Audiological Outcomes of Cochlear Implantation in Children with Inner-Ear Malformations

Background: Inner ear malformations have been shown to be present in a significant proportion of cochlear implant candidates and may result in poorer post-operative outcomes.

Objective: To study the audiological outcomes of a group of children with congenital inner ear malformations implanted at Shaare Zedek Medical Centre from 2009 – 2017.

Methods: A retrospective review of the surgical and audiological files of 37 children implanted with various levels of congenital cochleovestibular malformations was conducted. Results of preoperative CT & MRI scans were reviewed and used to classify the type of malformation. The location and extent of insertion of the electrode array was determined by intraoperative x-rays. Post-operative audiological results including aided audiograms, speech perception outcomes and map parameters were studied.

Results: Children with milder malformations were generally able to make use of all electrodes, with standard map parameters and achieve speech perception outcomes similar to implanted peers. Children with more significant malformations could not always utilize all electrodes (despite postoperative x-rays generally showing complete insertion of the array). Furthermore, these patients required significant adjustments to map parameters possibly contributing to the poorer speech perception outcomes observed in this group. A number of patients with questionable cochlear nerve integrity went on to have ABI surgery and showed significant improvement.

Conclusion: Cochlear implants may be a viable solution for patients with inner ear malformations. The type of malformation should be taken into account when counseling families prior to surgery, and the option of ABI could be considered in cases where cochlear implants provide limited benefit.