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Recording auditory evoked responses (AER) is done not only in hospitals and clinics worldwide to detect hearing impairments and estimate hearing thresholds, but also in research centers to understand and model the mechanisms involved in the process of hearing. This paper describes a high-performance, flexible, and inexpensive AER recording system. A full description of the hardware and software modules that compose the AER recording system is provided. The performance of this system was evaluated by conducting five experiments with both real and artificially synthesized auditory brainstem response and middle latency response signals at different intensity levels and stimulation rates. The results indicate that the flexibility of the described system is appropriate to record AER signals under several recording conditions. The AER recording system described in this article is a flexible and inexpensive high-performance AER recording system. This recording system also incorporates a platform through which users are allowed to implement advanced signal processing methods. Moreover, its manufacturing cost is significantly lower than that of other commercially available alternatives. These advantages may prove useful in many research applications in audiology.

In auditory animal research it is crucial to have precise information about basic hearing parameters of the animal subjects that are involved in the experiments. Such parameters may be physiological response characteristics of the auditory pathway, e.g. via brainstem audiometry (BERA). But these methods allow only indirect and uncertain extrapolations about the auditory percept that corresponds to these physiological parameters. To assess the perceptual level of hearing, behavioral methods have to be used. A potential problem with the use of behavioral methods for the description of perception in animal models is the fact that most of these methods involve some kind of learning paradigm before the subjects can be behaviorally tested, e.g. animals may have to learn to press a lever in response to a sound. As these learning paradigms change perception itself (1,2) they consequently will influence any result about perception obtained with these methods and therefore have to be interpreted with caution. Exceptions are paradigms that make use of reflex responses, because here no learning paradigms have to be carried out prior to perceptual testing. One such reflex response is the acoustic startle response (ASR) that can highly reproducibly be elicited with unexpected loud sounds in naïve animals. This ASR in turn can be influenced by preceding sounds depending on the perceptibility of this preceding stimulus: Sounds well above hearing threshold will completely inhibit the amplitude of the ASR; sounds close to threshold will only slightly inhibit the ASR. This phenomenon is called pre-pulse inhibition (PPI) (3,4), and the amount of PPI on the ASR gradually depends on the perceptibility of the pre-pulse. PPI of the ASR is therefore well suited to determine behavioral audiograms in naïve, non-trained animals, to determine hearing impairments or even to detect possible subjective tinnitus percepts in these animals. In this paper we demonstrate the use of this method in a rodent model (cf. also ref. (5)), the Mongolian gerbil (Meriones unguiculatus), which is a well know model species for startle response research within the normal human hearing range (e.g. (6)).

Objective: Both transitory auditory otoemissions (TEOAE) and automated auditory brainstem responses (AABR) are considered adequate methods for universal hearing screening. The goal of this study was to compare the results obtained with each device, applying the same screening procedure., Materials and Methods: From 2001 to 2003, all the newborns in our health area (2454 infants) were evaluated with TEOAE (ILO92, otodynamics) and all those born from 2004 to 2006 (3117) were evaluated with AABR (AccuScreen, Fischer-Zoth). The population studied included all well newborns and those admitted to neonatal intensive care units (NICU). The first screening was normally undertaken with well babies during the first 48h of life, before hospital discharge. Infants referred from this first step underwent a second screening after hospital discharge, before they were a month old., Results: The results from each study group were compared and analyzed for significant differences. TEOAE screening yielded 10.2% fail results from the first screening step; AABR gave 2.6%. In the second screening step, 2% of the newborns screened with TEOAE were referred, whereas 0.32% of those screened with AABR were referred. These differences are statistically significant., Conclusions: Although AABR screening tests involve a slightly higher cost in time and money than TEOAE, the results obtained compensate this difference. AABR gives fewer false positives and a lower referral rate; the percent of infants lost during follow-up is consequently smaller. Therefore, in our environment, universal newborn auditory screening with AABR is more effective than that with TEOAE.

The cost-effectiveness of current diagnostic approaches employed in patients with suspected acoustic neuroma was evaluated. Currently, patients with signs and symptoms suggestive of acoustic neuroma, such as sudden unilateral hearing loss and/or tinnitus, undergo auditory brainstem response (ABR) screening tests to rule out this condition. If the ABR is normal, acoustic neuroma can be ruled out. However, if the ABR is abnormal, magnetic resonance imaging (MRI) or computed tomography is necessary to confirm the diagnosis. When one considers the total costs of this screening approach, one can ask whether straight MRI screening of all of these patients would be a more cost-effective approach to diagnosing this condition. A retrospective chart review of patient records obtained from the acoustic diagnostics laboratory at Hotel Dieu Hospital, Kingston, Ontario, was performed. A database of patients who have undergone ABR testing over the past 2 years was compiled and analyzed to assess how many of them went on to receive MRI. The total costs (based on Ontario Health Insurance Plan [OHIP] fee schedule rates) of this approach were compared with the estimated costs of straight MRI screening performed on the same patient population. By making such an analysis, decisions regarding the most cost-effective approach to screening for acoustic neuroma can be objectively assessed.

