INTRODUCTION
Cochlear implantation (CI) is an important treatment for severe or profound sensorineural hearing loss (SNHL), and pediatric candidates with inner ear malformations (IEMs) can obtain long-term positive auditory and speech outcomes with CI. Some children with SNHL may also present congenital vestibular dysfunction because of the anatomical and embryological relationship between the cochlea and vestibule. The prevalence of vestibular dysfunction in children with SNHL ranges from 20% to 85%. Moreover, a recent review confirms that electrode insertion can induce various vestibular damages in 50%–85% of patients, and in the pediatric population, this figure is approximately 18–85%[1]. Children with vestibular dysfunction and SNHL generally present with profound hearing loss, and their gross motor functions, such as head control or independent walking, are usually delayed[2, 3]. Cochlear and vestibular dysfunctions can exist alone or coexist, but patients with IEMs are also susceptible to semicircular canal and saccular dysfunctions[4]. Jin et al.[5] performed the vestibular evoked myogenic potential (VEMP) test on seven patients with different degrees of IEMs, of which only two patients elicited VEMP on the malformed side. Notably, studies on vestibular function in patients with IEMs are limited.
Vestibular damage after CI is more severe if it is presented before 1 year of age, because during this time, infants have not yet developed their walking and balance abilities[6]. Hence, vestibular function should be evaluated before CI, and surgeons must avoid inducing vestibular injury during surgery.
Currently, VEMP is the most commonly used vestibular function test in children, which can reflect the neurophysiological function of the otolith organ and vestibular nerve[7, 8]. VEMP test includes cervical VEMP (cVEMP) and ocular VEMP (oVEMP)[9].
Considering that the number of SNHL children undergoing CI has increased, especially bilateral surgery[10], there is an urgent need to evaluate the effects of CI on the vestibular system. This study used VEMPs to investigate gross motor and vestibular function changes after CI in pediatric patients, especially in patients with IEMs.