[Incidence of hypoacusia secondary to hyperbilirubinaemia in a universal neonatal auditory screening programme based on otoacoustic emissions and evoked auditory potentials].

INTRODUCTION

Hyperbilirubinaemia is a neonatal risk factor that has been proved to be associated with sensorineural hearing loss. A high concentration of unconjugated bilirubin place newborn children at risk of suffering toxic effects, including hypoacusia.

OBJECTIVES

Review of the newborn screening results with a diagnosis of pathological hyperbilirubinaemia as part of a hearing-loss early detection protocol in the general population based on otoemissions and evoked potentials.

MATERIAL AND METHOD

Retrospective study of 21 590 newborn children screened between 2002 and 2006. The selection criteria for defining pathological hyperbilirubinaemia were bilirubin concentrations in excess of 14 mg/dL in pre-term infants and 20 mg/dL in full-term babies. The Universal Neonatal Hearing Screening Programme is a two-phase protocol in which all children are initially subjected to a transient otoacoustic emissions test (TOAE). Children presenting risk factors associated with auditory neuropathy were always given brainstem auditory evoked potentials (BAEP).

RESULTS

The patients identified as having severe hyperbilirubinaemia in the neonatal period numbered 109 (0.5 %) and 96 of these (88.07 %) passed the otoacoustic emissions test at the first attempt and 13 (11.93 %) did not; 11 of the 13 children in whom the otoacoustic emissions test was repeated passed it successfully. The 2 children who failed to pass the otoacoustic emissions test has normal BAEP results; 3 (2.75 %) of the newborn infants who passed the TOAE test did not pass the BAEP.

DISCUSSION

Hyperbilirubinaemia values previously considered safe may harm the hearing system and give rise to isolated problems in auditory processing without being associated with other signs of classical kernicterus. Our results show that hyperbilirubinaemia-related auditory neuropathy reveals changes over time in the audiometric outcomes.