Vestibular nerve functions in children with auditory neuropathy

Retro-labyrinthine Lesion Site Detected by Galvanic Vestibular Stimulation Elicited Vestibular-evoked Myogenic Potentials in Patients with Auditory Neuropathy

OBJECTIVE

Auditory neuropathy (AN) is a unique pattern of hearing loss with preservation of hair cell function. The condition is characterized by the presence of otoacoustic emissions (OAE) or cochlear microphonic (CM) responses with severe abnormalities of the auditory brainstem response (ABR). The vestibular branches of the VIII cranial nerve and the structures innervated by it can also be affected. However, the precise lesion sites in the vestibular system are not well characterized in patients with AN.

METHODS

The air-conducted sound (ACS) vestibular-evoked myogenic potentials (VEMPs) and galvanic vestibular stimuli (GVS)-VEMPs were examined in 14 patients with AN.

RESULTS

On examination of VEMPs (n=14, 28 ears), the absent rates of ACS-cervical VEMP (cVEMP), ACS-ocular VEMP (oVEMP), GVS-cVEMP, GVS-oVEMP and caloric test were 92.9% (26/28), 85.7% (24/28), 67.9% (19/28), 53.6% (15/28), and 61.5% (8/13), respectively. Impaired functions of the saccule, inferior vestibular nerve, utricle, superior vestibular nerve, and horizontal semicircular canal were found in 25.0% (7/28), 67.9% (19/28), 32.1% (9/28), 53.6% (15/28) and 61.5% (8/13) patients, respectively. On comparing the elicited VEMPs parameters of AN patients with those of normal controls, both ACS-VEMPs and GVS-VEMPs showed abnormal results in AN patients (such as, lower presence rates, elevated thresholds, prolonged latencies, and decreased amplitudes).

CONCLUSION

The study suggested that patients with AN often have concomitant vestibular disorders. Retro-labyrinthine lesions were more frequently observed in this study. GVS-VEMPs combined with ACS-VEMPs may help identify the lesion sites and facilitate detection of areas of vestibular dysfunction in these patients.

Importance of Vestibulo-ocular Reflex Gain and Refixation Saccade Analysis in Individuals with Auditory Neuropathy Spectrum Disorder

Introduction  Auditory neuropathy spectrum disorder (ANSD) features the presence of otoacoustic emissions, poor speech identification score and absent auditory brainstem response. Objective  The present study was designed to evaluate the functioning of all six semicircular canals in individuals with ANSD and to compare it with those of normal-hearing individuals. Methods  A total of 50 individuals participated in the present study, in which Group I comprised 25 normal-hearing individuals, and Group II comprised 25 individuals with ANSD. All of the participants underwent case history, pure tone audiometry, immittance, otoacoustic emissions, auditory evoked response and video head impulse test (vHIT). Results  The independent sample t-test revealed significantly lower vestibulo-ocular reflex gain values in individuals with ANSD. A presence of 100% corrective refixation saccades was observed in the same group. The Pearson correlation test revealed no significant correlation between vestibulo-ocular reflex (VOR) gain with duration of hearing loss and pure tone thresholds for any of the three orthogonal planes. The chi-squared test revealed no association between the VOR gain values and the presence or absence of saccades in any of the semicircular canals ( p  > 0.05). Conclusion  Huge percentages of individuals with ANSD have been found to have associated vestibular dysfunction as well. Therefore, the vHIT can be used as one of the important tests of the vestibular test battery to evaluate all six semicircular canals in individuals with ANSD.

Vestibular dysfunction in patients with auditory neuropathy detected by vestibular evoked myogenic potentials

OBJECTIVES

This study aimed to determine vestibular involvement in patients with auditory neuropathy (AN) using ocular vestibular evoked myogenic potential (oVEMP), cervical vestibular evoked myogenic potential (cVEMP), caloric tests, video Head Impulse Tests (vHIT), and Suppression Head Impulse Paradigm (SHIMP) tests.

METHODS

Twenty-two patients with AN (study group) and 50 age-and-gender-matched healthy subjects (control group) were enrolled. All patients underwent air-conducted sound oVEMP and cVEMP tests. In the study group, 20 patients underwent a caloric test, 10 patients underwent a video Head Impulse Test (vHIT), and nine patients underwent the Suppression Head Impulse Paradigm (SHIMP) test.

