Deciphering auditory processing disorders in children

Utility of deficit-specific computer-based training on children with temporal processing deficit

PURPOSE

Children with temporal processing deficits struggle to detect and discriminate syllables, phonemes, and stress patterns in speech. To overcome these deficits, computer-based auditory training programs have been widely used as one of the rehabilitation alternatives in recent years. The present study aimed to examine the usefulness of one such computer-based temporal processing training (CBTPT) module on children with temporal processing deficits.

METHOD

Sixteen children (8-15 years) with temporal processing deficits were enrolled in the study, further divided into active (CBTPT) and placebo (placebo training) groups. Further, 8 typically developing children (no training) were enrolled as a comparison group. The auditory outcome measures included Duration Pattern Test (DPT), Gap Detection Test (GDT), Dichotic CV (DCV), and Speech-in-Noise-Indian English (SPIN-IE) assessed before and after training for all three groups.

RESULTS

Wilcoxon-sign rank test showed a statically significant difference between pre and post-test scores of DPT, GDT, and SPIN (p < 0.001) except DCV among the active group. However, no significant differences were noted in the pre and post-test scores among the placebo and TD groups. Mann Whitney U test showed a significant difference in DPT and SPIN post-training scores between active and placebo groups; active and TD group; placebo and TD group.

CONCLUSION

From the above finding, it is inferred that the CBTPT module is useful among children having temporal processing deficits.

Auditory Processing Disorder: Protocols and Controversy

PURPOSE

This study examined current auditory processing disorder (APD) protocols and audiologists' perspectives on the active debate seen in the literature regarding the status of APD as a unique disorder.

METHOD

This study used a cross-sectional, nonexperimental survey design. The participants were 134 U.S. audiologists, representing diversity across experience level and work setting.

RESULTS

Popular APD tests from prior surveys remain popular, and a few new tests have emerged. Most audiologists use diverse strategies to identify potential comorbid disorders as part of their APD protocol, including multidisciplinary assessment and referral to other specialists. Most participants disagreed with the assertion that APD is not a unique disorder; however, many also pointed out that patients' struggles with listening need to be the primary focus of APD assessment and management, regardless of the label of the disorder. Qualitative analysis of participant comments on the controversy yielded six themes: Clinical Experience, Comorbidity, Listening Skills, Literature Support, Overdiagnosis, and More Information Needed.

CONCLUSION

Most participants consider APD to be a unique disorder, citing clinical experience and the literature for support; however, many also indicated APD is complicated by comorbidity and APD may be overdiagnosed.

Remote Microphone Technology for Children with Hearing Loss or Auditory Processing Issues

School classrooms are noisy and reverberant environments, and the poor acoustics can be a barrier to successful learning in children, particularly those with multiple disabilities, auditory processing issues, and hearing loss. A new set of listening challenges have been imposed by the recent global pandemic and subsequent online learning requirements. The goal of this article is to review the impact of poor acoustics on the performance of children with auditory processing issues, mild hearing loss, and unilateral hearing loss. In addition, we will summarize the evidence in support of remote microphone technology by these populations.

Comparison of Diagnostic Auditory Processing Test Scores Measured in Clinical and School Settings

Purpose

The study aimed to compare auditory processing and cognitive test scores measured in a clinical setting with that measured in a school setting using a repeated-measures design. This was done on typically developing children and children with auditory processing disorder (APD).

Method

Thirty-two children (16 typically developing and 16 with APD), aged 7 years, were evaluated using three diagnostic auditory processing tests and a cognitive test. The tests included the Speech Perception in Noise Test in Kannada, the Gap Detection Threshold Test, the Dichotic Consonant–Vowel Test, and the Auditory Memory and Sequencing Test in Kannada. All the children were evaluated in an audiological diagnostic setting, as well as in their school.

Results

No significant difference in scores was obtained in the two settings for all the four tests that were administered. This was seen in the typically developing children and the children with APD. Additionally, the pass/fail decision for each test did not alter in the two settings. Moderate to almost perfect agreement was seen between the tests carried out in the two settings in both groups, on a Kappa test of agreement. In both settings, the children with APD performed significantly poorer than the typically developing children on the four diagnostic tests.

