The importance of central auditory evaluation in Friedreich's ataxia / A importância da avaliação auditiva central na ataxia de Friedreich

ABSTRACT Objective To assess central auditory function in Friedreich's ataxia. Methods A cross-sectional, retrospective study was carried out. Thirty patients underwent the anamnesis, otorhinolaryngology examination, pure tone audiometry, acoustic immittance measures and brainstem auditory evoked potential (BAEP) assessments. Results The observed alterations were: 43.3% in the pure tone audiometry, bilateral in 36.7%; 56.6% in the BAEP test, bilateral in 50%; and 46.6% in the acoustic immittance test. There was a significant difference (p < 0.05) in the comparison between the tests performed. Conclusion In the audiological screening, there was a prevalence of the descending audiometric configuration at the frequency of 4kHz, and absence of the acoustic reflex at the same frequency. In the BAEP test, there was a prevalence of an increase of the latencies in waves I, III and V, and in the intervals of interpeaks I-III, I-V and III-V. In 13.3% of the patients, wave V was absent, and all waves were absent in 3.3% of patients.

RESUMO Objetivo Avaliar a função auditiva central na ataxia de Friedreich (AFRD). Métodos Foi realizado um estudo retrospectivo de corte transversal. 30 pacientes realizaram anamnese, avaliações otorrinolaringológica, audiológica, imitanciométrica e do potencial evocado auditivo de tronco encefálico (PEATE). Resultados As alterações observadas foram: 43,3% no exame audiométrico sendo 36,7% dos casos, bilateralmente; 56,6% na avaliação do PEATE com 50% dos casos, bilateralmente e 46,6% no exame imitanciométrico. Houve diferença significativa (p < 0,05) na comparação entre os exames realizados. Conclusão No exame audiológico, ocorreu uma preponderância maior da configuração audiométrica descendente a partir da freqüência de 4kHz e ausência do reflexo acústico na mesma frequência. No exame do PEATE, houve prevalência do aumento das latências nas ondas I, III e V, e nos intervalos dos interpicos I-III, I-V e III-V. Em 13,3% dos casos, a onda V estava ausente, e em 3,3% dos casos, todas as ondas estavam ausentes.

Monitoring auditory cortical plasticity in hearing aid users with long latency auditory evoked potentials: a longitudinal study

OBJECTIVE: The objective of this study was to compare long-latency auditory evoked potentials before and after hearing aid fittings in children with sensorineural hearing loss compared with age-matched children with normal hearing. METHODS: Thirty-two subjects of both genders aged 7 to 12 years participated in this study and were divided into two groups as follows: 14 children with normal hearing were assigned to the control group (mean age 9 years and 8 months), and 18 children with mild to moderate symmetrical bilateral sensorineural hearing loss were assigned to the study group (mean age 9 years and 2 months). The children underwent tympanometry, pure tone and speech audiometry and long-latency auditory evoked potential testing with speech and tone burst stimuli. The groups were assessed at three time points. RESULTS: The study group had a lower percentage of positive responses, lower P1-N1 and P2-N2 amplitudes (speech and tone burst), and increased latencies for the P1 and P300 components following the tone burst stimuli. They also showed improvements in long-latency auditory evoked potentials (with regard to both the amplitude and presence of responses) after hearing aid use. CONCLUSIONS: Alterations in the central auditory pathways can be identified using P1-N1 and P2-N2 amplitude components, and the presence of these components increases after a short period of auditory stimulation (hearing aid use). These findings emphasize the importance of using these amplitude components to monitor the neuroplasticity of the central auditory nervous system in hearing aid users.

Central auditory processing outcome after stroke in children / Processamento auditivo central em crianças com acidente vascular cerebral

Objective To investigate central auditory processing in children with unilateral stroke and to verify whether the hemisphere affected by the lesion influenced auditory competence. Method 23 children (13 male) between 7 and 16 years old were evaluated through speech-in-noise tests (auditory closure); dichotic digit test and staggered spondaic word test (selective attention); pitch pattern and duration pattern sequence tests (temporal processing) and their results were compared with control children. Auditory competence was established according to the performance in auditory analysis ability. Results Was verified similar performance between groups in auditory closure ability and pronounced deficits in selective attention and temporal processing abilities. Most children with stroke showed an impaired auditory ability in a moderate degree. Conclusion Children with stroke showed deficits in auditory processing and the degree of impairment was not related to the hemisphere affected by the lesion. .

