Brainstem response amplitudes in neonatal chronic lung disease and differences from perinatal asphyxia.

OBJECTIVE: To examine neuronal function of the auditory brainstem in neonatal chronic lung disease (CLD) and detect any differences from perinatal asphyxia.

METHODS: Infants with CLD and infants after perinatal asphyxia were studied at term (37-42 weeks postconceptional age). Wave amplitudes of maximum length sequence brainstem auditory evoked response (MLS BAER) were recorded and compared between CLD and asphyxia.

RESULTS: The amplitudes of waves I, III and V, and V/I and V/III amplitude ratios in CLD infants did not differ from those in normal term controls at all click rates 21-910/s. The slopes of amplitude-rate functions were all similar to those in the controls. In infants after asphyxia, however, wave III and V amplitudes were smaller than those in both the controls and CLD infants, particularly at high-rate stimulation. The intercepts of amplitude-rate functions for waves III and V were smaller than in both the controls and CLD infants, although there were no significant differences in the slopes of these functions.

CONCLUSIONS: No abnormalities in MLS BAER amplitudes were found in CLD infants but the amplitudes were significantly reduced in asphyxiated infants, resulting in major differences between CLD and perinatal asphyxia.

SIGNIFICANCE: There is no major neuronal impairment in the auditory brainstem in CLD but there is in perinatal asphyxia. This difference may be, at least partly, related to the difference in the nature of hypoxia associated with the two problems; the hypoxia is chronic and sublethal in CLD, but is often acute, lethal and associated with ischaemia in perinatal asphyxia.