Medidas de imitância acústica de banda larga em crianças com perda auditiva sensorial severa e profunda e diferentes achados timpanométricos

Abstract

Wideband acoustic immittance measurements in children with severe and profound sensorineural hearing loss, and different tympanometric findings. The evaluation of the integrity of the tympanic-ossicular system is a prerequisite for the child audiology diagnostic process to be completed accurately, thus, much has been discussed in relation to the procedures used in clinical practice to define the presence or absence of conductive problems. Hence, the wideband acoustic immittance measurements show to be an option to the advance in the field. As a result, the interest in expanding the knowledge and bringing the characteristics of wideband acoustic immittance measurements in the different conditions of middle ear, emerged. This study aimed at characterizing the wideband acoustic immittance measurements using pure and chirp stimuli in children presented with severe and profound sensorineural hearing loss and different tympanometric standards. 187 ears of 98 children in the age range six-sixty months, subdivided into groups according to pressure and compliance achieved through tympanometry with a 226 Hz probe, were assessed. Wideband acoustic immittance measurements were performed by the measuring system of the Acoustics' Middle-Ear Power Analyzer-MEPA, version 5.0, using pure and chirp tone stimuli, in a frequency ranging from 211 to 6000 Hz. The values of compliance and pressure obtained through conventional tympanometry were correlated with wideband acoustic immittance measures, by applying suitable statistical tests, with a 0.05 significance level. The results achieved evidenced the effect of frequency bands (low, medium and high) in all measures examined, with the exception of the reflectance delay. The Influence of pressures-100 daPa or more negative ones and also in positive pressures above 25 Pa, and compliance lower than 0.2 ml in the wideband acoustic immittance measurements, was verified. In addition, there was a significant difference between pure tone and chirp stimuli at low frequencies for impedance absorbance and magnitude, with a greater reflex of the variation of compliance and pressure values in the results obtained with the chirp stimulus. It is concluded that the characteristics of broadband acoustic immittance measures are related to the condition of middle ear condition and the frequency of the test stimulus. For Reflectance delay, a wide variability between frequencies was observed when analyzing the groups subdivided by pressure and also in the frequency of 258 Hz, when analyzing the groups subdivided by compliance.