Objective: Our goals were to define the most sensitive techniques of acoustic neuroma diagnosis, to examine their relative costs, and to propose diagnostic modality selection given the rarity of acoustic neuroma incidence and given the other costs that society faces in more commonly encountered diseases., Methods: We conducted a MEDLINE search of the English language from 1966 to 2001 using the following keywords: acoustic neuroma, acoustic tumor, vestibular schwannoma, diagnosis, cost effectiveness, MRI, auditory brainstem response, brainstem audiometric evoked response, incidence, and prevalence., Results: Although magnetic resonance imaging with gadolinium remains the most sensitive diagnostic modality in the discovery of acoustic neuromas, its cost may be prohibitive for some societies., Conclusion: Which modality to use in acoustic neuroma diagnosis is just as much a philosophical and macroeconomic question as a technological one., Clinical Significance: The cost of a timely diagnosis of acoustic neuromas must be weighed against using resources for other, more pressing, health concerns.

The aim of this study was to retrospectively assess during two periods (1991-1995 and 1996-2000) if MRI spreading had changed: (1) private ENT physicians screening habits; (2) the average tumor size at the time of diagnosis and the diagnostic delay of acoustic neuroma; and (3) the cost of acoustic neuroma diagnosis. In addition, the sensibility of each diagnostic test was calculated on 151 tumors. Our results show no significant change neither in the screening strategy (except a mild decrease in CT-scan utilization) nor in the tumor size, diagnostic delay or diagnostic cost between the two periods. Even if MRI is the gold standard for acoustic neuroma diagnosis, our 86%-sensibility of ABR, increased to 99% if combined with stapedial reflex and caloric test may still incline to use ABR in selected cases.

Objective: To compare the cost effectiveness of various strategies for neonatal hearing screening by estimating the cost per hearing impaired child detected., Design: Cost analyses with a simulation model, including a multivariate sensitivity analysis. Comparisons of the cost per child detected were made for: screening method (automated auditory brainstem response or otoacoustic emissions); number of stages in the screening process (two or three); target disorder (bilateral hearing loss or both unilateral and bilateral loss); location (at home or at a child health clinic)., Setting: The Netherlands, Target Population: All newborn infants not admitted to neonatal intensive care units., Main Outcome Measure: Costs per child detected with a hearing loss of 40 dB or more in the better ear., Results: Costs of a three stage screening process in child health clinics are 39.0 pounds (95% confidence interval 20.0 to 57.0) per child detected with automated auditory brainstem response compared with 25.0 (14.4 to 35.6) pounds per child detected with otoacoustic emissions. A three stage screening process not only reduces the referral rates, but is also likely to cost less than a two stage process because of the lower cost of diagnostic facilities. The extra cost (over and above a screening programme detecting bilateral losses) of detecting one child with unilateral hearing loss is 1500-4000 pounds. With the currently available information, no preference can be expressed for a screening location., Conclusions: Three stage screening with otoacoustic emissions is recommended. Whether screening at home is more cost effective than screening at a child health clinic needs further study.

Background: The necessity of screening examinations in newborns today cannot be denied. Up to now, it has only been achieved in a few countries to introduce a general hearing screening for newborns., Methods: We examined 100 newborns (200 ears) at their third day of life. All ears were evaluated with the TEOAE-screening-device ECHOSCREEN. In addition, we carried out BERA screening examinations with the ALGO PORTABLE or with the EVOFLASH on 100 of these 200 ears. As a reference method, we utilized TEOAE-examinations with the ILO-88 for all ears., Results: 4.5% of the 200 ears examined with the ECHOSCREEN were conspicuous due to accumulation of earwax problems. With the ALGO-system, none of the ears was conspicuous. Among the 100 ears examined with the EVOFLASH we found negative results with seven ears (4 children). These findings will be discussed in detail. Furthermore, we analyzed the costs for one-step- and two-step-screenings. Costs for a one-step-screening of both ears would be DM 14.27 with Echoscreen, DM 44.69 with ALGO, DM 32.19 with Evoflash for one patient including material and personnel costs. Costs for a two-step-screening would be DM 16.28 with Echoscreen and ALGO, DM 15.72 with Echoscreen and Evoflash, calculated per child on the basis of 812,173 newborn children in the year 1997 in Germany., Conclusion: On the basis of all these results, we recommend a two-step-screening with TEOAE and BERA-devices.

