Otoacoustic Emissions

The Impact of Pass/Refer Criteria in the Use of Otoacoustic Emission Technology for Newborn Hearing Screening

Purpose The current study aimed to compare the specificity of transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) in isolation and in combination, with varying pass/refer criteria for DPOAE technology. Method A longitudinal, repeated-measures design was employed. The current study sample comprised 91 of the initial 325 participants who returned for the repeat screening and diagnostic audiological assessment within a risk-based newborn hearing screening program. Results TEOAE screening had the highest specificity in comparison to DPOAE screening at the initial and repeat screening, irrespective of differences in DPOAE pass/refer criteria. DPOAE screening had a slightly higher specificity, with a three out of six rather than the four out of six frequency pass criteria. Conclusions Pass/refer criteria alone do not influence referral rates and specificity. Instead, consideration of other factors in combination with these criteria is important. More research is required in terms of the sensitivity and specificity of OAE screening technology using repeated-measures and diagnostic audiological evaluation as the gold standard.

Baseline audiological profiling of South African females with cervical cancer: an important attribute for assessing cisplatin-associated ototoxicity

BACKGROUND

Cisplatin is a popular antineoplastic agent used to treat cervical cancer in women from low and middle-income countries. Cisplatin treatment is associated with ototoxicity, often resulting in hearing loss. In light of this, it is crucial to conduct baseline audiological assessments prior to treatment initiation in order to evaluate the extent of cisplatin-associated-ototoxicity. Additionally, the identification of inherent risk factors and hearing patterns in specific patient cohorts is needed, especially in South Africa, a middle-income country characterized by the quadruple burden of disease (Human Immunodeficiency Virus (HIV), Tuberculosis (TB), Diabetes and Hypertension).

METHODS

This study aimed to describe a profile of risk factors and hearing in a cohort of females with cervical cancer before cisplatin treatment commenced. A descriptive study design that included 82 cervical cancer patients, who underwent audiological evaluation prescribed for ototoxicity monitoring was conducted.

RESULTS

All participants (n = 82) presented with risk factors (diabetes, hypertension, HIV, and antiretroviral therapy) for cisplatin ototoxicity and/or pre-existing sensorineural hearing loss. High-frequency tinnitus was the most common otological symptom experienced by 25 (31%) participants. Fifty-nine (72%) participants presented with normal hearing, twenty-two (27%) with a sensorineural hearing loss, and 36% were diagnosed with mild hearing loss. Abnormal Distortion Product Otoacoustic Emissions (DPOAE) findings were obtained bilaterally in two participants (2.4%), in the right ear only of another two (2.4%) participants and the left ear of three participants (3.7%). Most participants (94%) had excellent word recognition scores, demonstrating an excellent ability to recognize words within normal conversational levels under optimal listening conditions. Age was significantly associated with hearing loss at all thresholds. Among the co-morbidities, an HIV positive status significantly triggered hearing loss, especially at higher frequencies.

CONCLUSION

This study demonstrated that South African females with cervical cancer present with various co-morbidities, which may predispose them to develop cisplatin-associated -ototoxic hearing loss. Identification of these co-morbidities and hearing loss is essential for the accurate monitoring of cisplatin toxicities. Appropriate management of these patients is pivotal to reduce the adverse effects that hearing impairment can have on an individual's quality of life and to facilitate informed decision-making regarding the commencement of cisplatin chemotherapy.

Non-organic hearing loss in childhood

OBJECTIVE

The present study aimed to investigate the etiology, symptoms, diagnosis and prognosis of pediatric patients with non-organic hearing loss (NOHL), and to heighten awareness of this disorder among physicians.

METHODS

Between January 2000 and July 2009, we retrospectively reviewed the medical records of 47 pediatric patients (aged 6-18 years of age) diagnosed with NOHL. The diagnosis was made when there were audiometric discrepancies between the subjective and objective hearing thresholds of the patient in the absence of any organic disease.

