RESUMEN
Prenatal exposures to alcohol (PAE) and tobacco (PTE) are known to produce adverse neonatal and childhood outcomes including damage to the developing auditory system. Knowledge of the timing, extent, and combinations of these exposures on effects on the developing system is limited. As part of the physiological measurements from the Safe Passage Study, Auditory Brainstem Responses (ABRs) and Transient Otoacoustic Emissions (TEOAEs) were acquired on infants at birth and one-month of age. Research sites were in South Africa and the Northern Plains of the U.S. Prenatal information on alcohol and tobacco exposure was gathered prospectively on mother/infant dyads. Cluster analysis was used to characterize three levels of PAE and three levels of PTE. Repeated-measures ANOVAs were conducted for newborn and one-month-old infants for ABR peak latencies and amplitudes and TEOAE levels and signal-to-noise ratios. Analyses controlled for hours of life at test, gestational age at birth, sex, site, and other exposure. Significant main effects of PTE included reduced newborn ABR latencies from both ears. PTE also resulted in a significant reduction of ABR peak amplitudes elicited in infants at 1-month of age. PAE led to a reduction of TEOAE amplitude for 1-month-old infants but only in the left ear. Results indicate that PAE and PTE lead to early disruption of peripheral, brainstem, and cortical development and neuronal pathways of the auditory system, including the olivocochlear pathway.
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Nicotiana , Efectos Tardíos de la Exposición Prenatal , Niño , Potenciales Evocados Auditivos del Tronco Encefálico , Femenino , Humanos , Lactante , Emisiones Otoacústicas Espontáneas , EmbarazoRESUMEN
BACKGROUND: Audiologists often lack confidence in results produced by current protocols for diagnostic electrophysiologic testing of infants. This leads to repeat testing appointments and slow protocols which extend the time needed to complete the testing and consequently delay fitting of amplification. A recent publication (Sininger et al50) has shown how new technologies can be applied to electrophysiologic testing systems to improve confidence in results and allow faster test protocols. Average test times for complete audiogram predictions when using new technologies and protocols were found to be just over 32 minutes using auditory brainstem response (ABR) and just under 20 minutes using auditory steady-state response (ASSR) technology. PURPOSE: The purpose of this manuscript is to provide details of expedited test protocols for infant and toddler diagnostic electrophysiologic testing. SUMMARY: Several new technologies and their role in test speed and confidence are described including CE-Chirp stimuli, automated detection of ABRs using a technique called F MP, Bayesian weighting which is an alternative to standard artifact rejection and Next-Generation ASSR with improved response detection and chirp stimuli. The test protocol has the following features: (1) preliminary testing includes impedance measures and otoacoustic emissions, (2) starting test levels are based on Broad-Band CE-Chirp thresholds in each ear, (3) ABRs or ASSRs are considered present based on automated detection rather than on replication of responses, (4) number of test levels is minimized, (5) ASSR generally evaluates four frequencies in each ear simultaneously with flexibility to change all test levels independently. CONCLUSIONS: Combining new technologies with common-sense strategies has been shown to substantially reduce test times for predicting audiometric thresholds in infants and toddlers (Sininger et al50). Details and rationales for changing test strategies and protocols are given and case examples are used to illustrate.
