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Abstract Introduction Prenatal exposure to the Zika virus can impair neurodevelopment and cause auditory damage. Objective To analyze the frequency-following response (FFR) and the auditory behavior (with the LittlEars® questionnaire) of children with and without prenatal exposure to Zika virus infection. Methods A total of 30 children participated in the present study, divided into 3 groups: 10 children with microcephaly and prenatal exposure to the Zika virus; 10 normocephalic children with prenatal exposure to the Zika virus; and 10 children with no evidence of prenatal exposure to the virus. The FFR test was performed with the /da/ syllable. The LittlEars® questionnaire was used with parents/guardians. Results For the FFR measurements, there was no difference between the groups. The children with exposure to the Zika virus presented a final score in the questionnaire below what is expected from children with normal hearing. A significant difference was observed for the final, semantic, and expressive scores between the group with microcephaly and the other groups. A strong negative correlation was seen between the LittlEars® questionnaire final score and the FFR measurements for the group with microcephaly when compared with the other groups. Conclusion Children exposed to the Zika virus, with and without microcephaly, presented FFR patterns similar to what was seen in children with no evidence of virus exposure. However, they showed signs of immature auditory behavior, suggesting auditory development delay.
RESUMO
Abstract Introduction: Hearing aids are prescribed to alleviate loss of audibility. It has been reported that about 31% of hearing aid users reject their own hearing aid because of annoyance towards background noise. The reason for dissatisfaction can be located anywhere from the hearing aid microphone till the integrity of neurons along the auditory pathway. Objectives: To measure spectra from the output of hearing aid at the ear canal level and frequency following response recorded at the auditory brainstem from individuals with hearing impairment. Methods: A total of sixty participants having moderate sensorineural hearing impairment with age range from 15 to 65 years were involved. Each participant was classified as either Good or Poor Hearing aid Performers based on acceptable noise level measure. Stimuli /da/ and /si/ were presented through loudspeaker at 65 dB SPL. At the ear canal, the spectra were measured in the unaided and aided conditions. At auditory brainstem, frequency following response were recorded to the same stimuli from the participants. Results: Spectrum measured in each condition at ear canal was same in good hearing aid performers and poor hearing aid performers. At brainstem level, better F0 encoding; F0 and F1 energies were significantly higher in good hearing aid performers than in poor hearing aid performers. Though the hearing aid spectra were almost same between good hearing aid performers and poor hearing aid performers, subtle physiological variations exist at the auditory brainstem. Conclusion: The result of the present study suggests that neural encoding of speech sound at the brainstem level might be mediated distinctly in good hearing aid performers from that of poor hearing aid performers. Thus, it can be inferred that subtle physiological changes are evident at the auditory brainstem in a person who is willing to accept noise from those who are not willing to accept noise.
Resumo Introdução: Os aparelhos auditivos são prescritos para aliviar a perda de audibilidade. Tem sido relatado que 31% dos usuários rejeitam seu aparelho auditivo devido ao desconforto com o ruído de fundo. A razão para a insatisfação pode estar situada em qualquer local desde o microfone do aparelho auditivo até a integridade de neurônios ao longo da via auditiva. Objetivos: Medir espectros desde a saída do aparelho auditivo no nível do meato acústico externo e frequência de resposta (FFR) registrada no tronco encefálico de indivíduos com deficiência auditiva. Método: Foram selecionados 60 participantes com deficiência auditiva neurossensorial moderada, de 15 a 65 anos. Cada participante foi classificado como usuário bom ou mau de prótese auditiva (GHP ou PHP) com base na medida de nível de ruído aceitável (ANL). Estímulos/da/e/si/foram apresentados em alto-falante a 65 dB SPL. No meato acústico externo, os espectros foram medidos nas condições sem aparelho e com aparelho. No tronco encefálico auditivo, FFR foram registradas para os mesmos estímulos dos participantes. Resultados: Os espectros medidos em cada condição no meato acústico externo foram os mesmos em GHP e PHP. No nível do tronco cerebral, melhor codificação F0; energias de F0 e F1 foram significativamente maiores em GHP do que em PHP. Embora os espectros do aparelho auditivo fossem quase os mesmos entre GHP e PHP, existem variações fisiológicas sutis no tronco encefálico auditivo. Conclusão: O resultado do presente estudo sugere que a codificação neural do som da fala no nível do tronco encefálico pode ser mediada distintamente em GHP em comparação com PHP. Assim, pode-se inferir que mudanças fisiológicas sutis são evidentes no tronco encefálico em uma pessoa que está disposta a aceitar o ruído em comparação com aqueles que não estão dispostos a aceitar o ruído.