A system for recording of evoked potentials from auditory stimulation was developed. The system consists of a PC equipped with an audio bandwidth board with analog input and output channels. The sound stimulus signal is generated in the computer, D/A converted, and via audio amplifier fed to earphones on the test subject. Auditory evoked potentials in response to sound stimuli are recorded via electrodes, amplified and filtered in an EEG recording system and fed to an A/D converter. The signal is analysed in the PC. The modular design of the program makes it a flexible system where stimulus and recording parameters can easily be modified and new applications can be added to standard clinical measurements. Three applications that are not possible with commercially available systems were developed and evaluated. a) A diagnostic procedure to verify hydrops in patients with Meniere's disease. b) Intraoperative recordings of auditory evoked potentials during neurootological surgery. c) Recording of mismatch negativity (MMN) potentials in evaluation of central auditory functions.

Objective: To perform hearing screenings on all newborns before hospital discharge, using auditory brainstem evoked responses with analysis of time, cost, and failure rates to evaluate and determine the screening practicality., Method: Over a 3-year period from January 1, 1993 to December 31, 1995, auditory brainstem evoked response screenings were performed on 15 749 infants born at Saint Barnabas Medical Center, Livingston, New Jersey, before their hospital discharge by certified/licensed audiologists. The auditory brainstem evoked response screenings were conducted using the Nicolet Compass Evoked Potential System., Results: A 3-year experience of testing 15 749 infants proved to be a cost-effective program with costs less than $30.00/baby. To date, 46 babies have been identified with bilateral sensorineural hearing loss and 6 babies with unilateral sensorineural hearing loss., Conclusions: The universal newborn hearing screening program at Saint Barnabas Medical Center has proved to be effective, beneficial, and necessary for an institution with more than 5000 births, annually. Early identification of hearing loss has resulted in infants receiving early intervention, and the screening program has provided education and follow-up services to both parents and physicians.

The click-evoked otoacoustic emission (EOAE) recording procedure is a simple and quick test to perform. Some suggest that the EOAE is a more efficient newborn hearing screening procedure than the auditory brain stem response (ABR). However, one shortcoming of the EOAE is a high false-positive rate in newborns, which is attributed to ear-canal debris. The purposes of this study were to assess the initial pass/fail rates of ABR and EOAE measurements and the effectiveness of repeated EOAE measurements as a method of reducing the false-positive rate. Fifty healthy, low-risk newborns sequentially underwent ABR, repeated EOAE, otoscopy, EOAE, and ABR if necessary. The initial ABR passing rate was 98%, whereas the EOAE passing rate was 61%. The EOAE passing rate improved with each retest and approximated the ABR rate by the fourth test. EOAE failures and the overall level of the EOAE were found to be significantly related to the amount of ear-canal debris. These results indicate that some newborns will require four or more tests before they eventually pass. Further study is needed to determine the overall cost-effectiveness of the EOAE as compared with the ABR before specific recommendations for a universal hearing screening program are proposed.

Objective: To evaluate an infant hearing screening program utilizing the high risk register (HRR) and auditory brainstem response (ABR)., Design: A cost-effectiveness analysis of the screening program employing a retrospective cohort identified by chart review. The analysis was performed on a hypothetical cohort of 100,000 births and the results compared with a base model derived from literature review., Setting: Mount Sinai Hospital, New York City, an urban, tertiary care institution., Patients: All infants born between November 1990 and October 1993, approximately 16,500. Cost-effectiveness analysis focused on test results of 420 infants failing the HRR and 381 who subsequently received ABR., Results: Analysis of the Mount Sinai Hospital (MSH) protocol showed it to be less cost-effective than other similar programs. The cost per hearing loss was far more at MSH than that found elsewhere. Further, the MSH program was ineffective in detecting infants with congenital hearing loss--identifying only one case between 1990 and 1993. Analysis of high risk criteria finds a low incidence of family history of hearing loss in the Mount Sinai cohort while other studies find a very high incidence., Conclusions: It appears that the poor performance of the MSH protocol is due to low specificity and sensitivity of the HRR. This generates a costly and ineffective program as follow-up exams focus on ruling-out false-positives rather than correctly identifying true hearing losses. Further evaluation is needed to determine whether changes in the application of the HRR or utilization of newer, low-cost tests such as otoacoustic emissions (OAE) may be effective in universal infant hearing screening.

