Otoacoustic emissions and hearing impairment in newborns. The importance of high risk factors in Neonatal Intensive Care Units

 

 

Children in Neonatal Intensive Care Units (NICU) with risk factors for hearing loss (prematurity, birth weight < 1500 gr, apgar score < 3 in 5 minutes, etc.) have been the target of hearing screening because of the high possibility of detecting a hearing impairment and for practical reasons (prolonged stay and easy assessment of several newborns in the same area).

Although risk factors for hearing loss have been established since many years, there is no consensus with regard to the importance of each of these factors and the level of relative risk.

In two years period we examined with TEOAEs 25,288 newborns; 23,574 newborns in the regular hospital nursery and 1,714 in NICU.

From NICU newborns, 242 had an established risk-factor for hearing impairment according to the Joint Committee on Infant Hearing Position Statement. Newborns under 36 weeks of age, are not included in this study.

In table 1, we analyze the results of TEOAEs in high-risk NICU babies for every risk factor separately.

Newborns with congenital anomalies or syndromes had the higher rate of fail at NICU discharge (36,4%) and those with very low birth weight (≤1500 g) followed with a rate of 31,6%. The overall failure rate was 11%. It is interesting to compare this figure with the 6.6% failure rate of the remaining NICU newborns who did not have any risk factor for hearing loss and the 17% failure rate in high-risk newborns who were not in NICU as there was no medical reason for such admission.

Risk factors for hearing impairment in NICU population constitute a dynamic process that changes continuously. Today, newborns of very low birth weight and other serious problems survive due to new technologies and methods of management. On the other hand, common diseases in the past (congenital rubella, kernicterus) are now disappearing. Therefore, the relative importance of a certain risk factor for hearing loss is changing as well. Using TEOAEs, we are able today to follow this evolution.

 

 

  Table 1. Results of hearing screening with TEOAEs in high-risk NICU newborns according to each risk factor for hearing impairment