Facial nerve stimulation after cochlear implantation

OBJECTIVES: This study was designed to compare the incidence and nature of facial nerve stimulation (FNS) in patients receiving cochlear implants (CI) manufactured by Cochlear Corporation, Advanced Bionics Corporation, and MedEl. STUDY DESIGN: Retrospective chart review at a tertiary referral center. METHODS: The charts of 600 patients who received CIs from 1993 to 2003 with at least 1 year of follow-up were reviewed for significant FNS (FNS on at least 1 channel at functional stimulation levels). Data collected included age, sex, etiology of deafness, device type, electrode, FNS onset after initial stimulation, number and location of electrode contacts causing FNS, and loudness level at which FSN occurred. Nucleus straight and perimodiolar electrodes were also compared. RESULTS: Thirty-nine of 600 (6.5%) patients had FNS on at least one channel, (MedEl 3 of 43 [7.0%], Nucleus 29 of 440 [6.6%], and Clarion 7 of 117 [6.0%]). The incidence of FNS in Nucleus perimodiolar electrodes (16 of 250 [6.4%]) was similar to straight electrodes (13 of 190 (6.8%]), as was the mean number of electrodes causing FNS per patient (11 vs. 12). However, straight electrodes caused stimulation at significantly softer perceived loudness levels than perimodiolar electrodes (P < .0001). CONCLUSIONS: In this large series of CI FNS, the overall incidence of FNS is consistent with previous reports. All devices had a similar incidence of FNS, but perimodiolar electrodes produced FNS only at significantly higher loudness levels than straight electrodes, making them preferable for patients at risk for FNS receiving Nucleus devices.     

Facial nerve stimulation after cochlear implantation: Our experience in 448 adult patients

Facial nerve stimulation (FNS) after cochlear implant activation is a well-known side effect, with an incidence rate raging between 1% and 14.9%. Some causes of deafness have been associated with a higher incidence of this entity, however, there is still no consensus regarding its pathophysiological mechanisms. Although FNS can be solved with changes in speech processor programming, in some cases this can lead to a decrease in performance. The aim of this work was to review the epidemiologic, clinical aspects, and performance results in a group of FNS after cochlear implantation. It was conducted a retrospective chart review of 448 adult patients, all implanted between 1985 and 2016. Speech perception tests results were statistically analysed, using non-parametric tests. We registered a group of 13 patients with FNS, contributing to a prevalence of 2.9%. The causes of hearing loss in this group varied between otosclerosis, Menière’s disease, head trauma, and idiopathic cause. Six cases were managed by changing the programming strategy and the other seven required the deactivation of the affected electrodes. Statistical evaluation showed no statistically significant difference between the performance results of the groups with and without FNS. In this series, the overall incidence of FNS was consistent with the literature. Our study supports the current idea that FNS can frequently be eliminated by changing programming strategies or deactivating the involved electrodes, without affecting the implant’s performance.