Effect of auditory training on the middle latency response in children with (central) auditory processing disorder

The purpose of this study was to determine the middle latency response (MLR) characteristics (latency and amplitude) in children with (central) auditory processing disorder [(C)APD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (C)APD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (C)APD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (C)APD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 µV (mean), 0.39 (SD - standard deviation) for the (C)APD group and 1.18 µV (mean), 0.65 (SD) for the control group; C3-A2, 0.69 µV (mean), 0.31 (SD) for the (C)APD group and 1.00 µV (mean), 0.46 (SD) for the control group]. After training, the MLR C3-A1 [1.59 µV (mean), 0.82 (SD)] and C3-A2 [1.24 µV (mean), 0.73 (SD)] wave amplitudes of the (C)APD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (C)APD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (C)APD.

Effect of auditory training on the middle latency response in children with (central) auditory processing disorder.

The purpose of this study was to determine the middle latency response (MLR) characteristics (latency and amplitude) in children with (central) auditory processing disorder [(C)APD], categorized as such by their performance on the central auditory test battery, and the effects of these characteristics after auditory training. Thirty children with (C)APD, 8 to 14 years of age, were tested using the MLR-evoked potential. This group was then enrolled in an 8-week auditory training program and then retested at the completion of the program. A control group of 22 children without (C)APD, composed of relatives and acquaintances of those involved in the research, underwent the same testing at equal time intervals, but were not enrolled in the auditory training program. Before auditory training, MLR results for the (C)APD group exhibited lower C3-A1 and C3-A2 wave amplitudes in comparison to the control group [C3-A1, 0.84 microV (mean), 0.39 (SD--standard deviation) for the (C)APD group and 1.18 microV (mean), 0.65 (SD) for the control group; C3-A2, 0.69 microV (mean), 0.31 (SD) for the (C)APD group and 1.00 microV (mean), 0.46 (SD) for the control group]. After training, the MLR C3-A1 [1.59 microV (mean), 0.82 (SD)] and C3-A2 [1.24 microV (mean), 0.73 (SD)] wave amplitudes of the (C)APD group significantly increased, so that there was no longer a significant difference in MLR amplitude between (C)APD and control groups. These findings suggest progress in the use of electrophysiological measurements for the diagnosis and treatment of (C)APD.

A computer method for assessing satisfaction with hearing aids.

The purpose of this study was to evaluate a new clinical assessment, the Dynamic Assessment of Hearing Aids (DAHA), for a large clinical population. Unlike traditional questionnaire methods, the DAHA has patients use an intuitive graphical computer interface to record visual analogue ratings of satisfaction with various features of their hearing aids (e.g. clarity, cost, appearance). Data were collected from 191 participants.A subset of participants returned for retest. The DAHA items assess satisfaction with hearing aids within four domains: communication, physical features, sound quality, and personal reactions. The concurrent validity was determined by comparing DAHA results to those obtained with the satisfaction with amplification in daily life (SADL). Ratings for personal reactions to hearing aids indicate the most satisfaction, and ratings for communication (especially group conversations and phone use) indicate the least satisfaction. The DAHA total score was found to have good test/retest and high internal consistency. Concurrent validity was supported by a strong correlation between total scores on the DAHA and the SADL. Results suggest the DAHA maybe an effective tool for clinical use.

Auditory temporal processing deficits in patients with insular stroke.

OBJECTIVE: To assess central auditory function in a series of patients with stroke of the insula and adjacent areas. METHODS: The authors recruited eight patients with stroke affecting the insula and adjacent areas and eight neurologically normal controls (matched to the patients for age, sex, handedness, and hearing thresholds). The lesion spared the adjacent auditory areas in three patients and included other auditory structures in five cases. The authors conducted pure-tone audiometry and tympanometry and a central auditory test battery, which included the dichotic digits, and three temporal tests, the duration pattern, frequency pattern, and gaps in noise tests. They collected information from the hospital notes on symptoms at presentation and neuropsychological assessment data during the acute phase. RESULTS: The central auditory tests gave normal results in all controls. The temporal tests gave abnormal results in all three cases in which other auditory areas were spared, as well as in the other five cases. Results of the gaps in noise test were abnormal contralaterally to the lesion in three and bilaterally in five cases. The central auditory deficits did not cosegregate with the presence of cognitive impairment during the acute stage. CONCLUSION: Insular lesions may affect central auditory function and, in particular, temporal resolution and sequencing, consistent with neuroimaging studies.

Indication of a Lombard vocal response in the St. Lawrence River Beluga.

