Use Of Auditory Steady-state Responses Research Articles

Is Auditory Steady-State Response Testing the Key for Diagnosing Non-Organic Hearing Disorders? Implications for Current Audiological Practice.

Background and ObjectivesTo describe all possible facets of non-organic hearing disorders (NOHD) and emphasize the superiority of auditory steady-state response (ASSR) over previously employed hearing assessment tools.Subjects and MethodsA series of seven patients consisting of three males and four females with NOHD were assessed at Attikon University Hospital (age range: 17-59 years). Three patients had Munchausen syndrome, three intentionally feigned hearing loss, and one intentionally feigned normal hearing. The audiological evaluation consisted of tympanometry, pure-tone audiometry, and ASSR testing.ResultsThe hearing of all patients was accurately determined using ASSR. The results were confirmed by auditory brainstem responses (ABR) and otoacoustic emissions.ConclusionsNOHD is a multi-faceted condition encompassing various etiologies. ASSR testing represents an objective and reliable method of hearing assessment, which can serve as a gold standard method for distinguishing NOHD from actual hearing loss. It can reliably indicate the hearing levels at the four main frequencies (500, 1,000, 2,000, and 4,000 Hz) by obtaining a valid estimated audiogram through statistical measures. Compared to ABR testing, ASSR thresholds are closer to the actual audiometric thresholds in the presence of hearing impairment and are superior when the corresponding pure-tone audiogram is widely ranging between the adjacent frequencies or when the obtained ABR curves are not easily distinguished. A non-confrontational approach should be adopted by ENT doctors towards cases of suspected NOHD as the use of ASSR could reliably assess hearing even when medical or medico-legal implications are involved.

Comparison of frequency-Specific hearing thresholds between pure-tone audiometry and auditory steady-state response

Introduction: Hearing assessment in difficult to assess persons gives inconsistent response in free field hearing and pure-tone audiometry (PTA). We have been performing brainstem evoked response audiometry (BERA) as an objective assessment in such cases. BERA has limitations that it is not frequency specific, measures thresholds in higher frequencies only, signal intensity levels cannot be higher than 90 dB and presents the data in waveform which needs to be interpreted by experienced audiologist to deduce correct information. All these limitations can be negated with use of auditory steady-state response (ASSR) which can present intensity levels till 120 dB, is frequency specific, even for lower frequencies and has automated response and deduction analysis. The aim of our study was to compare pure-tone thresholds with ASSR thresholds in normal hearing and hearing loss subjects with an objective to validate the ASSR as a tool for objective hearing assessment. Materials and Methods: In this prospective cross-sectional study of 70 adults (n = 140 ears) of both genders, with and without hearing complaints, Group 1 consisted of 24 individuals of normal hearing, Group 2 consisted of 25 individuals of sensorineural hearing loss, and 21 individuals with conductive hearing loss in Group 3. The patients were evaluated with PTA and ASSR test. The mean pure tone and ASSR thresholds for each frequency were calculated and analyzed using the SPSS IBM software. Results: The mean difference of ASSR with PTA was noted at 9.92 dB in the right ear and 10 dB in the left ear. A high significant correlation was noted between ASSR and PTA with P(0.0005) across all the three groups. The relationship between the PTA and ASSR measurement for measuring average hearing threshold levels is described by the equation: PTA = ASSR mean × 0.99–9.92. Conclusion: ASSR is an excellent tool to predict accurate level of frequency-specific hearing threshold. It has constant relationship with pure tone thresholds. ASSR can predict true hearing thresholds in “difficult to assess” patients such as children and malingerers. This can also be used in the prediction of disability assessment objectively.

Intraoperative auditory steady-state monitoring during surgery in the cerebellopontine angle for estimation of postoperative hearing classes.

