Auditory Steady-state Response Testing Research Articles

Comparison of ASSR and frequency specificity ABR induced by NB CE-Chirp for prediction of behavioral hearing thresholds in children with conductive hearing loss

BackgroundElectrophysiological tests are often used to evaluate hearing loss in infants and young children with conductive hearing loss, no matter to quantify or characterize. However, there are advantages and disadvantages associated with the various electrophysiological tests that are currently available. Therefore, there is no gold standard test. This study aimed to compare the value of narrow-band (NB) CE-Chirp-induced auditory steady-state response (ASSR) and auditory brainstem response (ABR) for assessing hearing thresholds in children with conductive hearing loss. We hope to identify an effective electrophysiological testing method to evaluate conductive hearing loss and provide a reference for clinical hearing assessment of infants with conductive hearing loss. Subjectsand Methods: We selected 27 children (41 ears) aged 3–6 years with otitis media with effusion (OME). Within 1 day, they underwent behavioral audiometry and NB CE-Chirp-induced ASSR and ABR tests in sequence. Pearson's correlation analysis was performed to compare behavioral audiometry thresholds and ASSR and ABR response thresholds at 500, 1000, 2000, and 4000 Hz. ResultsThe behavioral audiometry thresholds of all children were strongly correlated with the response thresholds of the two electrophysiological tests, with correlation coefficients of 0.659, 0.605, 0.723, and 0.857 for ASSR, and 0.587, 0.684, 0.753, and 0.802 for ABR. The proportion of children with a difference of ≤10 dB between ASSR and behavioral audiometry thresholds or between ABR and behavioral audiometry thresholds was not high, especially in the low frequencies. ABR results were superior to ASSR results in terms of predicting actual hearing levels. At 0.5, 1, 2, and 4 kHz, the average differences between the behavioral hearing thresholds and ASSR thresholds in the 41 ears were 5.6, 5.7, 2, and 5.6 dB, respectively. The average differences between behavioral hearing thresholds and ABR thresholds was −5.6, −1.4, −6.8, and 3.2 dB, respectively. The hearing loss configuration of the ASSR exhibited a peaked pattern, similar to behavioral audiometry, whereas the ABR exhibited an ascending pattern. The time to perform the single-ear ASSR test was 5.9 min, whereas the ABR test took 17.0 min. ConclusionASSR and ABR induced by the NB CE-Chirp correlated well with behavioral audiometry in children with conductive hearing loss. The NB CE-Chirp ASSR has advantages in terms of testing time and hearing configuration evaluation, whereas ABR has better reliability than ASSR. However, the stability of ASSR and ABR induced by the NB CE-Chirp is poor, and the thresholds obtained cannot replace behavioral audiometry in evaluating the true hearing of children with conductive hearing loss. However, ASSR and ABR can be used as auxiliary tests for cross-validation.

Tips & Tricks for Hearing Evaluation using Next Generation Auditory Steady-state Response Testing

Tips & Tricks for Hearing Evaluation using Next Generation Auditory Steady-state Response Testing

Evaluation of the Viability of Auditory Steady State Response Testing for Detection of Pseudohypacusis in Serving Personnel of the Indian Armed Forces.

The most popular objective physiologic test for detecting hearing loss that is in use today is the ABR, however it is not frequency specific. The frequency specific tool available for evaluation of hearing is ASSR. The study is aimed to assess the ability of ASSR to estimate hearing thresholds and identify the ideal modulation frequency in hearing impaired personnel. All subjects and controls were subjected to PTA to determine presence/absence of hearing loss, and the nature and configuration of the hearing loss if any. The subjects were then subjected to ASSR testing to objectively ascertain hearing thresholds. The PTA thresholds obtained and the hearing thresholds obtained by ASSR were correlated in this study. The study was carried out in 100 subjects under the age of 50years (50 with normal hearing & 50 with impaired hearing by PTA) after obtaining informed consent. Moderate correlation was found between PTA and ASSR thresholds only in certain frequencies while in other frequencies the correlation though present, was low. This study concluded that ASSR system could be used to estimate hearing thresholds only approximately as no significant linear correlations were found between PTA thresholds and ASSR at the tested frequencies.

