Auditory function in Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease (PMD; MIM 312080), an inherited defect of central nervous system myelin formation, affects individuals in many ways, including their hearing and language abilities. The aim of this study was to assess the auditory abilities in 18 patients with PMD by examining the functional processes along the central auditory pathways using auditory brainstem responses (ABR) and cortical auditory evoked potentials (CAEP) in response to speech sounds. The significant ABR anomalies confirm the existence of dyssynchrony previously described at the level of the brainstem in patients with PMD. Despite the significant auditory dyssynchrony observed at the level of the brainstem, CAEPs were present in most patients, albeit somehow abnormal in terms of morphology and latency, resembling a type of auditory neuropathy spectrum disorder.

Potencial cortical P3: nível de dificuldade para diferentes estímulos / P3 cortical potential: difficulty level for different stimulus

Objetivo Avaliar o nível de dificuldade de identificação dos estímulos verbais e não verbais, segundo classificação dos próprios participantes, e comparar com a latência do potencial cortical P3. Métodos Foram avaliados 30 sujeitos, com média de idade de 23 anos, normo-ouvintes. O potencial P3 foi pesquisado com estímulos não verbais (tone burst)e verbais (/ba/ x /di/, /ba/ x /ga/, /ba/ x /da/). Cada sujeito classificou os estímulos em "mais fácil" e "mais difícil".Resultados : A maioria dos indivíduos classificou o contraste /ba/ x /di/ como sendo o mais fácil de identificar e o contraste /ba/ x /ga/, como o mais difícil. Os sujeitos referiram que os estímulos de fala foram mais fáceis de identificar quando comparados com tone burst. O nível de dificuldade descrito pelos indivíduos influenciou nas latências dos estímulos /Di/ e /Da/, classificados como mais fáceis, e evidenciados na menor latência do P3.Conclusão O contraste /Ba/ x /Di/ foi considerado o de maior facilidade de percepção, sendo evidenciado pela menor latência do P3. Os contrastes de fala foram classificados mais fáceis quando comparados com os estímulos tonais. Essas comparações auxiliam o clínico na escolha do estímulo utilizado e no correto diagnóstico audiológico.

Purpose Evaluating the level of difficulty of identifying verbal and non-verbal stimuli, according to the classification of the participants, as well as comparing the latency of the P3 cortical potential.Methods Thirty subjects, with a mean age of 23 years and normal hearing, were evaluated. The P3 potential was performed with non-verbal stimuli (tone burst) and verbal (/ba/ x /di/, /ba/ x /ga/, /ba/ x /da/). Each subject had to classify stimulus in "the easiest" and "the most difficult".Results Most subjects rated the /ba/ x /di/ contrast as the easiest to identify and the contrast /ba/ x /ga/ the most difficult. The subjects reported that the speech stimulus were easier to identify when compared to tone burst. The difficulty level described by the subjects influenced the latencies of stimuli /Di/ and /Da/, ranked as the easiest and they were evidenced in the lowest latency of P3.Conclusion The /Ba/ x /Di/ contrast was considered the easiest for perception, being evidenced by the lowest latency of P3. The speech contrasts were classified as the easiest when compared with the tonal stimuli. These comparisons help the clinician in selecting the stimuli and in the correct audiological diagnosis.

Central auditory processing disorders in children and adults.

Central auditory processing disorders (CAPD) can affect children and adults of all ages due to a wide variety of causes. CAPD is a neurobiologic deficit in the central auditory nervous system (CANS) that affects those mechanisms that underlie fundamental auditory perception, including localization and lateralization; discrimination of speech and non-speech sounds; auditory pattern recognition; temporal aspects of audition, including integration, resolution, ordering, and masking; and auditory performance with competing and/or degraded acoustic signals (American Speech-Language-Hearing Association, 2005a, b). Although it is recognized that central auditory dysfunction may coexist with other disorders, CAPD is conceptualized as a sensory-based auditory disorder. Administration of behavioral and/or electrophysiologic audiologic tests that have been shown to be sensitive and specific to dysfunction of the CANS is critical for a proper diagnosis of CAPD, in addition to assessments and collaboration with a multidisciplinary team. Intervention recommendations for CAPD diagnosis are based on the demonstrated auditory processing deficits and related listening and related complaints. This chapter provides an overview of current definitions and conceptualizations, methods of diagnosis of, and intervention for, CAPD. The chapter culminates with a case study illustrating pre- and posttreatment behavioral and electrophysiologic diagnostic findings.