Conclusions

The findings of the study indicate that the diagnostic auditory processing tests and the cognitive test can be carried out in school settings as effectively as tests carried out in an audiological diagnostic clinical setting. This will enable carrying out diagnostic tests on children in schools soon after they are referred on screening auditory processing tools, administered in the educational setting. This will prevent missing diagnosis of children who fail to report to a diagnostic audiological center for detailed auditory processing evaluation.

Auditory event-related potentials and function of the medial olivocochlear efferent system in children with auditory processing disorders

OBJECTIVE

The objectives were to investigate the function of central auditory pathways and of the medial efferent olivocochlear system (MOCS).

DESIGN

Event-related potentials (ERP) were recorded following the delivery of the stimulus /da/ in quiet and in ipsilateral, contralateral, and binaural noise conditions and correlated to the results of the auditory processing disorders (APD) diagnostic test battery. MOCS function was investigated by adding ipsilateral, contralateral, and binaural noise to transient evoked otoacoustic emission recordings. Auditory brainstem responses and pure tone audiogram were also evaluated.

STUDY SAMPLE

Nineteen children (7 to 12 years old) with APD were compared with 24 age-matched controls.

RESULTS

Otoacoustic emissions and ABR characteristics did not differ between groups, whereas ERP latencies were significantly longer and of higher amplitudes in APD children than in controls, in both quiet and noise conditions. The MOCS suppression was higher in APD children.

CONCLUSIONS

Findings indicate that children with APD present with neural deficiencies in both challenging and nonchallenging environments with an increase in the timing of several central auditory processes correlated to their behavioural performances. Meanwhile, their modulation of the auditory periphery under noisy conditions differs from control children with higher suppression.

Auditory Neuropathy/Dys-Synchrony Disorder: Diagnosis and Management

Auditory neuropathy/dys-synchrony disorder affects neural responses, either directly or indirectly. Patients may demonstrate good ability to detect sound, but have significant difficulty listening in noise. Clinical auditory physiologic measures are used to characterize cochlear, eighth nerve, and brainstem function, and are needed to accurately identify this disorder. Cochlear implants provide benefit to many patients, and some patients derive benefit from amplification. This disorder can be identified and managed in infants, may have later onset, may be a part of a syndrome, and may include fluctuation in hearing ability.

Auditory processing disorders with and without central auditory discrimination deficits

Auditory processing disorder (APD) is defined as a processing deficit in the auditory modality and spans multiple processes. To date, APD diagnosis is mostly based on the utilization of speech material. Adequate nonspeech tests that allow differentiation between an actual central hearing disorder and related disorders such as specific language impairments are still not adequately available. In the present study, 84 children between 6 and 17 years of age (clinical group), referred to three audiological centers for APD diagnosis, were evaluated with standard audiological tests and additional auditory discrimination tests. Latter tests assessed the processing of basic acoustic features at two different stages of the ascending central auditory system: (1) auditory brainstem processing was evaluated by quantifying interaural frequency, level, and signal duration discrimination (interaural tests). (2) Diencephalic/telencephalic processing was assessed by varying the same acoustic parameters (plus signals with sinusoidal amplitude modulation), but presenting the test signals in conjunction with noise pulses to the contralateral ear (dichotic(signal/noise) tests). Data of children in the clinical group were referenced to normative data obtained from more than 300 normally developing healthy school children. The results in the audiological and the discrimination tests diverged widely. Of the 39 children that were diagnosed with APD in the audiological clinic, 30 had deficits in auditory performance. Even more alarming was the fact that of the 45 children with a negative APD diagnosis, 32 showed clear signs of a central hearing deficit. Based on these results, we suggest revising current diagnostic procedure to evaluate APD in order to more clearly differentiate between central auditory processing deficits and higher-order (cognitive and/or language) processing deficits.

Central auditory processing and migraine: a controlled study

Background

This study aimed to verify and compare central auditory processing (CAP) performance in migraine with and without aura patients and healthy controls.

Methods

Forty-one volunteers of both genders, aged between 18 and 40 years, diagnosed with migraine with and without aura by the criteria of “The International Classification of Headache Disorders” (ICDH-3 beta) and a control group of the same age range and with no headache history, were included. Gaps-in-noise (GIN), Duration Pattern test (DPT) and Dichotic Digits Test (DDT) tests were used to assess central auditory processing performance.

