Clinical investigation of the Nucleus Slim Modiolar Electrode

Abstract

Aims: The Nucleus CI532 cochlear implant incorporates a new precurved electrode array, i.e., the Slim Modiolar electrode (SME), which is designed to bring electrode contacts close to the medial wall of the cochlea while avoiding trauma due to scalar dislocation or contact with the lateral wall during insertion. The primary aim of this prospective study was to determine the final position of the electrode array in clinical cases as evaluated using flat-panel volume computed tomography. Methods: Forty-five adult candidates for unilateral cochlear implantation were recruited from 8 centers. Eleven surgeons attended a temporal bone workshop and received further training with a transparent plastic cochlear model just prior to the first surgery. Feedback on the surgical approach and use of the SME was collected via a questionnaire for each case. Computed tomography of the temporal bone was performed postoperatively using flat-panel digital volume tomography or cone beam systems. The primary measure was the final scalar position of the SME (completely in scala tympani or not). Secondly, medial-lateral position and insertion depth were evaluated. Results: Forty-four subjects received a CI532. The SME was located completely in scala tympani for all subjects. Pure round window (44% of the cases), extended round window (22%), and inferior and/or anterior cochleostomy (34%) approaches were successful across surgeons and cases. The SME was generally positioned close to the modiolus. Overinsertion of the array past the first marker tended to push the basal contacts towards the lateral wall and served only to increase the insertion depth of the first electrode contact without increasing the insertion depth of the most apical electrode. Complications were limited to tip fold-overs encountered in 2 subjects; both were attributed to surgical error, with both reimplanted successfully. Conclusions: The new Nucleus CI532 cochlear implant with SME achieved the design goal of producing little or no trauma as indicated by consistent scala tympani placement. Surgeons should be carefully trained to use the new deployment method such that tip fold-overs and over insertion may be avoided.

The evaluation of a slim perimodiolar electrode: surgical technique in relation to intracochlear position and cochlear implant outcomes

“…To reduce intracochlear trauma during insertion, the slim perimodiolar electrode (SPE) was introduced in 2016. This electrode is 60% thinner and more flexible than the previous generation perimodiolar electrode produced by the same manufacturer [12]. The SPE has been developed for hypotraumatic insertion and preservation of residual hearing.…”

“…It was observed that independent of the type of electrode used, full scala tympani (ST) position [8] and preservation of residual hearing [8,10] is more likely using a RW or eRW approach, compared to the CS approach. These findings might contribute to the fact that to-date, eRW and RW approaches were used in 91.8% (236/257) of the participants in the five studies that investigated the SPE [11,12,[14][15][16].…”

“…The scalar position of the SPE, visualized in high-resolution imaging, was evaluated in 96 out of these 257 participants [11,12,15,16]. Out of these participants, 81 were implanted using the RW or eRW approach [11,12,15,16]; in 6 participants, a translocation had occurred [15]. In the remaining, relatively low number of 15 patients in whom the CS approach was used, no translocation was observed [12].…”

Outcomes for a clinically representative cohort of hearing-impaired adults using the Nucleus® CI532 cochlear implant

“…The Cochlear™ Slim Modiolar Electrode (CI532) is a perimodiolar array which was designed to be inserted with minimal damage to the cochlea and to bring the electrode contacts, which deliver the current to the nerve and spiral ganglion cells, closer to the modiolus [1][2][3].…”

“…A growing body of evidence suggests that patients with the electrode array positioned in the scala tympani have the best speech perception outcomes, and outcomes are poorer in patients where the array has dislocated through the basilar membrane and some or all of the electrode contacts reside within the scala vestibuli [2,4,8]. Previous studies using the Slim Modiolar electrode array showed consistent perimodiolar placement and scala tympani insertions in at least 87% of the patients assessed with imaging [1][2][3]. They reported hearing preservation is better than with older perimodiolar and straight designs, but possibly not as good as hybrid or electroacoustic devices that are specifically designed for hearing preservation [2,3,[9][10][11].…”