الفهرس 
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Abstract
The importance of studying the relationship between peripheral vestibular function in the setting of deafness is underlined by the fact that SNHL is the most common congenital sensory impairment occurring in 3 out of every 1000 live births (NCHAM, 2006). Should even a small proportion of these individuals with SNHL exhibit concurrent vestibular involvement, this would still account for large numbers of individuals with vestibular dysfunction requiring identification, education and therapy (Cushing et al., 2008).
Understanding the correlation between vestibular function and hearing impairment is important as vestibular dysfunction may lead to a delay in reaching motor milestones which may provide an indication of either a progressive or missed hearing loss. Proper assessment of a gross motor delay (sitting, walking) in the absence of deficits in fine motor function could lead to earlier identification than would occur with the failure to develop language, the true hallmark of hearing loss (Valente et al., 2005).
VEMP is a measure of the reflexive contraction of SCM of the neck in response to high intensity acoustic stimulation. It has emerged as an effective tool to assess the function of the saccule and the IVN as well as neural linkages in the brainstem and to the neck (Colebatch et al., 1992, 1994; Halmagyi et al., 1995; Robertson and Ireland, 1995).
VEMP has a number of advantages: It is an objective, non-invasive, low-cost, quick assessment that is easy to execute, with no discomfort for the individual being evaluated.
The aim of this study was to investigate saccular function using VEMPs in children with congenital or acquired sensorineural hearing loss.
This study was conducted on thirty children (12 males and 18 females) with different degrees of SNHL (from mild to profound hearing loss) and these constituted the patient group. Twenty five children (13 male and 12 female) with normal hearing levels served as the control group. The age range of all children was from 5 up to 18 years old.
All children underwent full history taking, otological examination, PTA, immitancemetry and VEMP to detect saccular function; all parameters of VEMP response were performed (P13 and N23 latencies, P13-N23 amplitude and VEMP threshold). CT scan was also performed to exclude any inner ear anomalies or pathologies.
The distribution of the SNHL in the patient’s group was: 7 ears (11.7%) with mild hearing loss, 11ears (18.3%) with moderate hearing loss, 11 ears (18.3%) with moderately severe hearing loss, 18 ears (30%) with severe hearing loss and 13 ears (21.7%) with profound hearing loss.
In our study, the patient and control – related variables (age, gender, hearing level, consanguinity, use of hearing aids) and VEMP related variables (P13 latency,N23 latency, VEMP amplitude, VEMP threshold) were analyzed. Comparisons and correlations between the studied parameters were carried out.
On comparing the patient and the control group, there was a non significant difference between the two groups regarding age and gender. While consanguinity and the use of H.As showed a highly significant difference between the two groups.
VEMP amplitude and VEMP threshold were highly statistically significant between the patient and the control groups (higher VEMP threshold and lower VEMP amplitude in the patient group) but insignificant differences in P13 and N23 latencies were detected.
There was highly significant positive correlation between hearing level and VEMP threshold, a highly significant negative correlation between hearing level and P13-N23 amplitude and insignificant correlation between hearing level and P13 and N23 latencies among the study groups.
In the patient group, VEMP threshold was higher in females than males (VEMP threshold demonstrated a significant difference as regards gender) with no significant difference between the other VEMP parameters and gender.
The correlation between hearing loss and VEMP results within the patient group revealed a highly significant positive correlation between hearing level and VEMP threshold with no significant difference in the other parameters of VEMP.
As for correlation between age and different VEMP outcomes, results demonstrated a significant positive correlation between age and P13 and N23 latencies with no significant correlation in P13-N23 amplitude and VEMP threshold among the patient group.
The comparisons of different VEMP measurements with different degrees of hearing level among the patient group showed that N23 latency and VEMP threshold increase with the increase in hearing loss.
We can conclude from this study that SNHL is associated with saccular dysfunction in the pediatric population as indicated by the presence of abnormal VEMP responses (decreased P13-N23 amplitudes and elevated VEMP thresholds). Female children with SNHL presented with higher VEMP threshold than males. The increase in hearing loss is associated with an increase in VEMP threshold and VEMP P13 and N23 latencies increase with age in children with SNHL. Comparisons of the different degrees of hearing loss in relation to VEMP outcomes revealed consistently that VEMP threshold was the most affected parameter and finally VEMPs could be recorded despite the presence of severe degrees of SNHL.
We recommend including VEMPs in the battery of evaluation of children with SNHL to detect early subtle changes in saccular function and also for CI candidates. Further research on the genes causing SNHL and its relation to VEMP findings.