OBJECTIVE Brainstem auditory evoked potentials (BAEPs) have been used for intraoperative monitoring of the auditory nerve for many years. However, BAEPs yield limited information about the expected postoperative hearing quality and speech perception. The auditory steady-state response (ASSR) enables objective audiograms to be obtained in patients under anesthesia. These ASSRs could be used for intraoperative estimation of hearing classes to improve the postoperative outcome and quality of life. Studies investigating the clinical use of ASSRs during total intravenous anesthesia are currently lacking. The work presented in this article therefore investigates the application of ASSRs for intraoperative estimation of hearing classes. METHODS In 43 patients undergoing surgery for vestibular schwannoma, ASSR measurements were performed at the beginning and end of the surgical procedure. ASSR stimuli consisted of 80-dB hearing level amplitude-modulated tones with 5-minute duration, 90-Hz modulation, and 3 different carrier frequencies: 500, 1000, and 2000 Hz. Stimulation was performed unilaterally with and without contralateral masking, using single and combined carriers. Evoked responses were recorded and analyzed in the frequency domain. ASSRs were compared with extraoperative hearing classes and BAEPs using ANOVA, correlation, and receiver operating characteristic statistics. RESULTS ASSRs yielded high and consistent area under the curve (AUC) values (mean 0.83) and correlation values (mean -0.63), indicating reliable prediction of hearing classes. Analysis of BAEP amplitude changes showed lower AUC (mean 0.79) and correlation values (0.63, 0.37, and 0.50 for Waves I, III, and V, respectively). Latencies showed low AUC values (mean 0.6) and no significant correlation. Combination of several carriers for simultaneous evaluation reduced ASSR amplitudes and respective AUC values. Contralateral masking did not show a significant effect. CONCLUSIONS ASSRs robustly estimate hearing class in patients under total intravenous anesthesia, even when using short measurement durations. The method provides a diagnostic performance that exceeds conventional BAEP monitoring and enables objective and automated evaluation. On the basis of these findings, continuous intraoperative auditory monitoring could become a promising alternative or adjunct to BAEPs.

Use of auditory steady-state responses in children and comparison with other electrophysiological and behavioral tests

ObjectiveIn patients who cannot or will not cooperate in behavioral hearing assessment, electrophysiological examinations are used, but are time-consuming because the subject has to remain immobile. The aim of this study was to assess whether auditory steady-state responses (ASSR) are sufficiently reliable, compared to auditory brainstem responses (ABR) and free-field audiometry, for assessment to begin with ASSR instead of ABR. Material and methodsA retrospective study was performed between January 2012 and April 2013, including children less than 6 years of age who could not be tested via headphones. ASSR and ABR were measured during natural sleep or under phenobarbital-alimemazine sedation. Subjective pure-tone audiometry was performed, using the visual reinforcement audiometry method, in 69 children who were able and willing to cooperate. ResultsA total of 175 children were included. ASSR and ABR thresholds showed good positive correlation (338 ears; Pearson's correlation coefficient, 0.87). Behavioral thresholds correlated significantly with ASSR thresholds (Student t-test for matched series; P<0.05). ASSR thresholds were usually better than behavioral thresholds, with a difference of 8–15dB HL. ConclusionASSR is reliable in children under 6 years of age, and should be performed before ABR when hearing threshold rather than latency is to be determined.

Effect of attention on 40 Hz auditory steady-state response depends on the stimulation type: Flutter amplitude modulated tones versus clicks

Auditory steady-state responses (ASSRs) are used to test the ability of local cortical networks to generate gamma frequency activity in patients with psychiatric disorders. For the effective use of ASSRs in research and clinical applications, it is necessary to find a comfortable stimulation type and to know how ASSRs are modulated by the tasks given to the subjects during the recording session. We aimed to evaluate the suitability of flutter amplitude modulated tone (FAM) stimulation for generation of ASSRs: subjective pleasantness of FAMs and attentional effects on FAM-elicited 40Hz ASSRs were assessed. Commonly used click stimulation was used for comparison. FAMs produced ASSRs that were stable over the variety of tasks − they were not modulated by attentional demands during the task; responses to clicks were reduced and less synchronized during distraction. FAM stimuli were rated as less unpleasant and less arousing than click stimuli, thus being more pleasant to the subjects. Our findings suggest that FAM stimulation might be more suitable in conditions, where attention is difficult to control, i.e. in clinical settings.