Waist circumference is associated with pitch pattern sequence score in older male adults.

OBJECTIVE: While obesity may increase the risk for neurodegenerative diseases such as Alzheimer's disease, the relationship between waist circumference (WC) and central auditory dysfunction is unknown. We aimed to investigate the relationship of WC and pitch pattern sequence (PPS) score in adults. DESIGN: The association of WC with PPS score was analysed. STUDY SAMPLE: Volunteer helpers at a community hospital, 391 adults ≥40 years, with normal or symmetrical sensorineural hearing loss were randomly selected. RESULTS: After adjusting for age, gender, pure-tone average, systemic diseases, and habits, WC was significantly negatively associated with PPS. In a subgroup analysis by gender and age, the PPS score was negatively associated with WC only for males who were older than 55 years old, but not for males who were younger than 55 years old or females in either age group. Meanwhile, central obesity showed positive association with abnormal PPS recognition ability (PPS score < 90%) of borderline significance only for males who were older than 55 years old, but not for males who were younger than 55 years old or females in both age groups. CONCLUSIONS: WC or central obesity is an independent risk factor for poor central auditory function, especially in older male subjects.

Auditory function in children with Charcot-Marie-Tooth disease.

The peripheral manifestations of the inherited neuropathies are increasingly well characterized, but their effects upon cranial nerve function are not well understood. Hearing loss is recognized in a minority of children with this condition, but has not previously been systemically studied. A clear understanding of the prevalence and degree of auditory difficulties in this population is important as hearing impairment can impact upon speech/language development, social interaction ability and educational progress. The aim of this study was to investigate auditory pathway function, speech perception ability and everyday listening and communication in a group of school-aged children with inherited neuropathies. Twenty-six children with Charcot-Marie-Tooth disease confirmed by genetic testing and physical examination participated. Eighteen had demyelinating neuropathies (Charcot-Marie-Tooth type 1) and eight had the axonal form (Charcot-Marie-Tooth type 2). While each subject had normal or near-normal sound detection, individuals in both disease groups showed electrophysiological evidence of auditory neuropathy with delayed or low amplitude auditory brainstem responses. Auditory perception was also affected, with >60% of subjects with Charcot-Marie-Tooth type 1 and >85% of Charcot-Marie-Tooth type 2 suffering impaired processing of auditory temporal (timing) cues and/or abnormal speech understanding in everyday listening conditions.

Sensitivity and specificity of auditory steady-state response testing.

INTRODUCTION: The ASSR test is an electrophysiological test that evaluates, among other aspects, neural synchrony, based on the frequency or amplitude modulation of tones. OBJECTIVE: The aim of this study was to determine the sensitivity and specificity of auditory steady-state response testing in detecting lesions and dysfunctions of the central auditory nervous system. METHODS: Seventy volunteers were divided into three groups: those with normal hearing; those with mesial temporal sclerosis; and those with central auditory processing disorder. All subjects underwent auditory steady-state response testing of both ears at 500 Hz and 2000 Hz (frequency modulation, 46 Hz). The difference between auditory steady-state response-estimated thresholds and behavioral thresholds (audiometric evaluation) was calculated. RESULTS: Estimated thresholds were significantly higher in the mesial temporal sclerosis group than in the normal and central auditory processing disorder groups. In addition, the difference between auditory steady-state response-estimated and behavioral thresholds was greatest in the mesial temporal sclerosis group when compared to the normal group than in the central auditory processing disorder group compared to the normal group. DISCUSSION: Research focusing on central auditory nervous system (CANS) lesions has shown that individuals with CANS lesions present a greater difference between ASSR-estimated thresholds and actual behavioral thresholds; ASSR-estimated thresholds being significantly worse than behavioral thresholds in subjects with CANS insults. This is most likely because the disorder prevents the transmission of the sound stimulus from being in phase with the received stimulus, resulting in asynchronous transmitter release. Another possible cause of the greater difference between the ASSR-estimated thresholds and the behavioral thresholds is impaired temporal resolution. CONCLUSIONS: The overall sensitivity of auditory steady-state response testing was lower than its overall specificity. Although the overall specificity was high, it was lower in the central auditory processing disorder group than in the mesial temporal sclerosis group. Overall sensitivity was also lower in the central auditory processing disorder group than in the mesial temporal sclerosis group.