RESULTS

Eighteen patients presented with unilateral hearing loss, and 29 showed bilateral hearing loss. Five patients received steroid treatment before the correct diagnosis was made, and six had secretory otitis media and underwent a tympanostomy tube placement.

CONCLUSION

If physicians are unaware of the possibility of NOHL; they may misdiagnose children with idiopathic sudden sensorineural hearing loss and administer high-dose steroid treatments or exploratory tympanotomies. Otoacoustic emissions are abolished when NOHL patients have secretory otitis media. In these cases, after tympanostomy tube placement, they should undergo objective electrophysiologic examinations to reevaluate NOHL.

The protective role of tiopronin in cisplatin ototoxicity in Wistar rats

The purpose of this study was to evaluate cisplatin-induced ototoxicity and the protective effects of tiopronin. Twenty-four adult Wistar rats served as subjects and were divided into three groups. Eight rats receiving only saline (group A) were used as controls. Eight rats received cisplatin (2 mg/kg) injections (group B) and eight rats received cisplatin and tiopronin (300 mg/kg) (group C) for 8 consecutive days. Both ears of all animals were tested by DPOAE before treatment and on the 4th and 9th days. Seventy-two hours after the final recording session, all animals were killed, and the left cochleas were prepared for electron microscopy and analysed. DPOAE responses were significantly reduced in group B compared to controls (p<0.05). When tiopronin was added, DPOAE responses were significantly increased compared to those obtained with the administration of cisplatin alone (p<0.05). The cochleogram showed that tiopronin had a significant protective effect in the basal half and in the lower half of the middle turn. We conclude that tiopronin, a drug effective in protecting against cisplatin nephrotoxicity, is also effective in protecting against cisplatin ototoxicity.

Cerebellar pilocytic astrocytoma with auditory presentation: case study

An 8-year-old girl complained of decreased hearing and difficulty hearing from her right ear while on the telephone. Pure-tone and speech audiometry, immittance (tympanometry, acoustic reflex thresholds), auditory brainstem response, and transient click-evoked otoacoustic emissions were administered. The results were suggestive of a space-occupying lesion, and the patient was referred to a pediatric neurologist and neurosurgeon. A cerebellar pilocytic astrocytoma was found. The patient's audiologic profile is described, along with implications for pediatric neurologic evaluations.

Distortion product otoacoustic emissions test is useful in children undergoing cisplatin treatment

BACKGROUND

Cisplatin is a widely used chemotherapy agent that has several adverse effects, such as ototoxicity. Evaluation of hearing loss due to cisplatin therapy in children is difficult. The purpose of this study was to compare the validity of distortion product otoacoustic emissions (DPOAEs) with pure tone audiometry (PTA) in assessing hearing loss in children under cisplatin therapy.

METHODS

We reviewed the files of 26 children aged between 2 and 15 years; 14 were girls. All were under treatment with cisplatin for malignancy. PTA and DPOAEs were obtained at the same session. Three subjects were studied twice; thus, there were 29 sets of studies.

RESULTS

Determining a cut-off point at 45 dB HL for PTA and 4 dB SPL difference for DPOAEs, diagnostic specificity for the latter was 0.97 while sensitivity was 0.57.

CONCLUSIONS

DPOAEs represent a highly valuable test for evaluating hearing loss due to cisplatin treatment. DPOAEs is a quick and objective hearing assessment method not requiring much cooperation from children.

The effect of midline petrous apex lesions on tests of afferent and efferent auditory function

OBJECTIVES

Historically, audiological procedures have focused on the assessment of the afferent (ascending) cochlear-VIIIth nerve system and have, for the most part, ignored the efferent (descending) auditory system. We report afferent and efferent auditory test results for two cases with a cholesterol cyst of the right petrous apex; one lesion involves the afferent segment of the auditory system, and the second lesion involves both the afferent and efferent segments of the auditory system. These "natural experiments" provide a unique opportunity to study the effect of a space-occupying lesion of the petrous apex on afferent and efferent function of the auditory system.

