Assessment of Vestibular Functions in Cochlear Implant Children
Eman Mohamed Galal Mohamed;
Abstract
Several authors have investigated the effect of cochlear implantation
on the vestibular system, with high variability in results.The aim of this
study was to study the influence of cochlear implantation on vestibular
functions in children in addition to the emphasis on the affection on the
functional aspects. The study included 54 children divided into 2 groups;
study group comprised of 40 children with severe to profound sensorineural
hearing loss and control group comprised of 14 children, both groups were
matching as regards age & gender. The most common etiology of HL among
study group was the heredofamilial cause (40%) followed by unknown
etiology representing (32.5%). Radiological studies showed abnormalities in
only 2/40 (5%).
All cases of study group underwent cochlear implantation through round
window approach and straight electrode was fully inserted in the scala
tympani.
The preoperative parental complaints were history of delayed walking
in 12/40 (30%) and imbalance while walking in 4/40 (10%). Then
postoperatively, it was found that only onenew case had imbalance and
motion sickness after 3 months. The other complaint was the facial nerve
stimulation, that was present in 7 /40 (17.5%) of cases which was associated
with headache to loud sounds in 2 cases.
Follow up was done for the entire study group twice; 1month and 3-6
months postoperatively by the sametests that were done preoperatively, in
addition to the CDP that was done only 3-6 months postoperatively.
Test findings revealedoVEMPabnormalities in11/29 (37.9%)
preoperatively that changed postoperatively to 13/29 (45%); denoting
minimal utricular affection after CI.
On the other hand, cVEMP showed abnormal responses in 22/40(55%) preoperatively. Then postoperatively, the responses were
categorized as either unchanged (stable) or changed (unstable) responses. Regarding the unchanged responses, it constituted the majority of the results (55%). On the contrary, the lost responses in both 1 and 3-6 months postoperative follow up represented 15%(6/ 40) of cases. There were cases with temporarily absent response in only the one month postoperative follow up then the response recovered in 3-6 months postoperative. It represented 15%(6/40). Finally the cases who showed deteriorated absent response at the 3-6 months follow up presented 10/40 (25%) of cases. Regarding the preoperatively versus the postoperative findings of office tests, results revealed the following increase in abnormalities; for mCTSIB and one leg stance tests abnormalities increased in 12.5%&12.1% respectively. For both BOT and FGI abnormalities increased in 2.8% and 3.9% of cases respectively. HTT showed abnormalityin 2/40 (5%) of cases that remained the same postoperatively. HST showed no abnormal cases preoperatively, and then only one case (1/40; 2.5%) had abnormal HSTonly in the 1 month follow up. This reflected minimal affection of the SCC-VOR. Fukuda testshowed no abnormal cases detected preoperatively, then 2/ 40(6.7%) of cases showed abnormality postoperatively. Additionally,CDP was performed at the 3-6 m postoperatively in 25/ 40 children, 6/25 (24 %) showed abnormality in the composite scores. Most of these cases had abnormal cVEMP both pre and postoperatively. Moreover, 28 out of 40 (70 %) had cVEMP response through the device. The response parameters of cVEMP through the CI showed non-significant difference between latencies of P13 and N23 waves and also amplitude of cVEMP through the CI and regular cVEMP in 1 month and 3-6 months follow up. There was significant correlation between the presence of facial nerve stimulation (FNS) and the presence of cVEMP response through the CI. All the cases suffered from FNS had cVEMP response through the CI.
Accordingly,pediatric cochlear implant candidates have a high incidence (55%) of vestibular impairments. Unilateral cochlear implantation in our study resulted in adverse effects on the otolith as measured by c & oVEMP (cVEMP affection was more than oVEMP) but with a lower extent of affection on the functional performance of balance as measured by the office tests. Meanwhile, postoperative complaints as reported by the parents were out of proportion to the vestibular affection as it was not associated with significant affection on the functional performance of balance in pediatric CI recipients. The extra-cochlear electric current spread resulted in facial nerve stimulation and vestibular nerve stimulation. Vestibular assessment protocols should beinstated for pediatric SNHL candidates for implantation.This would include at least a clinical vestibularexamination including the head thrust test, head shake test, mCTSIB test and cVEMP to decide which ear to be implanted (the most poorly functioning vestibule). Also, proper counseling regarding bilateral implantation. Nevertheless, weshould aim to preserve not only a residual hearing functionbut also the vestibular function of the implanted ear, usingminimally invasive surgical techniques
on the vestibular system, with high variability in results.The aim of this
study was to study the influence of cochlear implantation on vestibular
functions in children in addition to the emphasis on the affection on the
functional aspects. The study included 54 children divided into 2 groups;
study group comprised of 40 children with severe to profound sensorineural
hearing loss and control group comprised of 14 children, both groups were
matching as regards age & gender. The most common etiology of HL among
study group was the heredofamilial cause (40%) followed by unknown
etiology representing (32.5%). Radiological studies showed abnormalities in
only 2/40 (5%).