Sensitivity and specificity of auditory steady-state response testing

INTRODUCTION: The ASSR test is an electrophysiological test that evaluates, among other aspects, neural synchrony, based on the frequency or amplitude modulation of tones. OBJECTIVE: The aim of this study was to determine the sensitivity and specificity of auditory steady-state response testing in detecting lesions and dysfunctions of the central auditory nervous system. METHODS: Seventy volunteers were divided into three groups: those with normal hearing; those with mesial temporal sclerosis; and those with central auditory processing disorder. All subjects underwent auditory steady-state response testing of both ears at 500 Hz and 2000 Hz (frequency modulation, 46 Hz). The difference between auditory steady-state response-estimated thresholds and behavioral thresholds (audiometric evaluation) was calculated. RESULTS: Estimated thresholds were significantly higher in the mesial temporal sclerosis group than in the normal and central auditory processing disorder groups. In addition, the difference between auditory steady-state response-estimated and behavioral thresholds was greatest in the mesial temporal sclerosis group when compared to the normal group than in the central auditory processing disorder group compared to the normal group. DISCUSSION: Research focusing on central auditory nervous system (CANS) lesions has shown that individuals with CANS lesions present a greater difference between ASSR-estimated thresholds and actual behavioral thresholds; ASSR-estimated thresholds being significantly worse than behavioral thresholds in subjects with CANS insults. This is most likely because the disorder prevents the transmission of the sound stimulus from being in phase with the received stimulus, resulting in asynchronous transmitter release. Another possible cause of the greater difference between the ASSR-estimated thresholds and the behavioral thresholds is impaired temporal resolution. CONCLUSIONS: The overall sensitivity of auditory steady-state response testing was lower than its overall specificity. Although the overall specificity was high, it was lower in the central auditory processing disorder group than in the mesial temporal sclerosis group. Overall sensitivity was also lower in the central auditory processing disorder group than in the mesial temporal sclerosis group.

[Exploration of the auditory system in humans: From click to speech auditory brainstem responses]. / Exploration électrophysiologique des voies auditives sous-corticales chez l'humain : du clic au son de parole.

There is a growing and unprecedented interest in the objective evaluation of the subcortical processes that are involved in speech perception, with potential clinical applications in speech and language impairments. Here, we review the studies illustrating the development of electrophysiological methods for assessing speech encoding in the human brainstem: from the pioneer recordings of click-evoked auditory brainstem responses (ABR), via studies of frequency-following responses (FFR) to the most recent measurements of speech ABR (SABR) or ABR in response to speech sounds. Recent research on SABR has provided new insights in the understanding of subcortical auditory processing mechanisms. The SABR test is an objective and non-invasive tool for assessing individual capacity of speech encoding in the brainstem. SABR characteristics are potentially useful both as a diagnosis tool of speech encoding deficits and as an assessment tool of the efficacy of rehabilitation programs in patients with learning and/or auditory processing disorders.

Electrophysiological manifestations in adults with HIV/AIDS submitted and not submitted to antiretroviral therapy.

BACKGROUND: auditory evoked potentials (AEP) assess the neuroelectric activity on the auditory pathway -from the auditory nerve to the cerebral cortex - in response to an acoustic stimulus or event. Studies have demonstrated electrophysiological abnormalities in individuals with HIV/AIDS. AIM: to characterize the hearing electrophysiological manifestations in adults with HIV/AIDS by comparing the results obtained in the group exposed to antiretroviral therapy with those obtained in the group not exposed to such treatment. METHOD: electrophysiological evaluation of hearing (Auditory Brainstem Response - ABR, Auditory Middle Latency Response - AMLR and P300) was conducted in 56 individuals with HIV/AIDS: 24 participants composed group I (not exposed to antiretroviral treatment) and 32 participants composed group II (exposed to treatment). RESULTS: alterations in every AEP were observed in individuals with HIV/ AIDS, especially in the ABR. Indeed, the group exposed to antiretroviral treatment presented more alterations. CONCLUSION: individuals with HIV/AIDS may present alterations on the central and peripheral auditory nervous system. The group exposed to antiretroviral therapy presents more alterations on the brainstem auditory pathway.

