Does the Width of the Bony Cochlear Nerve Canal Predict the Outcomes of Cochlear Implantation?

Juyong Chung,Jeong Hun Jang,Seung-Ha Oh,Jae-Jin Song,Sun O Chang,So Young Kim,Jun Ho Lee,Sung-Woo Cho

doi:10.1155/2018/5675848

Abstract

A narrow bony cochlear nerve canal (BCNC) is associated with sensorineural hearing loss necessitating cochlear implantation (CI). This study evaluated the implications of BCNC width for post-CI outcomes. A total of 56 children who had received CIs were included. The patients were divided into three groups according to the width of the BCNC (Group 1: diameter < 1.4 mm, n = 17; Group 2: diameter 1.4–2.0 mm, n = 14; Group 3: diameter > 2.0 mm, n = 25). The post-CI speech performances were compared among the three groups according to BCNC width. The correlation between BCNC width and post-CI speech performance was evaluated. Logistic regression analysis was also performed to investigate factors that can impact post-CI speech performance. Cochlear nerve deficiency (CND) occurred more frequently in Group 1. Groups 1 and 2 had significantly worse post-CI outcomes. Patients with intact cochlear nerves had significantly better post-CI outcomes than those with CND. When the cochlear nerve was intact, patients with a narrower BCNC showed less favorable results. Therefore, patients with either a narrow BCNC or CND seemed to have poorer outcomes. A narrow BCNC is associated with higher CND rates and poor outcomes. Measurement of BCNC diameter may help predict CI outcomes.

Highlights

The cochlear implant (CI) is an innovative device that is used to treat patients with bilateral, severe, or profound sensorineural hearing loss
We aimed to evaluate the width distribution of the bony cochlear nerve canal (BCNC) in ears that had received CIs, to evaluate the association between BCNC width and cochlear nerve deficiency (CND), and to analyze the correlation between BCNC width and speech performance after CI
To rule out confounding factors related to Cochlear nerve deficiency (CND), we investigated the post-CI speech performance according to BCNC width when the cochlear nerve was present

Summary

Introduction

The cochlear implant (CI) is an innovative device that is used to treat patients with bilateral, severe, or profound sensorineural hearing loss It converts the auditory signal into an electrical signal, which in turn stimulates spiral ganglion neurons (SGNs), transmitting the signal to the auditory brainstem via the cochlear nerve. The bony cochlear nerve canal (BCNC) lies between the fundus of the internal auditory canal (IAC) and the base of the cochlea. If the width of the BCNC—the distance between the inner margins of the bony walls at the midportion—is less than 1.4 mm, the cochlear nerve may be abnormal [2] One study found such a narrow BCNC in approximately 60% of patients with unilateral sensorineural hearing loss (SNHL) [3].

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