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.

Do Room Acoustics Affect the Amplitude of Sound-Field Auditory Steady-State Responses?

The sound-field auditory steady-state response (ASSR) is a promising measure for the objective validation of hearing-aid fitting in patients who are unable to respond to behavioral testing reliably. To record the sound-field ASSR, the stimulus is reproduced through a loudspeaker placed in front of the patient. However, the reverberation and background noise of the measurement room could reduce the stimulus modulation used for eliciting the ASSR. As the ASSR level is heavily dependent on the stimulus modulation, any reduction due to room acoustics could affect the clinical viability of sound-field ASSR testing. This study investigated the effect of room acoustics on the level and detection rate of sound-field ASSR. The study also analyzed whether early decay time and an auditory-inspired relative modulation power model could be used to predict the changes in the recorded ASSR in rooms. A monaural auralization approach was used to measure sound-field ASSR via insert earphones. ASSR was measured for 15 normal-hearing adult subjects using narrow-band CE-Chirps® centered at the octave bands of 500, 1000, 2000, and 4000 Hz. These stimuli were convolved with simulated impulse responses of three rooms inspired by audiological testing rooms. The results showed a significant reduction of the ASSR level for the room conditions compared with the reference anechoic condition. Despite this reduction, the detection rates for the first harmonics of the ASSR were unaffected when sufficiently long recordings (up to 6 min) were made. Furthermore, the early decay time and relative modulation power appear to be useful predictors of the ASSR level in the measurement rooms.

A distributed frontotemporal network underlies gamma-band synchronization impairments in schizophrenia patients.

Synaptic interactions between parvalbumin-positive γ-aminobutyric acid (GABA)-ergic interneurons and pyramidal neurons evoke cortical gamma oscillations, which are known to be abnormal in schizophrenia. These cortical gamma oscillations can be indexed by the gamma-band auditory steady-state response (ASSR), a robust electroencephalographic (EEG) biomarker that is increasingly used to advance the development of novel therapeutics for schizophrenia, and other related brain disorders. Despite promise of ASSR, the neural substrates of ASSR have not yet been characterized. This study investigated the sources underlying ASSR in healthy subjects and schizophrenia patients. In this study, a novel method for noninvasively characterizing source locations was developed and applied to EEG recordings obtained from 293 healthy subjects and 427 schizophrenia patients who underwent ASSR testing. Results revealed a distributed network of temporal and frontal sources in both healthy subjects and schizophrenia patients. In both groups, primary contributing ASSR sources were identified in the right superior temporal cortex and the orbitofrontal cortex. In conjunction with normal activity in these areas, schizophrenia patients showed significantly reduced source dipole density of gamma-band ASSR (ITC > 0.25) in the left superior temporal cortex, orbitofrontal cortex, and left superior frontal cortex. In conclusion, a distributed network of temporal and frontal brain regions supports gamma phase synchronization. We demonstrated that failure to mount a coherent physiologic response to simple 40-Hz stimulation reflects disorganized network function in schizophrenia patients. Future translational studies are needed to more fully understand the neural mechanisms underlying gamma-band ASSR network abnormalities in schizophrenia.

Threshold Mismatches between Pure-Tone Audiometry and Auditory Steady State Response in Non-Auditory Neuropathy Adults

Background and Objectives To evaluate mismatches between pure-tone audiometry (PTA) and auditory steady-state response (ASSR) tests in non-auditory neuropathy adults and investigate brain lesions that may explain the mismatches, especially in cases where the ASSR threshold was worse than the estimated PTA threshold.Subjects and Method PTA, speech audiometry, auditory brainstem response, ASSR, and neuroimaging tests were carried out on individuals selected. Among them, medical records of 30 subjects (16 males, 14 females; mean age=54.4±13.2 years) with significant mismatches between PTA and estimated ASSR thresholds were analyzed retrospectively. All neuroimaging tests were reviewed to identify any neurologic abnormalities.Results Pathologic brain lesions were found in 19 cases (63.3%) in the study group, all of which showed significant mismatch in hearing threshold between PTA and ASSR. Seven case of ischemic brain lesions (23.3%), five tumorous lesions (16.6%), and four brain vessel anomalies (13.3%) were found. Brain hemorrhage due to trauma were found in two cases (6.6%) as well as one case (3.3%) of unruptured aneurysm. Central auditory pathway disorder was suspected in two cases. The 11 cases showing normal results in the imaging studies included one mental retardation, one brain concussion, and seven cases (23.3%) with no specific causes. Six tinnitus cases included two subjects showing discrepancies between frequency matching in the tinnitogram.Conclusion In adults with a mismatch between PTA thresholds and estimated ASSR thresholds, especially for those with moderate to profound hearing loss, additional neuroimaging tests and other audiologic tests may reveal other possible causes of hearing loss.

