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Abstract
Contralateral suppression of transient otoacoustic emissions in 42 premature babies (84 ears; post-conceptional age [PCA] 30–36 weeks) was compared to that of 39 full-term babies (78 ears; PCA: 37–45 weeks). Eighteen healthy adults and ten young children (5–14 years old) were studied as controls. Risk factors for hearing loss were registered in both preterm and full-term groups. An ILO–92 otoacoustic emission recording system was used to deliver linear clicks to the ear examined and broadband noise to the contralateral ear in an alternating on and off mode.
Suppression in full-term babies was statistically higher than in preterms, whereas no differences existed between children and adults and children and full-terms. Peripheral auditory lateralization was evident in adults but was observed only as a trend in newborns. Only prematurity at the time of examination and aminoglycoside treatment for more than seven days had a negative impact on suppression.
The results support the conclusion that maturation of the efferent system takes place from 30 to 45 weeks PCA. The exact age at which this maturation is accomplished has not yet been clearly determined.
| Acronyms | ||
| TEOAE | = | Transient otoacoustic emissions |
| MOCB | = | Medial olivocochlear bundle |
| PCA | = | Post-conceptional age |
| SPL | = | Sound pressure level |
| SL | = | Sensation level |
| RMS | = | Root mean square |
| BBN | = | Broadband noise |
| CAS | = | Contralateral acoustic stimulus |
| NICU | = | Neonatal intensive care unit |
| PTA | = | Pure-tone audiometry |
| ANOVA | = | Analysis of variance |
| Acronyms | ||
| TEOAE | = | Transient otoacoustic emissions |
| MOCB | = | Medial olivocochlear bundle |
| PCA | = | Post-conceptional age |
| SPL | = | Sound pressure level |
| SL | = | Sensation level |
| RMS | = | Root mean square |
| BBN | = | Broadband noise |
| CAS | = | Contralateral acoustic stimulus |
| NICU | = | Neonatal intensive care unit |
| PTA | = | Pure-tone audiometry |
| ANOVA | = | Analysis of variance |
Sumario
Se comparó la supresión contralateral de las emisiones otoacústicas evocadas por transitorios en 42 bebés prematuros (84 oídos edad calculada post-concepción [PCA] de 30–36 semanas) con la de 39 bebés de término (78 oídos; PCA: 37–45 semanas). Como grupo control se estudiaron 18 adultos sanos y 10 niños (5–14 años). Se registraron los factores de riesgo para hipoacusia tanto en los bebés prematuros como en los de término. Se usó un equipo de emisiones otoacústicas ILO-92 con clicks lineares en cada oído examinado y ruido de banda ancha para el contralateral en modo alterando on-off.
La supresión en los bebés de término fue estadísticamente mayor en los prematuros, mientras que no se encontró diferencia entre niños y adultos o entre niños y bebés de término. La lateralización auditiva periférica fue evidente en los adultos, mientras que en los neonatos se observó sólo como un rasgo. Unicamente la prematurez y el tratamiento con aminoglucósidos por más de siete días tuvieron un efecto negativo sobre la supresión.
Los resultados apoyan la conclusión de que la maduración del sistema eferente se presenta de la semana 30 a la 45 PCA. Aun no se ha determinado claramente la edad exacta en la que sucede esta maduración.