Vestibular dysfunction and postural balance in cochlear implant users: a narrative literature review

Abstract

Cochlear implants directly stimulate nerve fibers and ganglion cells of the auditory nerve, which transform sound energy into low levels of electrical current, stimulating the remaining fibers of the auditory nerve in patients with severe to profound hearing loss, in order to provide the significant range of auditory sensation and speech comprehension. Due to the close relationship between cochlea and vestibular receptors, some patients may present vestibular and postural balance changes concomitantly after surgery. This study aimed to perform a narrative review of the main studies that relate vestibular symptoms in patients implanted in the last six years. The research was performed through the databases: SciELO, LILACS and PubMed, using associated descriptors for "cochlear implant", "vestibular dysfunction", "vertigo" and "balance", totalizing 21 studies that fitted the inclusion criteria. The results were described in a chronological order of publication, showing the main conclusions. Of the total studies analyzed, 18 related vestibular function to cochlear implant and only 3 studies did not find such a relationship. The literature characterize the effects of the cochlear implant on the vestibular system, however, the results are contradictory.

Vestibular dysfunction after cochlear and auditory brainstem implantation: Madras ENT Research Foundation experience

“…3 Greater occurrence of vestibular alteration in patients with bilateral CI may be because those with unilateral implantation are more able to compensate for the vestibular alteration at the injured side. 7 Vestibular dysfunction has more often been recorded among adult post-lingual cochlear implantees, especially in profound deafness due to long standing Meniere's syndrome and cochlear otosclerosis. After cochlear implantation in very young pre-lingual children lesser than 5 years of age, clinical signs of vertigo like nystagmus are most often not seen and these children are not able to provide a history of vertiginous symptoms.…”

“…5 Preservation of the residual hearing and vestibular function should be attempted using minimally invasive surgical techniques. 7 Karimi et al reported that in 6 of 9 patients, resealing of the cochleostomy improved vertigo. 10 Nguyen et al described techniques of atraumatic implant insertion thereby conserving residual inner ear function.…”