A case report of absent auditory steady-state responses in an elderly person with moderate sensorineural hearing loss

Background: Auditory steady-state response (ASSR) is a test for the estimation of auditory thresholds. It is used in infants, children, and adults. This case report presented unusual ASSR results in an elderly person. The Case: Pure tone and speech audiometry, tympanometry and acoustic reflexes showed a moderate sensorineural hearing loss in both ears. However, the patient did not respond in the ASSR test to different carrier frequencies with frequency modulations of 40 and 80 Hz. Conclusion: To date, the results of the different effects of the aging process obtained from ASSR responses have been reported. However, the absence of any response in the ASSR test has never been reported. The patient in this case report may have these results because of a neural deficit.
 Keywords: Sensorineural hearing loss; aging; auditory steady-state response

Discrepancies in Hearing Thresholds between Pure-Tone Audiometry and Auditory Steady-State Response in Non-Malingerers.

To evaluate discrepancies between pure-tone audiometry (PTA) and auditory steady state response (ASSR) tests in non-malingerers and investigate brain lesions that may explain the discrepancies, especially in cases where the PTA threshold was worse than the estimated ASSR threshold. PTA, speech audiometry, auditory brainstem response, ASSR, and neuroimaging tests were carried out on individuals selected from 995 cases of hearing impairment. Among these, medical records of 25 subjects (19 males, 6 females; mean age = 46.5 ± 16.0 years) with significant discrepancy between PTA and estimated ASSR thresholds were analyzed retrospectively. To define acceptable levels of discrepancy in PTA and ASSR hearing thresholds, 56 patients (27 males, 29 females; mean age = 53.0 ± 13.6 years) were selected for the control group. Magnetic resonance images, magnetic resonance angiograms, and positron emission tomograms were reviewed to identify any neurologic abnormalities. Pathologic brain lesions were found in 20 cases (80%) in the study group, all of which showed a significant discrepancy in hearing threshold between PTA and ASSR. Temporal lobe lesions were found in 14 cases (70%), frontal lobe lesions in 12 (60%), and thalamic lesions without the frontal or temporal lobe in 2 cases (10%). On repeated PTA and ASSR tests a few months later, the discrepancy between ASSR and behavioral hearing thresholds was reduced or resolved in 6 cases (85.7%). Temporal lobe lesions were found in all 3 cases in which the estimated ASSR threshold worsened with unchanged PTA threshold, and frontal lobe lesions were found in all 3 cases in which the PTA threshold improved but the estimated ASSR threshold was unchanged. No neurological lesions were found in 5 cases (20%) of patients with a discrepancy between ASSR and behavioral hearing thresholds. Clinicians should not rely exclusively on ASSR, especially in cases of central nervous system including temporal, frontal lobe, or thalamus lesions. If no lesions are found in a neuroimaging study of a patient with a discrepancy between PTA thresholds and estimated ASSR thresholds, further functional studies of the brain may be needed. If clinicians encounter patients with a discrepancy between PTA thresholds and estimated ASSR thresholds, an evaluation of brain lesions and repeat audiologic tests are recommended in lieu of relying solely on ASSR.