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Potenciales Evocados Auditivos del Tronco Encefálico , Pruebas Auditivas/métodos , Pruebas de Impedancia Acústica , Umbral Auditivo , Teorema de Bayes , Preescolar , Fenómenos Electrofisiológicos , Humanos , LactanteRESUMEN
BACKGROUND: The Prenatal Alcohol and Sudden Infant Death Syndrome and Stillbirth Network, known as the "Safe Passage Study," enrolled approximately 12,000 pregnant women from the United States and South Africa and followed the development of their babies through pregnancy and the infant's first year of life to investigate the role of prenatal alcohol exposure in the risk for sudden infant death syndrome (SIDS) and adverse pregnancy outcomes, such as stillbirth and fetal alcohol spectrum disorders. PURPOSE: Auditory system tests were included in the physiologic test battery used to study the effects of prenatal alcohol exposure on neurophysiology and neurodevelopment, as well as potential causal relationships between neurodevelopmental disorders and SIDS and/or stillbirth. The purpose of this manuscript is to describe normative results when using the auditory test battery applied. RESEARCH DESIGN: The test battery included the auditory brainstem response (ABR) and transient-evoked otoacoustic emissions (TEOAEs). Data were collected on individual ears of newborns and 1-month-old infants. STUDY SAMPLE: From a cohort of 6,070 with auditory system exams, a normative subsample of 325 infants were selected who were not exposed prenatally to alcohol, cigarette smoke, or drugs nor were they preterm or low birthweight. The subsample is small relative to the overall study because of strict criteria for no exposure to substances known to be associated with SIDS or stillbirth and the exclusion of preterm and low birthweight infants. Expectant mothers were recruited from general maternity at two comprehensive clinical sites, in the northern plains in the United States and in Cape Town, South Africa. These populations were selected for study because both were known to be at high-risk for SIDS and stillbirth. DATA COLLECTION AND ANALYSIS: ABR and TEOAE recordings were stored electronically. Peak latency and amplitude analysis of ABRs were determined by study personnel, and results were evaluated for differences by age, sex, test site, race, and ear (left versus right). RESULTS: TEOAE findings were consistent with existing literature including the increase in signal-to-noise (SNR) over the first month of life. The SNR increase is due to an increase in amplitude of the emission. TEOAE amplitude asymmetry favoring the right ear was found, whereas SNR asymmetry was not, perhaps because of the small sample size. A nonsignificant trend toward larger responses in female babies was found; a result that is generally statistically significant in studies with larger samples. Latencies were found to be shorter in ABRs elicited in the right ear with amplitudes that were slightly bigger on average. An expected decrease in wave V latency was observed from birth to 1-month of age, but the finding was of borderline significance (p = 0.058). CONCLUSIONS: One month is a short time to judge development of the auditory system; however, the ABR and TEOAE findings were consistent with current literature. We conclude that the auditory system data acquired for the Safe Passage Study, as reflected in the data obtained from this cohort of "unexposed" infants, is consistent with published reports of these auditory system measures in the general population.
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Potenciales Evocados Auditivos del Tronco Encefálico/fisiología , Audición/fisiología , Emisiones Otoacústicas Espontáneas/fisiología , Estudios de Cohortes , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Medición de RiesgoRESUMEN
OBJECTIVES: The first objective of this study was to compare the predicted audiometric thresholds obtained by auditory steady state response (ASSR) and auditory brainstem response (ABR) in infants and toddlers when both techniques use optimal stimuli and detection algorithms. This information will aid in determining the basis for large discrepancies in ABR and ASSR measures found in past studies. The hypothesis was that advancements in ASSR response detection would improve (lower) thresholds and decrease discrepancies between the thresholds produced by the two techniques. The second objective was to determine and compare test times required by the two techniques to predict thresholds for both ears at the 4 basic audiometric frequencies of 500, 1000, 2000, and 4000 Hz. DESIGN: A multicenter clinical study was implemented at three university-based children's hospital audiology departments. Participants were 102 infants and toddlers referred to the centers for electrophysiologic testing for audiometric purposes. The test battery included wideband tympanometry, distortion-product