RESULTS

Significant differences in VEMP abnormalities were found between the two groups. Most AN patients showed no VEMP response, while only a few patients showed VEMP responses with normal parameters. Some AN patients presented abnormal VEMP parameters, including thresholds, latencies, and amplitudes. The abnormal rate (including no response and abnormal parameters) was 91% in the cVEMP test and 86% in the oVEMP test. No significant difference was found between oVEMP and cVEMP abnormalities. AN patients exhibited a 70% abnormal rate in the caloric test. Most AN patients showed normal VOR gains. Most patients showed no overt corrective saccades in vHIT, and exhibited normal anticompensatory saccades in the SHIMP test.

CONCLUSION

Many AN patients experience vestibular dysfunction, which may be detected by using a vestibular functional test battery.

SIGNIFICANCE

VEMP abnormalities might reflect the status and degree of vestibular involvement in AN.

Evaluation of saccular and inferior vestibular nerve function in children with auditory neuropathy spectrum disorder

PURPOSE

The aim of the current work was to evaluate the function of the saccule and inferior vestibular nerve in children with auditory neuropathy spectrum disorder (ANSD) by recording the cervical-evoked myogenic potentials (C-VEMP) on those children and to compare C-VEMP results in ANSD children of pre-lingual onset to those in ANSD children of post-lingual onset.

METHODS

The study included 38 ANSD children of pre-lingual onset, 16 ANSD children of post-lingual onset, and 20 control children. All participant children were subjected to C-VEMP testing using 500 Hz tone burst stimuli.

RESULTS

The vast majority of ANSD children of pre-lingual onset (35 out of 38; 92.1%) had bilateral intact C-VEMP response with C-VEMP parameters (amplitude, asymmetric ratio, latency, and inter-aural latency difference) that were not statistically different than those in the control children. Only three children had bilateral absent C-VEMP response. On the other hand, the majority of ANSD children of post-lingual onset (11 out of 16; 68.75%) had bilateral absent C-VEMP response. The remaining five children had bilateral intact C-VEMP response with C-VEMP parameters that were not statistically different than those in the control children.

CONCLUSIONS

The pathology of ANSD spares the saccule and inferior vestibular nerve in the vast majority of ANSD children of pre-lingual onset, while it involves them in the majority of ANSD of post-lingual onset reflecting different site(s) of lesion between the two ANSD categories. Such results have important clinical implications as regards to the management of ANSD in children.

Saccular dysfunction in children with sensorineural hearing loss and auditory neuropathy/auditory dys-synchrony

CONCLUSION

There is a correlation between the AN/AD disorder and the saccular dysfunction in children with severe sensorineural hearing loss, which means that saccular dysfunction can be a concomitant sign of AN/AD. In conclusion, the term of audio-vestibular dys-synchrony (AVS) is a more suitable description for this condition.

OBJECTIVES

Patients with auditory neuropathy/auditory dys-synchrony (AN/AD) characteristically demonstrate poor neural responses from the vestibulocochlear nerve and brainstem while displaying evidence of intact outer hair cells function. Therefore, the objective of this study is studying of the relationship of the saccular dysfunction with AN/AD disorder in children with sensorineural hearing loss.

METHODS

In this cross-sectional study, 100 children with bilateral severe-to-profound sensorineural hearing losses underwent audiologic tests and cervical vestibular-evoked myogenic potentials (cVEMPs) at the Audiology Department of Hamadan University of Medical Sciences (Hamadan, Iran).

RESULTS

Eleven children with bilateral severe sensorineural hearing loss were given to unilateral AN/AD disorder (11 ears), and two children (4 ears) had bilateral AN/AD (total = 13 children). The ears with AN/AD took the form of unrepeatable or absent waves of ABR and presence of OAEs. The statistical analysis of an independent t-test between AN/AD ears as compared to non-AN/AD ears of these 13 children showed that the mean latencies of p13 and the mean latencies of n23 and the mean peak-to-peak amplitude had significant differences.

Vestibular function in children with auditory neuropathy spectrum disorder

OBJECTIVE

Children with auditory neuropathy spectrum disorder (ANSD) account for about 10% of paediatric patients referred for cochlear implantation. Vestibulopathy may be associated with ANSD, and may have implications when formulating management plans in this patient group. We wanted to determine the incidence and predictive factors for vestibulopathy in this patient group to guide vestibular testing in this patient population, and give insight to the aetiology of ANSD.

METHODS

We reviewed the outcomes of vestibular function testing in a cohort of paediatric patients with ANSD.

RESULTS

Probable or definite vestibulopathy was seen in 42% of patients who were tested. Vestibulopathy was associated with medical co-morbidities, but was not associated with imaging findings.

CONCLUSIONS

Vestibulopathy is relatively prevalent in this patient group, and should be considered when planning the investigation and management of children with ANSD.

