|Year : 2017 | Volume
| Issue : 2 | Page : 74-77
Vestibular dysfunction in children with sensorineural hearing loss: A cross-sectional study
Poonam Raj1, Atul Gupta2
1 Department of ENT and HNS, Army Hospital (R and R), New Delhi, India
2 Department of ENT and HNS, Base Hospital, Delhi Cantt, New Delhi, India
|Date of Web Publication||14-Jun-2017|
Department of ENT and HNS, Army Hospital (R and R), New Delhi - 110 010
Source of Support: None, Conflict of Interest: None
Introduction: The cochlea and vestibule are anatomically and functionally related to each other and any dysfunction in each or both of them may result in vestibular functional derangement and subsequent deficit in the function of balance. This is especially true in children where the two systems are still evolving. Vestibular dysfunction has been reported in approximately 20-70 % of children with hearing loss of different causes. This study was aimed to detect and evaluate the prevalence of vestibular dysfunction in children with SNHL. Methods and Materials: Vestibular function assessment was done with monothermal warm air caloric test on 50 children less than 12 years of age with bilateral severe to profound SNHL. Recordings were made using a head band camera on SYNAPSYS Ulmer VNG software. “Monothermal Caloric Asymmetry” (MCA) was depicted in the recording software as unilateral weakness. MCA of >15 % was taken as evidence of canal paresis. Results: The mean age of the children was 5.48 years. Of the 48 children who successfully completed the test, 09 children had vestibular dysfunction indicative of canal paresis. Prevalence was 18.75 % with 95% CI (7.3, 30.2). Correlation between compensated vestibular function results with age and severity of SNHL was not significant. Conclusions: Children with SNHL should be evaluated for occult compensated vestibular dysfunction. It may also be relevant in the context of any further vestibular pathology the child may develop and should be kept in mind when surgical procedures like cochlear implantation are being contemplated.
Keywords: Caloric, sensorineural hearing loss, vestibular
|How to cite this article:|
Raj P, Gupta A. Vestibular dysfunction in children with sensorineural hearing loss: A cross-sectional study. Indian J Otol 2017;23:74-7
| Introduction|| |
During embryonal development, the audiovestibular system has a common origin. The peripheral end organ of the vestibular system precedes cochlear development and is developed by 49 days of gestation. This causes anatomical and functional inter-relation between the cochlea and vestibule. Hence, a dysfunction in any one of them may result in functional derangement of the other., Indeed vestibular dysfunction has been reported in approximately 20%–70% of children with hearing loss due to different causes. Since children may be asymptomatic as vestibular dysfunction may get compensated over time, tests such as caloric test, which can test each ear separately, can be used effectively to isolate this covert functional loss. This study aims at detecting and evaluating the prevalence of vestibular dysfunction in children with sensorineural hearing loss (SNHL) using monothermal warm air caloric test and correlating the vestibular function results with age and severity of SNHL. This study assumes importance because vestibular dysfunction if detected early would prevent delayed motor development in these children.
| Materials and Methods|| |
A cross-sectional study was carried out in a tertiary care hospital over a period of 1½ years. Fifty children <12 years of age with bilateral severe to profound SNHL who presented in the hospital for hearing rehabilitation and speech therapy were evaluated. This study group had children with comparable birth history, socioeconomic background, and developmental milestones. Children with any preexisting middle ear pathology, syndromic SNHL, visual or neurological condition, and with symptoms of acute vestibular dysfunction were excluded from the study. History was taken in detail, which included the onset, duration, and progression of hearing loss. This was followed by a detailed ENT examination of the child. Audiological workup included pure tone audiometry/behavioral observational audiometry, tympanometry, diagnostic otoacoustic emissions, and brainstem evoked response audiometry. High-resolution computed tomography scans of temporal bone and magnetic resonance imaging of brain were also done to rule out any structural abnormality of cochlea, central audiovestibular connections, and central nervous system. Written informed consent was taken from parents or guardians of all the children included in the study.
Vestibular function assessment was done by monothermal warm air caloric test. In monothermal air caloric testing, warm air was preferred over cold air because studies revealed that warm air is more sensitive than cool air for caloric responses., The British Society of Audiology guidelines also do not recommend the use of cool monothermal caloric test. During this test, child was placed on a reclining chair with head elevated at an angle of 30°to the horizontal. Uncooperative children were mildly sedated with syrup Triclofos at the dose of 0.5 mg/kg since this drug does not affect the vestibular function. Headband camera was placed over the eyes of the patient [Figure 1] and results recorded on Synapsys Ulmer VNG software (Synapsys S.A., Marseille, France). DIFRA coolstar air insufflator [Figure 2] was used to insufflate air at 8 L/min at temperature 50°C into the child's external auditory canal.
|Figure 1: Synapsys VNG headband camera on a child seated on reclining chair|
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The warm air insufflation was done for 60 s in one ear and caloric responses were recorded simultaneously on the software [Figure 3]. A gap of 5 min was given and similar responses were recorded in the opposite ear. “Monothermal caloric asymmetry” (MCA) was depicted in the recording software as “unilateral weakness.” This was based on the slow-phase velocity of the nystagmus generated by the warm air. MCA >15% was taken as evidence of canal paresis according to the British Society of Audiology guidelines.
