Presence Of Otoacoustic Emissions Research Articles

Assistive Devices for Patients with Auditory Neuropathy: Hearing Aid Use

Auditory neuropathy (AN) is a hearing disorder characterized by disruption of temporal coding of acoustic signals in the auditory nerve resulting from lesions involving auditory nerve fibers, the inner hair cells, or their synapses with auditory nerve terminals. Disruption of auditory nerve discharge underlies both the absence of auditory brainstem responses (ABRs) and impairment of speech perception. AN may be related to genetic disorders or result from a wide range of other etiologies. It can be identified either as an isolated disorder (isolated AN) or associated with multisystem involvement (non-isolated AN). Effectiveness and choice of assistive devices depend crucially upon etiology, site of lesion, and stage of the disease. Cochlear implants constitute an effective rehabilitative tool able to restore speech perception in many patients with genetic AN, especially those affected by the isolated form of the disorder. Some children with isolated AN have proved to be good hearing aid users, showing satisfactory open-set speech perception abilities in the aided condition. Over 50% of children discharged from neonatal intensive care units showing the electrophysiological profile of AN (absent ABRs, presence of otoacoustic emissions) benefit from hearing aid use, the provision of amplification resulting in remarkable improvement in speech perception. It can be concluded that differences in cochlear implant outcome or hearing aid use in patients with AN are related to the pathophysiological mechanisms underlying alteration of auditory nerve discharge associated with individual etiologies.

Neuropatia auditiva: alerta aos pediatras

OBJETIVO: Alertar os pediatras sobre a neuropatia auditiva, doença descrita recentemente e ainda desconhecida por muitos médicos. Descrever seus fatores de risco, características clínicas e diagnósticas, com a finalidade de possibilitar uma intervenção terapêutica precoce e eficaz. FONTES DE DADOS: Realizada pesquisa nas bases de dados PubMed, Lilacs e SciELO utilizando os descritores "neuropatia auditiva" e "auditory neuropathy", entre os anos de 1996 e 2010. SÍNTESE DOS DADOS: A neuropatia auditiva, também conhecida como dessincronia auditiva, descrita em 1996, caracteriza-se clinicamente pela dificuldade na compreensão das palavras, mesmo em casos de perdas auditivas leves ou moderadas. Foi relacionada a diversas neuropatias generalizadas e fatores de risco neonatais, como internação em terapia intensiva, hiperbilirrubinemia, sepse e hipóxia. Após suspeita clínica, o diagnóstico é confirmado pela presença das emissões otoacústicas associada a um potencial evocado auditivo de tronco encefálico ausente ou alterado. Sua terapêutica permanece controversa, tendo como opções a protetização auditiva, o acompanhamento fonoterápico para habilitação ou reabilitação da linguagem e, em casos de insucesso, há relatos de resultados satisfatórios com o implante coclear. CONCLUSÕES: Enfatiza-se a importância do reconhecimento pelo pediatra da neuropatia auditiva, entidade ainda pouco citada na literatura latino-americana da especialidade.

Case report of a child with otoacoustic emissions and profound hearing loss in whom otoacoustic emissions were preserved after cochlear implantation

The management of patients characterised by the presence of otoacoustic emissions and/or cochlear microphonics suggesting normal outer hair cell function in conjunction with absent or grossly abnormal auditory brainstem responses is often associated with particularly poor response to amplification. Cochlear implantation has been shown to be an option in affected patients. Here, we report a case of successful cochlear implantation and preserved otoacoustic emissions in a child suffering from this hearing disorder. Copyright © 2009 John Wiley & Sons, Ltd.

Presence of Otoacoustic Emissions in Patients with Otosclerosis before and after Surgery: Their Diagnostic Importance

Background and Aim: Stapes surgery, the first-choice treatment for otosclerosis, restores the ossicular chain mobility. Otoacoustic emissions, particularly transient-evoked (TEOAEs) and distortion product (DPOAEs), are capable of noninvasively recording both conductive hearing and cochlear function.