Auditory steady-state responses in school-aged children: a pilot study.

BackgroundThe use of Auditory Steady-State Responses (ASSRs) for auditory screening in school-aged children, particularly in children who are difficult to test and children with disabilities, has not been explored yet. This pilot study investigated the use of ASSR for auditory screening in school-aged children.Materials and methodsA cross-sectional pilot study of 23 children aged 9 to 11 with normal-hearing thresholds and seven age-matched children with permanent moderate-to-profound bilateral hearing loss were examined. The tested carrier frequencies were 500, 1,000, 2,000, and 4,000 Hz, and the stimulus was modulated between 77 and 107 Hz. The ASSRs decreased according to the tested intensity levels of 50, 40, and 30 dB sound pressure level (SPL). Sensitivity and specificity were estimated from the responses of the children with normal hearing and those with hearing loss.ResultsFor the children with normal hearing, the 2,000-Hz frequency was detected more often in both ears and at all intensity levels compared to the other frequencies. The 500- and 2,000-Hz frequencies resulted in different response patterns in both ears. The time until response detection increased in parallel with amplitude reduction, as expected. The overall time required for the test was 15 minutes, including the time spent in volunteer preparation. The sensitivity was 97% for the three intensities, and the best specificity value was 100%, which was observed at 50 dB.DiscussionThe response analysis indicated that a screening protocol for school-aged children could include 1,000, 2,000, and 4,000 Hz and that the recording of ASSRs was highly sensitive to internal and external factors. Fifty dB SPL should be considered a cut-off criterion for screening purposes because this was the intensity level with a sensitivity of 97% and a specificity of 100%.ConclusionThe use of ASSRs might be particularly useful in school-aged children who have difficulty performing subjective hearing tests. The sensitivity and specificity data suggested that the use of ASSRs was feasible as an auditory screening tool. In order to determine a protocol for screening, future studies should include a larger sample and children with mild hearing loss.

Comparison between Pure Tone Audiometry and Auditory Steady-State Responses in Korean Children and Adult

Received June 1, 2014 Revised August 26, 2014 Accepted September 17, 2014 Address for correspondence Chul Ho Jang, MD, PhD Department of OtolaryngologyHead and Neck Surgery, Chonnam National University Medical School, Chonnam National University Hospital, 42 Jebong-ro, Dong-gu, Gwangju 501-757, Korea Tel +82-62-220-6788 Fax +82-62-228-7743 E-mail chulsavio@hanmail.net Background and ObjectivesZZAssessing accurate audiometry might be an important index treating patients with hearing loss. So far there have been no studies on analysis of correlations between pure tone audiometry (PTA) and auditory steady-state response (ASSR) for children in Korea. We analyzed correlations between PTA and ASSR in order to investigate the usefulness of ASSR. Subjects and MethodZZPast medical records were retrieved from the patients who visited Department of Otolaryngology at Tertiary Referral Hospital from January 2012 to December 2012 and underwent the correlation study between ASSR and PTA with a correlation analysis of frequency. The participants over the age of 15 were classified into the adult group and those below in the children group. ResultsZZThere was a statistically significant correlation between the average hearing threshold of ASSR and PTA (correlation coefficient=0.934). There was a strong correlation between children and adult group, too. With the frequency range of 500, 1000, 2000, and 4000 Hz, the correlation coefficients were 0.875, 0.896, 0.915, and 0.900, respectively. The degree of hearing loss was classified by using PTA follows: below 25 dB as normal; between 26-55 dB as moderate hearing loss; above 56 dB as severe hearing loss. Correlation coefficients for the above hearing ranges were 0.527, 0.670, and 0.744, respectively. Strong correlation was found between children and adult group, too. ConclusionZZThe comparison results between the average hearing threshold of ASSR and PTA indicated that the threshold of ASSR could well reflect the results of both children and adult group. Korean J Otorhinolaryngol-Head Neck Surg 2015;58(3):182-6

