Vestibular function assessment in cochlear implant patients

Abstract

BackgroundAnatomical and embryological relations between cochlear and vestibular end organs predispose them to same noxious or developmental factors, thus these may affect either or both systems. Cochlear implantation being a widely used procedure for restoration of hearing in patients who are not candidates for regular amplification, may affect by different means the vestibular system. One of these factors include the surgical procedure. The aim of this study is to assess the vestibular function in cochlear implant candidates before surgery to exclude coexisting vestibular affection with the sensorineural hearing loss (SNHL). Reassessment after operation was done to determine the risk posed by surgery and for correlating the surgical approach to vestibular findings.Materials and methodsThe case series presented herein is of cochlear implant candidates who underwent full audiological and radiological assessment. Vestibular assessment was done before and after operation and included cervical vestibular evoked myogenic potential (cVEMP) and ocular vemp (oVEMP) for evaluation of otolith organs. Video head impulse test (VHIT) was used to evaluate semicircular canal.ResultsPreliminary results show that patients may exhibit vestibular loss concomitant to the SNHL even with the absence of vestibular complaints. Patients who had normal preoperative vestibular function showed affected vestibular tests after the surgery. There was a mismatch between these objective findings and the subjective complaint of imbalance or vertigo.ConclusionDespite the minor risk posed by cochlear implant (CI) surgery for the subjective vestibular affection, the side with worse vestibular function should be chosen for CI if other factors are equal to avoid postoperative vestibular loss.