Changes in Auditory Brainstem Response in very preterm and late preterm infants.

AIM

Aim of this study was to compare the absolute and interpeak latencies of Auditory Brainstem Responses (ABR) in very preterm and late preterm infants at 1 month and 3 months of corrected age.

METHOD

ology: ABR traces were obtained from 80 preterm infants (40 very preterm and 40 late preterm) at 1 month and 3 months of corrected age in a prospective, comparative cohort study. Auditory click stimuli at 70 dBnHL and 30 dBnHL, with repetition rate of 11.1/s were used. Absolute latencies of peak I, III, V and interpeak latencies of peak I-V, I-III and III-V were analyzed and compared between preterm groups at 1 month and 3 months of corrected age. Wilcoxon Signed Ranks test was used to compare the ABR variables. Mann Whitney test was used to make inferences between groups.

RESULTS

There was a statistically significant difference in absolute latencies and interpeak latencies between very preterm and late preterm infants at 1 month of corrected age (p < 0.05). Absolute latency of peak I was similar among both groups of preterms. Absolute latencies of peak III, V and interpeak latencies I-III, III-V and I-V were prolonged in very preterm infants at 1 month of corrected age. However, these latencies were significantly reduced at 3 months of corrected age. This indicated accelerated maturation/myelination of the central auditory nervous system in very preterm infants. Absolute latencies of peak III and V and interpeak interval I-V was reduced in late preterm infants at 3 months of corrected age and this was statistically significant. This reduction in latency was considered to be a normal age dependent change.

CONCLUSION

Findings of the current study revealed that there was no deviation in the pattern of auditory maturation among preterms; it followed the typical 'caudal to rostral' form of maturation. Very preterm infants have less mature neuronal development compared with late preterm infants at 1 month of corrected age which catches up at 3 months of corrected age.