Auditory pathway maturational study in small for gestational age preterm infants.

Rosanna Giaffredo Angrisani,Carla Gentile Matas,Ruth Guinsburg,Marisa Frasson de Azevedo,Alexandre Archanjo Ferraro,Edna Maria Albuquerque Diniz

doi:10.1590/2317-1782/201420130078

Abstract

To follow up the maturation of the auditory pathway in preterm infants small for gestational age (SGA), through the study of absolute and interpeak latencies of auditory brainstem response (ABR) in the first six months of age. This multicentric prospective cross-sectional and longitudinal study assessed 76 newborn infants, 35 SGA and 41 appropriate for gestational age (AGA), born between 33 and 36 weeks in the first evaluation. The ABR was carried out in three moments (neonatal period, three months and six months). Twenty-nine SGA and 33 AGA (62 infants), between 51 and 54 weeks (corrected age), returned for the second evaluation. In the third evaluation, 49 infants (23 SGA and 26 AGA), with age range from 63 to 65 weeks (corrected age), were assessed. The bilateral presence of Transient Evoked Otoacoustic Emissions and normal tympanogram were inclusion criteria. It was found interaural symmetry in both groups. The comparison between the two groups throughout the three periods studied showed no significant differences in the ABR parameters, except for the latencies of wave III in the period between three and six months. As for the maturation with tone burst 0.5 and 1 kHz, it was found that the groups did not differ. The findings suggest that, in the premature infants, the maturational process of the auditory pathway occurs in a similar rate for SGA and AGA. These results also suggest that prematurity is a more relevant factor for the maturation of the auditory pathway than birth weight.

Highlights

The multifactorial etiology of prematurity contributes to the possibility of several interoccurrences and serious sequelae
The NBs were summoned for the tests, which were conducted in the following order: inspection of the external acoustic meatus with a Welch Allyn otoscope, transient-evoked otoacoustic emissions (TEOAEs) test, and measurement of acoustic immittance to ensure the integrity of the cochlear function, of the external
In the cross-sectional study, we analyzed the absolute latencies of the waves I, III, and V, as well as the I-III, III-V, and I-V interpeak intervals, and latency of the wave V (TB) in each group

Summary

Introduction

The multifactorial etiology of prematurity contributes to the possibility of several interoccurrences and serious sequelae. The auditory system goes through two stages of maturational development: the peripheral portion is ready in structure and size between the fifth and sixth month of gestation, whereas the structures in the central portion (in the brainstem), present and functional at birth, continue to form synaptic connections and improve their efficiency during the first two years of life[4,5]. According to a research study, a child’s small head circumference and short neural pathway length can be expressed by shorter I-V and III-V interpeak intervals of BAEPs. During prenatal period, an increase in speed of nerve conduction compensates the growth of the auditory pathways, causing the BAEP conduction time to decrease drastically. The speed of conduction compensates precisely the increased length of the pathways, stabilizing the BAEP conduction time[7]

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