الفهرس 
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Abstract
Rehabilitation in a deaf child aims to enable the development of oral language and verbal communication. Nowadays, cochlear implantation (CI) is considered the procedure of choice for rehabilitation of children with severe to profound SNHL.
The potential of CI on vestibular system was reported in 30–75% of the cases, with higher proportion in children (50-85%). There are two types of post CI dizziness, one occurs immediately or soon after the surgery with subsidence within few weeks and the other lasted several months due to deficits in vestibular function.
Number of established laboratory-based tests are used to evaluate the function of different parts of vestibular system including, for example, ENG or VNG test batteries, rotational chair testing, vHIT and VEMP.
The rotatory chair test provides a vestibular function assessment through a quantitative evaluation of (a-VOR) function of the lateral semicircular canals. It expands the peripheral vestibular system assessment beyond the region of very low-frequency stimulation that is tested by caloric testing. Rotatory chair testing is traditionally used as a vestibular test of the children population.
This Study aimed to assess short- and long-term impact of unilateral CI in children on the angular vestibulocular reflex using rotatory chair test.
Study was carried out on 46 children with severe to profound SNHL who were candidates for CI and underwent unilateral CI operation. All patients included in the study were submitted to full history taking, ENT examination, basic audiological evaluation including and rotatory chair test, SHA paradigm.
The study group was further subdivided according to time elapsed since operation into two groups. Each group was consisted of 23 children.
group (A) were recently implanted children, 16 males (69.57%) and 7 (30.43%) females, with age ranged from 4 to 10 years with a mean age of 6.26 years ±2.45. Right sided implantation was in 17 patients (73.91%) and left sided implantation was in 6 patients (26.09%). Time elapsed since surgical intervention was ranging from 4 to 12 weeks with a mean of 6.391 weeks ± 2.74.
group (B) with surgery since longer periods, consisted of 11 males (47.8%) and 12 (52.2%) females, with age ranged from 5 to 18 years with a mean age of 7.83 years ± 3.56. With 19 right sided implanted patients (82.6%) and left side in 4 patients (17.4%). Surgical intervention was ranging from 1 to 7 years with a mean of 3.43 years ± 1.87.
Results of each group were compared to the manufacturer normative range for the three parameters (gain, asymmetry, and phase). Regarding gain parameter, gain results of implanted ears were compared with the results of the non-implanted ears within the same group and those of the implanted ears of both groups versus each other, making test more ear specific.
group A rotary chair test results showed only differences when compared to the normative data mainly at 0.02 Hz in average gain and 0.01 Hz in phase, and when the implanted ears were compared with the non-implanted ears, there was significant difference in the specific gain parameter only at 0.32 test frequency.
While group B results did not show any differences when compared either to the normative data or those of the implanted ears versus the non-implanted ears.
Both groups versus each other regarding the three parameters showed only significance in phase parameter at test frequencies 0.01 and 0.04, in average gain at 0.02 test frequency and in specific gain at both 0.16 and 0.32 test frequencies.