DESIGN

Transient evoked otoacoustic emission (TEOAE) suppression studies were performed to assess the effect of the cholesterol cyst on the efferent system of the two cases. In addition, three complementary afferent tests of brain stem auditory function were administered: 1) acoustic reflex thresholds (ARTs); 2) masking level difference (MLD); and 3) auditory brain stem response (ABR). These tests are complementary because the superior olivary complex (SOC) is involved not only in the mediation of the sound evoked efferent reflex assessed in TEOAE suppression, but in the mediation of the ARTs, the MLD, and the ABR.

RESULTS

The two cases with midline petrous apex lesions, one not involving the VIII-cochlear efferent auditory system, differed from each other with regards to TEOAEs suppression, and ARTs. Specifically, the case with only afferent involvement produced normal TEOAE suppression, a normal MLD, normal ARTs, and abnormal waves III and V of the ABR, whereas the case with both afferent and efferent involvement produced abnormal TEOAE suppression, a normal MLD, abnormal ARTs, and abnormal waves III and V of the ABR.

CONCLUSIONS

These cases illustrate that although several auditory tests can be mediated within the same or adjacent anatomical structures, i.e., the SOC, they may not be equally affected by the same lesion due to different physiology. Further, the TEOAE suppression paradigm is a clinically relevant test to assay the sound evoked efferent reflex that is mediated by the medial olivocochlear system of the SOC.

TEOAE monitoring of Cisplatin induced ototoxicity in guinea pigs: the protective effect of vitamin B treatment

OBJECTIVE

To evaluate Cisplatin (CP) induced ototoxicity and the effects of vitamin B treatment on ototoxicity in guinea pigs by using the Transient Evoked Otoacoustic Emission (TEOAE) technique.

METHODS

Eleven guinea pigs were divided into two groups and they were tested by TEOAE before and after the experiment. A TEOAE response was regarded as positive when all of the following criteria were met: 1. The mean amplitude of the cochlear response in dB pe SPL should be greater than that of the noise in the external auditory canal; 2. The reproducibility rate of the response should be greater than 50%; 3. The stimulus stability rate should be greater than 65%; 4. The signal to noise ratio of the response in 1, 2, 3, 4 and 5 kHz band frequencies should be greater than 3 dB pe SPL in at least two bands. The first group included five animals that had only CP injections. Six animals in the second group received additional 0.2 ml/kg combined vitamin B preparations for 7 consecutive days. Thereafter, the right and left ears of all animals in both groups were tested by TEOAE.

RESULTS

TEOAE responses recorded from 22 ears of 11 guinea pigs before drug administrations showed that the responses with maximum amplitude were originated from the mid-frequency region. Positive TEOAE responses were significantly reduced after CP administrations in both groups when compared with their respective pretreatment results (P<0.01). However, vitamin B injections, in addition to a single large dose of CP, resulted in significantly better TEOAE responses than those obtained after only CP injections (P<0.05).

CONCLUSIONS

The routine use of TEOAE monitoring is recommended in clinical CP treatment protocols for the early detection and follow up of ototoxicity. Also, prospective clinical trials are needed in order to validate the protective effects of vitamin B treatment against ototoxicity.

Outcome of newborn hearing screening by ABR compared with four different DPOAE pass criteria

The purpose of this study is to compare the effectiveness and utility of distortion product otoacoustic emission (DPOAE) and auditory brain stem response (ABR) testing as screening methodologies suitable for universal application at a large birthing hospital. Five hundred sixty-nine neonates (1184 ears) without risk indicators for hearing loss underwent DPOAE and ABR screening before hospital discharge at birth. All ears (100%) passed the ABR screening. DPOAE results were categorized on the basis of the number of frequencies at which emissions were obtained as well as presence versus absence of a replicated response at each test frequency. Pass and refer rates varied widely, on the basis of whether the presence of DPOAE response at 2000 Hz or replication were required. With the most stringent criteria, only 64.44% of ears passed, whereas with the least stringent criteria 88.94% passed. Given that 100% of ears passed according to the gold standard of the ABR screening, these results indicate false-positive rates ranging from 11% to 35% by DPOAE screening. This discrepancy in pass and refer rates when various criteria are applied indicates the need for standardization and further comparison of appropriate pass criteria for newborn hearing screening programs.

