Vestibular function after cochlear implant surgery.

OBJECTIVE: The aim of this study was to analyze vestibular function in cochlear implant (CI) patients for iatrogenic damage to vestibular function.

METHODS: Prospective clinical study. Tertiary care audiological center. Twenty-five subjects receiving surgery for cochlear implantation during 2012 and 2013 were analyzed. Both vestibulo-ocular and vestibulo-spinal responses before and 2 months after CI surgery were evaluated using several tests: analysis of spontaneous nystagmus, head shaking test (HST), and head impulse test recorded by videooculography; caloric stimulation at 44° and 30° in both ears; cervical evoked myogenic potentials and static stabilometry. Residual cochlear function was tested by air-conduction pure-tone audiometry.

RESULTS: Our tests showed damage to vestibular receptors after CI surgery in 12% of the patients; in particular, horizontal semicircular canal function and saccular function had lower responses after surgery. Audiometric results showed poorer thresholds after CI surgery. The static stabilometry results indicate good vestibulo-spinal responses and patients did not report disequilibrium nor postural deficit.

CONCLUSION: All data suggest an efficient vestibular compensation mechanism in CI patients.