Electrophysiological characterization of hearing in small for gestational age premature infants

To characterize the Auditory Brainstem Response (ABR) of small for gestational age preterm newborns and to compare the findings to those of appropriate for gestational age premature newborns in order to verify whether the small for gestational age condition is a risk factor for hearing loss.

This prospective cross-sectional multicenter study evaluated 72 preterm newborns of both genders (35 small and 37 appropriate for gestational age), who were born at 30 to 36 weeks of gestational age and were evaluated before hospital discharge. Only newborns with present transient evoked otoacoustic emissions and tympanometry type A were included. The ABR was performed with click stimuli. The quantitative data analysis was performed using mean and standard deviation measures for each group. For qualitative analysis, the ABR results were classified as normal or altered according to the absolute latencies of waves I, III, V and interpeaks I-III, III-V, I-V. The analysis was carried out considering the age of the newborn at the time of examination.

Alterations were evident in 32 newborns (44.44%), being 15 small (43%) and 17 appropriate for gestational age (46%), with no between-groups difference. Of the 15 small for gestational age newborns with altered ABR, six presented as auditory risk only the small for gestational age condition. In the group of adequate for gestational age newborns, there was a higher occurrence of alteration in males.

There was no difference in responses of auditory evoked potential between small and appropriate for gestational age preterm newborns. Therefore, the condition does not behave as a risk factor for retrocochlear impairment.