Multi-variant analysis of otoacoustic emissions and estimation of hearing thresholds: transient evoked otoacoustic emissions

Evaluation of cochlear hearing loss by means of transiently evoked otoacoustic emissions is already established in clinical practice. However, accurate prediction of pure-tone thresholds is still questioned and is still regarded as troublesome. Both click- and tone-burst-evoked otoacoustic emissions at several intensity levels were measured and analysed in 157 ears from normally hearing and 432 ears from patients with different degrees of pure sensory hearing loss using the ILO88/92 equipment. Results of otoacoustic emissions (OAE), elicited by clicks and tone-bursts at centre frequencies from 1 to 5 kHz, were analysed using two different statistical methods. Both multivariate discriminant analysis and forward multiple regression analysis were used to determine which OAE variables were most discriminating and best at predicting hearing thresholds. We found that a limited set of variables obtained from both tone-burst and click measurements can accurately predict and categorize hearing loss levels up to a limit of 60 dB HL. We found correct classification scores of pure-tone thresholds between 500 and 4000 Hz up to 100 per cent when using combined click and tone-burst otoacoustic measurements. Prediction of pure-tone thresholds was correct with a maximum estimation error of 10 dB for audiometric octave frequencies between 500 and 4000 Hz. Measurements of multiple tone-bursts OAEs have a significant clinical advantage over the use of clicks alone for clinical applications, and a good classification and prediction of pure-tone thresholds with otoacoustic emissions is possible.

Infant hearing screening: a comparison of two techniques

Hearing screening programs for Australian children are known to have poor coverage in many areas. In addition, only a minority of children are screened for hearing loss before 2 years of age. However, early detection of hearing loss and early treatment are generally considered very important to successful rehabilitation outcomes. Traditional methods of screening infants have limitations with their accuracy in detecting children with hearing loss. This study compared the results obtained with a traditional questionnaire approach to screening and a newer objective technique involving otoacoustic emission measures. Poor correlation was found between pass rates for the two techniques, suggesting that the questionnaire approach is not an accurate screening method for detecting infant hearing loss. With further development, otoacoustic emission testing holds promise as an objective alternative hearing screening procedure.

Identification of Hearing Loss in Children and Young Adults Using Measures of Transient Otoacoustic Emission Reproducibility

Measures of transient evoked otoacoustic emission (TEOAE) reproducibility were obtained for 506 ears of 260 children and young adults. Frequency-specific and whole reproducibility (WR) data were obtained using ILO88 hardware and software and were analyzed with respect to pure-tone threshold and immittance data for the same ears. Reproducibility scores were most robust in the frequency region of 2,000 Hz. In addition, the 2,000-Hz reproducibility score was the most efficient of all measurements (0.85 to 0.91) in separating normal and hearing-impaired ears, regardless of the frequency or frequencies at which the hearing loss occurred. Conductive hearing loss precluded detection of emissions. The present findings suggest that TEOAEs provide useful information in routine clinical practice and that they may be employed to screen for the presence of hearing loss in children and young adults.