Analyses of audiological examination in children without auditory brainstem response

Objective: To investigate residual hearing of children severe and profound sensorineural deafness in whom wave V was not found in auditory brainstem response(ABR) testing, and to emphasize the importance of objective audiological tests. Methods: Two hundred and fifty-two children who were admitted to the Second Affiliated Hospital of Zhengzhou University between January 2015 and April 2018, with an average age of 20 months from 72 days to 4 years, received a full battery of objective audiological tests consisting of distortion product otoacoustic emission(DPOAEs), tympanometry, auditory brainstem responses(ABRs), 40 Hz auditory event related potential(40 HzAERP) and auditory steady-state response(ASSRs).There were 159 males(318 ears) and 93 females(186 ears). Residual hearing obtained by 40 HzAERP、ASSR of 252 children with sensorineural deafness was studied in relation to the absence of wave V in click ABR. SPSS 16.0 software was used to analyze the data. Results: Four hundred and forty-four ears of 504 ears have residual hearing of different degrees at different frequencies(88.1%),60 ears (11.9%) were found in whom responses was not found in 40 HzAERP、ASSR testing; Seventy-two ears(14.3%) in 38 patients were tested cochlear microphonic potentials (CMs). Conclusion: In children hearing evaluations,a full battery of objective audiological tests could better investigate residual hearing; The CMs were tested could provide the Audiotery Neuropathy diagnosis in infants with OAEs and ABR absent.

Comparative study of auditory brainstem response and auditory steady-state response as an objective measure for hearing aid verification

Introduction: Hearing aid benefit could be measured objectively by electrophysiological tests. Objective measures are important for hearing assessment in individuals who are unable to provide behavioural responses to reach optimal hearing aids fitting verification.Purpose: This study was designed to compare the Functional Gain (FG) of Auditory Steady State Response (ASSR) and Tone Burst Auditory Brainstem Response (TB ABR) as objective tools with the subjective FG using sound field pure tone audiometry (PTA) in adult patients with sensorineural hearing loss using two hearing aid fitting formulae; DSL v5 and NAL-NL2.Material and methods: This study included twenty hearing-impaired adults, their hearing thresholds ranged from moderate to moderately severe sensorineural hearing loss with flat or gradually falling configuration. Their age ranged from eighteen to sixty years. Subjects were examined in three scheduled sessions; unaided, aided NAL-NL2 and aided DSL V5. Each session included free field PTA, TB ABR and ASSR testing at four tested frequencies 500, 1000, 2000 and 4000 Hz.Results: The mean difference between free field PTA FG and TB ABR FG was 6.02 ± 5.11 and 6.51 ± 4.53 by NAL-NL2 and DSL v5 respectively. The cumulative percentage of cases who had mean total differences within ±2 SD (< ±15 dB) was 100% in both formulae. The mean difference between free field PTA FG and ASSR FG was 2.00 ± 7.48 and 2.00 ± 6.99 by NAL-NL2 and DSL v5 formulae respectively. The cumulative percentage of cases who had mean total differences within ±2 SD (< ±15 dB) was 90% in NAL-NL2 formula and 95% in DSL v5 formula. When using identical test conditions and the same type of stimulus, NAL-NL2 and DSL v5 revealed similar functional gain measurements.Conclusions: Both TB ABR and ASSR are valuable objective measures for thresholds detection. The FG measured by TB ABR and ASSR could be applied as an objective tool for hearing aid fitting verification in hearing impaired individuals.

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.

Evaluation of the Newborn Hearing Screening Program in The Medical City based on Joint Commission on Infant Hearing (JCIH) 2007 Position Statement Quality Indicators

Objective : The objective of this study is to evaluate the newborn hearing screening program in The Medical City based on the Joint Committee on Infant Hearing (JCIH) 2007 Position Statement Quality Indicators.&#x0D; Methods:&#x0D; Study Design: Cross - Sectional Survey&#x0D; Setting: Tertiary Private Hospital&#x0D; Participants : All newborns who underwent newborn hearing screening in The Medical City for the year 2015.&#x0D; Results: Of 2,010 patients delivered in the hospital in year 2015, 1,986 (98.8%) were screened. Among the 59 babies with initial “refer” results, 15 (25.42%) “referred” a second time while 24 (40.68%) “passed” the rescreening. Twenty (33.89%) did not undergo rescreening (10 were classified as dropouts, while another 10 did not undergo rescreening for various reasons. Of those who “referred” during rescreening, only 9 (60%) had further evaluation done with ABR/ASSR. Among these, 4 (26.66%) had hearing loss and proceeded with the appropriate monitoring and management while 5 (33.33%) had normal hearing.&#x0D; Conclusion : The current newborn hearing screening program in the Medical City was able to reach JCIH 2007 quality indicators for screening but not for confirmation of hearing Loss. All patients with hearing loss were managed with early rehabilitation.&#x0D; Keywords: Newborn hearing screening, otoacoustic emission test, auditory brainstem response test, auditory steady state response test