otoacoustic emissions, and threshold measurements at four frequencies in both ears using ABR and ASSR (randomized) as implemented on the Interacoustics Eclipse systems with "Next-Generation" ASSR detection and FMP analysis for ABR. Both methods utilized narrow band CE-Chirp stimuli. Testers were trained on a specialized test battery designed to minimize test time for both techniques. Testing with both techniques was performed in one session. Thresholds were evaluated and confirmed by the first author and correction factors were applied. Test times were documented in system software. RESULTS: Corrected thresholds for ABR and ASSR were compared by regression, by the Bland-Altman technique and by matched pairs t tests. Thresholds were significantly lower for ASSR than ABR. The ABR-ASSR discrepancy at 500 Hz was 14.39 dB, at 1000 Hz was 10.12 dB, at 2000 Hz was 3.73 dB, and at 4000 Hz was 3.67 dB. The average test time for ASSR of 19.93 min (for 8 thresholds) was found to be significantly lower (p < 0.001) than the ABR test time of 32.15 min. One half of the subjects were found to have normal hearing. ASSR thresholds plotted in dB nHL for normal-hearing children in this study were found to be the lowest yet described except for one study which used the same technology. CONCLUSIONS: This study found a reversal of previous findings with up to 14 dB lower thresholds found when using the ASSR technique with "Next-Generation" detection as compared with ABR using an automated detection (FMP). The test time for an audiogram prediction was significantly lower when using ASSR than ABR but was excellent by clinical standards for both techniques. ASSRs improved threshold performance was attributed to advancements in response detection including utilization of information at multiple harmonics of the modulation frequency. The stimulation paradigm which utilized narrow band CE-Chirps also contributed to the low absolute levels of the thresholds in nHL found with both techniques.
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Audiometría/métodos , Umbral Auditivo , Potenciales Evocados Auditivos del Tronco Encefálico , Audiometría de Respuesta Evocada , Niño , Preescolar , Femenino , Audición/fisiología , Pérdida Auditiva/diagnóstico , Humanos , Lactante , MasculinoRESUMEN
Individuals with autism spectrum disorders (ASD) frequently demonstrate preserved or enhanced frequency perception but impaired timing perception. The present study investigated the processing of spectral and temporal information in 12 adolescents with ASD and 15 age-matched controls. Participants completed two psychoacoustic tasks: one determined frequency difference limens, and the other determined gap detection thresholds. Results showed impaired frequency discrimination at the highest standard frequency in the ASD group but no overall difference between groups. However, when groups were defined by auditory hyper-sensitivity, a group difference arose. For the gap detection task, the ASD group demonstrated elevated thresholds. This supports previous research demonstrating a deficit in ASD in temporal perception and suggests a connection between hyper-sensitivity and frequency discrimination abilities.
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Percepción Auditiva , Trastornos Generalizados del Desarrollo Infantil/psicología , Percepción del Tiempo , Adolescente , Femenino , Humanos , Masculino , PsicoacústicaRESUMEN
Laterality (left-right ear differences) of auditory processing was assessed using basic auditory skills: (1) gap detection, (2) frequency discrimination, and (3) intensity discrimination. Stimuli included tones (500, 1000, and 4000 Hz) and wide-band noise presented monaurally to each ear of typical adult listeners. The hypothesis tested was that processing of tonal stimuli would be enhanced by left ear (LE) stimulation and noise by right ear (RE) presentations. To investigate the limits of laterality by (1) spectral width, a narrow-band noise (NBN) of 450-Hz bandwidth was evaluated using intensity discrimination, and (2) stimulus duration, 200, 500, and 1000 ms duration tones were evaluated using frequency discrimination. A left ear advantage (LEA) was demonstrated with tonal stimuli in all experiments, but an expected REA for noise stimuli was not found. The NBN stimulus demonstrated no LEA and was characterised as a noise. No change in laterality was found with changes in stimulus durations. The LEA for tonal stimuli is felt to be due to more direct connections between the left ear and the right auditory cortex, which has been shown to be primary for spectral analysis and tonal processing. The lack of a REA for noise stimuli is unexplained. Sex differences in laterality for noise stimuli were noted but were not statistically significant. This study did establish a subtle but clear pattern of LEA for processing of tonal stimuli.