Manifestações eletrofisiológicas em adultos com HIV/AIDS submetidos e não-submetidos à terapia anti-retroviral / Electrophysiological manifestations in adults with HIV/AIDS submitted and not submitted to antiretroviral therapy

BACKGROUND: auditory evoked potentials (AEP) assess the neuroelectric activity on the auditory pathway -from the auditory nerve to the cerebral cortex - in response to an acoustic stimulus or event. Studies have demonstrated electrophysiological abnormalities in individuals with HIV/AIDS. AIM: to characterize the hearing electrophysiological manifestations in adults with HIV/AIDS by comparing the results obtained in the group exposed to antiretroviral therapy with those obtained in the group not exposed to such treatment. METHOD: electrophysiological evaluation of hearing (Auditory Brainstem Response - ABR, Auditory Middle Latency Reponse - AMLR and P300) was conducted in 56 individuals with HIV/AIDS: 24 participants composed group I (not exposed to antiretroviral treatment) and 32 participants composed group II (exposed to treatment). RESULTS: alterations in every AEP were observed in individuals with HIV/ AIDS, especially in the ABR. Indeed, the group exposed to antiretroviral treatment presented more alterations. CONCLUSION: individuals with HIV/AIDS may present alterations on the central and peripheral auditory nervous system. The group exposed to antiretroviral therapy presents more alterations on the brainstem auditory pathway.

TEMA: os potenciais evocados auditivos (PEA) avaliam a atividade neuroelétrica na via auditiva, desde o nervo auditivo até o córtex cerebral, em resposta a um estímulo ou evento acústico. Estudos demonstram anormalidades eletrofisiológicas em indivíduos com HIV/AIDS. OBJETIVO: caracterizar as manifestações eletrofisiológicas da audição em adultos com HIV/AIDS, comparando os resultados obtidos no grupo exposto a tratamento anti-retroviral com os obtidos no grupo não exposto a tratamento. MÉTODO: realizada avaliação eletrofisiológica da audição (PEATE, PEAML e P300) em 56 indivíduos portadores do HIV/AIDS, sendo 24 do Grupo I (não expostos ao tratamento anti-retroviral) e 32 do Grupo II (expostos ao tratamento). RESULTADOS: foram encontradas alterações em todos os PEA nos indivíduos com HIV/AIDS, principalmente no PEATE; sendo que neste, o grupo exposto ao tratamento antiretroviral apresentou mais alterações. CONCLUSÃO: indivíduos com HIV/AIDS podem apresentar alterações no sistema nervoso auditivo periférico e central, sendo que o grupo exposto a tratamento anti-retroviral apresenta mais alterações na via auditiva em tronco encefálico.

Cognitive deficits associated with acquired amusia after stroke: a neuropsychological follow-up study.

Recent evidence on amusia suggests that our ability to perceive music might be based on the same neural resources that underlie other higher cognitive functions, such as speech perception and spatial processing. We studied the neural correlates of acquired amusia by performing extensive neuropsychological assessments on 53 stroke patients with a left or right hemisphere middle cerebral artery (MCA) stroke 1 week, 3 months, and 6 months after the stroke. In addition, structural magnetic resonance imaging (MRI) was performed on all patients 1 week and 6 months post-stroke. Based on their performance on a shortened version of the Montreal Battery of Evaluation of Amusia (MBEA), the patients were classified as amusic (n=32) or non-amusic (n=21). MRI results showed that the incidence of auditory cortex and frontal lobe damage was significantly higher in the amusic group than in the non-amusic group, but the two groups did not differ in respect to lesion laterality. Cognitively, amusia was associated with general deficits in working memory and learning, semantic fluency, executive functioning, and visuospatial cognition, as well as hemisphere-specific deficits in verbal comprehension, mental flexibility, and visuospatial attention (unilateral spatial neglect). Moreover, the recovery of music perception ability was related to the recovery of verbal learning, visuospatial perception and attention, and focused attention, especially in amusic patients. Together, these results suggest the ability to perceive music is closely linked to other higher cognitive functions.