Comparison of click auditory brainstem response and chirp auditory steady-state response thresholds in children

ObjectivesDuring the last twenty years, auditory steady-state responses (ASSRs) are being used as an alternative and adjunct to the auditory brainstem response (ABR) for threshold estimation. This study aims at comparing and finding correlations between air-conduction thresholds using the traditional click ABR and the relatively recently used chirp ASSR test methods, for a large pediatric population. MethodsOne hundred and thirty children referred to our Clinic from Hospitals and Clinics of Western Greece ranging in age from 5 to 79 months (mean age = 32.7 ± 14.0 months) participated prospectively. ResultsStrong and statistically significant correlations were found between the average of the 1000, 2000 and 4000 Hz chirp ASSR thresholds and click ABR thresholds (rs = .826, p < .001), and the average of the 2000 and 4000 Hz chirp ASSR and click ABR thresholds (rs = .824, p < .001). Additionally, there have been measurements for some children with hearing loss in the severe-to-profound range during the ASSR test, but no ABR at the upper limits of the equipment. Click ABR and chirp ASSR thresholds averaged at 2000 and 4000 Hz were within 20 dB in 90% of the ears tested. ConclusionsThe results of this study support the inclusion of chirp ASSRs into the pediatric test battery and indicate that they may provide an essential adjunct to the click ABR, especially in the management of very young children with severe-to-profound hearing loss.

Effect of Mild Cognitive Impairment and Alzheimer Disease on Auditory Steady-State Responses.

Introduction:Mild Cognitive Impairment (MCI), a disorder of the elderly people, is difficult to diagnose and often progresses to Alzheimer Disease (AD). Temporal region is one of the initial areas, which gets impaired in the early stage of AD. Therefore, auditory cortical evoked potential could be a valuable neuromarker for detecting MCI and AD.Methods:In this study, the thresholds of Auditory Steady-State Response (ASSR) to 40 Hz and 80 Hz were compared between Alzheimer Disease (AD), MCI, and control groups. A total of 42 patients (12 with AD, 15 with MCI, and 15 elderly normal controls) were tested for ASSR. Hearing thresholds at 500, 1000, and 2000 Hz in both ears with modulation rates of 40 and 80 Hz were obtained.Results:Significant differences in normal subjects were observed in estimated ASSR thresholds with 2 modulation rates in 3 frequencies in both ears. However, the difference was significant only in 500 Hz in the MCI group, and no significant differences were observed in the AD group. In addition, significant differences were observed between the normal subjects and AD patients with regard to the estimated ASSR thresholds with 2 modulation rates and 3 frequencies in both ears. A significant difference was observed between the normal and MCI groups at 2000 Hz, too. An increase in estimated 40 Hz ASSR thresholds in patients with AD and MCI suggests neural changes in auditory cortex compared to that in normal ageing.Conclusion:Auditory threshold estimation with low and high modulation rates by ASSR test could be a potentially helpful test for detecting cognitive impairment.

