Função do sistema olivococlear medial em crianças com desvio fonológico / Function of the medial olivocochlear system in children with phonological disorders

OBJETIVO: Verificar se crianças com desvio fonológico apresentam alterações do sistema olivococlear medial. MÉTODOS: Trata-se de estudo prospectivo e transversal. Foram avaliadas 19 crianças normo-ouvintes, de ambos os gêneros, com idades entre 4 e 7 anos, que foram divididas em dois grupos: 11 crianças sem desvio fonológico (grupo controle) e oito com desvio fonológico (grupo estudo). A condição auditiva foi verificada por meio da inspeção visual do meato acústico externo, audiometria tonal liminar e imitanciometria. Foram incluídas em ambos os grupos somente as crianças com limiares tonais iguais ou inferiores a 15 dB, timpanometria tipo A e reflexos acústicos presentes. Para avaliar a função do sistema olivococlear medial procedeu-se à avaliação das emissões otoacústicas evocadas transientes (EOAET) com e sem aplicação de ruído branco na intensidade de 60 dBNA contralateralmente. Os dados foram analisados estatisticamente. RESULTADOS: A ocorrência e a média dos valores de supressão das EOAET das orelhas direita e esquerda não apresentaram diferenças nas frequências de 1, 2, 3 e 4 kHz intragrupos estudo e controle. Na comparação da média e ocorrência do efeito supressor das emissões otoacústicas evocadas transientes entre grupo controle e grupo estudo, também não houve diferenças nas frequências analisadas. CONCLUSÃO: Crianças com desvio fonológico não apresentam alterações do sistema olivococlear medial, aspecto evidenciado pela ocorrência do efeito supressor das emissões otoacústicas evocadas transientes.

PURPOSE: To verify whether children with phonological disorders present alterations in the medial olivocochlear system. METHODS: This is a prospective cross-sectional study in which 19 normal hearing children of both genders, with ages between 4 and 7 years, were divided into two groups: 11 children without phonological disorders (control group) and eight with phonological disorders (study group). The auditory condition was verified by visual examination of the external ear canal, pure tone audiometry, and tympanometry. The study included only children with hearing thresholds below or equal to 15 dB, type A tympanometry, and presence of acoustic reflexes. To evaluate the function of the medial olivocochlear system, it was carried out the evaluation of transient evoked otoacoustic emissions (TEOAE) with and without contralateral white noise at 60 dBHL. Data were statistically analyzed. RESULTS: The occurrence and average values of TEOAE suppression in right and left ears did not present differences in the frequencies of 1, 2, 3 and 4 kHz within groups. In the comparison of the mean and the occurrence of the suppressive effect of TEOAE between control and study groups, there was also no difference in the frequencies analyzed. CONCLUSION: Children with phonological disorders do not present alterations in the medial olivocochlear system, as evidenced by the occurrence of the suppressive effect of transient evoked otoacoustic emissions.

Function of the medial olivocochlear system in children with phonological disorders.

PURPOSE: To verify whether children with phonological disorders present alterations in the medial olivocochlear system. METHODS: This is a prospective cross-sectional study in which 19 normal hearing children of both genders, with ages between 4 and 7 years, were divided into two groups: 11 children without phonological disorders (control group) and eight with phonological disorders (study group). The auditory condition was verified by visual examination of the external ear canal, pure tone audiometry, and tympanometry. The study included only children with hearing thresholds below or equal to 15 dB, type A tympanometry, and presence of acoustic reflexes. To evaluate the function of the medial olivocochlear system, it was carried out the evaluation of transient evoked otoacoustic emissions (TEOAE) with and without contralateral white noise at 60 dBHL. Data were statistically analyzed. RESULTS: The occurrence and average values of TEOAE suppression in right and left ears did not present differences in the frequencies of 1, 2, 3 and 4 kHz within groups. In the comparison of the mean and the occurrence of the suppressive effect of TEOAE between control and study groups, there was also no difference in the frequencies analyzed. CONCLUSION: Children with phonological disorders do not present alterations in the medial olivocochlear system, as evidenced by the occurrence of the suppressive effect of transient evoked otoacoustic emissions.

