Moderate compromise in postnatal brainstem auditory function in low-risk very preterm infants and differences from late preterm infants.

OBJECTIVE

To investigate the postnatal function of the brainstem auditory pathway in low-risk very preterm infants and define differences from that in late preterm infants.

METHODS

Brainstem auditory evoked responses (BAERs) were studied at 3 months of corrected age in 44 very preterm infants (24-32 weeks of gestation) who had no major perinatal or postnatal problems. The responses were elicited with clicks presented at 21, 51, and 91/s. The results were compared with those in normal term controls and late preterm infants (33-36 weeks of gestation).

RESULTS

Compared with normal term controls, the very preterm infants manifested moderately elevated BAER threshold. The latencies of BAER waves III, and particularly V were significantly prolonged from all 21 to 91/s click rates. The I-V and III-V interpeak intervals were also prolonged, especially at higher rates. The I-III interval was prolonged at the highest 91/s clicks. The amplitudes of waves I, III and V were reduced across all rates. These abnormalities in very preterm infants were generally more pronounced than in late preterm infants who manifested prolonged interpeak intervals only at higher click rates.

CONCLUSION

The low-risk very preterm infants manifested a moderate abnormality in BAER, indicating a moderate compromise in postnatal brainstem auditory function. This compromise is more pronounced than the minor auditory abnormality observed in late preterm infants. These findings underscore a moderate compromise in postnatal auditory function in very preterm infants, even though they have no overt peri- or postnatal problems.