Noise pollution is recognized as a potential danger to marine mammals in general, and to the St. Lawrence beluga in particular. One method of determining the impacts of noise on an animal's communication is to observe a natural and repeatable response of the vocal system to variations in noise level. This is accomplished by observing intensity changes in animal vocalizations in response to environmental noise. One such response observed in humans, songbirds, and some primates is the Lombard vocal response. This response represents a vocal system reaction manifested by changes in vocalization level in direct response to changes in the noise field. In this research, a population of belugas in the St. Lawrence River Estuary was tested to determine whether a Lombard response existed by using hidden Markhov-classified vocalizations as targets for acoustical analyses. Correlation and regression analyses of signals and noise indicated that the phenomenon does exist. Further, results of human subjects experiments [Egan, J. J. (1966), Ph.D. dissertation; Scheifele, P. M. (2003), Ph.D. dissertation], along with previously reported data from other animal species, are similar to those exhibited by the belugas. Overall, findings suggest that typical noise levels in the St. Lawrence River Estuary have a detectable effect on the communication of the beluga.

Defective auditory interhemispheric transfer in a patient with a PAX6 mutation.

Heterozygous PAX6 mutation is associated with an absent or hypoplastic anterior commissure and a reduction in the area of the corpus callosum. The authors found deficient auditory interhemispheric transfer in a 53-year-old woman with a PAX6 mutation who had an absent anterior commissure but normal callosal volume.

Aetiology and clinical presentations of auditory processing disorders--a review.

Auditory processing disorders may have detrimental consequences on a child's life, if undiagnosed and untreated. We review causes of auditory processing disorders in order to raise clinical awareness. Auditory processing disorders may present against a background of neurological disease or developmental disorders, as well as in isolation. Clinicians need to be aware of potential causes and implications of auditory processing disorders.

Hearing loss in space.

BACKGROUND: Temporary and, in some cases, permanent hearing loss has been documented after long-duration spaceflights. METHODS: We examined all existing published data on hearing loss after space missions to characterize the losses. RESULTS: Data from Russian missions suggest that the hearing loss, when it occurs, affects mainly mid to high frequencies and that using hearing protection often might prevent the loss. Several significant questions remain about hearing loss in space. While the hearing loss has been presumed to be noise-induced, no clear link has been established between noise exposure and hearing loss during spaceflight. In one documented case of temporary hearing loss from the Shuttle-Mir program, the pattern of loss was atypical for a noise-induced loss. Continuous noise levels that have been measured on the Mir and previous space stations, while above engineering standards, are not at levels usually associated with hearing loss in ground-based studies (which have usually been limited to 8-10 h exposure periods). Attempts to measure hearing in space using threshold-based audiograms have been unsuccessful in both the American and Russian programs due to noise interference with the measurements. CONCLUSIONS: The existing data highlight the need for reliable monitoring of both hearing and noise in long-duration spaceflight.

Differential diagnosis and management of central auditory processing disorder and attention deficit hyperactivity disorder.

Children diagnosed with attention deficit hyperactivity disorder (ADHD) frequently present difficulties performing tasks that challenge the central auditory nervous system. The relationship between ADHD and central auditory processing disorder (CAPD) is examined from the perspectives of cognitive neuroscience, audiology, and neuropsychology. The accumulating evidence provides a basis for the overlapping clinical profiles yet differentiates CAPD and ADHD as clinically distinct entities. Common and distinctive management strategies are outlined.

Neuroaudiological effects in a case of fatal dimethylmercury poisoning.

OBJECTIVE: The audiological examination of this patient was to determine the degree and type of hearing loss that was incurred from apparent dimethylmercury poisoning. DESIGN: This was a single subject case study design. Audiologic tests were selected to help determine sensory from neural and/or central auditory system dysfunction. RESULTS: This patient demonstrated an inability to understand speech, both in formal and informal assessments, yet relatively good hearing sensitivity for pure tones bilaterally. Distortion product otoacoustic emissions showed only minimal deficits in each ear. The auditory brain stem response was abnormal bilaterally, indicating neural and/or central involvement. CONCLUSION: Dimethylmercury poisoning, in this case, resulted in compromise of the auditory neural system with little effect on the sensory (cochlea) mechanism.

Central auditory tests.

This article overviews some selected central auditory test procedures as well as some popular issues that surround them. Both behavioral and electrophysiologic central auditory tests are discussed in reference to their clinical value as judged by their sensitivity, specificity, administration time, and reliability. Also discussed are diagnostic trends that are noted on behavioral and electrophysiologic procedures. Relationships are drawn between children with auditory processing deficits associated with learning problems and individuals with neurological lesions of the central auditory nervous system.

Selected management approaches to central auditory processing disorders.

This is a commentary on three key aspects of the management of central auditory processing disorders in children. It is an update on some selected approaches for the management of auditory processing problems. Auditory training techniques that are theoretically based and for which empirical data are emerging are addressed. The second part of our commentary deals with methods of enhancing acoustic speech signals. Discussions on clear speech, acoustic modifications of the listening environment, and the utilization of assistive listening devices are presented. The final part of the article reviews linguistic and cognitive interventions for people with auditory processing problems. Topics in this section include approaches to facilitate phonological awareness, vocabulary building, prosodic feature recognition, and use of metacognitive abilities.

