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

[The 'major' complications of cochlear implantation]

AIM

The objective of the present study was to improve the selected surgical stages of cochlear implantation (CIP) taking into consideration the results of the analysis of the outcomes of re-operations.

MATERIAL AND METHODS

A total of 53 patients (4 adults and 49 children) were referred to our clinic for re-operations deemed to be required for the management the major complications following CI during the period from 2014 to 2017. Primary cochlear implantation was performed in other clinics. Re-operations were carried out at different time intervals after the primary surgical intervention under the guidance of a single experienced surgeon.

RESULTS

The technical malfunction of the inner part of the implant prevailed among the causes behind the major complications of CI. It accounted for 47% of the total number of complications and required the replacement of the device. The next most frequent form of the complications (that accounted for 15% of all the cases) was the introduction of an active electrode into the cells of hypotympanum. The remaining complications occurred only in isolated cases. The detailed analysis of all the revealed complications was undertaken with the description of their causes and variants and the surgical strategy chosen for the management of each concrete patient. The decision about the necessity of either the removal or the substitution of the implant was taken on an individual basis. The successful outcome of the surgical treatment of all the operated patients with the major complications of cochlear implantation was achieved.

CONCLUSION

The frequency and severity of the major complications of cochlear implantation are directly dependent on the patient's anatomical features, surgeon's qualifications, the quality of the implants, and lifestyle factors (e.g. head trauma, etc.). Cochlear implantation continues to be the only method for hearing rehabilitation in the patients suffering from severe sensorineural impairment of hearing. In the cases of cochlear implantation with the prospects of delayed re-implantation, leaving the active electrode in the scala tympani of the cochlea is a necessary measure to prevent synechiae.

[The complications of cochlear implantation and the methods for their treatment]

The objective of the present study was to improve the surgical component of cochlear implantation (CI) with special reference to the prevention and correction of its complications. A total of 967 cochlear implantation were performed on 847 patient treated based at the A. Geidarov Republican Hospital, Ministry of Internal Affairs of Azerbaijan, and the Research and Clinical Centre of Otorhinolaryngology, FMBA of Russia during the period from 2014 till 2017. The majority of the patients (n=540) were the children at the age varying from 1 to 4 years. All surgical interventions were carried out under the supervision of a single experienced specialist. The check-up examinations were performed every three months during the postoperative period. The postoperative complications were categorized in terms of severity (as major and minor) and time of the first manifestation (intraoperative and delayed). The detailed analysis of all documented complications was performed including the description of their variants and causes as well as of the surgical strategy applied in each concrete case. The frequency of major and minor complications was estimated at 2.6 and 1.6% respectively. It is concluded that cochlear implantation performed by an experienced surgeon provides a relatively safe method for the treatment of the patients in the clinics with a low frequency of complications of such interventions. The most common cause of the major complications of cochlear implantation is the technical defect of the implants the frequency of which amounted to 68% in the present study.

Magnetic resonance imaging after cochlear implants

Introduction

Most cochlear implants are currently compatible with magnetic resonance imaging (MRI) up to 3 T. Nevertheless, this does not completely eliminate the risk of serious accidents. Implant displacements and other adverse events with compatible implants have been reported in the literature.

Case reports

Among the six patients who had MRI after receiving implants at our center, we report three cases with adverse events related to the examination. The first case was complicated by magnet displacement with partial demagnetization. The second case showed total demagnetization, which necessitated removal and reimplantation of the implant. The third case involved severe pain sensation which disrupted the MRI scan. The smallest artifact was found with 3D MRI angiography, and largest artifact was found with diffusion and T2 FLASH.

Discussion

Moving the patient into the MRI apparatus must be supervised by an otorhinolaryngology specialist or an experienced radiologist. It is important to consider the magnetic field directions, so that angle between the implant magnetic fields and the MRI B0 always remains less than or equal to 90°. In addition, we recommend the use of an "arrow drawing" to facilitate the orientation of the magnetic field directions. Furthermore, to prevent magnet displacement, we recommend systematic use of a protective splint in addition to bandaging.