Central auditory processing in children with a history of neonatal jaundice
An experimental group (Group A) of 22 children around 7 years of age who had normal hearing for pure tones but who had experienced neonatal jaundice with peak bilirubin levels of at least 300 µmol/l was tested on a range of audiological tests selected to assess aspects of their central auditory processing. Children who had not been tested for bilirubin level were selected as control subjects (Group B); they were matched on the variables gender, race, gestational age, birthweight, Apgar scores and occurrence of respiratory problems. A smaller experimental group, Group C (n=7), with peak bilirubin levels between 250 and 299 µmol/l but with perinatal complications was also studied. The experimental groups had higher mean acoustic reflex thresholds and lower mean reflex amplitudes than the control group. Acoustic reflex threshold patterns of abnormality consistent with central dysfunction occurred in two children from the main experimental group and two children in the control group. None of the children from Group C showed abnormal reflex thresholds. Acoustic reflex amplitude patterns of abnormality consistent with central dysfunction were present in six children from Group A and two children from Group C, compared with three children from the control group. Masking level differences were absent in five subjects from Group A and three children from Group C, compared with three control subjects. No group differences were evident for ABR latency or amplitude measures, but poor morphology or repeatability of wave V was observed in ten subjects from Group A and three children from Group C, compared with five children from the control group. A larger number of failures within the experimental groups was found for two of the four speech tests, that is, for interrupted and filtered speech tests, but not speech in noise or competing words tests. Five children from Group A (but none from Group C) performed poorly on the interrupted speech test, compared with two from Group B. The filtered speech test was failed by six children from Group A and two children from Group C, compared with two from Group B. Parental reports of behavioural or learning disorders were distributed equally among the groups and were not associated with particular patterns of test failure. Overall, children in the experimental groups failed significantly more tests of central auditory functioning than did children in the control group (F(2,48)=5.5,p<.01). The results were interpreted as implicating jaundice in long-term central auditory processing abnormalities.