Results

The volunteers were divided into 3 groups: Migraine with aura (11), migraine without aura (15), and control group (15), matched by age and schooling. Subjects with aura and without aura performed significantly worse in GIN test for right ear (p = .006), for left ear (p = .005) and for DPT test (p < .001) when compared with controls without headache, however no significant differences were found in the DDT test for the right ear (p = .362) and for the left ear (p = .190).

Conclusions

Subjects with migraine performed worsened in auditory gap detection, in the discrimination of short and long duration. They also presented impairment in the physiological mechanism of temporal processing, especially in temporal resolution and temporal ordering when compared with controls. Migraine could be related to an impaired central auditory processing.

Clinical trial registration

Research Ethics Committee (CEP 0480.10) – UNIFESP

The filtered words test and the influence of lexicality

PURPOSE

In the present study, the authors aimed to investigate the language confounds of filtered words tests by examining the repetition of real words versus nonsense words as a function of level of filtering.

METHOD

Fifty-five young, native-English-speaking women with normal hearing were required to repeat 80 real-word and 80 nonsense-word monosyllables that were matched for phonemic content and low-pass filtered. Thirty participants were tested using a harsher filter range of 2000 to 500 Hz, and 25 participants were tested using a milder filter range of 3000 to 1500 Hz.

RESULTS

Paired-sample t tests compared accuracy (percentage of phonemes correct) for word and nonsense-word stimuli at each filter level. At filter levels between 3000 and 1750 Hz, performance for word stimuli was significantly better than for nonsense-word stimuli. Conversely, at filter levels between 500 and 1250 Hz, performance was significantly better for nonsense words.

CONCLUSIONS

The linguistic content of real-word stimuli benefits performance on low-pass filtered speech tests at filter levels above 1500 Hz. Caution must be taken when using real-word stimuli in low-pass filtered speech tests as part of an auditory processing diagnostic test battery, because language ability will impact on performance.

Audiometric thresholds and auditory processing in children with early malnutrition: a retrospective cohort study

CONTEXT AND OBJECTIVE

Malnutrition is one of the causes of changes in cell metabolism. The inner ear has few energy reserves and high metabolism. The aim of this study was to analyze whether malnutrition at an early age is related to impairment of auditory processing abilities and hearing abnormalities.

DESIGN AND SETTING

Retrospective cohort study conducted in a tertiary public hospital.

METHODS

45 children participated, divided as follows: G1, children diagnosed with malnutrition in their first two years of life; G2, children without history of malnutrition but with learning difficulties; G3, children without history of malnutrition and without learning difficulties. Tympanometry, pure-tone audiometry and the Staggered Spondaic Word (SSW) test (auditory processing) were performed. Statistical inferences were made using the Kruskal-Wallis test (α = 5%) and the test of equality of proportions between two samples (α = 1.7%).

RESULTS

None of the 45 children participating in this study presented hearing deficiencies. However, at six of the eight frequencies analyzed, the children in G1 presented hearing thresholds lower than those of the other groups. In the auditory processing evaluation test, it was observed that 100% of the children in G1 presented abnormal auditory processing and that G1 and G2 had similar proportions of abnormalities (P-values: G1/G2 = 0.1; G1/G3 > 0.001; G2/G3 = 0.008).

CONCLUSIONS

Malnutrition at an early age caused lowering of the hearing levels, although this impairment could not be considered to be a hearing deficiency. Every child in this group presented abnormalities in auditory processing abilities.

Avaliação audiológica comportamental e eletrofisiológica no transtorno do espectro do autismo

Objetivo descrever os achados das avaliações audiológicas comportamentais e eletrofisiológicas de pacientes com diagnóstico de transtorno do espectro do autismo. Métodos estudo descritivo, de coorte contemporânea com corte transversal, composto por nove pacientes com diagnóstico de transtorno do espectro do autismo, submetidos a avaliação comportamental e eletrofisiológica da audição. Os resultados foram analisados por meio de estatística descritiva. Resultados todos os pacientes avaliados apresentaram limiares audiométricos dentro dos padrões de normalidade. Oito pacientes apresentaram curva timpanométrica do tipo A, e um do tipo C. Observou-se emissões otoacústicas por produto de distorção presentes em todos os pacientes avaliados. Os resultados do potencial evocado auditivo de tronco encefálico demonstraram integridade das vias auditiva. Conclusão a população estudada apresentou resultados compatíveis com a normalidade tanto na avaliação comportamental como na avaliação eletrofisiológica da audição. Pelo fato de não haver consenso, na literatura especializada, quanto aos achados audiológicos nesta população, principalmente no que se refere à avaliação eletrofisiológica do processamento auditivo, sugere-se a realização de novos estudos.

