Modifications of auditory brainstem responses (ABR): observations in full-term and pre-term newborns

Objective: In this study, we have evaluated by means of auditory brainstem responses (ABR), in a population derived from a newborn hearing screening protocol, some aspects of maturation of the auditory pathways in the first months after birth, and the possible repercussions on early treatment. Materials and methods: In this retrospective study newborns were recruited through our hearing screening program, and an ABR evaluation was performed on 339 newborns, that had risk factors or had failed the screening, or both. Such population was divided in two groups for statistical analysis purposes: full-term and pre-term. The initial ABR was pathological in 70 infants. Results: We observed an improvement over time of the estimated hearing threshold in follow-up ABRs in 43 newborns (26 in the full-term group, mean improvement 27.9 dB SPL, and 17 in the pre-term group, mean improvement 34.6 dB SPL); such an improvement might be related to a maturation of the auditory pathways that was not complete at birth. Conclusions: The auditory system might not be completely developed at birth, and might require some months to complete; hence any early clinical approach should consider the possibility of an overtreatment, and any therapeutic strategy should only be considered once the diagnosis is certain and definitive.