**1. Introduction**

Sensorineural hearing loss is the most common sensory deficit [1]. A cochlear implant (CI) is a neuroprosthetic device that enables the restoration of sound perception for patients receiving little or no benefit from hearing aids. In children with severe and profound sensorineural hearing loss, cochlear implantation is the reference rehabilitation [2,3]. Cochlear implantation is a safe and effective procedure, and CIs are considered the most reliable neuroprosthetic device. However, in 1.3 to 11.2% [4–8], reimplantation can be required. The causes include medical complications and device malfunctions. Device malfunctions can be separated into hard device failure (acute and complete loss of connection between the external and internal device with abnormal electrophysiological testing) and soft device failure (audiological performance decrement and exclusion of detectable hardware or softwarerelated causes) [9,10]. More recently, the indication of reimplantation for technological upgrading of older implants has been discussed [11,12].

Offering stable or better audiological results after reimplantation is a major challenge. We hypothesized that the audiological outcomes may be influenced by several intrinsic and extrinsic factors: sex, age, etiology of deafness, timing of intervention, electrode array insertion, or the speech rehabilitation followed after reimplantation.

**Citation:** Blanc, F.; Blanchet, C.; Sicard, M.; Merklen, F.; Venail, F.; Mondain, M. Audiological Outcomes and Associated Factors after Pediatric Cochlear Reimplantation. *J. Clin. Med.* **2022**, *11*, 3148. https://doi.org/ 10.3390/jcm11113148

Academic Editors: Eng Ooi and Nicolas Guevara

Received: 29 April 2022 Accepted: 30 May 2022 Published: 1 June 2022

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In addition, few specific pediatric cohorts have been published regarding the percentage of success of this intervention. Cochlear reimplantation does not guarantee a resolution of the problem necessitating the intervention. Indeed, reimplantations sometimes fail to solve the medical problems or the suspected device malfunctions driving the intervention [6,9,13].

This study aimed to identify factors influencing speech perception recovery and evaluate the success rate of cochlear reimplantation in the pediatric population.

#### **2. Materials and Methods**

We retrospectively collected the indications and the outcomes of 67 consecutive reimplantations in one CI center over 30 years (1989–2019). We included all consecutive cochlear reimplantations concerning patients that received their first CI before 18 years old. Overall, the reimplantation rate was 8.6% during the period (67/781 cochlear implantations). Cumulative survival was measured for each indication; subjects were censored yearly, and reimplantation dates were considered events (see Supplementary Figure S1).

The mean age at implantation was 4.8 +/− 3 years, ranging from 12 months to 15 years. Thirty-one boys and thirty-five girls with an age of 15.3 +/− 6.9 years underwent reimplantation. The time since initial implantation was 10.6 +/− 6.6 years, ranging from 3 months to 28 years. Etiologies of deafness are detailed in Table 1. The majority of etiology was genetic-related (46%).

**Table 1.** Etiologies of deafness.


<sup>1</sup> Including 6 patients with Usher syndrome.

The primary outcome was the audiological performance, evaluated with open-set word testing in quiet of the phonetically balanced kindergarten words (PBK) [14]. The best scores obtained 1, 2, or 3 years after reimplantation were compared to the best results obtained before reimplantation. The consequence of reimplantation was thus expressed as a percentage decrease or increase in scores. Medical records were reviewed to identify the associated factors correlated with the evolution of word discrimination scores after reimplantation: sex, age, etiology of deafness, indication, best scores before reimplantation, time since the first implantation, difference in the angle of reinsertion of the electrode array (measured by cone-beam computed tomography according to Connor et al. [15]), and adherence to the speech rehabilitation program after re-implantation. Speech rehabilitation was systematically proposed to patients after cochlear reimplantation, on the same schedule than initial cochlear implantation. Participation in less than 50% of the speech rehabilitation sessions was considered "suboptimal" and represented 12% of the cohort.

No children with cochlear malformation underwent reimplantation in our cohort. Two children presented an enlarged vestibular aqueduct; complete reinsertion of the electrode array was possible in both cases.

Device failures were divided into hard failure 50% (*n* = 32), soft failure 30% (*n* = 20), and device failure in a context of head trauma 6% (*n* = 4). Medical indications included: infections in 7.5% (*n* = 5), 2 patients requiring deep brain stimulation to control severe dystonia (Mohr–Tranebjaerg syndrome), 1 patient presenting a displacement of the CI, and

3 patients presenting with non-auditory atypical symptoms during activation of the CI (headache, nausea, vomiting).

The success rate of reimplantation was assessed using specific criteria for each indication: better or stable audiological outcomes for the suspected device failures, recovery of the infection without recurrence of infections, and recovery of the non-auditive symptoms for the other causes.

Prism 9.0.2 (GraphPad Software LLC, San Diego, CA, United States of America) was used for statistical analysis. Statistical differences in the audiological outcomes were compared using a non-parametric test for paired data (Wilcoxon's rank test). The difference in the audiological outcomes as a function of the different putative associated factors were analyzed using a non-parametric test for unpaired data (Kruskal–Wallis and Mann– Whitney tests) whereas the correlation with quantitative associated factors were analyzed with the Spearman correlation coefficient.

All subjects gave their informed consent for inclusion before they participated in the study. The study was conducted in accordance with the Declaration of Helsinki.