[Performance of normal young adults in two temporal resolution tests]. / Desempenho de adultos jovens normais em dois testes de resolução temporal.

BACKGROUND: temporal auditory processing is defined as the perception of sound or of sound alteration within a restricted time interval and is considered a fundamental ability for the auditory perception of verbal and non verbal sounds, for the perception of music, rhythm, periodicity and in the discrimination of pitch, duration and of phonemes. AIM: to compare the performance of normal Brazilian adults in two temporal resolution tests: the Gaps-in-Noise Test (GIN) and the Random Gap Detection Test (RGDT), and to analyze potential differences of performance in these two tests. METHOD: twenty-five college students with normal hearing (11 males and 14 females) and no history of educational, neurological and/or language problems, underwent the GIN and RGDT at 40dB SL. RESULTS: statistically significant gender effects for both tests were found, with female participants showing poorer performance on both temporal processing tests. In addition, a comparative analysis of the results obtained in the GIN and RGDT revealed significant differences in the threshold measures derived for these two tests. In general, significantly better gap detection thresholds were observed for both male and female participants on the GIN test when compared to the results obtained for the RGDT. CONCLUSION: male participants presented better performances on both RGDT and GIN, when compared to the females. There were no differences in performance between right and left ears on the GIN test. Participants of the present investigation, males and females, performed better on the GIN when compared to the RGDT. The GIN presented advantages over the RGDT, not only in terms of clinical validity and sensibility, but also in terms of application and scoring.

Desempenho de adultos jovens normais em dois testes de resolução temporal / Performance of normal young adults in two temporal resolution tests

TEMA: o processamento auditivo temporal se refere a percepção de um evento sonoro ou de uma alteração no mesmo, dentro de um intervalo definido de tempo e é considerado uma habilidade fundamental na percepção auditiva de sons verbais e não verbais, na percepção de música, ritmo e pontuação e na discriminação de pitch, de duração e de fonemas. OBJETIVO: realizar um estudo comparativo do desempenho de adultos jovens normais nos testes de resolução temporal, Random Gap Detection Test (RGDT) e Gaps-in-Noise (GIN) e analisar diferenças entre esses dois métodos de avaliação. MÉTODO: 25 universitários, 11 homens e 14 mulheres, com audição normal e sem histórico de alterações educacionais, neurológicas e/ou linguagem, foram submetidos ao RGDT e ao GIN, a 40dB NS. RESULTADO: observou-se diferença estatisticamente significante entre os sexos sendo que as mulheres apresentaram pior desempenho nos dois testes. No estudo comparativo dos resultados do RGDT e GIN, observaram-se diferenças significativas no desempenho da amostra. De maneira geral, os limiares de detecção de gap no teste GIN foram melhores do que os limiares obtidos no RGDT. CONCLUSÃO: o sexo masculino teve melhor desempenho tanto no teste RGDT quanto no GIN, quando comparado ao feminino. Além disso, não houve diferença significante nas repostas do GIN nas orelhas direita e esquerda. Os sujeitos deste estudo tiveram melhor desempenho no teste GIN, quando comparado ao RGDT, tanto no sexo masculino quanto no feminino. Portanto, o teste GIN apresentou vantagens sobre o RGDT não apenas quanto à sua validade e sensibilidade, mas também com relação a sua aplicação e correção dos resultados.

BACKGROUND: temporal auditory processing is defined as the perception of sound or of sound alteration within a restricted time interval and is considered a fundamental ability for the auditory perception of verbal and non verbal sounds, for the perception of music, rhythm, periodicity and in the discrimination of pitch, duration and of phonemes. AIM: to compare the performance of normal Brazilian adults in two temporal resolution tests: the Gaps-in-Noise Test (GIN) and the Random Gap Detection Test (RGDT), and to analyze potential differences of performance in these two tests. METHOD: twenty-five college students with normal hearing (11 males and 14 females) and no history of educational, neurological and/or language problems, underwent the GIN and RGDT at 40dB SL. RESULTS: statistically significant gender effects for both tests were found, with female participants showing poorer performance on both temporal processing tests. In addition, a comparative analysis of the results obtained in the GIN and RGDT revealed significant differences in the threshold measures derived for these two tests. In general, significantly better gap detection thresholds were observed for both male and female participants on the GIN test when compared to the results obtained for the RGDT. CONCLUSION: male participants presented better performances on both RGDT and GIN, when compared to the females. There were no differences in performance between right and left ears on the GIN test. Participants of the present investigation, males and females, performed better on the GIN when compared to the RGDT. The GIN presented advantages over the RGDT, not only in terms of clinical validity and sensibility, but also in terms of application and scoring.