Ten(HL)-test results and psychophysical tuning curves for subjects with auditory neuropathy

Auditory neuropathy is a hearing disorder characterized by abnormal or absent auditory brainstem responses, and the presence of otoacoustic emissions and/or cochlear microphonics, indicating normal functioning of the outer hair cells. Here, subjects with auditory neuropathy, with near-normal hearing to moderate hearing loss, were tested using the TEN(HL) test for diagnosis of dead regions and also using psychophysical tuning curves (PTCs). Results for the majority of subjects met the TEN(HL)-test criteria at one or more frequencies (often at several or all frequencies). However, the PTCs did not show shifted tips. Hence, the positive results of the TEN(HL) test should not be interpreted as indicating the presence of dead regions. Rather, it appears that high thresholds in noise are caused by poor processing efficiency, perhaps associated with loss of neural synchrony.

A two-step scenario for hearing assessment with otoacoustic emissions at compensated middle ear pressure (in children 1–7 years old)

Otoacoustic emissions (OAEs) are widely used for assessing congenital and early-acquired sensorineural hearing loss in young children. Middle ear pathology has a negative effect on the presence of OAEs. In this study we investigated whether measuring OAEs at compensated middle ear pressure (CMEP) resulted in a higher pass rate than at ambient pressure. Secondly, we analysed the influence of 12 different pass definitions on the pass rates. One hundred and eleven children (age 1-7 years, mean 4 years and 5 months) were measured twice in one session: first at ambient pressure and then at CMEP. The study showed a higher pass rate of OAEs at CMEP than at ambient pressure. A two-step scenario reduced the number of fails by 18-26%, depending on the pass/fail definition used. Measuring OAEs at CMEP results in higher pass rates. Secondly, pass/fail definitions have a large influence on pass rates and this issue deserves further attention. Further studies must be done, before this method is readily applicable to universal neonatal screening.

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Auditory neuropathy (AN) is characterized by preservation of cochlear outer hair cell function, as evidenced by the presence of otoacoustic emissions and/or measurable cochlear microphonics, when the ABR is absent. Possible sites of AN are the inner hair cells, the auditory nerve and synaptic juncture between inner hair cells and the dendritic processes of the spiral ganglion cells. Thus hearing loss in AN may not be clearly categorized as cochlear or retrocochlear deafness using the currently available auditory testing methods. AN is found in patients ranging in age from infants to adults and can be clinically classified into two types, postlingual (adult) and the prelingual (infant) types, according to the age of onset. Two typical AN cases from each type are presented to discuss appropriate clinical management including cochlear implants for these patients. Despite increasing evidence from overseas showing the potential benefit of cochlear implants in prelingual-type AN, caution should be exercised when considering cochlear implantation in the postlingual type. Promontory stimulation test is thought to be useful in order for predicting postoperative performance with cochlear implants in adult patients.

Sacculo-collic pathway dysfunction accompanying auditory neuropathy

Conclusions. In a patient with bilateral auditory neuropathy (AN), the vestibular-evoked myogenic potential (VEMP) was probably absent because of a neuropathy involving the inferior vestibular nerve and/or its end organ, the saccule. Our result can therefore be interpreted as a concomitant unilateral sacculo-collic neuropathy. We suggest the use of more precise terms to characterize AN patients with involvement of different parts of the inner ear and its innervations. We encourage detailed vestibular assessment in patients with AN in order to assess the co-existence of any symptomatic or asymptomatic vestibular disorder. Information such as that provided in this report will be valuable for clinicians caring for this group of patients. Objective. AN is a disorder characterized by the absence or severe impairment of auditory brainstem responses in the presence of normal cochlear outer hair cell function as revealed by otoacoustic emissions (OAEs) and/or electrocochleography (ECoG). A variety of processes and etiologies are thought to be involved in its pathophysiology. In most literature reports the auditory profile of patients with AN is discussed. However, the extent of vestibular involvement, especially that involving the saccule, is not known. We performed vestibular tests to assess the status of the saccule in a patient with AN. Material and methods. One patient with AN was studied. The patient was a right-handed 21-year-old female with chief complaints of hearing loss and speech perception difficulty. Results. The auditory test results were consistent with the diagnosis of AN, i.e. absent auditory brainstem responses, moderate hearing loss, an inappropriately profound speech discrimination score and the presence of OAEs and measurable cochlear microphonics on ECoG. On neurological examination, gait and balance tests were normal. Ice-water caloric testing induced a sensation of dizziness in both ears. Short tone-burst VEMPs showed no response on left-ear stimulation and a biphasic response with normal latency and amplitude on right-ear stimulation.

