Wafaa A. Kaf

Reliability of electric response audiometry using 80 Hz auditory steady-state responses

The reliability of the Auditory Steady State Response (ASSR) has not been thoroughly evaluated despite its recent application as a clinical tool for threshold estimation. The purpose of this study was to examine test-retest (TR) reliability of ASSR threshold estimates in an empirical research design. The ASSR, tested using modulation frequencies approximately 80 Hz and above, was evaluated against pure tone audiometry (PTA), and the slow vertex potential (SVP, N1-P2). Sixteen normal-hearing young female adults were tested twice, one week apart. Varying degrees of sensorineural hearing loss of a notched configuration were simulated with filtered masking noise. Test-retest reliability was assessed using Pearson-product moment correlation analysis, supplemented by other post-hoc analyses. Results demonstrated moderately strong TR reliability for ASSR at 1000, 2000 and 4000 Hz (r = 0.83–0.93); however, the reliability of ASSR at 500 Hz was weaker (r = 0.75). Results suggest that ASSR-ERA is a reliable test at mid–high frequencies, at least with the configuration and degrees of simulated sensorineural hearing loss examined in this study.

Validity and accuracy of electric response audiometry using the auditory steady-state response: evaluation in an empirical design.

The validity and accuracy of the application of the auditory steady-state response (ASSR) to electric response audiometry (ERA) was tested further in a study permitting subjects to be their own controls for hearing loss. Simulated sensorineural hearing loss (SSHL) of complex configuration and varying degrees was effected using filtered masking noise. Thresholds estimated via ASSR-ERA were compared to those measured via conventional pure-tone audiometry. Further, the slow vertex potential N1–P2 was recorded to permit a comparison with an evoked-response test of common content validity and known accuracy. Results in a homogeneous subject sample demonstrated strong intertest correlation and agreement within 10 dB at 1000 to 4000 Hz (on average), but not at 500 Hz. The configurations determined by ASSR-ERA followed behavioral audiometric patterns well, except for the mildest degree of SSHL tested. Consequently, limitations of ERA remain, although ASSR-ERA appears to be quite valid overall and promises (justifiably) broad clinical applicability.

DPOAEs and contralateral acoustic stimulation and their link to sound hypersensitivity in children with autism

Abstract Objective: The hypersensitivity of children with autism to sound is a relatively unexplained behavior. The goal of the current study was to investigate the DPOAE characteristics of children with autism compared to a control group. Design: DPOAEs with and without contralateral stimuli were measured in two groups in three different conditions. Study sample: The study employed 14 children with autism and a control group with 28 age-matched participants. Results: In the without-contralateral stimulus condition, the overall S/N of DPOAEs was greater for the control group compared to the autism group (p < 0.0005). For both groups, the DPOAE S/N increased as a function of frequency in both ears. In the with contralateral stimulus condition, group and ear effects were noticed, however, no age, frequency, or contralateral stimulus type (BBN vs. 1000 Hz) effect could be detected. Conclusions: Presence of reduced DPOAEs in the autism group does not support the hypothesis that sound hypersensitivity in children with autism may be related to overactive outer hair cells function; rather it may be due to early cochlear dysfunction. Also, sound hypersensitivity in the autism group may be due to abnormality of the efferent auditory pathway as shown by lack of sufficient contralateral suppression.

Wideband energy reflectance findings in presence of normal tympanogram in children with Down's syndrome

OBJECTIVES The prevalence of middle ear disorders in children with Down syndrome is higher than normal children due to the associated craniofacial abnormalities. The goal of this study is to evaluate middle ear function using wideband energy reflectance at ambient pressure in 14 young children with Down syndrome and matched control group (2½-5 years old; N=19 ears per group) who each have a normal 226Hz tympanogram. METHODS All children underwent otoscopic examination, hearing screening using play audiometry (500-4000Hz), and middle ear testing using 226Hz tympanometry and wideband energy reflectance. The chirp signals for the wideband energy reflectance were presented to the childs ear at 65dB SPL stimulus level and the recording was done over 220-8000Hz range. The measured energy reflectance represents the ratio of the sound energy reflected from the tympanic membrane to the incident sound energy transmitted to the middle ear at a specific frequency. Paired Samples t-test was computed for the mean, 95th, 75th, 25th, and 5th percentile data of each frequency of the two groups. RESULTS Despite the presence of normal tympanometric findings in both groups, results revealed abnormal wideband energy reflectance findings in 63% of the children with Down syndrome compared to the normal wideband energy reflectance findings in the control group. The mean energy reflectance ratio of the Down syndrome group was abnormally lower than that of the control at 5700-8000Hz (p<0.0005). The 5th and 95th percentile ratios of the Down syndrome group fell outside the 5th and 95th percentile of the control group (p<0.0005). CONCLUSIONS Abnormally low energy reflectance ratios above 4000Hz in the presence of normal tympanograms in the Down syndrome group may suggest associated congenital middle ear anomalies in children with DS. The present findings suggest that wideband energy reflectance has the potential to be of more practical value in children with DS than tympanometry. Further research with a larger number of Down syndrome children will illuminate the potential of wideband energy reflectance in diagnosing middle ear disorders in children with Down syndrome.