Objetivo Investigar as habilidades de processamento auditivo central em crianças com acidente vascular cerebral (AVC) unilateral e verificar se o hemisfério cerebral afetado influiu na competência auditiva. Método 23 crianças (13 meninos) entre 7 e 16 anos foram avaliados através dos testes de fala com ruído (fechamento auditivo); dicótico de dígitos e de dissílabos alternados (atenção seletiva); padrão temporal de frequência e duração (processamento temporal) e seus resultados comparados aos de crianças controles. A competência auditiva foi estabelecida segundo o desempenho na habilidade de análise auditiva. Resultados Foi constatado desempenho similar entre os grupos na habilidade de fechamento auditivo e défices acentuados nas habilidades de atenção seletiva e processamento temporal. A maioria das crianças com AVC apresentou comprometimento da habilidade auditiva em grau moderado. Conclusão Crianças com AVC apresentaram alterações do processamento auditivo e o grau do comprometimento não se relacionou com o hemisfério afetado pela lesão. .

Noise-induced tinnitus: auditory evoked potential in symptomatic and asymptomatic patients

OBJECTIVES: We evaluated the central auditory pathways in workers with noise-induced tinnitus with normal hearing thresholds, compared the auditory brainstem response results in groups with and without tinnitus and correlated the tinnitus location to the auditory brainstem response findings in individuals with a history of occupational noise exposure. METHOD: Sixty individuals participated in the study and the following procedures were performed: anamnesis, immittance measures, pure-tone air conduction thresholds at all frequencies between 0.25-8 kHz and auditory brainstem response. RESULTS: The mean auditory brainstem response latencies were lower in the Control group than in the Tinnitus group, but no significant differences between the groups were observed. Qualitative analysis showed more alterations in the lower brainstem in the Tinnitus group. The strongest relationship between tinnitus location and auditory brainstem response alterations was detected in individuals with bilateral tinnitus and bilateral auditory brainstem response alterations compared with patients with unilateral alterations. CONCLUSION: Our findings suggest the occurrence of a possible dysfunction in the central auditory nervous system (brainstem) in individuals with noise-induced tinnitus and a normal hearing threshold. .

Estudo da maturação das vias auditivas pós-implante coclear por meio dos potenciais evocados auditivos de longa latência / Auditory pathways' maturation after cochlear implant via cortical auditory evoked potentials

Introdução: A avaliação de potenciais evocados auditivos de longa latência em crianças usuárias de implante coclear tem se mostrado um método eficaz para avaliar a maturação cortical após estimulação elétrica. Objetivo: Analisar as modificações nos valores de latência do potencial evocado auditivo cortical antes e três meses após o uso do implante coclear. Material e método: Estudo de caso-controle em um grupo de cinco crianças usuárias do implante coclear que aguardavam a ativação dos eletrodos, e um grupo controle constituído por cinco crianças ouvintes. A avaliação eletrofisiológica da audição foi realizada por meio do registro dos potenciais evocados auditivos corticais em duas diferentes etapas: anterior à ativação do implante coclear e após três meses de adaptação. Resultados: Os resultados demonstraram diminuição significativa em relação ao tempo de latência do componente P1 no grupo estudo, cujos valores foram maiores daqueles do grupo controle. Quanto menor a idade na ativação, maior a redução no tempo de latência do componente P1. Conclusão: Modificações nas características dos potenciais evocados auditivos corticais podem ser observadas em crianças que recebem o implante coclear e estas modificações têm uma relação com a idade de intervenção, sugerindo uma rápida maturação das vias auditivas após estimulação elétrica. .

Introduction: Evaluation of cortical auditory evoked potentials in children with cochlear implants has been proven to be an effective method for assessing cortical maturation after electrical stimulation. Objective: To analyze the changes in latency values of cortical auditory evoked potentials before and three months after cochlear implant use. Material and methods: This was a case-control study with a group of five children using cochlear implant awaiting activation of the electrodes, and a control group composed of five normal-hearing children. Auditory electrophysiological assessment was performed by the testing of the cortical auditory evoked potentials at two different periods: prior to cochlear implant activation and after three months of cochlear implant use. Results: A significant decrease in the latency time of the P1 component was observed after three months of stimulation via cochlear implant, whose values were higher than those from the control group. The younger the child was at electrode activation, the greater the reduction in latency of the P1 component. Conclusion: Changes in the characteristics of cortical auditory evoked potentials can be observed in children who receive cochlear implants; these changes are related to the age of intervention, suggesting a rapid maturation of the auditory pathways after electrical stimulation. .