Exposição a níveis de pressão sonora em sala de aula, imitanciometria e teste SSW em escolares de 3º e 4º ano do ensino fundamental

OBJETIVO: investigar os efeitos dos níveis de pressão sonora elevados em sala de aula e das alterações imitanciométricas sobre as habilidades auditivas de crianças em fase inicial de letramento. MÉTODOS: estudo quantitativo e exploratório. Medições acústicas por meio de dosímetro; inspeção visual do conduto auditivo externo; audiometria tonal e vocal; imitanciometria. Os resultados das mensurações acústicas realizadas por meio de dosímetro em quatro escolas de Santa Maria - RS, dividiu a amostra de 87 crianças do 3º e 4º ano do ensino fundamental, na faixa etária de oito a dez anos em dois grupos - Grupo 1 / não expostos e Grupo 2 / expostos a níveis maiores que 80dB(A). A amostra também foi separada em 38 crianças sem alterações imitanciométricas e 49 com alterações, avaliadas em suas habilidades auditivas pelo teste dicótico de Dissílabos Alternados - SSW. RESULTADOS: o G1 apresentou melhores resultados na DC e EC em ambas às condições imitanciométricas, sem evidenciar diferença estatística. Foi constatada maior quantidade de acertos para a OE; a média do total de acertos evidenciou desempenhos semelhantes entre os grupos; o G1 apresentou melhores resultados na decodificação fonêmica, porém piores resultados nos subperfis codificação e organização. CONCLUSÕES: o presente estudo demonstrou que níveis de pressão sonora elevados em sala de aula não interferem nas habilidades auditivas testadas por meio do SSW, de crianças em processo de aprendizagem.

Development of an adaptive low-pass filtered speech test for the identification of auditory processing disorders

OBJECTIVE

One type of test commonly used to examine auditory processing disorders (APD) is the low-pass filtered speech test (LPFST), of which there are various versions. In LPFSTs, a monaural, low-redundancy speech sample is distorted by using filtering to modify its frequency content. Due to the richness of the neural pathways in the auditory system and the redundancy of acoustic information in spoken language, a normal listener is able to recognize speech even when parts of the signal are missing, whereas this ability is often impaired in listeners with APD. One limitation of the various versions of the LPFST is that they are carried out using a constant level of low-pass filtering (e.g. a fixed 1kHz corner frequency) which makes them prone to ceiling and floor effects. The purpose of this study was to counter these effects by modifying the LPFST using a computer-based adaptive procedure, and to evaluate the performance of normal-hearing participants of varying ages on the test.

METHODS

In this preliminary study, 33 adults and 30 children (aged 8-11 years) with no known history of listening difficulties were tested. The University of Canterbury Adaptive Speech Test (UCAST) platform was used to administer a four-alternative forced-choice adaptive test that altered a low-pass filter (LPF) to track the corner frequency at which participants correctly identified a certain percentage of the word stimuli.

RESULTS

Findings on the University of Canterbury Adaptive Speech Test-Filtered Words (UCAST-FW) indicated a significant maturational effect. Adult participants performed significantly better on the UCAST-FW in comparison to the child participants. The UCAST-FW test was reliable over repeated administrations.

CONCLUSIONS

An adaptive low-pass filtered speech test such as the UCAST-FW is sensitive to maturational changes in auditory processing ability.

[Auditory processing evaluation in children born preterm]

PURPOSE

To verify the performance of children born preterm on auditory processing evaluation, and to correlate the data with behavioral hearing assessment carried out at 12 months of age, comparing the results to those of auditory processing evaluation of children born full-term.

METHODS

Participants were 30 children with ages between 4 and 7 years, who were divided into two groups: Group 1 (children born preterm), and Group 2 (children born full-term). The auditory processing results of Group 1 were correlated to data obtained from the behavioral auditory evaluation carried out at 12 months of age. The results were compared between groups.