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Envejecimiento/fisiología , Percepción Auditiva/fisiología , Lateralidad Funcional/fisiología , Estimulación Acústica/métodos , Adolescente , Adulto , Femenino , Humanos , Masculino , Música , Ruido , Discriminación de la Altura Tonal/fisiología , Prohibitinas , Caracteres Sexuales , Factores de TiempoRESUMEN
OBJECTIVE: The purpose of this study was to determine the influence of selected predictive factors, primarily age at fitting of amplification and degree of hearing loss, on auditory-based outcomes in young children with bilateral sensorineural hearing loss. DESIGN: Forty-four infants and toddlers, first identified with mild to profound bilateral hearing loss, who were being fitted with amplification were enrolled in the study and followed longitudinally. Subjects were otherwise typically developing with no evidence of cognitive, motor, or visual impairment. A variety of subject factors were measured or documented and used as predictor variables, including age at fitting of amplification, degree of hearing loss in the better hearing ear, cochlear implant status, intensity of oral education, parent-child interaction, and the number of languages spoken in the home. These factors were used in a linear multiple regression analysis to assess their contribution to auditory-based communication outcomes. Five outcome measures, evaluated at regular intervals in children starting at age 3, included measures of speech perception (Pediatric Speech Intelligibility and Online Imitative Test of Speech Pattern Contrast Perception), speech production (Arizona-3), and spoken language (Reynell Expressive and Receptive Language). RESULTS: The age at fitting of amplification ranged from 1 to 72 mo, and the degree of hearing loss ranged from mild to profound. Age at fitting of amplification showed the largest influence and was a significant factor in all outcome models. The degree of hearing loss was an important factor in the modeling of speech production and spoken language outcomes. Cochlear implant use was the other factor that contributed significantly to speech perception, speech production, and language outcomes. Other factors contributed sparsely to the models. CONCLUSIONS: Prospective longitudinal studies of children are important to establish relationships between subject factors and outcomes. This study clearly demonstrated the importance of early amplification on communication outcomes. This demonstration required a participant pool that included children who have been fit at very early ages and who represent all degrees of hearing loss. Limitations of longitudinal studies include selection biases. Families who enroll tend to have high levels of education and rate highly on cooperation and compliance measures. Although valuable information can be extracted from prospective studies, not all factors can be evaluated because of enrollment constraints.
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Implantes Cocleares , Audífonos , Pérdida Auditiva Bilateral/terapia , Trastornos del Desarrollo del Lenguaje/prevención & control , Desarrollo del Lenguaje , Trastornos del Habla/prevención & control , Factores de Edad , Niño , Preescolar , Cognición , Pérdida Auditiva Sensorineural/terapia , Humanos , Lactante , Pruebas de Inteligencia , Destreza Motora , Multilingüismo , Relaciones Padres-Hijo , Valor Predictivo de las Pruebas , Índice de Severidad de la Enfermedad , Habla , Inteligibilidad del Habla , Percepción del Habla , Resultado del TratamientoRESUMEN
BACKGROUND: Newborn Hearing Screening (NHS) programs aim to reduce the age of identification and intervention of infants with hearing loss. It is generally accepted that NHS programs achieve that outcome, but few studies have compared children who were screened to those not screened in the same study and during the same time period. This study takes advantage of the emerging screening programs in California to compare children based on screening status on age at intervention milestones. PURPOSE: The purpose of this studywas to compare the outcomes of cohorts of children with hearing loss, some screened for hearing loss at birth and others not screened. Specifically, the measures compared are the benchmarks suggested by the Joint Committee on Infant hearing for determining the quality of screening programs. STUDY SAMPLE: Records from 64 children with bilateral