Contralateral suppression of non-linear click-evoked otoacoustic emissions

Click-evoked otoacoustic emissions from nominal 80 dB pSP (peak sound pressure) 80-microseconds pulses presented at 50 pulses per second were collected from the right ears of eleven normal hearing subjects using an ILO88 Otodynamic Analyzer in the non-linear mode. Clicks, pure tones, and narrow bands of noise were then presented to their left ears through insert earphones. The 80-microseconds contralateral clicks ranged in intensity from 80 dB pSP in 5 dB steps down to 60 dB pSP but data on only 10 of the subjects were collected successfully. The pure tones and narrow bands of noise centered at 250, 500, 1000, 2000, and 4000 Hz were also presented through insert phones at 20, 40, 60 and 80 dB HL (Hearing Level) to all 11 subjects. The mean overall 'echo amplitude' without contralateral stimuli was 11 dB SPL and underwent more than 3 dB of overall suppression in response to the noises which were the most effective of the contralateral suppressors. When we analyzed the echo suppression to noise in 2-ms segments, we found consistent contralateral suppression of 3-4 dB concentrated in the time zones after 8 ms. Time shifts of more than 200 microseconds between the control and experimental traces were also observed in the same zones. The clicks were the next most effective suppressors, but showed their amplitude and time effects in somewhat earlier time zones. The tones were the least effective suppressors suggesting that efferent effects we measured in the human system are not strongly tonotopic. Because 'non-linear' mode high intensity clicks were deliberately selected as stimuli to evoke the TEOAE's, the emissions and their suppression can represent neither the 'true' TEOAE nor all of the efferent system's suppression abilities.

Does type I afferent neuron dysfunction reveal itself through lack of efferent suppression?

We present here two patients and three control subjects to demonstrate the clinical utility of studying evoked otoacoustic emissions and their contralateral suppression, as an aid to the delineation of afferent neuron dysfunction and possible lack of efferent suppression. The key patients here who fail to show contralateral suppression of their very robust otoacoustic emissions, concomitantly show paradoxically absent auditory brainstem responses (ABRs) and absence of middle ear muscle reflexes despite normal audiograms in the 2 kHz region and normal tympanograms. One of these patients has nearly normal pure tone sensitivity up to 3 kHz. The other has normal sensitivity in the 2 kHz region, but poor sensitivity on either side of that frequency. In addition, the two patients of interest show absent masking level differences and inordinately poor speech discrimination. Three 'foils' are presented: one patient with poor hearing on either side of 2 kHz, one with Bell's Palsy, and the third with bilateral temporal lobe disease. These patients show respectively that (1) isolated normal hearing at 2 kHz, (2) absence of middle ear muscle reflexes and (3) conscious cortical awareness of sound do not contribute directly to this intriguing clinical state. We propose that these patients with absent ABRs suffer from an auditory nervous system dysfunction which disrupts access to the efferent system. This condition also disables whatever systems contribute to the neural synchrony inherent in recording compound far-field action potentials such as the ABR. There are a number of hypotheses to be considered here. One suggests that the key patients are deficient in synchronous activation of Type I afferent fibers to the degree that they cannot activate efferent feedback, or they may be able to use only so-called Type II afferent neurons to support their normal zones of pure tone sensitivity. A less likely consideration focuses on the notion that discharge of primary neurons might be in some way synchronized by an efferent system which in these patients is the primary source of deficit.

Recent Advances in Tinnitus

Tinnitus can be the most debilitating symptom faced by people with hearing impairments. In the past 10 years, there has been a large increase in tinnitus research and in the development of clinical protocols. New animal models and physiological procedures provide an important contribution to the understanding and measurement of tinnitus. The annoyance of tinnitus likely depends on its loudness and the psychological makeup of the patient. The loudness of a person's tinnitus can be compared with the equivalent loudness of a 1000 Hz tone in a normal ear. Several questionnaires have recently been introduced to quantify the handicap caused by tinnitus. Tinnitus maskers are apparently ineffective for most patients but they can be helpful in a few patients. Medications are largely ineffective in reducing tinnitus in most people. However, several psychological techniques for reducing the stress associated with tinnitus are currently under investigation, and preliminary results show some promise. Tinnitus can be reduced by electrical stimulation in a few patients, and this is also an important area for future research.