Characterization of the thresholds of Auditory Steady State evoked potentials in the first six months of life

Author(s)

Luciana Cristina de Oliveira

• Document type: Master's Dissertation
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2012-09-28

Examining board members

Katia de Freitas Alvarenga; Regina Celia Bortoleto Amantini; Lilian Cássia Bornia Jacob Corteletti

• Advisor: Katia de Freitas Alvarenga

Abstract

Introduction: The thresholds of the auditory steady-state evoked potentials (ASSEP) in newborns and infants up to the sixth month of life help to predict the psychoacoustic thresholds in a period in which they do not precisely respond to behavioral tests. Objective: To characterize the thresholds of ASSEP related to age in term newborns and infants, so as to verify the influence of the maturational process on the hearing systems electric response. Methodology: A cross-sectional study which assessed 60 newborns and infants divided into three groups: GI - zero to a month and 29 days, n=20; GII two to three months and 29 days, n=20; GIII four to six months, n=20. The ASSEP research used pure tones in the carrier frequencies of 0,5, 1, 2 and 4 kHz modulated 100% in amplitude and 20% in frequency, with a modulation of 91,406, 93,750, 96,094 and 98,437 Hz, respectively, in the intensity, ranging from 60 to 0 dB NA, presented through ER-3A insertion phones, simultaneous and mono-aurally; electrodes in Fz (active), Oz (reference) and Fpz (ground); gain of 50000, pass band filter 1-300 Hz, 6 dB/octave. The Real-Ear to Dial Difference (REDD) was measured in the external auditory canal (EAC) by using a silicone probe microphone of the Hearing aid Analyzer FONIX FP 35 equipment (Frye Electronics) . Results: A statistically significant difference was seen among the groups for REDD values only in the frequency of 4 kHz, but not observed for ASSEP thresholds. In relation to the carrier frequency variable, a significant difference was observed for both REDD and ASSEP, with association among them, that is, the ASSEP thresholds decreased for the frequency interval 0,5 to 2,5 kHz and increased when the frequency was 4 kHz, the opposite occurring for REDD. Conclusion: The characterization of ASSEP thresholds in the first six months of life showed that the same threshold can be used as a normality reference for this age range, with distinct values for the different carrier frequencies. The influence of EAC amplification in the ASSEP thresholds should be taken into account, since it may mask the influence of the maturational process on the auditory systems electric response. (AU)

• FAPESP's process: 10/13810-2 - Characterization of auditory steady-state responses thresholds in the first six months of life
• Grantee: Luciana Cristina de Oliveira
• Support Opportunities: Scholarships in Brazil - Master