The advent of magnetic resonance imaging has greatly improved our ability to diagnose acoustic tumors, but it is a relatively expensive imaging modality. In the present climate of medical cost restraints, methods that reduce costs but maintain quality are extremely desirable. We report a new magnetic resonance imaging technique that uses fast spin echo without gadolinium. It provides ultrahigh-resolution images of the internal auditory canal and cerebellopontine angle. The sensitivity of this technique for the detection of acoustic tumors is equivalent to conventional gadolinium-enhanced magnetic resonance imaging, but the global cost is comparable with that of brain stem audiometry. In our practice fast spin echo magnetic resonance imaging has replaced brain stem audiometry as a screening modality to evaluate most acoustic tumor suspects. Also, the intricate detail of the internal auditory canal anatomy provided by this technique is useful in planning surgical removal of acoustic tumors.

Demonstrating improved outcomes and cost containment are current health care imperatives. For many diseases, competing diagnostic tests are available. Each has a direct economic cost and indirect costs based on missed disease. It is often difficult to determine the most efficient testing strategy for a given patient. Clinical Decision Analysis can optimise diagnostic strategies to maximise cost-effectiveness. Analytic techniques are developed to allow analysis of diagnostic strategies that include multi-test protocols. The test parameters required for modelling these strategies are derived from a literature analysis.

Magnetic resonance imaging (MRI) is accepted as the 'gold standard' in diagnosing acoustic neuromas. Limited availability and perceived high costs have prevented clinicians from using it as a first-line investigation. A prospective study was set up in a specially designated screening session to audit the cost effectiveness and accuracy of audiovestibular investigations compared to MRI. Ninety-nine patients with asymmetrical audiovestibular symptoms or signs were investigated. Of these 54 evoked response audiometry tests, and 39 calorics were either not performed or were inconclusive. One patient refused to enter the MRI machine. All others received an unequivocal report after MRI and four tumours (three intracanalicular) were detected. The total cost of the audiovestibular protocol was 12,545 pounds compared to 12,900 pounds for the MRI protocol, which is a diagnostic and well-tolerated procedure. This study shows that MRI can be cost effective, as well as accurate, when used as a single screening procedure for acoustic neuromas.

The auditory brainstem response (ABR), as well as associated audiologic and radiographic studies of 175 patients suspected of having cerebellopontine angle tumors were reviewed. The majority of patients presented with asymmetric hearing loss. Eight acoustic neuromas were identified. All eight had abnormal ABRs. The false-positive rate was 22%. Rollover and acoustic reflex testing played a minimal role in the decision as to whether or not an ABR was ordered and, as a result, are not important in the search for retrocochlear disease. The cost per tumor diagnosed was roughly $7600. A rational approach to tumor screening based on the efficiency and cost of the screening tests, the frequency of abnormal ABRs, and the cost per tumor diagnosed is presented.

We used cost-effectiveness analysis to compare two strategies for screening for severe hearing loss in the neonatal intensive care unit (NICU): the auditory brain stem response (ABR) and the Crib-O-Gram (COG). We studied hypothetical cohorts of infants using data derived from the literature on screening test characteristics. We included the costs of initial screening and those of further diagnostic testing for infants who fail the screening test. The ABR cost more per test administered than COG, but had higher sensitivity and specificity to detect hearing loss. We found the ABR, therefore, to be more cost effective than the COG. Using best-estimate assumptions, ABR cost $10,610 for each correctly detected case of hearing loss; COG cost $14,310 for each correctly detected case; among every 1,000 NICU infants screened, furthermore, ABR detected all cases of hearing loss, whereas COG failed to detect five hearing-impaired infants. We conclude that cost-effectiveness analysis justifies using ABR as a screening tool.

As the first in a series, the present study was designed to compare and provide a consumer-oriented overview of commercially available auditory evoked potential (AEP) units with a basic price of less than $10,000 (i.e., the "economy" units). The following AEP units fell under this category: Algo-1/Algo-1PLUS, Amplaid MK-10, Nicolet Audit V, Bio-logic PASS, GSI-55, and Modular M-100. Descriptive information and the names and addresses of at least 10 users were solicited from the manufacturers for each of these units. Questionnaires were sent to the users, which asked them to provide information on how their unit was used and to rate some of its features. Results indicate that the economy units generally meet the needs and expectations of the users. They offer the advantages of being easy to use, portable, and reliable. Primary disadvantages relate to lack of flexibility, a problem that could generally be accommodated by upgrading to more sophisticated (and expensive) units.