Auditory evoked potentials: predicting speech therapy outcomes in children with phonological disorders

OBJECTIVES: This study investigated whether neurophysiologic responses (auditory evoked potentials) differ between typically developed children and children with phonological disorders and whether these responses are modified in children with phonological disorders after speech therapy. METHODS: The participants included 24 typically developing children (Control Group, mean age: eight years and ten months) and 23 children clinically diagnosed with phonological disorders (Study Group, mean age: eight years and eleven months). Additionally, 12 study group children were enrolled in speech therapy (Study Group 1), and 11 were not enrolled in speech therapy (Study Group 2). The subjects were submitted to the following procedures: conventional audiological, auditory brainstem response, auditory middle-latency response, and P300 assessments. All participants presented with normal hearing thresholds. The study group 1 subjects were reassessed after 12 speech therapy sessions, and the study group 2 subjects were reassessed 3 months after the initial assessment. Electrophysiological results were compared between the groups. RESULTS: Latency differences were observed between the groups (the control and study groups) regarding the auditory brainstem response and the P300 tests. Additionally, the P300 responses improved in the study group 1 children after speech therapy. CONCLUSION: The findings suggest that children with phonological disorders have impaired auditory brainstem and cortical region pathways that may benefit from speech therapy. .

Desde la corteza auditiva a la cóclea: progresos en el sistema eferente auditivo / From auditory cortex to cochlea: progress in the auditory efferent system

El sistema eferente auditivo está constituido por el sistema olivococlear y por vías descendentes que provienen de la corteza auditiva y se dirigen a la cóclea. El sistema olivococlear se divide en una porción medial y una lateral, con neuronas que inervan a las células ciliadas externas y a fibras del nervio auditivo respectivamente. El principal neurotransmisor de las sinapsis olivococleares es acetilcolina, y tanto las células ciliadas externas como las fibras del nervio auditivo poseen receptores para esta molécula. El sistema eferente córtico-coclear se origina en la capa V y VI de la corteza auditiva y proyecta a los colículos inferiores y complejo olivar superior, donde a través del sistema olivococlear se conecta con el órgano receptor auditivo. En este artículo se revisan importantes hallazgos obtenidos en los últimos años que involucran (i) nuevos neurotransmisores y receptores del sistema eferente auditivo; (ii) vías descendentes de la corteza auditiva y su rol fisiológico sobre las respuestas cocleares y (iii) rol del sistema eferente auditivo en patologías audiológicas y neuropsiquiátricas.

The auditory efferent system is composed by the olivocochlear fibers and descending projections that originate in the auditory cortex and end in the cochlea. The olivocochlear system is divided into a medial and lateral division, with fibers directed to the outer hair cells and to the auditory nerve fibers respectively. It is known that acetylcholine is the main neurotransmitter of the olivocochlear synapses and that outer hair cells and auditory nerve fibers have receptors to this molecule. The cortico-cochlear efferent system originates in layers V and VI of the auditory cortex. These descending projections are directed to the inferior colliculus and superior olivary complex, a site in which the olivocochlear fibers emerge and connect the brain with the cochlear receptor. In this article recent discoveries obtained in the last years are reviewed: (i) new neurotransmitters and receptors of the olivocochlear system; (ii) anatomy and physiology of descending pathways from the auditory cortex to the cochlea and, (iii) clinical role of auditory efferents in audiological and neuropsychiatric pathologies.