Evaluation of patients with vertigo of vertebrobasilar insufficiency origin using auditory brainstem response, electronystagmography, and transcranial Doppler

Abstract Objectives: Vertigo can be a manifestation of underlying vertebrobasilar stroke in older adults. The study objectives were to investigate the correlation, sensitivity, and specificity of the auditory brainstem response (ABR), electronystagmorgraphy (ENG), and transcranial Doppler (TCD) collectively to distinguish between vertigo due to vertebrobasilar insufficiency (VBI) and vertigo due to non-VBI. Design: Prospective experimental study comparing ENG, ABR, and TCD battery findings between two groups of patients with vertigo and a control group. Study sample: Participants included 14 patients with vertigo of VBI origin, 14 patients with vertigo of non-VBI, and 11 matched controls. Results: Participants with VBI had more abnormal findings in the ENG (86%), TCD (72%), and ABR (64%) compared to the non-VBI group (64%, 21%, and 7%, respectively) and the control group. The combined battery revealed positive correlations, 64% sensitivity, and 84% positive predictive value (PPV) in the VBI group, and 100% specificity with lack of correlations in the non-VBI group. Conclusions: The modest sensitivity and PPV helps with early detection of VBI, thus preventing risk of vertebrobasilar stroke in 84% to 64% of patients. The 100% specificity in the non-VBI group rules out VBI, thus reducing the referral rate for unnecessary, diagnostic evaluations and ineffective treatment.

Distortion-product otoacoustic emissions and contralateral suppression findings in children with Asperger's Syndrome

OBJECTIVES Children with Aspergers Syndrome (AS) often demonstrate auditory behaviors such as hypersensitivity to sounds and poor performance in noisy environments. These auditory behaviors may be related to cochlear dysfunction and abnormal medial olivocochlear bundle (MOCB) activity. The objective of this study was to examine the distortion-product otoacoustic emissions (DPOAEs) with and without contralateral white noise to evaluate outer hair cell activity and MOCB activity in children with AS. METHODS A case control study where 18 boys with AS and 18 age-matched control subjects participated in the study. For both groups, DPOAEs were recorded at 4031, 2627, 1969, and 1359 Hz f2 frequencies with and without contralateral white noise at 30 dB SL. DPOAE SNRs and difference scores were analyzed for possible differences between both groups and age subgroups (young and old children). RESULTS In the quiet condition, there were no significant group or ear differences in DPOAEs SNR. However, DPOAEs SNR were larger at 4031 Hz than at lower frequencies in both groups, mostly due to negative effect of background noise on low frequency response. Contralateral noise resulted in both suppression and enhancement of the DPOAE SNRs in 93% of the control group and 90% of the AS group. However, there were no significant differences in suppression and enhancement between the two groups or age subgroups. The young controls had right ear advantage and significantly larger suppression at all frequencies except 4031 Hz than old controls. The young children with AS had slight left ear advantage and significantly larger suppression only at 2672 Hz compared to the old children with AS. CONCLUSIONS The results, indicating minor differences in DPOAEs and contralateral suppression and enhancement of DPOAEs between both control and AS groups and age subgroups, suggest subtle differences in the function of the outer hair cells and the MOCB activity. Therefore, other central auditory processing in the temporal lobe, limbic system and autonomic nervous system may be involved in the generation of hypersensitivity to sounds and difficulty understanding in noisy environments in children with AS.

Tinnitus and hyperacusis in autism spectrum disorders with emphasis on high functioning individuals diagnosed with Asperger's Syndrome

