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Hear Res. 2017 Feb;344:90-97. doi: 10.1016/j.heares.2016.11.002. Epub 2016 Nov 5.

Damage to inner ear structure during cochlear implantation: Correlation between insertion force and radio-histological findings in temporal bone specimens.

Author information

1
Sorbonne Universités, Université Pierre et Marie Curie Paris 6, Inserm, Unité Réhabilitation chirurgicale mini-invasive et robotisée de l'audition, Paris, France; AP-HP, GHU Pitié-Salpêtrière, Service ORL, Otologie, implants auditifs et chirurgie de la base du crâne, Paris, France; Department of Sense Organs, Sapienza University of Rome, Rome, Italy. Electronic address: daniele_deseta@yahoo.it.
2
Sorbonne Universités, Université Pierre et Marie Curie Paris 6, Inserm, Unité Réhabilitation chirurgicale mini-invasive et robotisée de l'audition, Paris, France.
3
Sorbonne Universités, Université Pierre et Marie Curie Paris 6, Inserm, Unité Réhabilitation chirurgicale mini-invasive et robotisée de l'audition, Paris, France; AP-HP, GHU Pitié-Salpêtrière, Service ORL, Otologie, implants auditifs et chirurgie de la base du crâne, Paris, France; Department of Sense Organs, Sapienza University of Rome, Rome, Italy.
4
INSERM UMR 957, Pathophysiology of Bone Resorption and Therapy of Primary Bone Tumors, Nantes, France; Department of Oncology and Metabolism, University of Sheffield, The Medical School, England, UK.
5
Department of Oncology and Metabolism, University of Sheffield, The Medical School, England, UK.
6
Sorbonne Universités, Université Pierre et Marie Curie Paris 6, Inserm, Unité Réhabilitation chirurgicale mini-invasive et robotisée de l'audition, Paris, France; AP-HP, GHU Pitié-Salpêtrière, Service ORL, Otologie, implants auditifs et chirurgie de la base du crâne, Paris, France.

Abstract

Cochlear implant insertion should be as least traumatic as possible in order to reduce trauma to the cochlear sensory structures. The force applied to the cochlea during array insertion should be controlled to limit insertion-related damage. The relationship between insertion force and histological traumatism remains to be demonstrated. Twelve freshly frozen cadaveric temporal bones were implanted with a long straight electrodes array through an anterior extended round window insertion using a motorized insertion tool with real-time measurement of the insertion force. Anatomical parameters, measured on a pre-implantation cone beam CT scan, position of the array and force metrics were correlated with post-implantation scanning electron microscopy images and histological damage assessment. An atraumatic insertion occurred in six cochleae, a translocation in five cochleae and a basilar membrane rupture in one cochlea. The translocation always occurred in the 150- to 180-degree region. In the case of traumatic insertion, different force profiles were observed with a more irregular curve arising from the presence of an early peak force (30 ± 18.2 mN). This corresponded approximately to the first point of contact of the array with the lateral wall of the cochlea. Atraumatic and traumatic insertions had significantly different force values at the same depth of insertion (p < 0.001, two-way ANOVA), and significantly different regression lines (y = 1.34x + 0.7 for atraumatic and y = 3.37x + 0.84 for traumatic insertion, p < 0.001, ANCOVA). In the present study, the insertion force was correlated with the intracochlear trauma. The 150- to 180-degree region represented the area at risk for scalar translocation for this straight electrodes array. Insertion force curves with different sets of values were identified for traumatic and atraumatic insertions; these values should be considered during motorized insertion of an implant so as to be able to modify the insertion parameters (e.g axis of insertion) and facilitate preservation of endocochlear structures.

KEYWORDS:

Basilar membrane; Cochlear implant; Inner ear trauma; Insertion force; Scala tympani; Translocation

PMID:
27825860
DOI:
10.1016/j.heares.2016.11.002
[Indexed for MEDLINE]
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