P300 em trabalhadores expostos a ruído ocupacional / P300 in workers exposed to occupational noise

O prejuízo do ruído para as vias auditivas centrais em trabalhadores expostos a ruído ocupacional tem sido pouco estudado. OBJETIVO: Avaliar as vias auditivas centrais por meio do potencial evocado auditivo de longa latência (P300), em indivíduos normo-ouvintes expostos a ruído. MÉTODO: Estudo prospectivo em que foram avaliados 25 indivíduos com limiares auditivos dentro da normalidade. Tais indivíduos foram divididos em dois grupos: expostos a ruído ocupacional (13 sujeitos, grupo pesquisa-GP) e não expostos a ruído ocupacional (12 sujeitos, grupo controle-GC). Foi realizado o P300, utilizando estímulos verbais e não verbais. RESULTADOS: Não houve diferença estatisticamente significante entre as orelhas para nenhum dos estímulos, em nenhum dos grupos. Tanto para o estímulo verbal como para o não verbal houve diferença estatisticamente significante entre os grupos, sendo que o GP apresentou latências maiores que o GC. Na análise qualitativa, observou-se maior número de resultados alterados para o P300 com estímulo não verbal e verbal para o GP, apesar de não haver diferença estatisticamente significante entre eles. CONCLUSÃO: Os indivíduos expostos a níveis de pressão sonora elevados apresentaram, tanto para estímulo verbal quanto para estímulo não verbal, médias de latências do P300 maiores quando comparadas com as do grupo controle.

The harm upon the central auditory pathways of workers exposed to occupational noise has been scarcely studied. OBJECTIVE: To assess the central auditory pathways by testing the long latency auditory evoked potentials (P300) of individuals exposed to occupational noise and controls. METHOD: This prospective study enrolled 25 individuals with normal hearing thresholds. The subjects were divided into two groups: individuals exposed to occupational noise (13 subjects; case group) and individuals not exposed to occupational noise (12 subjects; control group). The P300 test was used with verbal and non-verbal stimuli. RESULTS: No statistically significant differences were found between ears for any of the stimuli or between groups. The groups had no statistically significant difference for verbal or non-verbal stimuli. Case group subjects had longer latencies than controls. In qualitative analysis, a greater number of altered P300 test results for verbal and non-verbal stimuli was seen in the case group, despite the absence of statistically significant differences between case and control subjects. CONCLUSION: Individuals exposed to high sound pressure levels had longer P300 latencies in verbal and non-verbal stimuli when compared to controls.

Auditory middle latency response in children with learning difficulties

Introduction: This is an objective laboratory assessment of the central auditory systems of children with learning disabilities. Aim: To examine and determine the properties of the components of the Auditory Middle Latency Response in a sample of children with learning disabilities. Methods: This was a prospective, cross-sectional cohort study with quantitative, descriptive, and exploratory outcomes. We included 50 children aged 8-13 years of both genders with and without learning disorders. Those with disorders of known organic, environmental, or genetic causes were excluded. Results and Conclusions: The Na, Pa, and Nb waves were identified in all subjects. The ranges of the latency component values were as follows: Na = 9.8-32.3 ms, Pa = 19.0-51.4 ms, Nb = 30.0-64.3 ms (learning disorders group) and Na = 13.2-29.6 ms, Pa = 21.8-42.8 ms, Nb = 28.4-65.8 ms (healthy group). The values of the Na-Pa amplitude ranged from 0.3 to 6.8 ìV (learning disorders group) or 0.2-3.6 ìV (learning disorders group). Upon analysis, the functional characteristics of the groups were distinct: the left hemisphere Nb latency was longer in the study group than in the control group. Peculiarities of the electrophysiological measures were observed in the children with learning disorders. This study has provided information on the Auditory Middle Latency Response and can serve as a reference for other clinical and experimental studies in children with these disorders...

The role of the cerebellum in auditory processing using the SSI test / A participação do cerebelo no processamento auditivo com o uso do teste SSI

The Synthetic Sentence Identification (SSI) test assesses central auditory pathways by measuring auditory and visual sensitivity and testing selective attention. Cerebellum activation in auditory attention and sensorial activity modulation have already been described. Assessing patients with cerebellar lesions alone using the SSI test can confirm the role of the cerebellum in auditory processing. AIM: To evaluate the role of the cerebellum in auditory processing in individuals with normal hearing and in those with chronic cerebellum lesions, using the SSI test. MATERIALS AND METHODS: Cross-sectional cohort study. A study group comprising 18 patients with chronic cerebellar lesion and a control group of 20 healthy individuals were assessed. The SSI test was applied in an Ipsilateral Competitive Message (ICM) and Contralateral Competitive Message (CCM) modes. To compare the results between groups, we used the chi-square test for qualitative variables. RESULTS: A statistically significant difference was found between the study and control groups using the ICM mode of the SSI test (p=0.035), but not in the CCM mode (p=0.083). CONCLUSION: The results on the SSI confirmed cerebellar participation in auditory processing in individuals with chronic cerebellar lesions and in those with normal hearing assessed in this study.