Changes in brainstem auditory evoked response latencies in term neonates with hyperbilirubinemia.

Ninety term neonates with hyperbilirubinemia were studied with brainstem auditory evoked response to clarify the ototoxic effect of hyperbilirubinemia, and detect any differences in ototoxic effect between different levels of total serum bilirubin. The response threshold in these neonates was significantly elevated (P < 0.001). All wave latencies and I-V interval increased significantly (P < 0.05-0.0001), and correlated weakly with total serum bilirubin (r = 0.24-0.28, all P < 0.05). Twenty-five neonates (28%) had abnormal responses, including 14 (16%) with elevated thresholds or increased wave I latency, suggesting peripheral auditory impairment, and 16 (18%) with increased I-V interval, suggesting central auditory impairment. Wave V latency and I-V interval were longer in neonates with total serum bilirubin of <20 mg/dL than in those with bilirubin 11-15 mg/dL (P < 0.05). However, there were no significant differences in response variables between neonates with total serum bilirubin 11-15 mg/dL and those with bilirubin 16-20 mg/dL, and between neonates with bilirubin 16-20 mg/dL and those with bilirubin >20 mg/dL. Thus, although the acute ototoxic effect of hyperbilirubinemia tends to be more significant at a higher rather than lower level of total serum bilirubin, auditory impairment does not increase closely with the increase in bilirubin.

Evidence for a neurophysiologic auditory deficit in children with benign epilepsy with centro-temporal spikes.

Benign focal epilepsy in childhood with centro-temporal spikes (BECTS) is one of the most common forms of epilepsy. Recent studies have questioned the benign nature of BECTS, as they have revealed neuropsychological deficits in many domains including language. The aim of this study was to investigate whether the epileptic discharges during the night have long-term effects on auditory processing, as reflected on electrophysiological measures, during the day, which could underline the language deficits. In order to address these questions we recorded base line electroencephalograms (EEG), sleep EEG and auditory event related potentials in 12 children with BECTS and in age- and gender-matched controls. In the children with BECTS, 5 had unilateral and 3 had bilateral spikes. In the 5 patients with unilateral spikes present during sleep, an asymmetry of the auditory event related component (P85-120) was observed contralateral to the side of epileptiform activity compared to the normal symmetrical vertex distribution that was noted in all controls and in 3 the children with bilateral spikes. In all patients the peak to peak amplitude of this event related potential component was statistically greater compared to the controls. Analysis of subtraction waveforms (deviant - standard) revealed no evidence of a mismatch negativity component in any of the children with BECTS. We propose that the abnormality of P85-120 and the absence of mismatch negativity during wake recordings in this group may arise in response to the long-term effects of spikes occurring during sleep, resulting in disruption of the evolution and maintenance of echoic memory traces. These results may indicate that patients with BECTS have abnormal processing of auditory information at a sensory level ipsilateral to the hemisphere evoking spikes during sleep.

Hearing threshold estimation in infants using auditory steady-state responses.

Successful early intervention in children with permanent hearing loss requires assessment techniques that can accurately reflect the behavioral audiogram in infancy. This retrospective study compared auditory steady-state response (ASSR) findings from subjects tested in the first three months of life with subsequently obtained behavioral hearing levels. ASSR audiograms were established using amplitude and frequency modulated tones at octave frequencies (500 Hz to 4 kHz). Results obtained from 575 subjects including 285 with normal hearing, 271 with sensorineural hearing loss, and 19 with auditory neuropathy-type hearing loss are presented. ASSR and behavioral hearing thresholds for subjects in the normal and sensorineural groups were highly correlated, with Pearson r values exceeding 0.95 at each of the test frequencies. In contrast, ASSR thresholds in children with AN-type hearing loss did not accurately reflect the behavioral audiogram. Overall, the findings indicate that ASSR testing can offer useful insights into the hearing acuity of children tested in infancy.

