Cochlear Implantation in Inner Ear Malformations

Research Article

Austin J Otolaryngol. 2024; 10(1): 1131.

Cochlear Implantation in Inner Ear Malformations

Bencheikh R²; Hjaouj K¹; Oujilal A²; Benbouzid A²; Essakalli L²

¹Resident physician in Otolaryngology, Department of Otolaryngology, Head and Neck Surgery, Ibn Sina University, Hospital, Faculty of Medicine, Mohammed V University, Morocco

²Professor of Otolaryngology, Department of Otolaryngology, Head and Neck Surgery, Ibn Sina University Hospital, Faculty of Medicine, Mohammed V University, Morocco

*Corresponding author: Hjaouj Resident physician in Otolaryngology, Department of Otolaryngology, Head and Neck Surgery, Ibn Sina University, Hospital, Faculty of Medicine, Mohammed V University, Rabat, Morocco. Email: khalil.hjaouj@gmail.com

Received: November 02, 2023 Accepted: December 30, 2023 Published: January 06, 2024

Abstract

Introduction: Cochlear Implantation (CI) has proven to be an effective treatment for severe bilateral Sensorineural Hearing Loss (SNHL). Inner ear malformation is a rare anomaly and occurs in approximately 20% of cases with congenital SNHL. There are particular challenges in the implantation of malformed cochleae, such as in cases of facial nerve anomalies, Cerebrospinal Fluid (CSF) leaks or facial stimulation, and the outcomes may differ depending on the severity of the malformation. The aim of this study was to assess the impact of Inner Ear Malformations (IEMs) on surgical complications and outcomes of cochlear implantation.

Methods: Between 2018 and 2022, 9 patients with inner ear malformations were implanted in our department and completed at least 1 year of follow-up. The age range was between 2 years and 4 months and 5 years (average, 3.36 yr). Auditory performance, receptive and expressive language skills, and production and use of speech were evaluated preoperatively and at least 1 year after implantation.

Results: In the study group, the most common malformation was an isolated Enlarged Vestibular Aqueduct (EVA) (55,5%). Overall, the patients with IEMs showed significant improvement in auditory-verbal skills. In general, the patients who had normal cochleae scored significantly better compared to patients with IEMs.

Conclusion: Based on these findings, cochlear implantation is surgically feasible in patients with common cavity, IP types I and II, and EVA. The surgeon should be ready to make modifications in the surgical approach because of the abnormal course of the facial nerve and be ready to produce special precautions to cerebrospinal fluid gusher. Patients with EVA were the best performers in terms of auditory-verbal skills.

Keywords: Cochlear implant; Congenital hearing loss; Gusher; Inner ear malformation

Introduction

Inner ear malformations are present in about 20% of patients with congenital sensorineural hearing loss [1]. Cochlear implantation in children with congenital deafness is an accepted auditory rehabilitation treatment for more than 20 years [2]. With the advances in radiological imaging over the last decades, new imaging techniques have revealed a wide variety of anomalies of the bony labyrinth. Jackler et al. [1] described the first classification of congenital malformations of the inner ear, which were detected by radiologic imaging. They claimed that the type and severity of IEMs depend on the arrested stage of embryogenesis in a linear developmental model. A further detailed classification based on this theory was made by Sennaroglu and Saatci [3].

In their study, cochlear, vestibular, Semicircular Canal (SCC), Internal Acoustic Canal (IAC), and vestibularcochlear aqueduct malformations were classified into subgroups. As a result of this examination, cochlear malformations were divided into 7 groups (Figure 1) as Michel deformity, common cavity, cochlear aplasia, hypoplasic cochlea, Incomplete Ppartition type I (IP-I), incomplete partition type II (IP-II/Mondini deformity), and incomplete partition type III (IP-III); vestibular malformations were divided into 3 groups as vestibular dilatation, SCC malformations, and IAC anomalies; and vestibular and cochlear aqueduct malformations were divided into 2 groups as vestibular aqueduct anomalies and cochlear aqueduct anomalies.