Tight modiolar proximity and feasibility of slim modiolar cochlear implant electrode array insertion in diverse...

To report on our experience with the slim modiolar electrode (SME) especially focusing on the wide range of etiologies including inner ear anomalies, tumors, ossifications, and even revision surgeries.

All the cochlear implantation cases performed from June 2018 to September 2019 by a single surgeon was prospectively recruited. The molecular/radiological etiology of hearing loss, intraoperative outcomes, and radiographic studies of cases where the SME was implanted was reviewed to evaluate compatibility of SME for the wide range of etiologies. For cases where SME replaced the other electrode as a revision, audiologic assessment was also made.

Among the 99 ears implanted during the study period, the SME was successfully implanted in 86 ears. These SME cases comprised inner ear anomaly/cochear nerve deficiency (n = 21) including cochlear hypoplasia type IV with the modiolus, intracochlear schwannoma (n = 1), far advanced otosclerosis (n = 1) and 7 revision cases. The SME was successfully used in 7 revision surgeries to replace the existing electrode. Shorter spiral diameter and decreased intracochlear position index for SME was found compared with their previous electrodes. Four out of the 6 patients who received revision implantation showed better speech perception after their surgeries.

The SME can be implanted in any cases unless the integrity of the modiolus is totally compromised. Due to its slim design and tight modiolar-hugging feature, good functional outcome can also be anticipated. Additionally, it is suitable for revision surgeries possibly allowing better hearing outcomes which may be attributed to its closer proximity to the modiolus.