Saccular function evolution related to cochlear implantation in hearing impaired children

Abstract

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.

Alteration of Vestibular Function in Pediatric Cochlear Implant Recipients

“…It is noteworthy that the approach of electrode insertion and the electrode type caused a difference in the incidence of CI-induced negative effect on caloric test and rotation test but not on cVEMP. Our results are compatible with previous studies that showed no significant differences in cVEMP between electrode types (44) and between approaches of electrode insertion (22).…”

“…Reduction in caloric response and damped rotation response was more frequently observed in patients who underwent cochleostomy, and use of a perimodiolar electrode more frequently caused deterioration of caloric response compared with the use of a straight electrode. Previous studies have demonstrated that CI has a significant negative effect on the results of caloric and cVEMP test results in adults (5) and children (22). A wide range of rates of negative effects has been reported in caloric test (0-30%) (23,24) and cVEMP test (20-100%) (25)(26)(27), and cochleostomy has also been identified as a risk factor for loss of vestibular function in adults (9).…”

Changes in Vestibular Function Following Pediatric Cochlear Implantation: a Prospective Study

“…Also, higher rates of postoperative vestibular loss in literature might be related to the use of different surgical techniques. Although literature on this matter is still inconclusive, some studies indicate that cochleostomy might be more traumatic for the vestibular apparatus than the round window approach, the latter being applied for all subjects in our study (Todt et al 2008; Tsukada et al 2013; Cozma et al 2020). Three recent studies reported cVEMP measurements in children after CI surgery with round window approach (Ajalloueyan et al 2017; Cozma et al 2020; Li and Gong 2020).…”

“…Although literature on this matter is still inconclusive, some studies indicate that cochleostomy might be more traumatic for the vestibular apparatus than the round window approach, the latter being applied for all subjects in our study (Todt et al 2008; Tsukada et al 2013; Cozma et al 2020). Three recent studies reported cVEMP measurements in children after CI surgery with round window approach (Ajalloueyan et al 2017; Cozma et al 2020; Li and Gong 2020). With 27% (12/45) postoperative losses, Cozma et al (2020) reported a remarkably larger proportion of saccular loss in their round window subgroup compared to our study.…”

“…Remarkably, our results are in line with the results of the third recent study that used the round window approach, which reported an isolated case of postoperative AC cVEMP loss in a group of 27 children (Ajalloueyan et al 2017). Therefore, the question arises if in the studies of Li and Gong (2020) and Cozma et al (2020) other factors such as the etiology of the hearing loss (Thierry et al 2015) or the presence of inner ear anomalies (Reynard et al 2021) could have played a role, as no details were provided on these matters.…”