RESULTS

Subjects in Group 1 presented at least one risk indicator for hearing loss at birth. In the behavioral auditory assessment carried out at 12 months of age, 38% of the children in Group 1 were at risk for central auditory processing deficits, and 93.75% presented auditory processing deficits on the evaluation. Significant differences were found between the groups for the temporal order test, the PSI test with ipsilateral competitive message, and the speech-in-noise test. The delay in sound localization ability was associated to temporal processing deficits.

CONCLUSION

Children born preterm have worse performance in auditory processing evaluation than children born full-term. Delay in sound localization at 12 months is associated to deficits on the physiological mechanism of temporal processing in the auditory processing evaluation carried out between 4 and 7 years.

[Central auditory processes evaluated with psychoacoustic tests in normal children]

OBJECTIVE

To identify the natural tendencies of hits and calculate the cutoff for a test group of central auditory processes (CAP): binaural fusion, filtered words, dichotic digits, frequency patterns and duration patterns and ambient sounds in normal 5-, 7-, 9- and 11-year-old children.

MATERIAL AND METHODS

We studied 369 children (738 ears) who attend public schools in Puebla City, administering 6 CAP tests (two binaural and four monaural); we used an audiometer at 50dB SL re-threshold at 1 kHz, from a CD recorded at the CCECADET-UNAM-INR (Centre for Applied Science and Technological Development at the National Autonomous University of Mexico and the National Institute for Rehabilitation).

RESULTS

We determined the cutoff points for the six tests.

CONCLUSION

This information represents an advance in the normative standards in the field of psychoacoustic tests for CAP in Spanish and in the socio-educational context prevalent in Mexico. It is important to evaluate these results against CAP disorders.

Auditory processing disorder and speech perception problems in noise: finding the underlying origin

PURPOSE

A hallmark listening problem of individuals presenting with auditory processing disorder (APD) is their poor recognition of speech in noise. The underlying perceptual problem of the listening difficulties in unfavorable listening conditions is unknown. The objective of this article was to demonstrate theoretically how to determine whether the speech recognition problems are related to an auditory dysfunction, a language-based dysfunction, or a combination of both.

METHOD

Tests such as the Speech Perception in Noise (SPIN) test allow the exploration of the auditory and language-based functions involved in speech perception in noise, which is not possible with most other speech-in-noise tests. Psychometric functions illustrating results from hypothetical groups of individuals with APD on the SPIN test are presented. This approach makes it possible to postulate about the origin of the speech perception problems in noise.

CONCLUSION

APD is a complex and heterogeneous disorder for which the underlying deficit is currently unclear. Because of their design, SPIN-like tests can potentially be used to identify the nature of the deficits underlying problems with speech perception in noise for this population. A better understanding of the difficulties with speech perception in noise experienced by many listeners with APD should lead to more efficient intervention programs.

[Assessment of central auditory processes in Spanish in children with dyslexia and controls. Binaural Fusion Test and Filtered Word Test]

OBJECTIVES

The aim is to assess the ability to discriminate words, using two psychoacoustic verbal tests of central auditory processes in Spanish: Binaural Fusion Test (BFT in its Spanish version) and Filtered Word Test (FWT in its Spanish version) in children with dyslexia and controls.

METHODS

One group of 40 dyslexic children was receiving therapy for dyslexia at the time of the tests. 40 children without dyslexia were selected as controls, out of 298 children who attended a public school.

RESULTS

The rate of males to females was 2/1 in the dyslexic group. The average correct answers for the BFT were 65-66% in dyslexic group and 75-80% in the control group. For the FWT they were 50-54% in the dyslexic group and 67-71% in the control group (student t <0.05).

CONCLUSIONS

These results contribute to make evident disorders in central auditory processing in children with dyslexia. We suggest using the tests with each patient in order to elaborate a rehabilitation plan.