O teste de Identificação de Sentenças Sintéticas (SSI) avalia as vias centrais da audição utilizando a sensibilidade auditiva e visual e testando a atenção seletiva. A ativação do cerebelo na atenção auditiva, assim como na modulação da atividade sensorial, já é descrita. Avaliar pacientes com lesão exclusiva do cerebelo por meio do teste SSI pode confirmar ou refutar a hipótese da participação do cerebelo no processamento auditivo. OBJETIVO: Avaliar pelo teste SSI a participação do cerebelo no processamento auditivo, em indivíduos com lesão crônica do cerebelo e audição normal. MATERIAL E MÉTODOS: Estudo coorte contemporânea com corte transversal. Grupo controle de 20 indivíduos sadios, grupo de estudo de 18 indivíduos com lesão crônica do cerebelo. Aplicado o teste SSI nas modalidades ICM (mensagem competitiva ipsilateral) e CCM (mensagem competitiva contralateral). Na comparação dos resultados entre os grupos, utilizou-se o teste qui-quadrado para as variáveis qualitativas. RESULTADO: Identificada diferença estatística significante entre os grupos controle e estudo na modalidade ICM do teste SSI (p = 0,035), mas não na modalidade CCM (p = 0,083). CONCLUSÃO: Os resultados obtidos pelo teste SSI identificam a participação do cerebelo no processamento auditivo nos indivíduos com lesão crônica do cerebelo e audição normal avaliados neste estudo.

Associação entre funções da via auditiva eferente e genotoxicidade em adultos jovens / Association between auditory pathway efferent functions and genotoxicity in young adults

Funções da via auditiva eferente incluem a modulação das células ciliadas externas, proteção contra ruído e melhora na detecção da fonte sonora em ambientes ruidosos. Genotoxicidade são danos ao DNA. OBJETIVOS: Analisar associação entre funções da via auditiva eferente com marcadores genotóxicos. Adicionalmente, considerou-se tabagismo e gênero como principais variáveis intervenientes. MATERIAL E MÉTODO: Estudo prospectivo-clínico, quantitativo, transversal, contemporâneo. Foi realizada uma análise da função da via auditiva eferente e indicadores de genotoxicidade em 60 voluntários adultos jovens. RESULTADOS: Idade média dos voluntários foi de 24,86±3,68 anos; 30 do gênero masculino e 30 do gênero feminino, 15 de cada gênero tabagistas e 15 não tabagistas; indivíduos do gênero masculino tabagistas apresentaram maior ocorrência de efeito de supressão das EOAEPDs nas frequências de 2000 e 6000Hz na orelha do lado esquerdo; mulheres tabagistas apresentaram maior prevalência de queixa de dificuldade de ouvir em ambiente ruidoso; indivíduos tabagistas e mulheres apresentaram maiores danos ao DNA; indivíduos com queixas de dificuldade auditiva e zumbido apresentaram maiores índices de genotoxicidade. CONCLUSÕES: Em adultos jovens normo-ouvintes que referem queixas relacionadas às funções da via auditiva eferente, como zumbido e dificuldade auditiva, já é possível observar associação com genotoxicidade considerando interações entre gênero e tabagismo.

Efferent auditory pathways modulate outer hair cells of the cochlea, protect against noise, and improve the detection of sound sources in noisy environments. Genotoxicity is DNA damage. AIM: To study the association between auditory pathway efferent functions with genotoxic markers. The study also considered smoking and gender as two main variables. METHODS: A prospective-clinical, quantitative, cross-sectional, contemporary study. The function of efferent auditory pathways and genotoxicity tests in 60 healthy young subjects were assessed. RESULTS: The mean age of subjects was 24.86 years +/- 3.68 years; there were 30 males and 30 females, 15 of each gender smokers and 15 non-smokers. Male smokers had a higher incidence of DPOEA suppression effect at 2000 and 6000 Hz in the left ear; female smokers had a higher prevalence of complaints of difficulty to hear in noisy environments; smokers and women had a higher mean DNA damage; subjects with complaints of hearing loss and tinnitus had higher genotoxicity. CONCLUSIONS: In young normal-hearing adults that complain about efferent auditory pathways functions, such as tinnitus and hearing impairment, there are possible associations with genotoxicity; interactions between gender and smoking are considered.

