Saccular function evolution related to cochlear implantation in hearing impaired children

Vestibular sensorial input is essential for psychomotor development of the very small children. In consequence, possible vestibular impairment induced by cochlear implantation in deaf children could affect the balance and walking learning process. Some of cochlear implanted children can present congenital vestibular deficit. The anatomical and embryological relation between auditory and vestibular system explains why congenital neurosensorial hearing loss may associate vestibular impairment. The cochlear implant surgery presents a vestibular lesion risk. Bilateral vestibulopathy, as it appears in early childhood, has a poor prognosis for the psychomotor and cognitive development. Even probably rare, bilateral vestibulopathy induced by simultaneous bilateral cochlear implantation can delay the acquisition of motor skills. This pathology can be avoided by an appropriate surgical indication related to the vestibular preoperative status. This study reports the vestibular saccular functional modifications after the cochlear implantation in children. The cervical vestibular evoked myogenic potentials (cVEMPs) were performed in children before and after the cochlear implantation. Since previous studies report different vestibular impairment related to the portelectrode insertion approach, another objective of our study was to assess the saccular postoperative status depending of the insertion by cochleostomy (CO) or through the round window (RW). We performed cVEMPs for 80 patients (135 cochlear implanted ears) before and after cochlear implantation. We have detected preoperative saccular areflexia in 33 (24.4%) ears. In the group of 102 (75.6%) ears with preoperative normal saccular function, 72 (70.6%) ears preserved the cVEMP response after the surgery, while in 30 (29.4%) ears the cVEMP response was lost. Reporting our findings to the portelectrode insertion method, we found normal saccular function in 73.3% of the cochlear implanted ears by RW surgical approach and in 68.42% ears by CO approach. These results suggest that the RW portelectrode insertion is the recommended strategy in order to avoid the saccular vestibular impairment.