Psychometric evaluation of children with suspected auditory processing disorders (APDs) using a parent-answered survey

Difficulty with auditory processing in children is of increasing interest but is the subject of some controversy in the literature This paper describes a psychometric evaluation of differences between children with suspected auditory processing disorders (APDs) and a control group, using a parent-answered questionnaire. The questionnaire comprised 51 items associated with auditory processing as well as speech/language- and behaviour-related areas. It was found that most of the items separated significantly (p<0.01) between the children with suspected APDs and the control group. A factor analysis identified seven components (speech understanding in demanding situations, speech/language abilities, general behavioural issues, reactions to questions and demands, discrimination of speech sounds, musical cues, loudness perception) underlying the contrasts between the two study populations. The examination might serve as a basis for the development of an APD-related questionnaire. However, the validity of such a questionnaire is questionable at present, since APD is not very well specified, and standardized diagnostic tests are lacking.

Electrophysiologic assessment of central auditory processing by auditory brainstem responses in children with autism spectrum disorders

In addition to aberrant features in the speech, children with Autism Spectrum Disorder (ASD) may present unusual responses to sensory stimuli, especially to auditory stimuli. We investigated the auditory ability of children with ASD by using Auditory Brainstem Responses (ABR) as they can directly judge both hearing status and the integrity of auditory brainstem pathways. One hundred twenty-one children (71: ASD; M 58/ F 13, mean age; 41.8 months, 50: control group; M 41/ F 9, mean age; 38 months) were included in the study. As compared with the values in the control group, the latency of wave V, wave I-V, and wave III-V inter-peak latencies were significantly prolonged (p<0.05) in the ASD group. The findings indicate that children with ASD have a dysfunction or immaturity of the central auditory nervous system. We suggest any children with prolonged III-V inter-peak latencies, especially high functioning children should be further evaluated for central auditory processing to set up a more appropriate treatment plan.

Resolução temporal: análise em pré-escolares nascidos a termo e pré-termo

TEMA: processamento auditivo. OBJETIVO: verificar o comportamento auditivo de resolução temporal de crianças na faixa etária de cinco a seis anos, nascidas pré-termo, sem evidências de alterações neurológicas e compará-lo com o mesmo comportamento auditivo de crianças na mesma faixa etária, nascidas a termo, com baixo risco para alteração do desenvolvimento, considerando as variáveis: limiar de detecção de intervalo de tempo por freqüência sonora pré-estabelecida apresentada na forma binaural e monoaural por ordem de orelha que iniciou o teste e gênero. MÉTODO: 70 sujeitos: 44 nascidos a termo reunidos em grupos de 20 indivíduos do sexo feminino e 24 do sexo masculino, denominado Grupo 1, e 26 nascidos pré-termo, sendo 12 indivíduos do sexo feminino e 14 do sexo masculino, denominado Grupo 2, foram submetidos a avaliação audiológica composta por audiometria tonal limiar, limiar de reconhecimento de fala, imitânciometria e aplicação do teste de fusão auditiva denominado de Random Gap Detection. RESULTADOS: os nascidos a termo apresentaram menores limiares de detecção de intervalo de tempo no teste de fusão auditiva, nas formas de apresentação binaural e monoaural em todas as freqüências sonoras pré-estabelecidas, do que os nascidos pré-termo com diferença estatisticamente significante. As médias dos limiares de detecção de intervalo de tempo do Grupo 1 aumentaram conforme a freqüência sonora aumentou. No Grupo 2 não foram encontradas diferenças estatisticamente significantes quanto as médias de limiares de detecção de intervalo de tempo na forma de apresentação binaural e monoaural. CONCLUSÃO: os nascidos pré-termo se diferenciam dos nascidos a termo quanto ao comportamento auditivo de resolução temporal e o teste de fusão auditiva utilizado pode servir como ferramenta para a avaliação do processamento auditivo, uma vez que a detecção precoce de alteração dos processos temporais indica uma intervenção para minimizar ou evitar futuros prejuízos de linguagem.

Cortical activity of children with dyslexia during natural speech processing: evidence of auditory processing deficiency