Diagnosis and management of somatosensory tinnitus: review article

Tinnitus is the perception of sound in the absence of an acoustic external stimulus. It affects 10-17 percent of the world's population and it a complex symptom with multiple causes, which is influenced by pathways other than the auditory one. Recently, it has been observed that tinnitus may be provoked or modulated by stimulation arising from the somatosensorial system, as well as from the somatomotor and visual-motor systems. This specific subgroup -somatosensory tinnitus - is present in 65 percent of cases, even though it tends to be underdiagnosed. As a consequence, it is necessary to establish evaluation protocols and specific treatments focusing on both the auditory pathway and the musculoskeletal system.

Brainstem auditory evoked potentials and electrocochleographic findings in patients with idiopathic sudden sensorineural hearing loss

To determine the status of cochlea, auditory pathway and hearing threshold by recording brainstem auditory evoked potential [BAEP] and electrocochleography in patients with idiopathic sudden sensorineural hearing loss [ISSNHL]. Observational study. Department of Clinical Physiology at King Abdul Aziz University Hospital, Riyadh, Saudi Arabia, from May 2002 to November 2007. Patients diagnosed with idiopathic sudden sensorineural hearing loss [ISSNHL] based on clinical features and pure tone audiometry were studied. Brainstem auditory evoked potential [BAEP] and electrocochleography [ECOG] was performed in them according to standard protocols for assessment of auditory pathway and hearing threshold. Out of 23 patients [14 males and 9 females] left ear was affected in 9 [39.1%] patients, right ear in 13 [56.5%] and both in 1 [4.3%]. Absolute latency of wave I and wave V were significantly prolonged in affected ear compared to unaffected ears [p=0.0031], while interpeak I-V latency was significantly higher in affected ears versus unaffected ears [p=0.0544]. Six patients [26.1%] had type II Diabetes mellitus, five cases [21.7%] had hypertension and 5 cases [21.7%] had dyslipidemia. ECOG revealed absence of summation potential [SP] and action potential [AP] response even at 95 dB in 17 out of 23 cases [73.9%]. Patients with ISSNHL had significant abnormalities in BAEP and ECOG recordings showing predominantly cochlear involvement. Thus, these tests provide useful diagnostic information in patients with ISSNHL in addition to pure tone audiometry

Efectos de la glicina sobre los trastornos de conducción del nervio auditivo en pacientes diabéticos tipo 2 con otoneuropatía / Effects of glycine on auditory evoked potentials among diabetic patients with auditory pathway neuropathy

Background: Glycine inhibits the formation of advanced glycation end products that may cause central and peripheral neuronal damage, affecting also the auditory nerve. Aim: To evaluate the effect of glycine on auditory nerve conduction and hearing level among patients with type 2 diabetes mellitus and auditory neuropathy. Material and Methods: Twenty grams of oral glycine per day were administered during 6 months to 28 type 2 diabetic patients aged 58 ± 6 years, with auditory pathway neuropathy. Hearing tests and evoked otoacustic potentials were performed regularly. Fifteen diabetic patients aged 49 ± 8 years, without auditory nerve neuropathy did not receive glycine and were followed as a control group. Results: Among patients receiving glycine, a significant improvement in left ear audiometry at 125, 250 and 500 Hz and right ear audiometry at 500 Hz, was observed. Waves I, III and V (p= 0.02) of evoked otoacustic potentials improved significantly in the left ear and wave I in the right ear. Among controls, waves V and III of evoked otoacoustic potentials had a significant impairment in the left ear. Conclusions: There was an improvement in auditory evoked potentials in patients receiving glycine and an impairment in untreated control patients.

Auditory evoked potentials and multiple sclerosis / Potenciais evocados auditivos e esclerose múltipla

Multiple sclerosis (MS) is an inflammatory, demyelinating disease that can affect several areas of the central nervous system. Damage along the auditory pathway can alter its integrity significantly. Therefore, it is important to investigate the auditory pathway, from the brainstem to the cortex, in individuals with MS. OBJECTIVE: The aim of this study was to characterize auditory evoked potentials in adults with MS of the remittent-recurrent type. METHOD: The study comprised 25 individuals with MS, between 25 and 55 years, and 25 age- and gender-matched healthy controls (research and control groups). Subjects underwent audiological and electrophysiological evaluations. RESULTS: Statistically significant differences were observed between the groups regarding the results of the auditory brainstem response and the latency of the Na and P300 waves. CONCLUSION: Individuals with MS present abnormalities in auditory evoked potentials indicating dysfunction of different regions of the central auditory nervous system.