Contralateral suppression of linear and nonlinear transient evoked otoacoustic emissions in neonates at risk for hearing loss.

UNLABELLED: To investigate the transient evoked otoacoustic emissions (TEOAE) contralateral suppression in neonates at risk for hearing loss, 55 neonates at risk for hearing loss (risk group) and 72 full-term neonates not at such risk (control group) were bilaterally tested. In all neonates, the TEOAE were recorded in two stimulation modes (linear and nonlinear clicks), with and without contralateral acoustic stimulation. Findings revealed significant contralateral suppression of otoacoustic emissions in both groups, but the amount of TEOAE contralateral suppression was reduced for at risk group (p=0.001), supporting the hypothesis that medial olivocochlear bundle function is reduced in neonates at risk for hearing loss. The combination of contralateral acoustic stimulation and TEOAE enables easy and noninvasive study of auditory efferent function. However it should be emphasized that the reduction in TEOAE contralateral suppression in the risk group, statistically identified as a group effect, might not be detectable in individual cases. Further studies are needed in order to determine whether the lower amount of TEOAE contralateral suppression in neonates at risk for hearing loss represents a risk for developing auditory processing disorders. LEARNING OUTCOMES: The reader will be introduced to the study using auditory efferent pathway activation by contralateral acoustic stimulation (CAS), resulting in the TEOAE suppression effect. The characteristics of TEOAE suppression in the neonatal population, in which it provides evidence of the reduced medial olivocochlear system function in those at risk for hearing loss, will also be addressed.

Effects of pentylenetetrazole and 4-aminopyridine on the auditory brainstem response (ABR) and on the hearing sensitivity in the guinea pig in vivo.

For exploring a possible connection between the reduced hearing sensitivity and certain abnormalities in the auditory brainstem responses (ABRs) in generalized epilepsy, the effects of two convulsing agents, namely pentylenetetrazole (PTZ) and of 4-aminopyridine (4-AP), on: (1). the cortical activity (EEG), (2). the hearing threshold and (3). the amplitudes and latencies of the ABR waves evoked by a stimulus of high intensity (100 dB) were investigated in guinea pigs. All animals injected (i.p.) with 100mg/kg PTZ or with 2mg/kg 4-AP developed generalized seizures, followed by characteristic EEG patterns for the post-ictal period, that were accompanied by a marked reduction of the hearing sensitivity (as indicated by the elevated threshold of the ABR), as well as by retro-cochlear changes (as judged by the changes in the later ABR waves in response to 100 dB). For instance, both convulsing agents decreased the amplitude and increased the latency of P4, that is the wave component of the ABRs generated in the lateral superior olivary nucleus and while PTZ increased the latency of P3, the wave component of the ABRs generated in the medial superior olivary nucleus, 4-AP dramatically increased its amplitude. Comparison of recordings taken at specific times for the duration of the post-ictal period (i.e. within about 1h for PTZ and 2h for 4-AP) reveals that the extent of the changes on the EEG matches with the increase in the auditory threshold and with the extent of the changes on the later waves of the ABR elicited by 100 dB. These data indicate that changes in the activity of the lateral and the medial nuclei of the superior olivary complex (SOC) accompany the hearing loss and the post-ictal epileptic cortical activity.

Fluoxetine-induced tremor: clinical features in 21 patients.

We report a cohort of 21 patients (12 females and nine males), with a mean age of 42.4 years, who developed tremor after receiving fluoxetine at a mean dose of 25.7 mg per day. The mean latency period for tremor appearance was 54.3 days. Severity was found to be mild. In all patients, tremor was postural, with P<0.0005, compared to patients with rest tremor and P<0.05 compared to action/intention-tremor patients. The frequency range was 6-12 Hz/s. After fluoxetine was discontinued, tremor disappeared in 10 patients after a mean latency period of 35.5 days. In the remaining 11 patients, tremor persisted up to the end of the observation period (a mean of 449 days). We believe that this tremor phenomenon is due to the involvement of the red nucleus and the inferior olivary nucleus through their projections to the thalamus and the spinal cord.