Investigating Facial Nerve Stimulation After Cochlear Implantation in Adult and Pediatric Recipients

Abstract

Objectives/Hypothesis Facial nerve stimulation (FNS) can occur after cochlear implantation for a small number of recipients. This study aimed to investigate if a correlation exists between the variables involved in FNS. Study Design Retrospective cohort review. Methods There were 32 out of 1,100 cochlear implant recipients who experienced FNS in our clinic between 2010 and 2019. The following variables were recorded from a retrospective chart review: grade of FNS, onset of FNS, the number of channels stimulating FNS, and radiological findings of abnormalities in the inner ear. Statistical analyses were performed to identify a correlation between any of the variables involved. The techniques used to reduce FNS were analyzed. Results Eleven adult ears had progressive hearing loss, three had idiopathic sudden sensorineural hearing loss (SNHL), and one congenital SNHL. All pediatric ears were diagnosed with congenital SNHL, except for one ear with idiopathic sudden SNHL. The grade of FNS ranged from mild stimulation or slight motion in the eye, mouth, nasolabial, or forehead regions (n = 8) to total severe stimulation of the facial musculature and/or severe pain (n = 3). The onset of FNS occurred immediately after activation for nine ears, and up to 16 months later for the other subjects. A significant correlation was observed between the number of channels stimulating FNS, the grade of FNS, and the radiological findings of the inner ear. FNS was completely resolved for 30 ears and partially resolved for two ears. Conclusions FNS can occur any time after cochlear implantation and can affect both adult and pediatric. However, it can be effectively resolved using specific fitting techniques. Level of Evidence 2c Laryngoscope, 131:374–379, 2021

Facial nerve stimulation in adult cochlear implant recipients with far advanced otosclerosis

“…In our study, in six patients, FNS occurred later. In the few studies describing Late‐FNS, it was suggested that progression of otosclerosis with changes of tissue impedance and/or erosion of the thin bony layer between the scala tympani and the facial nerve was greater than in patients without otosclerosis 27,28 . Surprisingly, in our study, all the six patients with Late‐FNS already had extensive otosclerotic lesions on preoperative CT‐scan.…”

Anodic Polarity Minimizes Facial Nerve Stimulation as a Side Effect of Cochlear Implantation

“…We found FNS in at least one recording in all of our 26 animals and in 178 of 393 recordings. This represents a high incidence (45%) compared to about 10% that was usually reported in human CI users [5,9,13,24,29]. The first potential underlying cause of this difference is related to the species: The anatomy of the inner ear and facial nerve (FN) is different in guinea pigs and humans.…”

“…FNS may occur directly after CI activation, but sometimes starts with a time delay of up to several years of CI usage [7,9]. The FNS is due to the anatomical proximity of the intrascalar CI contacts to the facial nerve (FN), a proximity that allows the current to reach the FN.…”

Mythbusters! The Truth about Common Misconceptions in Cochlear Implantation

“…In adults, facial nerve stimulation from a CI ranges between 0.9 and 15%. [59][60][61] Altered taste is another potential complication after CI implant surgery. It results when the chorda tympani nerve is disturbed during surgery.…”