permanent hearing loss who were enrolled in a study of communication outcomes served as data for this study. Of these children, 47 were screened with 39 failing and 8 passing, and 17 were not screened. INTERVENTION: This study was observational and involved no planned intervention. DATA COLLECTION AND ANALYSIS: Outcome benchmarks included age at diagnosis of hearing loss, age at fitting of amplification, and age at enrollment in early intervention. Delays between diagnosis and fitting or enrollment were also calculated. Hearing screening status of the children included screened with fail outcome, screened with pass outcome, and not screened. Analysis included simple descriptive statistics, and t-tests were used to compare outcomes by groups: screened/not screened, screened pass/screened failed, and passed/not screened. RESULTS: Children with hearing loss who had been screened as newborns were diagnosed with hearing loss 24.62 months earlier, fitted with hearing aids 23.51 months earlier, and enrolled in early intervention 19.98 months earlier than those infants who were not screened. Screening status did not influence delays in fitting of amplification or enrollment in intervention following diagnosis. Eight of the infants with hearing loss (12.5%) passed the NHS, and the ages at benchmarks of those children were slightly but not significantly earlier than infants who had not been screened. CONCLUSIONS: The age at achievement of benchmarks such as diagnosis, fitting of amplification, and enrollment in early intervention in children who were screened for hearing loss is on target with stated goals provided by the Academy of Pediatrics and the Joint Committee on Infant Hearing. In addition, children who are not screened for hearing loss continue to show dramatic delays in achievement of benchmarks by as much as 24 months. Evaluating achievement of benchmarks during the start-up period of NHS programs allowed a direct evaluation of ability of these screening programs to meet stated goals. This demonstrates, unequivocally, that the NHS process itself is responsible for improvements in age at diagnosis, hearing aid fitting, and enrollment in intervention.
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Audífonos , Pérdida Auditiva/congénito , Pérdida Auditiva/diagnóstico , Tamizaje Neonatal , Preescolar , Pérdida Auditiva/rehabilitación , Humanos , Lactante , Recién NacidoRESUMEN
OBJECTIVES: In general, auditory cortex on the left side of the brain is specialized for processing of acoustic stimuli with complex temporal structure including speech, and the right hemisphere is primary for spectral processing and favors tonal stimuli and music. This asymmetry in processing is further emphasized when hemisphere-favored stimuli are presented to the contralateral ear. The purpose of the first experiment is to further investigate the properties that dictate lateralized processing of auditory stimuli by ear and the relationship between auditory task and stimulus type. Next, it is not clear what compensation may exist for the loss of function of one ear and consequently, reduced access to functions primary performed in the opposite hemisphere, in the case of early unilateral profound hearing loss. The purpose of experiment 2 is to determine if any compensation for loss of function is seen in persons with early unilateral deafness. DESIGN: Experiment 1: Gap detection thresholds were determined in 30 right-handed listeners with normal hearing using wide-band noise markers (temporally complex), 400 and 4000 Hz pure tones presented individually to the left and right ears. Experiment 2: The same procedure was administered to listeners with early-onset, severe-to-profound unilateral deafness (seven left ear deaf and five right ear deaf) in the hearing ear alone. RESULTS: A significant right ear advantage was found for gap detection threshold using noise markers and a smaller left ear advantage was found for tonal stimuli. Listeners with unilateral deafness demonstrated that the hearing ear, left or right, performed in a manner similar to listeners with normal hearing. CONCLUSIONS: Results indicate that (1) gap marker, more than task, was the salient feature in determining laterality of processing in this experiment, (2) the two ears have distinct processing capacity based on stimulus type, and (3) compensation for loss is not apparent in persons with congenital unilateral deafness.
