5|DISCUSSION
In clinical practice, children with LVAS always were such a group
attracting our special care and attention, not only because of
fluctuated hearing level, but also balance problems(3,4). While, were
there any differences in development level between LVAS subjects and
children without LVAS? In order to solve the problem, we selected the
specific two groups: children with LVAS and without LVAS but with the
same hearing impairment, and compared the performance between the two
groups, particularly discussing motor development in-depth.
Our study showed developmental retardation both in LVAS children and
non-LVAS children. The retardation not only occurred in verbal
development but also in non-verbal developments. Through the grading the
developments, we found that the majority of children in this study had
mild neurological damage. Of all sub-developments, language developed
worst and motor developed best. According to the results, developments
of deaf children were worthy attention. Of note, the children in our
study were the group with sever or profound hearing loss. Thus the
developments in our study could not represent the whole performance of
the group with hearing impairments, because the hearing level was
associated with the developments revealed in previous research (24-26).
In previous literatures, delayed ambulation and poor coordination in
LVAS children were reported(8,10,11), which was consistent with our
above findings. Prior to foregoing study, we evaluated more
comprehensively including the gross motor such as sitting, walking and
balance ability, and fine motor such as grabbing, pitching and
coordination ability. In this study, compared with normal developmental
criteria, LVAS children had developmental delay in gross motor, while
non-LVAS children had the normal performance in gross motor. For the
children with LVAS, a special group of hearing impairment, were their
developmental level different from the other deaf children? To addressed
the question, we compared the performance between the two groups and
didn’t found any significant difference including gross motor.
Although vestibular weakness have been marked in LVAS patients in
previous study(3,4), while motor retardation and disbalance of LVAS
children in our study couldn’t be concluded caused by vestibular
disorder. According to our study, we could only describe such a
phenomenon and couldn’t conclude whether the vestibular dysfunction
induced by LVAS has effects on development, of which the reasons could
be summarized as follows. Firstly, the progress of hearing loss in LVAS
patients was fluctuate(27), whereas the hearing thresholds of LVAS
children in our study tend to their worst hearing level because they
were candidate to cochlear implantation in our hospital. So, the hearing
threshold couldn’t represent the real average auditory level of LVAS
children. Secondly, the age of hearing loss occurring, the duration of
disease, and the usage of hearing aids, which might affect the
developments, weren’t normalized. Last but not least, although the LVAS
patients were with high rates of vestibular dysfunction, the children
with abnormal vestibular test results might not appear vestibular
symptoms (8). In addition, balance ability were affected not only by
vestibular consciousness but also by vision and proprioception(28). When
one of them was damaged, the other functions would form
compensation(29).Therefore, longitudinal follow-up study, vestibular
tests, more evaluation specially for motor and balance should be adopted
to address these issues.
In the clinical practice, regardless whether the vestibular dysfunction
caused by LVAS had additional effects on developments, the phenomenon
that there was no difference in developments between the two above
groups was a great news for us. If so, we didn’t pay extra attention to
the developments in LVAS, compared with the other deaf children.
Meanwhile, we could focus on the prevention to hearing deterioration in
LVAS children and the search of good intervention methods after hearing
impairments occurred.
Our study also found that age of intervention was the negative related
factors for developments except fine motor. Thus, we further compared
the developments among the different age group and found that the delay
appearance infancy (6-12 months) to toddler (12-36 months) stage,
whereas the developmental levels of the toddler and preschool (36-72
months) stages were no obvious difference. So, we could say that the
delay started from the 1-year-old, which suggesting that the
intervention should be performed before 1- year-old. Until now, hearing
aids and cochlear implantation have been effective approach for
increasing auditory perception(1,30,31). According to previous
literature that intervention as soon as possible could improve the
prognosis of hearing-impaired children(32,33). Moreover, children with
LVAS undergoing cochlear implantation did well audiometrically and
functionally as other deaf children without LVAS(34,35).
Considering the variety of hearing performance in LVAS children, we paid
particular attention to the difference between binaural hearing. Of the
LVAS subjects in our study, the mean difference between binaural hearing
was more than 10 dB nHL with more than half of asymmetric hearing loss
rates. Individuals with asymmetric sensorineural hearing loss have
reported discomfort in daily living, both audiologically and
psychosocially due to poor localization of sound and poor speech
recognition in noise(36-38). whether would the asymmetric hearing loss
affect the development of children especially the motor development?
Then, we include the symmetry of the binaural hearing as a potential
related factor. Through the analysis, we found that no matter the value
of difference between binaural hearing or the symmetry couldn’t affect
the developments of LVAS children, including the motor development.
Owing the children in our study were all with sever or profound hearing
loss, it’s possible that the influence from the symmetry was covered up
by the effects from auditory deprivation
As potential limitation we have stressed in the article, this study was
a cross-sectional study and vestibular function wasn’t been evaluated in
this study. So, whether vestibular function affected development of
children couldn’t be deduced. In addition, the age of hearing loss
occurring and diagnosis, the duration of disease, and the usage of
hearing aids, which might be the important factors for developments
weren’t into use in this study. Longitudinal follow-up study,
professional evaluation specially for motor, balance vestibular tests,
and vestibular function, and fully integrated information, should be
adopted to address these issues. Of note, both objective and subjective
evaluation on vestibular function were difficult to perform on young
children, especially on deaf children. While, some scale such as Gesell
development schedule adopted in this study was an effective and feasible
method to evaluate performance of deaf children, which was further
beneficial to formulate intervention strategy of cochlear implantation
and rehabilitation strategy.