Children with dyslexia have difficulties with phonological processing. It is assumed that deficits in auditory temporal processing underlie the phonological difficulties of dyslectic subjects (i.e. the processing of rapid acoustic changes that occur in speech). In this study we assessed behavioral and electrophysiological evoked brain responses of dyslectic and skilled reading children while performing a set of hierarchically structured auditory tasks. Stimuli consisted of auditory natural unmodified speech that was controlled for the parameter of changing rate of main acoustic cues: vowels (slowly changing speech cues: /i/ versus /u/) and consonant-vowel (CV) syllables (rapidly changing speech cues: /da/ versus /ga/). Brain auditory processing differed significantly between groups: reaction time of dyslectic readers was prolonged in identifying speech stimuli and increased with increased phonological demand. Latencies of auditory evoked responses (auditory event related potentials [AERPs]) recorded during syllable identification of the dyslectic group were prolonged relative to those of skilled readers. Moreover, N1 amplitudes during vowel processing were larger for the dyslectic children and P3 amplitudes during CV processing were smaller for the dyslectic children. From the results of this study it is evident that the latency and amplitude of AERPs are sensitive measures of the complexity of phonological processing in skilled and dyslectic readers. These results may be signs of deficient auditory processing of natural speech under normal listening conditions as a contributing factor to reading difficulties in dyslexia. Detecting a dysfunction in the central auditory processing pathway might lead to early detection of children who may benefit from phonetic-acoustic training methods.

Sensitividade e especificidade do potencial de média latência

O Potencial Evocado Auditivo de Média Latência (PEAML) foi primeiramente descrito por Geisler, Frishkopf, Rosenblith em 1958.¹ É caracterizado por uma série de ondas/respostas neuroelétricas gravadas no cérebro através de eletrodos de superfície. Atualmente, tem sido visto como um dos testes eletrofisiológicos mais promissores para a avaliação das disfunções e/ou alterações do Sistema Nervoso Auditivo Central. Suas ondas aparecem no intervalo entre 10 e 80 milissegundos (ms) após o início do estímulo auditivo. A onda Pa é a mais estudada por ser a mais visível e robusta deste potencial. Esse teste ainda é pouco utilizado na prática clínica pelo fato de existir uma grande variabilidade nos resultados encontrados intersujeitos, o que torna difícil o estabelecimento de medidas de normalidade. OBJETIVO: O objetivo desse trabalho foi estabelecer a efetividade - sensitividade e especificidade do PEAML para que este potencial possa ser mais utilizado com maior fidedignidade. FORMA DE ESTUDO: Caso-controle. MATERIAL E MÉTODO: Fizeram parte desse estudo indivíduos com idade entre 15 e 55 anos, portadores de lesões de Sistema Nervoso Auditivo Central, comprovada através de diagnóstico por imagem ou que tenham sido submetidos a cirurgias crânio-encefálicas, indivíduos portadores de Transtornos do Processamento Auditivo (TPA) comprovadas através de avaliação comportamental e indivíduos normais (Grupo Controle). RESULTADOS: Os resultados mostram que o corte de 30% apresentou melhores resultados, tanto para o efeito de eletrodo quanto para o efeito de orelha. O efeito de orelha foi mais fidedigno para evidenciar Transtornos de Processamento Auditivo, enquanto o efeito de eletrodo foi mais efetivo para evidenciar lesão.

Protein analysis in the rat auditory brainstem by two-dimensional gel electrophoresis and mass spectrometry

A catalogue of the protein repertoire of processing centres in the central auditory system would greatly foster our knowledge on the anatomical and functional properties of this sensory system. Towards this goal, we report on the first mapping study of the protein content in the superior olivary complex (SOC) and the inferior colliculus (IC) of the rat auditory brainstem. The protein content of these two structures was assessed by means of two-dimensional gel electrophoresis (2-DGE) and mass spectrometry. To do so, proteins were first separated into four fractions by differential centrifugation. For comparison, corresponding cerebellar fractions were also analysed. Immunoblot analysis revealed highly enriched microsomal and cytosolic fractions; the other two fractions were mixtures of various subcellular compartments. Separation of the 800 g pellets (enriched for nuclear and plasma membrane proteins) and the 100,000 g supernatants (enriched for cytosolic proteins) by 2-DGE yielded between 456 and 674 distinct protein spots after silver staining. The overall protein pattern of all three tissues was similar for a given fraction. Fifty prominent protein spots of the SOC cytosolic fraction were identified by mass spectrometry and yielded information on thirty different genes with various cellular functions, e.g. primary metabolism, cytoarchitecture, and signal transduction. Sequencing of eleven corresponding spots from the SOC and IC cytosolic fractions confirmed the great similarity between the two samples. The results of this analysis are part of a novel integrated database of the gene repertoire of the auditory brainstem (ID-GRAB), that is publicly available (http://www.id-grab.de).