Disturbance of vestibular function attributable to cochlear implantation in children.

OBJECTIVES/HYPOTHESIS: To investigate the prevalence and severity of vestibular impairment in children with cochlear implant (CI) and raise the awareness of vestibular disturbance following cochlear implantation.

STUDY DESIGN

Cohort study in a pediatric tertiary care facility.

METHODS

Outcome analysis of the vestibular evaluation, including vestibule-ocular reflex (VOR), computerized dynamic posturography (CDP), and vestibular evoked myogenic potential (VEMP) testing, from a total of 42 patients with cochlear implants. Intrasubject comparison of pre- and postcochlear implantation VEMP measurements were conducted in a group of 19 patients who were newly implanted.

RESULTS

Our review found vestibular impairment present in 60% of patients with CI, e.g., reduced gain of VOR, weakness in posture, elevation of VEMP thresholds, and decrease in VEMP amplitude. The degree of functional reduction varied from subject to subject. Pre- and postimplantation VEMP study revealed more than 80% of the subjects had a change in saccular function, indicated by VEMP measurements, regardless of the etiology of the hearing loss.

CONCLUSIONS

Our study supports the potential negative impact on vestibular function caused by cochlear implantation, especially for children who receive bilateral implantation. Vestibular impairment or dysfunction after cochlear implantation is clinically significant and should be well addressed preoperatively. Vestibular evaluation such as VOR and VEMP testing can be used in screening vestibular function for children who are candidates for CI. Future improvements in design of CI electrodes and surgical technique may minimize the traumatic impact of cochlear implantation on the inner ear structures and functionality.