Development of the brainstem auditory pathway in low birthweight and perinatally asphyxiated children with neurological sequelae.

Low birthweight (LBW) and perinatal asphyxia are known to be high-risk factors for a number of neurodevelopmental deficits. In this study, we analyzed brainstem auditory evoked response (BAER) in 18 LBW and 36 perinatally asphyxiated children with non-progressive neurological sequelae after the age of 6 months to inspect and compare the long-term influence of LBW and perinatal asphyxia on the brainstem auditory pathway. The typical changes in the BAER of children born with LBW were slightly shorter III-V interpeak interval and smaller III-V/I-III interval ratio than normal controls. On the contrary, the abnormalities in the BAER of 36 children surviving perinatal asphyxia were characterized by a reduction of the amplitude of wave V with normal intervals. This discrepancy in the BAER between the children born with LBW and those with perinatal asphyxia implies that the two high-risk factors exert different long-term influences on the development of the brainstem auditory pathway. It is hypothesized that these characteristic changes may be indicative of a major influence of LBW on the generators contributing to wave III and that of asphyxia on the generators contributing to wave V. An increase in response threshold with abnormal latency-intensity function was found in 11% of the LBW children and 19% of the asphyxiated children, suggesting that sensorineural hearing impairment occurred more frequently in children surviving perinatal asphyxia than in those born with LBW. Follow-up study demonstrates that the abnormalities in the brainstem auditory pathway of LBW and asphyxiated children after the age of 6 months is likely to be persistent.