|Figure 3: Results of monothermal warm air caloric test: SYNAPSYS Ulmer VNG software|
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The resultant vestibular dysfunction was correlated with the age, severity, and cause of SNHL. Correlation was done between these parameters and the vestibular function test results using Wilcoxon rank-sum test and Fisher's test and “P” value was obtained.
| Results|| |
The study included 50 children with SNHL, out of which 16 were female and 34 were male. The youngest child was 4 years old and the oldest was 9. The mean age of the children was 5.48 years (male: 5.53 years, female: 5.38 years). All the 50 children had congenital nonsyndromic SNHL with 45 children with profound and 5 with severe SNHL. Among 50 children who underwent warm air monothermal caloric testing, 48 were able to complete the testing. Two children were uncooperative while doing the procedure. Of the 48 children who successfully completed the test, 9 children had vestibular dysfunction indicative of canal paresis (defined as >15% MCA). This is depicted in [Figure 4].
|Figure 4: Dot diagram showing monothermal caloric test results in sensorineural hearing loss children|
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The MCA (expressed in percentage) as determined by warm monothermal air caloric test had a mean value of 10.76% with minimum and maximum values being 2.4% and 24%, respectively. Correlation between compensated vestibular function results with age is depicted in [Table 1]. [Table 2] correlates compensated vestibular function results with severity of SNHL.
|Table 2: Correlation of severity of sensorineural hearing loss with compensated vestibular dysfunction|
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| Discussion|| |
Due to the proximity of the cochlea and the vestibular apparatus (in terms of embryological development, innervation, and vascular supply), it is plausible that in children with SNHL, the cause of insult to the cochlea could probably also damage vestibular structures. The resultant dysfunction (unilateral or bilateral) in vestibular system may lead to subsequent derangement of the function of balance., However, attenuation/modification of this dysfunction may take place by vestibular compensation mechanisms and with visual and proprioceptive cues.
In the absence of sophisticated equipment and vestibular laboratory facilities, caloric testing is said to be the “gold standard” test for detecting unilateral vestibular dysfunction. This is also true as this test is cheap and easy to perform with acceptable reliability. It also tests the function of the lateral semicircular canal of both the ears separately. The British Society of Audiology guidelines (2010) have recommended that monothermal caloric test can be used effectively for screening children for evidence of vestibular dysfunction. As per these guidelines, the MCA should be >15% to establish evidence of vestibular dysfunction. The use of warm monothermal caloric testing is preferred over cold monothermal caloric testing as a superior modality. In a study by Longridge and Leatherdale, warm caloric screening was superior to bithermal caloric test results as excess false positive results were absent.
According to a study by Melagrana et al., use of monothermal warm air caloric test gave good sensitivity and specificity with respect to bithermal caloric test (83% and 90% for 90% probability; 78% and 92.5% for 95% probability). Lightfoot et al. in their study concluded that monothermal warm air caloric test could be used as an alternative to bithermal caloric test in children to detect vestibular dysfunction.
In our study, the prevalence of compensated vestibular dysfunction in children with SNHL (mean age 5 years) who presented for hearing rehabilitation and speech therapy was 18.75%. This is comparable to other studies which show that vestibular dysfunction has a high frequency of occurrence (up to 80%) in children with severe to profound hearing impairment.,, A study done by Arnvig also concluded that prevalence of vestibular dysfunction in children with deafness ranges between 20% and 70%. In a recent study by Cushing et al., vestibular end organ dysfunction occurred in half of all children with profound SNHL (69 out of 139 cases). Arnvig found vestibular responses (both caloric and rotatory) in 41% of 468 deaf children to be either absent or abnormal as did Rosenblüt in 49% of 107 deaf children (caloric responses).,
The prevalence in these studies was slightly more than our study, probably because multiple objective modalities of investigations - vestibular-evoked myogenic potential, rotary chair testing, and caloric testing were used for evaluation.
The median age of children who tested positive for vestibular dysfunction was 5 years. In our study, the prevalence of compensated vestibular dysfunction was independent of age as it was insignificant on statistical analysis. There are no relevant clinical studies correlating age as a factor for vestibular dysfunction in SNHL children. All the children in our study had SNHL, which was congenital and nonsyndromic. Studies have also found that the prevalence of vestibular dysfunction in postmeningitic SNHL children is higher; however, in our study, postmeningitic SNHL children were excluded being a neurological condition which can independently affect vestibular function.
In our study, 5 cases had severe SNHL and majority of the children, 45 in number, had profound SNHL. One out of five children with severe SNHL had evidence of vestibular dysfunction, whereas the other eight children with vestibular dysfunction had profound SNHL. Very few studies have been published relating severity of hearing loss to vestibular dysfunction. In a study by Pajor et al., no correlation was found between magnitude and type of hearing loss and vestibular impairment. In our study also, we found no correlation between severity of hearing loss and vestibular dysfunction as the results were statistically insignificant.
| Conclusions|| |
It is recommended that all children with SNHL should be evaluated for occult compensated vestibular dysfunction since our study has shown a significant prevalence of vestibular functional derangement in children with cochlear dysfunction. We also recommend the use of warm air caloric testing as a preliminary tool of testing as it has a high degree of sensitivity and specificity while still being inexpensive and easy to perform. Early detection of occult compensated vestibular dysfunction in cases of hearing loss will be helpful in planning surgical procedures including cochlear implantation. It may also be relevant in the context of any further vestibular pathology the child may develop.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]