OBJECTIVES To evaluate the prevalence of tinnitus and hyperacusis in individuals with Aspergers Syndrome (AS). METHODS A home-developed case-history survey and three item-weighted questionnaires: Tinnitus Reaction Questionnaire (TRQ), Tinnitus Handicap Inventory (THI), and the Hyperacusis Questionnaire (HQ) were employed. These tools categorize the subjective response to tinnitus and hyperacusis. The research tools were mailed to a mailing list of individuals with Aspergers Syndrome. RESULTS A total of 55 subjects diagnosed with AS were included in the analysis (15.5% response rate). Sixty-nine percent of all respondents (38/55) reported hyperacusis with an average HQ score of 20.7. Furthermore, 35% (19/55) reported perceiving tinnitus with average scores of 27 for the TRQ and 23 for the THI. Thirty-one percent (17/55) reported both hyperacusis and tinnitus. The prevalence of hyperacusis in the AS respondents remained relatively constant across age groups. CONCLUSIONS Hyperacusis and tinnitus are more prevalent in the ASD population subgroup diagnosed with AS under DSM-IV criteria than in the general public. Hyperacusis also appears to be more prevalent in the AS population than in the ASD population at large. Future research is warranted to provide insight into the possible correlation between tinnitus and hyperacusis symptoms and the abnormal social interactions observed in this group.

Fast Click Rate Electrocochleography and Auditory Brainstem Response in Normal-Hearing Adults Using Continuous Loop Averaging Deconvolution.

Objectives: Using the continuous loop averaging deconvolution (CLAD) technique for conventional electrocochleography (ECochG) and auditory brainstem response (ABR) recordings, the effects of testing at high stimulus rates may have the potential to diagnose disorders of the inner ear and auditory nerve. First, a body of normative data using the CLAD technique must be established. Design: Extratympanic click ECochG and ABR to seven stimulus rates using CLAD were measured simultaneously from a tympanic membrane electrode and surface electrodes on the forehead and mastoid of 42 healthy individuals. Results: Results showed that the compound action potential (AP) of the ECochG and waves I, III, and V of the ABR decreased in amplitude and increased in latency as stimulus rate was increased from standard 7.1 clicks/s up to 507.81 clicks/s, with sharp reduction in AP amplitude at 97.66 clicks/s and reaching asymptote at 292.97 clicks/s. The summating potential (SP) of the ECochG, however, stayed relatively stable, resulting in increased SP/AP ratios with increasing rate. The SP/AP amplitude ratio showed more stability than AP amplitude findings, thus it is recommended for use in evaluation of cochlear and neural response. Conclusions: Results of both amplitude and latency data from this normative neural adaptation function of the auditory pathway serves as guide for improving diagnostic utility of both ECochG and ABR using CLAD as a reliable technique in distinguishing inner ear and auditory nerve disorders.

Assessment of low-frequency hearing with narrow-band chirp-evoked 40-Hz sinusoidal auditory steady-state response.

Abstract Objective To determine the clinical utility of narrow-band chirp-evoked 40-Hz sinusoidal auditory steady state responses (s-ASSR) in the assessment of low-frequency hearing in noisy participants. Design Tone bursts and narrow-band chirps were used to respectively evoke auditory brainstem responses (tb-ABR) and 40-Hz s-ASSR thresholds with the Kalman-weighted filtering technique and were compared to behavioral thresholds at 500, 2000, and 4000 Hz. A repeated measure ANOVA and post-hoc t-tests, and simple regression analyses were performed for each of the three stimulus frequencies. Study sample Thirty young adults aged 18–25 with normal hearing participated in this study. Results When 4000 equivalent response averages were used, the range of mean s-ASSR thresholds from 500, 2000, and 4000 Hz were 17–22 dB lower (better) than when 2000 averages were used. The range of mean tb-ABR thresholds were lower by 11–15 dB for 2000 and 4000 Hz when twice as many equivalent response averages were used, while mean tb-ABR thresholds for 500 Hz were indistinguishable regardless of additional response averaging. Conclusion Narrow-band chirp-evoked 40-Hz s-ASSR requires a ∼15 dB smaller correction factor than tb-ABR for estimating low-frequency auditory threshold in noisy participants when adequate response averaging is used.

Immigration Within the United States: Prevalence of Childhood Hearing Loss Revisited

PURPOSE As more adult and child immigrants enter the United States each year, there is a high likelihood that the prevalence of childhood hearing loss in the United States is underestimated, given estimations of the number of immigrant children entering the country with hearing loss. METHOD Information was collected using online search engines and peer-reviewed journals. The most recent articles available through search engines included in EBSCOhost at the time were used. The gathered data were organized by emigrating country, and the 2 countries with the highest immigration rates were presented. Estimations of the number of children immigrating with hearing loss were made using data from published peer-reviewed articles and government reports on immigration. CONCLUSIONS The prevalence of hearing loss in the United States is underestimated when considering undetected hearing loss in immigrant children. The addition of the immigrant children from only Mexico and China presents a 7.5% increase in the total number of children in the United States with hearing loss. This reinforces the importance of early detection of hearing loss in these children, resulting in more accurate estimation of the rate of childhood hearing loss in the United States and better planning for intervention programs.