Endogenous dynorphins: possible role in peripheral tinnitus.

Tinnitus has been defined as the perceptual correlate of altered spontaneous neural activity occurring without an external auditory stimulus. Hyperacusis, defined as a collapse of tolerance to sound, is present in 40-86% of those who suffer from disabling forms of tinnitus. Both phenomena often are induced or exacerbated by physical or psychological stress. Biological systems known to regulate the body's overall response to stress use and release endogenous neuroactive opioid peptides. These stress-related neuromodulators consist of products derived from three genetically distinct precursor hormones. Two of these precursor hormones are proenkephalin and prodynorphin. Enkephalin and dynorphin-related peptides exist within the efferent olivocochlear systems (lateral and medial) of several mammalian species, including humans. Prodynorphin derivatives, however, may be restricted exclusively to lateral efferent neurons. Descending lateral efferent axons terminate solely on primary (type I) auditory dendrites innervating cochlear inner hair cells in most species. This action indicates that they play an important role in modulating auditory nerve sensitivity and spontaneous discharge. In a fashion similar to that exhibited by the observed excitatory mechanism of action of dynorphins in the spinal cord, sodium salicylate (aspirin) recently was shown to facilitate the excitatory effects of glutamate in the cochlea. This article provides support for a neurochemical model in which endogenous dynorphins may induce hyperacusis and can contribute to the induction, maintenance, or exacerbation of tinnitus in the auditory periphery by altering auditory type I neural excitability to glutamate.

Professional education and assessment practices in central auditory processing.

A 17-item questionnaire probing professional preparation and current practices in central auditory assessment was mailed to 500 audiologists selected randomly from the membership directory of the American Academy of Audiology. Data from 183 respondents, representing a 37 percent response rate, were analyzed. The majority of respondents reported minimal academic and clinical preparation in assessment of the central auditory nervous system. Eighty percent of respondents had not taken any graduate course explicitly dedicated to central auditory processing. However, 80 percent had taken at least one basic science course in central audition and 83 percent reported having taken at least one graduate course that included some coverage of central auditory processing and/or the central auditory nervous system. A mean of 3 clinical clock hours accrued in this area was reported. Not surprisingly, 78 percent reported a satisfaction rating of < or =50 percent relative to the graduate education they received in this area and only 41 percent reported providing central auditory assessment. Comparisons with prior surveys show substantial change in the preferred test battery. Most notable is the pivotal role of physiologic measures, with the acoustic reflex and auditory brainstem response listed along with the SCAN as the three most frequently used assessment tests/procedures. Overall, the results suggest a need for improvement in professional preparation in evaluation of central auditory function.

Neuroanatomical correlates to central deafness.

Our research experience with five centrally deaf patients showed that damage to various anatomical sites could result in central deafness. This finding was contrary to the commonly held notion that both Heschl's gyri must be severely damaged to yield central deafness. To discover whether lesions in various brain areas could cause central deafness, we reviewed 33 cases of central deafness reported in the literature which had sufficient radiological data to determine the anatomical regions involved. Both Heschl's gyri were involved in the majority of these cases, but there were definite exceptions. In these exceptional cases of central deafness, subcortical areas were involved (usually the internal capsule), as was the insula. Overall findings are discussed and recommendations are offered for the future study of centrally deaf patients.

Effectiveness of three central auditory processing (CAP) tests in identifying cerebral lesions.

The effectiveness of three central auditory processing (CAP) tests was evaluated using clinical decision analysis (CDA) procedures. The tests under study were the Dichotic Digits Test (DDT), the Auditory Duration Patterns Test (ADPT), and the P300 evoked potential test (P300). Subjects with normal hearing, sensorineural hearing loss (SNHL), and central lesions provided the data for CDA analyses. To identify the most effective test, we used the conventional CDA parameters of hit rate (sensitivity), false-positive rate (1 - false-positive rate = specificity), and A' (test performance at specific hit/false-positive combinations). Further, we illustrated the extension of the conventional CDA parameters to posterior probability determination, which incorporates disorder prevalence to compute the likelihood of a patient having a disorder when a test result is positive (Pr[D/+]) or not having a disorder when the test result is negative (Pr[N/-]). Last, we used the CDA parameter of hit rate and disorder prevalence to determine cost effectiveness.

Distortion product otoacoustic emissions: hit and false-positive rates in normal-hearing and hearing-impaired subjects.

