gms | German Medical Science

Introduction: Although electrode migration after successful cochlear implantation is reported in 1.4%, wrong placement of the electrode is not discussed frequently.

Method: After 20 years of experience in implanting intracochlear multichannel systems, more than 1000 cases have been retrospectively reviewed and electrode migration has never been observed.

Results: Postoperative correct electrode placement has been radiologically confirmed in all cases and intracochlear position never changed. However, false placement of the electrode in the hypotympanon or in the carotid canal was found in 4 cases, although correct intraoperative placement but migration had been reported by the previous surgeons in two cases and wrong placement was not detected in the other two! In three cases the cochlea was patent and in one case obliterated after meningitis, so that partial insertion could be achieved in the revision surgery. Further, the electrode array was placed in the lateral part of the basal cochlear turn due to medial obliteration after fracture requiring revision surgery in one case and in the internal auditory canal in another case with X-linked deafness. This has been detected intraoperatively by X-ray and successfully repositioned.

Conclusion: Postoperative electrode migration seems to be very rare. Probably most of the reported cases were initial wrong placements that have been explained as migrations. Thus, intaoperative electrophysiological or even radiological control is recommended in any uncertain case or inexperienced surgeon.