[Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications].

INTRODUCTION

Cochlear implants are, for many reasons, expirable electronic devices and occasionally may have to be replaced. The surgical cochlear reimplantation technique is not substantially different from the initial implantation but does have some peculiarities. These peculiarities are analyzed in this paper not only from the point of view of surgical technique but also with respect to the complications involved and the functional auditive outcome obtained.

OBJECTIVES

An accurate description of the surgical findings, peculiarities of the surgical technique and complications found during the process of cochlear reimplantation. An evaluation of the audiometric functional outcome of the reimplantation.

MATERIAL AND METHOD

A descriptive retrospective review of 34 reimplantations in the same ear, carried out at our department during the period between 1993 and 2008, in 27 patients in a tertiary hospital by the same team of seniors surgeons. The cochlear implants replaced were 2 Ineraid (Smith & Nephew Richards, TN), 23 Laura (Philips Hearing Implants), 8 nucleus 24K (Cochlear Corp., Englewood, CO), 1 Clarion (r) (Advanced Bionics, Sylmar, CA).

RESULTS

The rate of reimplantation in the same ear was 18.5% per patient. The most frequent reason in our series was internal failure of the device (14 cases). Other causes were substitution for a technological update (7 cases), misplacement of electrodes (8 cases), necrosis/infection of the skin flap with exposure of the implant (3 cases) and external injuries (2 cases). The most important surgical findings were partial mastoidectomy reossification, absence of ossification in the posterior tympanostomy and the permeability of the basal turn of the cochlea when it housed the electrodes. A complete reintroduction of the electrodes was achieved in 25 patients and a partial one in 2 patients. The rate of complications generated was similar in reimplantation and in virgin ear implantation, except for when the original implant was an Ineraid device.

CONCLUSIONS

The surgical technique of reimplantation and multireimplantation technique has characteristic peculiarities at each step, but in general terms, its complexity is similar to that of implantation in virgin ears and the rate of complications is also similar. The introduction of the new electrodes is simple and complete in the immense majority of cases, given that the cochlea remains permeable, as long as it houses the electrodes; otherwise it tends to become reossified. The functional auditory outcome of the new implant is in relation with its capacities. If they are equal to those of the initial implant then the auditory outcome will be similar and if they are better, then so will the outcome be, with the exception of ears with long periods of auditive deprivation.