Perception of complex sounds in autism: abnormal auditory cortical processing in children.

OBJECTIVE: The authors have previously described less activation of left speech-related temporal areas in adults with autism when listening to speech-like sounds than in normal adults. Here, they investigated whether this abnormal cortical processing was also present in children with primary autism. METHOD: Regional cerebral blood flow was measured with positron emission tomography after premedication in 11 autistic children and six nonautistic mentally retarded children during rest and while they were listening to speech-like sounds. RESULTS: As with autistic adults, direct comparison between the two groups revealed significantly less activation in the autistic group localized in left speech-related areas. CONCLUSIONS: For the first time to their knowledge, an activation study was performed in children with autism and has confirmed previous results obtained in adults. The abnormal cortical auditory processing observed in both children and adults with autism could be involved in inadequate behavioral responses to sounds and in language impairments characteristic of autism.

Auditory backward-masking performance by children who stutter and its relation to dysfluency rate.

The fluency of people who stutter is affected markedly when auditory feedback is altered, suggesting that stuttering may be associated with hearing. Peripheral hearing problems, however, are no more common in people who stutter than in those who do not. Performance was investigated in a task that involves central auditory processing (backward masking). Children who stuttered had deficits in backward masking (indicated by higher thresholds) compared with a group of fluent control children. The backward-masking thresholds were positively correlated with frequency of stuttering.

Central deafness in a young child with Moyamoya disease: paternal linkage in a Caucasian family: two case reports and a review of the literature.

A case of 'central deafness' is presented in a 3-year-old male Caucasian child with Moyamoya disease (MMD); a rare, progressive and occlusive cerebrovascular disorder predominantly affecting the carotid artery system. Documentation of normal peripheral auditory function and brainstem pathway integrity is provided by acoustic admittance, otoacoustic emission and brainstem auditory evoked potential measurements. The lack of behavioral response to sound, and absent middle and long latency auditory evoked potentials suggest thalamo-cortical dysfunction. Magnetic resonance imaging showed diffuse ischemic damage in subcortical white matter including areas of the temporal lobes. In addition, there were multiple and focal cortical infarctions in both cerebral hemispheres, focused primarily in the frontal, parietal and temporal areas. Taken together, these structural and functional abnormalities in addition to severely delayed speech and language development are consistent with the diagnosis of central deafness and suggest a disconnection between higher brainstem and cortical auditory areas. The child's father also has MMD, but was diagnosed only recently. The presence of paternal linkage is informative since it rules out x-linked recessive and maternal inheritance. To our knowledge, this represents the first documented case of paternal linkage in MMD with central deafness in a Caucasian child with no apparent Japanese ancestry. Herein, we focus on central auditory dysfunction and consider how lesion-induced changes have contributed to a deficit in basic auditory responsiveness, including a severe disturbance in receptive and expressive auditory-based speech and language skills.

Dorsal cochlear nucleus blood flow during acoustic stimulation.

Dynamic in vivo changes in dorsal cochlear nucleus blood flow during pure-tone stimulation were assessed with intravital microscopy. Subjects were stimulated with 5-, 10-, or 15-kHz pure tones at 70, 80, and 90 dB sound pressure level. Measurements in red blood cell velocity and vessel diameter were made in capillaries overlying the 10-kHz isofrequency band of the dorsal cochlear nucleus. Stimulation with 10 kHz induced intensity-dependent increases in local blood flow in the 10-kHz isofrequency band of the dorsal cochlear nucleus. Stimulation with 5 kHz and 15 kHz, frequencies represented in remote locations on the dorsal cochlear nucleus surface, did not significantly alter blood flow in the defined 10-kHz isofrequency band. These data demonstrate a direct relationship between spectral and intensity-dependent pure-tone stimulation of the dorsal cochlear nucleus and increases in local blood flow. These findings suggest that tonal stimulation of the dorsal cochlear nucleus induces an increase in local metabolic demands with resultant rapid blood flow increases.