Distortion-Product and Click-Evoked Otoacoustic Emissions of Preterm and Full-Term Infants

Abstract

Full-term and preterm infants were evaluated with click+voked and distortionproduct otoacoustic emissions [CEOEs and DPOEs]. The CEOEs and D W E s recorded from each individual ear were analyzed by calculating the rootimean-square levels within halfa%ave bands. The fail criterion of the OE tests was that the halfoctave RMS DPOE or CEOE levels of an ear under test were below the 1 0 t h percentile of full-term newborns in t w o o r more bands. The DPOE data were collected from 118 ears of 61 premature babies; 80 (68%] ears passed the DPOE test, 30 [25%] ears without middle ear effusions failed the test, and 8 (7%] ears with effusions also failed. The CEOE data were collected from 128 ears of 65 premature babies; 102 (80%) ears passed the CEOE test, 18 (14%) ears without middle ear effusions failed the test, and 8 (6%] ears with effusions also failed. In 23 of 80 ears (29%) that passed the D W E test and in 23 of 102 ears (23%] that passed the CEOE test, RMS OE levels of preterm infants were above the 9 0 t h percentile of fulLterm newborns. The analyses of the combined DPOE and CEOE data obtained from a group of 25 ears of full-term newborns and from a group of 72 ears of preterm babies showed statistically significant correlations between the DPOE and CEOE rootmean-square levels in each of the half-octave bands in the 1.4 to 4 kHz region. For 42 preterm infants tested with auditory brain stem response [ABR), specificity was 86% for CEOE and 74% for DPOE. All infants who failed the ABR also failed OE tests. To the best of our knowledge, this study is the first using combined D W E s , CEOEs, and ABRs for preterm babies. It showed the feasibility of D W E s and CEOEs for this population.

Análise das emissões otoacústicas evocadas por produto de distorção em neonatos prematuros

“…This corroborates the studies of Couto et al 7 and Smurzynski et al 5 that report that there is greater concentration of distortion product otoacoustic emissions at high frequencies and also that there is a greater tendency of the distortion product otoacoustic emissions to approach to normal values at higher frequencies.…”

“…First, a descriptive analysis of the data with measures of central tendency and dispersion was carried out, followed by test of variances equality. The method of analysis of purpose of the otoacoustic emissions in neonatal screening is to early detect cochlear hearing loss in children, allowing the confirmation of the integrity of the mechanism of the outer hair cells of the cochlea [4][5][6] . The otoacoustic emissions can be directly influenced by the conditions of the external auditory meatus and "transmission properties" of the neonate 7 .…”

“…Such stimulation generates a cochlear response in the form of a third tone whose frequency (2f1-f2) constitutes a distortion product of the stimulus frequencies 7 . Prematurity may be a factor that influences the amplitude of response of the DPOAEs, since the cochlea of the premature neonate presents subtle immaturity of the function and the auditory system may present changes in the development until the completion of maturation [2][3][4][5][6][7][8][9] . In a study, three infants with lower gestational ages (28 to 30 weeks or less) were evaluated and they presented lower levels of response than the infants born after a longer gestational period 10 .…”

Emissão otoacústica evocada transitória: instrumento para detecção precoce de alterações auditivas em recém-nascidos a termo e pré-termo

“…Os dados do presente estudo apresentaram-se semelhantes aos obtidos por Smurzynski et al 16 que encontraram uma razão de "passar" em 90% para os recém-nascidos a termo -em nosso estudo, encontramos 95% -e de 80% para os pré-termo -em nosso estudo, encontramos 77,8% para os AIG e 83% para os PIG. Os autores citados não fizeram a divisão relacionada ao peso de nascimento e idade gestacional.…”

Medidas da latência das emissões otoacústicas - produto de distorção em neonatos

“…É sabido que a cóclea ainda está imatura nas altas freqüências após o nascimento, explicando um maior tempo de latência em recém-nascidos. Smurynsky, 1993 17 , realizou um estudo de latência em prematuros, recém-nascidos a termo e adultos. Seus resultados mostraram uma maior latência nos neonatos em comparação com os adultos para freqüências de 2 a 4 KHz; esta diminuição da latência de acordo com a idade foi explicada pelas mudanças maturacionais da orelha externa, média e interna.…”