Cochlear implantation in postlingually hearing-impaired adults: choosing the most appropriate ear

Influence of Semicircular Canal Dehiscence on Cochlear Implant Outcome

INTRODUCTION

Semicircular canal dehiscence (SCD) is defined as a defect of the bone overlying the semicircular canal. It has a relatively high prevalence of 3% in the general population, which makes it likely that a certain number of patients receiving a cochlear implant (CI) would have it. However, little is known about the influence of SCD on the CI outcome. Therefore, the aim of this study was to determine the influence of SCD on CI outcome with regard to short- and long-term word perception and hearing preservation.

METHODS

This study was a retrospective analysis of postoperative word perception ability in the electric-only condition after 6, 12, and ≥18 months and of hearing preservation 4 weeks after surgery in CI recipients with and without SCD. All patients received a preoperative 1.5- or 3-tesla magnetic resonance imaging.

RESULTS

Fifty-five patients were included. Forty-eight patients (87%) had no SCD, and 7 patients (13%) had SCD. Mean postoperative word perception scores were 66% in the non-SCD group versus 50% in the SCD group (p = 0.17) after 6 months, 74 versus 64% (p = 0.28) after 12 months, and 77 versus 73% (p = 0.62) after 18 or more months. The mean postoperative hearing loss in patients with functional residual hearing before surgery (n = 34) was 22 dB in the non-SCD group versus 31 dB in the SCD group (p = 0.15).

CONCLUSIONS

CI outcome is comparable between recipients without and with SCD. Specifically, hearing preservation rate and word perception ability in the electric-only condition seem not affected by SCD. The rate of progress of word perception ability in the first 12 months after cochlear implantation is not influenced by SCD.

Cochlear implant outcomes in patients with superior canal dehiscence

OBJECTIVE

To determine whether adult cochlear implant (CI) users with superior canal dehiscence syndrome (SCDS) or asymptomatic superior semicircular canal dehiscence (SCD) have different surgical, vestibular, and audiologic outcomes when compared to CI users with normal temporal bone anatomy.

METHODS

A retrospective single institution review of CI users with either superior semicircular canal dehiscence syndrome or asymptomatic superior semicircular canal dehiscence identified eight post-lingually deafened adults with unilateral or bilateral cochlear implantation between 2006 and 2010. Preoperative and postoperative speech perception scores as well as medical and epidemiological data were recorded and analyzed.

RESULTS

One patient with superior canal dehiscence syndrome and seven patients with asymptomatic superior semicircular canal dehiscence were identified, representing 7% or 8/113 of CI patients that fulfilled selection criteria. Average dehiscence length was 3.3 mm ± 0.79 SEM. Three patients received bilateral implants and five patients received a unilateral implant. Among asymptomatic superior semicircular canal dehiscence patients, subjective rates of post-operative dizziness were similar to those seen in patients with normal temporal bone anatomy (12.5 % vs. 15.9%, respectively). Speech perception abilities after surgery were poorer in SCD patients compared to the non-SCD cohort (Consonant Nucleus Consonant 33.7 ± 7.78 SEM vs. 56.7 ± 2.15 SEM P = 0.011), although both groups improved substantially relative to pre-operative performance. We also completed detailed analyses of auditory and vestibular outcomes in one patient with SCDS who underwent CI surgery in the symptomatic ear, which demonstrated preservation of vestibular function post-operatively, improved quality-of-life measures, and reduced dizziness symptomatology.

CONCLUSIONS

Our data suggest that patients with asymptomatic superior canal dehiscence at the time of CI surgery have similar albeit decreased speech perception scores compared to non-SCD adult CI users. Subjective rate of dizziness or vertigo following CI surgery was similar in both asymptomatic SCD and non-SCD cohorts, with detailed analyses of a single symptomatic SCD patient revealing improved vestibular function and reduced SCD symptoms following CI.

Pre-, per- and postoperative factors affecting performance of postlinguistically deaf adults using cochlear implants: a new conceptual model over time

OBJECTIVE

To test the influence of multiple factors on cochlear implant (CI) speech performance in quiet and in noise for postlinguistically deaf adults, and to design a model of predicted auditory performance with a CI as a function of the significant factors.

STUDY DESIGN

Retrospective multi-centre study.

METHODS

Data from 2251 patients implanted since 2003 in 15 international centres were collected. Speech scores in quiet and in noise were converted into percentile ranks to remove differences between centres. The influence of 15 pre-, per- and postoperative factors, such as the duration of moderate hearing loss (mHL), the surgical approach (cochleostomy or round window approach), the angle of insertion, the percentage of active electrodes, and the brand of device were tested. The usual factors, duration of profound HL (pHL), age, etiology, duration of CI experience, that are already known to have an influence, were included in the statistical analyses.

RESULTS

The significant factors were: the pure tone average threshold of the better ear, the brand of device, the percentage of active electrodes, the use of hearing aids (HAs) during the period of pHL, and the duration of mHL.

CONCLUSIONS

A new model was designed showing a decrease of performance that started during the period of mHL, and became faster during the period of pHL. The use of bilateral HAs slowed down the related central reorganization that is the likely cause of the decreased performance.