Reliability of auditory steady-state response to bone conduction stimuli in assessing hearing loss in children

Abstract This study was designed to investigate bone Conduction (BC)/auditory steady state response (ASSR) in children with normal hearing, together with various types of hearing loss, to find out an objective method to differentiate between different types of hearing loss. A total of 80 children (with ages ranging between 3 and 6 years) were subjected to history taking, otological examination, and basic audiological evaluation in the form of pure-tone audiometry (air Conduction (AC), BC). Single monotic ASSR (AC, BC) was tested at 0.5, 1, 2, and 4 kHz. They were classified on the basis of hearing status into three categories (20 children each): category I, normal hearing; category II, sensorineural hearing Loss (SNHL) (subdivided into two groups: group 1, mild-to-moderate SNHL; and group 2, severe-to-profound SNHL), and category III, conductive hearing loss. BC thresholds were poorer for ASSR testing compared with thresholds obtained with behavioral testing in normal category using 9, 7.5, 5.5, and 10.5 dBHL at 0.5, 1, 2, and 4 kHz, respectively. In category II, in the mild-to-moderate SNHL group, it was poorer using 16.25, 5.75, 12.25, and 11.75 dBHL at the same measured frequencies. Minimum levels at which spurious BC/ASSR occurred were established in the group with severe-to-profound SNHL as 52, 66.5, 69, and 64 dBHL at 0.5, 1, 2, and 4 kHz, respectively (no BC/pure tone audiometry (PTA) could be measured). In conductive hearing loss (CHL) category, it was poorer using 12.5, 8.5, 9.5, and 9 dBHL at 0.5, 1, 2, and 4 kHz, respectively. Preliminary normal levels for BC/ASSR at 0.5, 1, 2, and 4 kHz were 23.5, 22.5, 20, and 25 dBHL, respectively. In children with conductive hearing loss, the average BC/ASSR thresholds corresponded closely to those in the normal-hearing group. BC/ASSR thresholds could be recorded reliably in children with normal hearing and conductive hearing losses. Meanwhile, BC/ASSR may not provide a reliable measure in cases of SNHL, especially cases with moderate or greater loss due to the low levels at which spurious responses may occur.

Microtia: A Combined Approach by Genetics and Audiology

Abstract Microtia is a condition in which the external portion of the ear (the auricle) is malformed. In the strictest definition, there is also narrowing or absence of the external auditory canal (external auditory meatus). Microtia varies in severity from barely discernible to an external ear with major structural changes. Hearing loss is a common feature that can be associated with microtia. There are different types of hearing loss–conductive, sensorineural, or mixed–depending on which part of the ear is not working as it should. The present study was designed with the following aims: (i) identification of the genetic etiology and patterns of inheritance of microtia for proper genetic counseling; (ii) early detection and identification of associated hearing impairment for proper management including use of a hearing aid and surgical intervention. Twenty children with microtia ranging in age between 1 and 15 years (mean: 6.2 ± 3.68 years) irrespective of sex were included in this study: 14 males and six females. All children were subjected to a full assessment of medical history, a general examination, an ENT examination, tympanometry, pure tone audiometry, and an auditory steady-state response test for patients not responding to a conventional audiometric test. Karyotyping, fluorescence in-situ hybridization (FISH) for Treacher Collins cases, radiological investigations, and fundus examination were also performed. Syndromic microtia was more frequent than nonsyndromic microtia. Treacher Collins syndrome was the most clinically diagnosed syndrome, followed by Goldenhar’s syndrome. There was one case of Down’s syndrome and another single case of Johnson–McMillin syndrome. Meatal atresia and preauricular tags were frequently present in the microtia cases, whereas middle ear and inner ear anomalies were only found in some cases. The most common presenting symptom of microtia is hearing loss. Its degree and type differ according to the severity of the disease and frequencies affected. In total, 88.5% (23 ears) have conductive hearing loss and 11.5% (three ears) have mixed hearing loss. Karyotyping was performed for 10 cases; nine cases were normal, whereas one case was abnormal (47XY, +21) (Down’s syndrome), which represents 5% of all cases studied. FISH was performed for four cases of Treacher Collins syndrome using a probe for chromosome 5 with gene map locus 5q31q33, but no deletion was found in the chromosome 5 Treacher Collins–Franceschetti 1 (TCOF1) gene. Genetic predisposition for both autosomal dominant and autosomal recessive inheritance seems to be a strong determinant factor in the etiology of microtia than the environmental one. As for Treacher Collins, which is the most frequently clinically diagnosed syndrome in the current study, the FISH study showed that the 5q31-q33 locus may not carry the causative mutation as no single case was positive for this locus. Hearing impairment, of the conductive type, is the most frequent symptom that leads parents to seek medical advice and genetic counseling.

