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Partial withdrawal of deeply inserted cochlear electrodes: observations of two patients

Kos, Maria-Izabel ; Boex, Colette ; Guyot, Jean-Philippe ; Pelizzone, Marco

In: European Archives of Oto-Rhino-Laryngology, 2007, vol. 264, no. 11, p. 1369-1372

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    Titre
    • Partial withdrawal of deeply inserted cochlear electrodes: observations of two patients
    Auteur
    • Kos, Maria-Izabel. Department of Otolaryngology, Head and Neck Surgery, University Hospitals of Geneva, 1211, Geneva 14, Switzerland
    • Boex, Colette. Department of Otolaryngology, Head and Neck Surgery, University Hospitals of Geneva, 1211, Geneva 14, Switzerland
    • Guyot, Jean-Philippe. Department of Otolaryngology, Head and Neck Surgery, University Hospitals of Geneva, 1211, Geneva 14, Switzerland
    • Pelizzone, Marco. Department of Otolaryngology, Head and Neck Surgery, University Hospitals of Geneva, 1211, Geneva 14, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • European Archives of Oto-Rhino-Laryngology, 2007, vol. 264, no. 11, p. 1369-1372. Springer-Verlag
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:319805
    Summary
    Three patients implanted in our department received the preformed Clarion S-Series cochlear implant with the electrode Positioning System (EPS). The EPS is a device designed to bring the electrode array closer to the modiolus and deeper into the cochlea. Two of these patients still complained because they were perceiving too low pitch sounds, and because of the presence of echoes and poor discrimination after 3years of implant use and many tuning sessions. We hypothesized that the electrode array was too deeply inserted and could be stimulating overlapping populations of neurons in the low frequency range. The EPS was removed through a transcanal tympanotomy under local anesthesia and the array was pulled 2-3mm out of the cochlea. The angle of electrode insertion into the cochlea and the patients' performances on consonant identification tests were evaluated before and after the removal surgery and over the long term, 3years after the surgery. Immediately after the removal surgery the angle of insertion of the electrode array decreased from 720° to 485° in one case and from 675° to 485° in the other. Both patients reported subjective improvements after the removal which were confirmed by tests of performance at the long term by one of the patients. These observations show that (1) the electrode array can be moved without deterioration of performances even several years after being implanted; revision surgery may be beneficial in some cases, (2) neighboring electrodes might stimulate overlapping populations of neurons, inducing a deterioration of performances; for anatomical reasons, this is most likely to occur in the apex of the cochlea and (3) tuning of the external processor should be a customized procedure