Otoacoustic emissions at compensated middle ear pressure: preliminary results

Otoacoustic emissions (OAEs) are widely accepted for neonatal screening of congenital and early acquired sensori-neural hearing loss. The presence of middle ear pathology has a negative effect on the presence of OAE. In this study we investigated whether measuring OAEs at compensated middle ear pressure (CMEP) resulted in a higher pass rate than at ambient pressure. The results showed a higher pass rate of OAEs at CMEP than at ambient pressure, but in individual cases measurement at CMEP can result in a fail while there was a pass at ambient pressure.

The Aging Ear: Results from Animal and Human Studies

The most common causes of hearing loss are exposure to noise, aging, and the combined effects of the two. Anatomically, noise-induced hearing loss (NIHL) is characterized by a loss of sensory cells and secondary neural degeneration. Physiologically, NIHL is characterized by threshold elevations of the compound action potential of the auditory nerve, auditory brainstem response, and higher-level potentials. The endocochlear potential is most commonly unaffected. A distinctive feature of NIHL is the loss of cochlear nonlinearities, including otoacoustic emissions and two-tone rate suppression measured in single fibers of the auditory nerve. Degeneration of the stria vascularis is typically not associated with NIHL. The pathological anatomy and physiology of the aging ear is different from that associated with NIHL. The most dominant pathology is degeneration of the stria vascularis/lateral wall of the cochlea with a reduction in the endolymphatic potential from 90 to 100 mV to values as low as 10 to 20 mV. Blood supply is compromised and correlated with the extent of strial degeneration. A distinctive anatomic feature of the aging ear is the presence and normality of sensory cells except in the most basal and most apical regions. A distinctive physiological feature is the presence of otoacoustic emissions and two-tone rate suppression. There is significant degeneration of spiral ganglion cells in the presence of a normal population of sensory cells, thus suggesting an age-related primary degeneration of the auditory nerve. Thus, age-related hearing loss is not a sensorineural problem, as is NIHL, but is a vascular, metabolic, neural disorder.

Otoacoustic emissions and auditory perception.

The literature on the impact of otoacoustic emissions and their underlying mechanisms on the perception of sounds will be reviewed. Although stable spontaneous otoacoustic emissions are not normally heard, any rapid change in the frequency and level of an emission may cause it to be audible. Spontaneous emissions interact with external tones which may be responsible for some instances of monaural diplacusis. Otoacoustic emissions are associated with local minima in hearing thresholds measured with small frequency increments (threshold microstructure). Changes in the level and frequency of the emissions (occurring either naturally or during aspirin consumption and noise exposure) are correlated with changes in threshold microstructure. Frequency and intensity discrimination and perceived loudness of low level tones and nonsimultaneous masking of higher level tones are modified by the presence of otoacoustic emissions. Combination tones have been evaluated psychoacoustically for over 20 yr. Differences between psychoacoustic and otoacoustic estimates of combination tones will be discussed.

Frequency microstructure of pitch‐level functions

In a previous paper [E. M. Burns, J. Acoust. Soc. Am. Suppl. 1 77, S95 (1985)], the finding of no correlation between the frequency microstructure of the absolute threshold, associated with the presence of otoacoustic emissions, and the form of pitch‐level functions measured at various points on the threshold microstructure was reported. In the experiments reported in this paper, pitch‐level functions are measured at finer (20‐Hz) frequency intervals. Cyclical changes in the magnitude and direction of the low‐level portions (20–40 dB SPL) of the pitch‐level functions that correlate strongly with the approximately cyclical changes in threshold microstructure are found. [Work supported by NINCDS.]