Otolith and balance function evolution related to cochlear implantation in hearing loss with inner ear malformations

Objectives: In recent years, with the incidence of bilateral cochlear implantation (CI) increasing, understanding the impact of CI on otolith function is of greater necessity. This study aims to investigate the development of gross motor and otolith function in patients with inner ear malformations (IEMs) by vestibular evoked myogenic potentials (VEMP).

Materials and Methods: A total of 78 patients with sensorineural hearing loss (SNHL) (age 5.7±4.1 years) were divided into two groups based on the presence (IEM group, n=39) or absence (control group, n=39) of IEMs. VEMP was conducted before and 1–3 months after CI, and gross motor development assessed.

Results: The mean ages of head control and independent walking were delayed in the IEM group compared with control group (p =0.02). The preoperative cVEMP and oVEMP response rates were higher in the control groups (60% and 86.95%) than in the IEM group (57.69% and 74.35%) (p <0.05). Additionally, abnormal cVEMP was associated with delayed acquisition of independent walking (p =0.017). Saccular and utricular functions after CI were lost by 40% and 31.75%, respectively, in group of patients present preoperatively VEMPs waveform (n=25).

Conclusions: Balance development is more reduced in patients with SNHL and IEMs than in patients without IEMs. The otolith-vestibular nerve conduction pathway can be affected by CI and lead to otolith function impairment. As such, evaluating the otolith and balance functions before CI is necessary and should be considered in clinical practice.

Keywords: Otolith function, Cochlear implantation, Inner ear malformation, Pediatric, Balance function

Key Points

There is limited studies on otolith function in patients with IEMs before and after cochlear implants (CI).

We conducted a prospective study of otolith function with IEMs using vestibular evoked myogenic potentials (VEMP).

We included 78 children (41 females and 37 males) who underwent CI, all patients were divided into two groups based on the presence (IEM group) or absence of IEMs (control group)

The IEM group had a lower response rate of cVEMP (X² =4.768, p =0.003) and oVEMP (X² =4.408, p =0.003) compared to the control group. The abnormal cVEMP and oVEMP rate after surgery was increased in the control group (p< 0.001) but decreased in the IEM group.

Evaluating the otolith and balance functions before CI is necessary and should be considered in clinical practice.