Auditory dyssynchrony or auditory neuropathy: understanding the pathophysiology and exploring methods of treatment

OBJECTIVE

To review the literature on auditory dyssynchrony (AD) or neuropathy which is characterized by absent auditory brainstem responses, normal otoacoustic emissions, and word discrimination disproportional to the pure tone audiogram.

RESULTS

Several papers attempt to estimate the prevalence of AD that seems to range between 0.23 and 2% in infants "at risk" for hearing impairment and it is considered to be responsible for approximately 8% of newly diagnosed cases of hearing loss in children per year. The prevalence gets even higher, reaching 10% in children with permanent hearing loss. It seems that AD is not a single disease but a spectrum of pathologies that affect the auditory pathway at the level of the inner hair cells, the synapses, or the auditory nerve. Many predisposing or contribution factors have been reported, including prematurity, hyperbilirubinemia, hypoxia, low-birth weight, immunological conditions, infectious diseases, etc. Before proposing any method of management, parents should be informed about the variation among patients and the changes that may appear in some children's audition over time. Sigh language, speech and language therapy, hearing-aids, and cochlear implantation have been used in the treatment of AD. In general, AD is rather refractory to conventional amplification and cochlear implantation has been found an effective method of management in young implanted children with severe/profound deafness and AD. However, the situation is more complicated and challenging in milder hearing losses.

CONCLUSION

The selected and proposed 30 related articles published in the International Journal of Pediatric Otorhinolaryngology aim to stimulate the related research in order to further explore the etiology, pathophysiology, and management of AD.

Cervical and Ocular Vestibular Evoked Myogenic Potentials Test Results in Individuals with Auditory Neuropathy Spectrum Disorders

Auditory neuropathy spectrum disorder is a clinical disorder where the outer hair cell functioning is intact but the functioning of the auditory nerve is affected. Since, the 8(th) nerve is constituted by both the auditory and vestibular branch of nerve fibers, there are chances that the vestibular nerve might also be affected. Hence, the current study was carried out in order to determine the functioning of vestibular nerve in individuals with auditory neuropathy. A total of 11 participants were considered for the current study. Cervical vestibular evoked myogenic potentials (cVEMPs) and ocular vestibular evoked myogenic potentials (oVEMPs) were administered using the conventional protocol. In all the participants (100%) the oVEMPs were absent whereas in 20 ears out of 22 ears tested (90.90%) the cVEMPs were absent. The results of the present study indicate a high incidence of vestibular involvement in individuals with auditory neuropathy spectrum disorders. Also, it necessitates the inclusion of vestibular tests in the test battery used to assess individuals with auditory neuropathy spectrum disorder.

Vestibular test findings in individuals with auditory neuropathy: review

Background:

The vestibulocochlear nerve is a sensory nerve that serves the organs of hearing and equilibrium. Neuropathies of the nerve, particularly auditory neuropathy, may be caused by primary demyelination or axonal disease. Cochlear amplification function is normal in cases of auditory neuropathy, but afferent neural conduction in the auditory pathway is disordered. It is highly probable that the vestibular nerve has some involvement in disorders affecting the cochlear nerve.

Objective:

To provide an overview of vestibular test findings in individuals with auditory neuropathy.

Method:

A structured literature search was carried out, with no restrictions to the dates searched.

Conclusion:

Auditory neuropathy implicated the vestibular branch of the VIIIth cranial nerve as well as the cochlear nerve. However, there was variability in terms of vestibular test findings.

Vestibular evoked myogenic potential (VEMP) in patients with auditory neuropathy: Auditory neuropathy or audiovestibular neuropathy?

CONCLUSION

Our results suggest that isolated auditory or vestibular involvement is unlikely and in fact audiovestibular neuropathy can better explain auditory neuropathy.

OBJECTIVE

The purpose of this study was to investigate saccule and related neural pathways in auditory neuropathy patients.

METHODS

Three males and five females diagnosed with auditory neuropathy were included in this prospective study. Patients' ages ranged from 21 to 45 years with a mean age of 28.6 ± 8.1 years and the history of disease was between 4 and 19 years. A group of 30 normal subjects served as the control group. The main outcome measures were the mean peak latency (in ms) of the two early waves (p13 and n23) of the vestibular evoked myogenic potential (VEMP) test in patients and controls.

RESULTS

Of the 8 patients (16 ears), normal response was detected in 3 ears (1 in right and 2 in left ears). There were unrepeatable waves in four ears and absent VEMPs in nine ears.