Short-term outcome of brainstem auditory function in term infants after discharge from the neonatal intensive care unit

OBJECTIVES

To examine short-term outcome of brainstem auditory function in term infants after discharge from the neonatal intensive care unit (NICU).

METHODS

Brainstem auditory evoked response (BAER) was recorded and analysed at various click rates at 2-4 months of age in 43 term NICU graduates. The data were compared with those in age-matched normal controls.

RESULTS

The threshold of BAER in the NICU graduates was marginally elevated. The graduates also showed an increase in wave III latency at 91/s and wave V latency at all 21-91/s. The I-V interval was increased at 51 and 91/s, whereas the I-III and III-V intervals were slightly increased, with no significant differences from normal controls at any click rates. The amplitudes of waves I and V in the NICU graduates were moderately reduced at all click rates. Wave III amplitudes were reduced at 51 and 91/s. None of the slopes of BAER variables-rate functions in the NICU graduates differed significantly from normal controls.

CONCLUSIONS

The BAER was moderately abnormal in the NICU graduates, suggesting that brainstem auditory function is moderately impaired at 2-4 months of age after discharge. There is a need to monitor postnatal auditory and neural development for NICU graduates.

Reduced wave amplitudes of brainstem auditory response in high-risk babies born at 28-32week gestation

OBJECTIVE

To examine brainstem auditory electrophysiology in high-risk babies born at 28-32week gestation by analysing the amplitudes of wave components in maximum length sequence brainstem auditory evoked response (MLS BAER).

METHODS

94 preterm babies, ranging in gestation 28-32weeks, with perinatal problems (high-risk) were recruited. The amplitudes of MLS BAER wave components were studied at term age (37-42weeks postconceptional age).

RESULTS

Compared with normal term controls, the amplitude in the high-risk preterm babies was significantly smaller at the highest click rate 910/s for wave I (p<0.01), at all 91-910/s for wave III (all p<0.01) and at 455 and 910/s (p<0.05 and 0.01) for wave V. Compared with age-matched low-risk preterm controls, the amplitude was significantly smaller at 455 and 910/s for wave I (p<0.05 and 0.05), 91-910/s for wave III (p<0.05-0.001), and 227-910/s (p<0.05 and 0.01) for wave V. No differences in the V/I and V/III amplitude ratios were found between the high-risk preterm babies and the controls.

CONCLUSIONS

The amplitudes of MLS BAER wave components, mainly more central components, were reduced in the high-risk preterm babies born at 28-32week gestation. Electrophysiological activity of the brainstem auditory neuron in such babies is depressed, mainly attributed to or related to the associated perinatal problems.

Brainstem auditory electrophysiology is supressed in term neonates with hyperbilirubinemia

BACKGROUND

Whether hyperbilirubinemia suppresses electrophysiological activity of the neonatal auditory brainstem remains to be investigated.

AIM

To determine whether hyperbilirubinemia suppresses the brainstem auditory electrophysiology in term neonates.

METHODS

Maximum length sequence brainstem auditory evoked response (MLS BAER) was recorded shortly after confirming hyperbilirubinemia in 58 term neonates. Wave amplitudes of the response were analyzed in detail.

RESULTS

Compared with age-matched term controls, the neonates with hyperbilirubinemia showed a significant reduction in the amplitudes of MLS BAER waves III and particularly V at all click rates 91-910/s. The reduction tended to be more significant at higher than lower rates. Wave I amplitude was reduced at 910/s. V/I amplitude ratio was decreased at all click rates. Therefore, the amplitudes of MLS BAER, particularly later, waves were all reduced. The amplitudes of all MLS BAER waves tended to be reduced with the increase in total serum bilirubin level. All wave amplitudes were correlated with the level of total serum bilirubin at some or most click rates.

CONCLUSIONS

Brainstem auditory electrophysiology is suppressed in neonates with hyperbilirubinemia, which related to the severity of hyperbilirubinemia. Wave amplitudes are valuable BAER variables to detect functional impairment of the brainstem and auditory pathway in neonatal hyperbilirubinemia, and are recommended to be used in assessing bilirubin neurotoxicity to the neonatal brain.