All cases of study group underwent cochlear implantation through round
window approach and straight electrode was fully inserted in the scala
tympani.
The preoperative parental complaints were history of delayed walking
in 12/40 (30%) and imbalance while walking in 4/40 (10%). Then
postoperatively, it was found that only onenew case had imbalance and
motion sickness after 3 months. The other complaint was the facial nerve
stimulation, that was present in 7 /40 (17.5%) of cases which was associated
with headache to loud sounds in 2 cases.
Follow up was done for the entire study group twice; 1month and 3-6
months postoperatively by the sametests that were done preoperatively, in
addition to the CDP that was done only 3-6 months postoperatively.
Test findings revealedoVEMPabnormalities in11/29 (37.9%)
preoperatively that changed postoperatively to 13/29 (45%); denoting
minimal utricular affection after CI.
On the other hand, cVEMP showed abnormal responses in 22/40(55%) preoperatively. Then postoperatively, the responses were
categorized as either unchanged (stable) or changed (unstable) responses. Regarding the unchanged responses, it constituted the majority of the results (55%). On the contrary, the lost responses in both 1 and 3-6 months postoperative follow up represented 15%(6/ 40) of cases. There were cases with temporarily absent response in only the one month postoperative follow up then the response recovered in 3-6 months postoperative. It represented 15%(6/40). Finally the cases who showed deteriorated absent response at the 3-6 months follow up presented 10/40 (25%) of cases. Regarding the preoperatively versus the postoperative findings of office tests, results revealed the following increase in abnormalities; for mCTSIB and one leg stance tests abnormalities increased in 12.5%&12.1% respectively. For both BOT and FGI abnormalities increased in 2.8% and 3.9% of cases respectively. HTT showed abnormalityin 2/40 (5%) of cases that remained the same postoperatively. HST showed no abnormal cases preoperatively, and then only one case (1/40; 2.5%) had abnormal HSTonly in the 1 month follow up. This reflected minimal affection of the SCC-VOR. Fukuda testshowed no abnormal cases detected preoperatively, then 2/ 40(6.7%) of cases showed abnormality postoperatively. Additionally,CDP was performed at the 3-6 m postoperatively in 25/ 40 children, 6/25 (24 %) showed abnormality in the composite scores. Most of these cases had abnormal cVEMP both pre and postoperatively. Moreover, 28 out of 40 (70 %) had cVEMP response through the device. The response parameters of cVEMP through the CI showed non-significant difference between latencies of P13 and N23 waves and also amplitude of cVEMP through the CI and regular cVEMP in 1 month and 3-6 months follow up. There was significant correlation between the presence of facial nerve stimulation (FNS) and the presence of cVEMP response through the CI. All the cases suffered from FNS had cVEMP response through the CI.
Accordingly,pediatric cochlear implant candidates have a high incidence (55%) of vestibular impairments. Unilateral cochlear implantation in our study resulted in adverse effects on the otolith as measured by c & oVEMP (cVEMP affection was more than oVEMP) but with a lower extent of affection on the functional performance of balance as measured by the office tests. Meanwhile, postoperative complaints as reported by the parents were out of proportion to the vestibular affection as it was not associated with significant affection on the functional performance of balance in pediatric CI recipients. The extra-cochlear electric current spread resulted in facial nerve stimulation and vestibular nerve stimulation. Vestibular assessment protocols should beinstated for pediatric SNHL candidates for implantation.This would include at least a clinical vestibularexamination including the head thrust test, head shake test, mCTSIB test and cVEMP to decide which ear to be implanted (the most poorly functioning vestibule). Also, proper counseling regarding bilateral implantation. Nevertheless, weshould aim to preserve not only a residual hearing functionbut also the vestibular function of the implanted ear, usingminimally invasive surgical techniques
Other data
| Title | Assessment of Vestibular Functions in Cochlear Implant Children | Other Titles | تقييم وظائف الجهازالدهليزي في أطفال زراعة القوقعة | Authors | Eman Mohamed Galal Mohamed | Issue Date | 2015 |
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