Steady-state MEG responses elicited by a sequence of amplitude-modulated short tones of different carrier frequencies

The auditory steady-state response (ASSR) is a weak potential or magnetic response elicited by periodic acoustic stimuli with a maximum response at about a 40-Hz periodicity. In most previous studies using amplitude-modulated (AM) tones of stimulus sound, long lasting tones of more than 10 s in length were used. However, characteristics of the ASSR elicited by short AM tones have remained unclear. In this study, we examined magnetoencephalographic (MEG) ASSR using a sequence of sinusoidal AM tones of 0.78 s in length with various tone frequencies of 440–990 Hz in about one octave variation. It was found that the amplitude of the ASSR was invariant with tone frequencies when the level of sound pressure was adjusted along an equal-loudness curve. The amplitude also did not depend on the existence of preceding tone or difference in frequency of the preceding tone. When the sound level of AM tones was changed with tone frequencies in the same range of 440–990 Hz, the amplitude of ASSR varied in a proportional manner to the sound level. These characteristics are favorable for the use of ASSR in studying temporal processing of auditory information in the auditory cortex. The lack of adaptation in the ASSR elicited by a sequence of short tones may be ascribed to the neural activity of widely accepted generator of magnetic ASSR in the primary auditory cortex.

Distraction task rather than focal attention modulates gamma activity associated with auditory steady-state responses (ASSRs)

Objective To explore the modulation of auditory steady-state response (ASSR) by experimental tasks, differing in attentional focus and arousal level. Methods 20 Hz and 40 Hz click trains were used to elicit ASSRs. Experiment 1 consisted of two runs of closed eyes and two runs of open eyes. Experiment 2 consisted of six tasks: counting 20 Hz and 40 Hz stimuli, sitting with closed and open eyes, reading an article, and performing a search task. Phase locking factor, evoked amplitude and total intensity were decomposed by non-negative multi-way factorization. Results The total intensity of 40 Hz ASSR was enhanced during closed eyes condition in comparison to the open eyes condition. The evoked amplitude and phase locking factor of 40 Hz ASSR were attenuated during distraction, while there were no differences between attention to stimulation and no task. 20 Hz ASSR and 20 Hz ASSR-related 40 Hz activity were not modulated by the tasks. Conclusions The phase-locked measures of 40 Hz ASSR are attenuated when attention to the stimulation is low, i.e. the subject is effortfully focused on the competitive “distraction” task performance. Lower arousal level increases the total intensity of 40 Hz ASSRs. Significance Improvements of the practical use of ASSRs are suggested: a careful monitoring for arousal fluctuations during ASSR recordings should be performed; when ASSRs are applied to investigate the ability to generate high frequency cortical activity a “distraction” task is not favorable.

Threshold Estimation in Children Using Auditory Steady-State Responses to Multiple Simultaneous Stimuli

Objective: It was the aim of this study to explore the use of auditory steady-state response (ASSR) to multiple simultaneous stimuli for threshold estimation in young children. Method: The subjects consisted of 40 children, aged from 6 months to 5 years, with variant degrees of sensorineural hearing loss. Simultaneous tonepips (0.5, 1, 2 and 4 kHz) with an amplitude modulated at different rates from 77 to 103 Hz were presented to both ears by insert phones. All children were tested with ASSR and age-appropriate behavioral tests. Results: We found that (1) ASSR thresholds were usually higher than behavioral thresholds with a difference of 8–15 dB, (2) the behavioral thresholds were significantly correlated with ASSR thresholds (p = 0.000), and (3) there was a great difference between ASSR thresholds and behavioral thresholds found in a child with auditory neuropathy. Conclusion: Being objective, frequency specific and well correlated with behavioral thresholds, ASSR to multiple simultaneous stimuli was proven to be a good tool to predict behavioral hearing thresholds.