RESUMO
INTRODUCTION: Infant hearing loss is a highly prevalent disorder which untreated can severely disrupt normal brain development. As a result there is a significant delay in language acquisition as well as many cognitive and emotional problems in the child. Over the last decades important advances have occurred in the available technology for early detection and assessment of hearing impairment. Therefore many countries worldwide have become aware of the need for hearing screening programs. The optimal protocols depending on the local conditions of health care as well as the availability of technological and human resources. AIM: To summarize the results obtained over the last 20 years by an ongoing hearing screening protocol. DEVELOPMENT: Data on the coverage program, sensitivity and specificity, age of identification of hearing losses, diagnostic and intervention stages will be summarized and discussed. Also the long terms effects of early detection on the child cognitive and language development are analyzed. Finally, the possible role of a new technique based on the recording of multiple auditory steady state potentials with Cuban equipment (AUDIX system) was evaluated within this context. CONCLUSIONS: The Cuban targeting multiple high risk hearing screening program is a useful alternative to early detection of hearing losses. The average detection age of hearing loss was 10 months during the period of optimal functioning. Cognitive, emotional and linguistic development are improved by early detection and intervention. The multiple auditory steady state responses can provide valuable audiometric information within a screening context.
Assuntos
Perda Auditiva , Testes Auditivos/estatística & dados numéricos , Programas de Rastreamento , Triagem Neonatal , Criança , Pré-Escolar , Cognição/fisiologia , Cuba/epidemiologia , Diagnóstico Precoce , Potenciais Evocados Auditivos do Tronco Encefálico , Perda Auditiva/diagnóstico , Perda Auditiva/epidemiologia , Perda Auditiva/terapia , Humanos , Lactente , Recém-Nascido , Desenvolvimento da Linguagem , Sensibilidade e EspecificidadeRESUMO
INTRODUCTION: An essential step, prior to the introduction into paediatric practice of visual evoked potentials (VEP) caused by stimulation with light emitting diodes (LED) is their description at different stages of maturity of the nervous system. PATIENTS AND METHODS: We obtained VEP to LED in a group of 60 children aged between 1 and 5 years, who were functionally healthy and equally distributed with regard to age and sex. In each case we recorded the responses to monocular stimulation (right and left), binocular stimulation and without stimulation (replicas of each condition). The recordings were made under sedation with secobarbital at a dose of 3 mg/kg body weight. RESULTS: Our results showed a significant reduction in the latency of all components (except P3) and the amplitude of N1 and P1, as a function of the age of the child. The response to LED is reproducible (especially intra individual) with up to three types of morphology observed. Sedation did not affect detection of the response. The only significant effect was a reduction in the amplitude of P1. CONCLUSIONS: We confirmed the changes due to maturity, reflected in a significant reduction of the latency of most components with increasing age. By between 4 and 6 years old the figures obtained were similar to those in adults. The results obtained give us the opportunity chance of publishing this standard data so that better use and interpretation of VEP to LED at an early age may be possible.
Assuntos
Potenciais Evocados Visuais/fisiologia , Testes Neuropsicológicos/normas , Sistema Nervoso Central/crescimento & desenvolvimento , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Estimulação Luminosa , Tempo de ReaçãoRESUMO
OBJECTIVE: To evaluate, using receiver operation characteristic (ROC) curves, the performance of several statistical indicators in the objective detection of 80 Hz steady state auditory evoked responses. DESIGN: Steady state auditory evoked responses elicited by amplitude modulated tones of 500 and 1000 Hz, were obtained in 16 normal adults. Recordings were made at intensities ranging from 80 to 30 dB SPL and without stimulation. Four statistics: coherence synchrony measure, circular T2, a new variant of Hotelling T2 (labeled HT2) and a test for hidden periodicity (F test) were calculated. The statistics were compared using ROC curves and bootstrapping techniques. Two outcome measures were considered: behavioral threshold prediction and averaging efficiency. RESULTS: All indicators were highly accurate to detect a response (8 to 9 dB above mean behavioral threshold for the 1000 Hz and 14 to 16 dB for the 500 Hz carrier). Responses could be reliable detected after averaging about five individual epochs of long duration. No statistically significant differences were evidenced though in their capability to predict behavioral threshold or their averaging efficiency. CONCLUSIONS: Despite the more adequate statistical properties of some of these indicators no significant differences were found in their performance. Thus all of these indicators could be recommended for automatic detection of 80 Hz auditory steady state responses.
Assuntos
Potenciais Evocados Auditivos , Modelos Estatísticos , Adolescente , Adulto , Estimulação Elétrica , Feminino , Humanos , Masculino , PeriodicidadeRESUMO
MANOVA and repeated measures ANOVA approaches have provided evidence of a number of limitations in several event-related potential (ERP) studies due to violations of their statistical assumptions and the typically moderate size of the available sample. Alternative, computer-intensive methods based on permutation principles have recently been developed. Up to now this methodology has focused mostly on magnitude differences between scalp distributions as measured by t statistics. In this paper the scope of permutation techniques in ERP analysis was widened. A new statistic (D statistic) is introduced to compare the shapes of scalp distributions of ERPs. Additionally a general non-parametric combinatory technique is introduced to evaluate, by means of multivariate permutation tests, several time points and/or recording sites in ERP data. The methodology described here was used to test if two ERP components elicited during word-pair matching tasks to semantic or phonological incongruences had different scalp distributions.
Assuntos
Encéfalo/fisiologia , Potenciais Evocados/fisiologia , Adolescente , Adulto , Análise de Variância , Mapeamento Encefálico , Eletroencefalografia , Feminino , Humanos , MasculinoRESUMO
Auditory brainstem responses to tone bursts of constant rise and fall time and variable plateau were obtained in 7 normal hearing adults with a vertex to mastoid electrode configuration. In all records, two vertex-positive components (A, B) were present. Peak A is probably an onset response. Peak B latency increased linearly with plateau duration (r = 0.93) and seems to be an off response. White and notched acoustic noise masking had a different effect on the two components. A greater latency shift was observed for peak A than for peak B, thus reducing the interpeak interval in the masked response. When using high-pass noise, as we lowered the cut-off points from 4 to 0.5 kHz, there was also a greater latency increment for peak A than for peak B. These results suggest a more apical cochlear origin for the off response.
Assuntos
Potenciais Evocados Auditivos , Adulto , Tronco Encefálico/fisiologia , Cóclea/fisiologia , Feminino , Humanos , Masculino , Ruído , Mascaramento Perceptivo/fisiologia , Tempo de Reação/fisiologiaRESUMO
The performance of statistical evoked-potential detection methods was compared with that of human observers and among themselves by means of receiver operating characteristics (ROC) curves. The test material was a collection of brain stem auditory-evoked responses obtained from 98 infants with 60 and 30 dB nHL clicks. The observers and the statistical methods had to discriminate these responses from control recordings obtained without acoustic stimulation. Although the observers' criteria on different days varied considerably, the discrimination capacity was more stable. The discrimination capacity depended on the observers' experience. The statistical methods tested were the correlation coefficient (CCR), the standard deviation ratio (SDR) and a new method named T2R. The most efficient detection method was T2R. For false-alarm rates of 0.01 the statistical methods were more efficient than the human observers. Signal detection theory is useful for the evaluation of evoked-potential analysis methods.