A esclerose múltipla é uma doença inflamatória desmielinizante que pode se desenvolver em diversas regiões do sistema nervoso central. O comprometimento da via auditiva central pode alterar significativamente a integridade desta e, portanto, a investigação desta região em indivíduos com esclerose múltipla, desde o tronco encefálico até o córtex, torna-se importante. OBJETIVO: Caracterizar os resultados dos potenciais evocados auditivos em adultos com esclerose múltipla do tipo remitente-recorrente. MÉTODO: Foram submetidos às avaliações audiológica e eletrofisiológica 25 indivíduos pertencentes ao grupo controle e 25 ao grupo pesquisa, com idades entre 25 e 55 anos. RESULTADOS: Verificou-se diferença estatisticamente significante entre os grupos quanto à ocorrência de resultados normais e alterados no potencial evocado auditivo de tronco encefálico e latências das ondas Na e P300. CONCLUSÃO: Indivíduos com esclerose múltipla apresentam alterações nos potenciais evocados auditivos, indicando comprometimento de diferentes regiões do sistema nervoso auditivo central.

Bases fisiopatológicas del tratamiento del tinnitus neurosensorial: rol del sistema auditivo eferente / Physiopathological bases of subjective tinnitus treatment: role of the efferent auditory system

El tinnitus neurosensorial o acúfenos es actualmente un problema de difícil solución para el especialista. Los actuales conocimientos han permitido diferenciar el acúfeno periférico del acúfeno central, constituyendo este último, la gran mayoría. El acúfenos se origina por un desbalance GABA-glutamato del sistema auditivo aferente, que se manifiesta finalmente por un reordenamiento neuronal de la corteza auditiva primaria, provocado por la excitotoxicidad deliglutamato y por la neuroplasticidad del SNS, originándose así, una "epilepsia auditiva" Este desbalance de los neurotransmisores de la vía auditiva aferente, tendría su origen en una disfunción del sistema auditivo eferente, que se inicia por un da±o de las células ciliadas externas que regulan la tonicidad de la membrana basilar lo que se traduce en una liberación excesiva deiglutamato (excitatorio) por las células ciliadas internas, a lo cual se une liberación patológica postsináptica periférica de dinorfina a través del fascículo eferente olivococlear lateral la que potencia los receptoresiglutámicos postsinápticos NMDA. Las alternativas terapéuticas, además de las técnicas de habituación, serían principalmente dos: una, corregir farmacológicamente el desbalance GABA-glutamato, para lo cual se cuenta actualmente con algunos fármacos que podrían en algunos casos, modificar este desbalance, y dos actuar directamente sobre el foco auditivo hiperactivo cortical, inhibiendo su actividad a través de estímulos eléctricos. Sin embargo, los conocimientos actuales, no permiten una solución adecuada a la mayoría de los pacientes aquejados de acúfenos.

Tinnitus is, at present, a problem of difficult solution for the ENT specialist. Current knowledge makes easier to discern peripheral from central tinnitus, with the latter being by far more common. Tinnitus is triggered by a GABA-glutamate imbalance of the afferent auditory system. As a consequence of this, a neuronal reorganization of the auditory cerebral cortex takes place, by neural plasticity secondary toiglutamate excitotoxicity resulting thus in an "auditory epilepsy". This imbalance could originate in a dysfunction of the efferent auditory system, which could be caused by damage of the outer hair cells that regulate basilar membrane movement. This would result in excessiveiglutamate release by the inner hair cells. in addition, there is a pathological dynorphin post-synaptic peripheral release, through the olivocochiear lateral efferent fibers; which could lead to an enhancement of NMDA receptor- mediated synaptic transmission. in addition to habituation techniques, therapeutic choices could be: a) to pharmacologically correct the GABA-glutamate imbalance. At present, there are some drugs that might modify, in some cases, this imbalance; b) to act directly over the cortical hyperactive auditory locus by means of electrical stimuli, thus inhibiting its activity. However, our current knowledge on this topic does not provide a suitable solution for most patients suffering from tinnitus.