Comparative Study of Hearing Impairment among Healthy and Intensive Care unit Neonates in Mashhad, North East Iran.

According to World Health Organization (WHO) 2001 statistics, hearing disorders are the most common congenital disease, and the incidence rate among high-risk newborns is as much as ten times as high as that in healthy neonates. However, 78% of screening test failures are well-baby nursery babies. The Joint Committee on Infants' Hearing (JCIH) has emphasized the importance of early diagnosis and treatment in neonates with hearing impairments in order to preserve their maximum linguistic skills. The aim of our study was to compare the prevalence of hearing loss among babies in the neonatal intensive care unit (NICU) and the rooming-in unit (RIU). Neonates born in three hospitals in Mashhad between 2008 to 2010 were studied prospectively and screened for auditory disorders using the oto acoustic emission (OAE) test at the time of discharge and 3 weeks later. To confirm hearing loss, the auditory steady state response (ASSR) test was used among those participants who failed both OAE tests. Two-thousand and sixty-three neonates from the NICU were screened and compared with a control group consisting of 8,724 neonates from the RIU or the well-baby nursery. At the end of the study, hearing impairment as confirmed by failure in the ASSR test was diagnosed in 31 neonates (26 in the control group [0.30%] and five in the NICU group [1.94%]). In our study, the prevalence of hearing disorders among NICU neonates was 6.5-times greater than that among babies from the RIU or well-baby unit. This observation demonstrates the importance of universal screening programs particularly for high-risk population neonates.

Are Auditory Steady-State Responses Useful to Evaluate Severe-to-Profound Hearing Loss in Children?

Objective. To evaluate Auditory Steady-State Responses (ASSR) at high intensities in pediatric cochlear implant candidates and to compare the results to behavioral tests responses. Methods. This prospective study evaluated 42 children with suspected severe-to-profound hearing loss, aged from 3 to 72 months. All had absent ABR and OAE responses. ASSR were evoked using binaural single frequency stimuli at 110 dB HL with a 10 dB down-seeking procedure. ASSR and behavioral test results were compared. Results. Forty-two subjects completed both ASSR and behavioral evaluation. Eleven children (26.2%) had bilateral responses. Four (9.5%) showed unilateral responses in at least two frequencies, all confirmed by behavioral results. Overall 61 ASSR responses were obtained, most (37.7%) in 500 Hz. Mean thresholds were between 101.3 and 104.2 dB HL. Among 27 subjects with absent ASSR, fifteen had no behavioral responses. Seven subjects showed behavioral responses with absent ASSR responses. No spurious ASSR responses were observed at 100 or 110 dB HL. Conclusion. ASSR is a valuable tool to detect residual hearing. No false-positive ASSR results were observed among 42 children, but in seven cases with absent ASSR, the test underestimated residual hearing as compared to the behavioral responses.

Utility of auditory steady-state and brainstem responses in age-related hearing loss in rats

Conclusions: The results support the idea that auditory steady-state response (ASSR) is a more accurate test for studying age-related hearing loss (ARHL) in Sprague-Dawley rats. Differences in the rat middle ear may explain the variations of the click properties, with a displacement of the energy toward the 8 and 10 kHz frequencies compared with humans. Objectives: The purpose of this study was to evaluate ARHL in older and younger Sprague-Dawley rats using auditory clicks and tone burst with auditory brainstem response (ABR), in addition to ASSR. Methods: This was a prospective cohort study with 50 animals divided into 5 groups based on their age in months. A total of 100 registers were elicited from each one of the 3 auditory measurements systems in an electrically shielded, double-walled, sound-treated cabin. Nine frequencies, from 0.5 to 16 kHz were analyzed with the auditory steady-state response and compared with the results elicited by the clicks and tone-burst ABR. Results: Comparisons between the different frequencies showed lower thresholds in those frequencies below 2 kHz, independently of their age in months. The ARHL was detected by each one of the three auditory measurement systems, but with lower thresholds with the ASSR test. Finally, auditory clicks showed better correlations with 8 and 10 kHz elicited by ASSR, which was different to what was expected, based on human studies.