OBJECTIVE: This study aimed to establish hit and false-positive rates for distortion product otoacoustic emissions (DPOAEs) using a commercial instrument. STUDY DESIGN: This was a prospective study. The examiners performing the DPOAEs were blinded to pure-tone audiometric results. A decision matrix analysis was used to determine hit and false-positive rates for absolute amplitude, three amplitude-to-noise ratios, and three conditions that combined these two parameters. SETTING: The study was performed at a tertiary care, outpatient clinical laboratory facility. PATIENTS: Subjects with normal hearing and those with sensorineural hearing loss participated in the study. MAIN OUTCOME MEASURES: Main outcome measures were hit and false-positive rates for various DPOAE measures. RESULTS: Hit and false-positive rates were better for high than low frequencies. As absolute amplitude and amplitude-to-noise ratios increased hit and false-positive rates improved. Optimal hit rates generally exceeded 80%; false-positive rates were approximately 20% in the high-frequency range. Although the absolute amplitude measures seemed more useful than various ratio measures, there were advantages to using both parameters clinically. CONCLUSIONS: DPOAEs have acceptable hit and false-positive rates for high frequencies but not for lower frequencies. DPOAE amplitude-to-noise ratios of +3 and even +6 dB may not be clinically feasible based on the current data. The overall findings obtained on the commercial instrument in this study compare favorably with previous studies of a similar nature.

Brainstem evoked response abnormalities in late-life depression with vascular disease.

OBJECTIVE: The purpose of this study was to examine whether the brainstem evoked responses of geriatric depressed patients with vascular disease show greater changes in wave V latency after increased stimulation than do responses of geriatric depressed patients without vascular disease and elderly comparison subjects with and without vascular disease. METHOD: Geriatric patients with unipolar depression (N = 53) were recruited from a university psychiatric hospital. Elderly comparison subjects (N = 23) were recruited through advertisements. All subjects were assessed for depressive symptoms, cognitive performance, overall medical burden, vascular disease, and disability. Brainstem evoked response was elicited at stimulation rates of 11.4 and 80.0 clicks/sec. RESULTS: The interaction between depression and vascular disease had a significant effect on change in wave V latency. This effect was synergistic, more than an additive effect. Post hoc comparisons showed that the depressed patients with vascular disease had greater changes in wave V latency that did the depressed patients without vascular disease, comparison subjects with vascular disease, and comparison subjects without vascular disease. Linear discriminant function analysis showed that 82% of the subjects with abnormal changes in wave V latency (sensitivity: 75%, specificity: 81%) could be identified on the basis of ratings for depression and vascular disease. CONCLUSIONS: Demyelination afflicting the pons and mesencephalon may explain the greater change in wave V latency for the brainstem evoked response in depressed patients with vascular disease. Further studies combining brainstem evoked response with brain imaging may determine whether depression develops only after vascular disease leads to demyelination.

Conventional and maximum length sequences middle latency response in patients with central nervous system lesions.

Conventional and maximum length sequence (MLS) middle latency response (MLR) procedures were compared across several parameters for control patients and patients with central nervous system lesions. There were similar findings for both populations and both types of MLR for the absolute latencies of Na and Pa waves. Middle latency waves were absent more often in the neurologic than control subjects for both the conventional and MLS-MLR procedures. Overall, more MLR waves were present for the MLS technique than for the conventional MLR technique. Differences in wave amplitude were significant for several recording sites when comparing neurologic with control groups, but findings were similar for wave amplitude when comparing the two types of MLR procedures for the neurologic population. Based on these findings, no clear diagnostic advantage was shown for using the MLS-MLR technique. These findings are further discussed.

Blockade of opioid-induced changes in auditory function at the level of the cochlea.

OBJECTIVE: We have previously investigated the auditory neural effects of the kappa-opioid receptor agonist, (-)pentazocine. When administered intravenously (i.v.), this drug temporarily alters auditory nerve compound action potential (CAP) amplitudes. To test the hypothesis that the observed neural effects of i.v. (-)pentazocine occur via kappa-receptor interactions within the cochlea, we attempted to block these effects by employing a specific kappa-opioid receptor antagonist applied directly to the cochlear round window (RW) membrane. DESIGN: In 31 normal-hearing, male pigmented chinchillas, amplitude changes in the click-evoked auditory CAP (N1) were tracked at six stimulus intensities during a baseline and a postbaseline period in which i.v. (-)pentazocine (8 mg/kg) was administered. (-)Pentazocine administration was preceded by the delivery to the cochlear RW membrane of an artificial perilymph solution given alone or containing the kappa-opioid receptor selective antagonist, norbinaltorphimine (Nor-BNI), which was administered at two concentrations in separate groups of animals. RESULTS: The amplitude increase in the CAP after (-)pentazocine was significantly reduced when i.v. (-)pentazocine was preceded by RW-administered Nor-BNI (4 mM). CONCLUSIONS: The reversibility of agonist effects by Nor-BNI indicates direct or indirect opioid kappa-receptor-mediated auditory neural effects at the level of the cochlea and suggests a connection between kappa-receptors and auditory neural function.