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.