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Corteza Auditiva/fisiología , Sordera/epidemiología , Sordera/fisiopatología , Lateralidad Funcional/fisiología , Pérdida Auditiva Unilateral/epidemiología , Pérdida Auditiva Unilateral/fisiopatología , Audición/fisiología , Trastornos de la Percepción/diagnóstico , Trastornos de la Percepción/epidemiología , Percepción del Tiempo , Adolescente , Adulto , Umbral Auditivo/fisiología , Sordera/diagnóstico , Femenino , Pérdida Auditiva Unilateral/diagnóstico , Humanos , Masculino , Persona de Mediana Edad , Índice de Severidad de la EnfermedadRESUMEN
Lateralized processing of auditory stimuli occurs at the level of the auditory cortex but differences in function between the left and right sides are not clear at lower levels of the auditory system. The current study is designed to (1) investigate asymmetric auditory function at the ear and brainstem in human infants and (2) investigate possible mechanisms for asymmetry at these levels. Study 1 evaluated auditory brainstem responses (ABRs) in response to high and low-level clicks presented to the right and left ears of neonates. Wave V was significantly larger in amplitude and waves III and V were shorter in latency when the ABR was generated in the right ear. Study 2 investigated two possible mechanisms of such asymmetry by (a) using contralateral white noise masking to activate the medial olivocochlear system and (b) increasing stimulus rate to reveal neural conduction and synaptic mechanisms. ABR wave V, evoked by clicks to the left ear, showed a greater reduction in amplitude with contralateral noise than the response evoked from the right ear. No systematic asymmetries in ABR latencies or amplitudes were found with increased stimulus rate. We conclude that (1) the click-evoked ABR in neonates demonstrates asymmetric auditory function with a small but significant right ear advantage and (2) asymmetric activation of the medial olivocochlear system, specifically greater contralateral suppression of ABR produced by the left ear, is a possible mechanism for asymmetry.
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Corteza Auditiva/fisiología , Potenciales Evocados Auditivos del Tronco Encefálico/fisiología , Lateralidad Funcional/fisiología , Tiempo de Reacción/fisiología , Estimulación Acústica , Análisis de Varianza , Femenino , Humanos , Recién Nacido , Masculino , Ruido , Enmascaramiento PerceptualRESUMEN
PURPOSE: The purpose of this review is to provide the reader with current information regarding the standards for audiologic assessment of infants and very young children. The nature of the appropriate test battery and the need for adjusting test procedures to meet the specific needs of infants and toddlers are emphasized. RECENT FINDINGS: The basic measures in the audiologic test battery include frequency-specific threshold tests by air and bone conduction, predicted by electrophysiologic measures when necessary; immittance measures including tympanometry and acoustic reflex using a high-frequency probe tone for infants under 4 months of age; and otoacoustic emissions. The ABR can be used with frequency-specific stimuli to predict the audiogram in newborns with a great deal of accuracy. Newer techniques, such as Auditory Steady State Response, are promising but need further study before they can be used reliably to predict hearing levels in infants. Finally, infants with hearing loss can be fit with amplification using prescriptive formulae, such as the Desired Sensation Level, which give appropriate hearing aid characteristics for infants based on their hearing thresholds. These fittings must be verified using objective electro-acoustic measures tailored to infants. SUMMARY: Infants failing newborn hearing screenings can be evaluated by audiologists to predict all necessary audiologic data and those found to have hearing loss can be fitted with appropriate amplification in the newborn period. Procedures must be carefully tailored to this age group.
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Audiometría , Pruebas de Impedancia Acústica , Audiometría de Tonos Puros , Potenciales Evocados Auditivos del Tronco Encefálico , Humanos , Lactante , Emisiones Otoacústicas EspontáneasRESUMEN
Auditory neuropathy (AN) is a term used to describe an auditory disorder in which there is evidence of normal outer hair cell function (otoacoustic emissions and/or cochlear microphonics) and poor function of the auditory nerve (absent or highly distorted auditory brain stem response starting with wave I). Many of these patients have evidence of generalized peripheral nerve disease, leading to an assumption that the peripheral portion of the auditory nerve is the most likely site of lesion. A small group of these patients has received cochlear implants, and the majority of them achieve average to above-average performance. Although this outcome may seem incongruous with neural disease, average performance by patients with AN may be a result of the reintroduction of neural synchrony by electrical stimulation and/or the fact that most deaf patients have poor nerve survival. Although cochlear implants are promising for deaf patients with AN, more study of the disorder is needed.