically approved
In thesis
1. Hearing Preservation CI Surgery and Hybrid Hearing: From Anatomical Aspects to Patient Satisfaction
Open this publication in new window or tab >>Hearing Preservation CI Surgery and Hybrid Hearing: From Anatomical Aspects to Patient Satisfaction
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

A common cause of profound deafness is hair cell dysfunction in the cochlea. Cochlear implants (CI) bypass the hair cells via an electrode and stimulate the cochlear nerve directly. Nowadays, it is possible to preserve residual hair cell function and hearing through flexible electrodes and a-traumatic CI surgery techniques; called hearing preservation CI surgery. This may suit partially deaf patients who can use natural low frequency hearing in combination with electric high frequency hearing; so-called hybrid hearing. The aim of this thesis was to elucidate the effectiveness of hearing preservation CI surgery. The thesis demonstrates human cochlear anatomy in relation to CI and evaluates hearing and patient satisfaction after hearing preservation CI surgery.

Analyses of human cochlear moulds belonging to the Uppsala collection showed large variations in dimensions and coiling characteristics of the cochlea. Each cochlea was individually shaped. The size and shape of the cochlea influences the position of the electrode. The diameter of the basal cochlear turn could predict insertion depth of the electrode, which is crucial for hearing preservation. The first 21 patients operated with hearing preservation CI surgery in Uppsala, showed preserved hearing.

Nine-teen partially deaf patients receiving implants intended for hybrid hearing, were evaluated concerning pure tone audiometry, monosyllables (MS) and hearing in noise test (HINT). They also responded to a questionnaire, consisting of the IOI-HA, EQ-5D VAS and nine questions about residual hearing. The questionnaire results indicated a high degree of patient satisfaction with improved speech perception in silence and noise. This was also reflected by improved results in MS and HINT. Hearing was preserved in all patients, but there was an on-going deterioration of the residual hearing in the operated ear which surpassed the contralateral ear. There were no correlations between the amount of residual hearing and patient satisfaction or speech perception results. Electric stimulation provides a major contribution to speech comprehension in partially deaf patients. All the patients showed a high degree of satisfaction with their CI, regardless of varying hearing preservation.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 70 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 997
anatomic variations, human cochlea, cochlear implantation, EAS, electro-acoustic stimulation, residual hearing, partial deafness, IOI-HA, EQ-5D
National Category
Research subject
urn:nbn:se:uu:diva-221536 (URN)978-91-554-8949-6 (ISBN)
Public defence
2014-06-05, Skoogsalen, ingång 78/79, Akademiska sjukhuset, Uppsala, 09:00 (Swedish)
Available from: 2014-05-14 Created: 2014-04-01 Last updated: 2014-06-30

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Erixon, ElsaRask-Andersen, Helge
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