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 induded 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.

Functional status of auditory pathways in hypothyroidism: evoked potential study.

Hypothyroidism is known to be associated with mental retardation, motor dysfunction, memory deficits and hearing impairment. In the present study, the functional integrity of the thalamocortical projections to the primary auditory cortex and association cortex has been assessed by using Auditory Evoked Responses i.e Auditory Brainstem (ABR), Mid Latency Response (MLR) and Slow Vertex Response (SVR). Thirty newly diagnosed hypothyroid patients and thirty healthy controls were taken for the study and ABR, MLR and SVR were recorded on computerized evoked potential recorder using 10-20 system of electrode placement. The second recordings for the hypothyroid patients were done 3 months after treatment with attainment of euthyroid states. The present study revealed a slight increase in absolute latency of wave III of ABR in hypothyroid patients and significant decrease in absolute latency of wave III and interpeak latency of I-III after treatment. There was a significant decrease in amplitude of wave V in hypothyroid patients and significant increase in amplitudes of ABR wave I and wave V after treatment. There was a significant increase in latency of wave Na of MLR and wave P2 of SVR in hypothyroid patients. The latencies of waves Na, Pa, Nb of MLR and waves PI and N2 of SVR showed significant improvement with thyroid hormone treatment. The results of the present study indicates that in hypothyroid state there might be slow conduction at the periphery and with treatment there is better recruitment of neuronal pool of the generators of the waves of ABR in the brainstem. We can also conclude that the thalamocortical projections of the auditory pathways are adversely affected in the hypothyroid state and this improves after treatment.

Audiçäo central (I): nas lesöes supratentoriais das vias auditivas / Central hearing (I): in the supratentorial lesions of the auditory pathways

Os testes auditivos indicados para diferenciar patologicas periféricas normalmente näo säo apropriados para avaliaçäo das patologias centrais e vice versa. Os problemas centrais mostram limiar normal ou próximo do normal e sintomas contralaterais. O presente estudo avaliou a audiçäo central e periférica de dez indivíduos com patologias que acometiam o lobo temporal, utilizando exames audiométricos convencionais, testes de audiçäo central (SSI - Synthetic Sentences Intelligibility) e avaliaçäo da comunicaçäo. Apesar das poucas queixas auditivas dos pacientes com lesöes do Sistema Auditivo Central, houve grande incidência de sinais relacionados aos testes de audiçäo e comunicaçäo (como a afasia). O desempenho dos pacientes frente ao teste de inteligibilidade de fala, utilizando frases curtas, foi ruim notadamente no ouvido contralateral à lesäo, quando a mesma era unilateral, demonstrando assim alteraçöes das vias auditivas centrais, mesmo quando a discriminaçäo de monossílabos e outros testes audiométricos convencionais eram normais. Desta forma, um teste que utilize frases pode ser um importante meio para avaliaçäo da inteligibilidade da fala, de fácil interpretaçäo, e se mostra melhor que os testes de discriminaçäo de monossílabos para avaliaçäo de comprometimento das vias auditivas centrais em pacientes com patologias do lobo temporal, fornecendo também informaçöes quanto ao lado acometido.

Uma via para transmissäo de informaçäo ao ouvido / A pathway for information transmission to the ear

O uso de implantes cocleares como auxiliar na disacusia neurossensorial está se tornando procedimento bem estabelecido. A transmissäo de um sinal de fala, após processamento digital, pode ser feita por via transcutânea por conexäo com acoplador (maior risco de infecçäo). Para superar essas desvantagens, um sistema de transmissäo de luz infravermelha foi desenvolvido e testaddo. O transmissor usado foi um diodo de emissäo de luz infravermelha 9LED; 9920nm) e o receptor uma célula fotovoltáica. O LED foi colocado dentro do conduto auditivo externo de quatro cäes e a célula fotovoltáica, no ouvido médio em cima do promontório. Um sinal modulador senoidal foi aplicado ao LED. O sinal emitido foi detectado sem distorçäo após atravessar a membrana timpânica, com absorbância média de 20 por cento. Os autores concluem que a membrana timpânica pode ser considerada uma interface translúcida para transmitir dados sonoros aos ouvidos médio e interno com pequena perda de potência, boa freqüência de respostas e imunidade à interferência