[Evaluation of serial EEG recordings and auditory brainstem responses in the early preterm infants]

EEGs were recorded serially throughout the neonatal period and auditory brainstem responses (ABRs) in the late neonatal period in 105 preterm infants with the gestational age of less than 33 weeks and birth weights of less than 1,750g in order to study the relation between abnormal findings and neurological outcome. A study of serial EEG recordings revealed that a disorganized pattern following severe depression of background EEG activities was closely associated with deep white matter injuries detected by ultrasonography and that infants showing such features are likely to suffer from cerebral palsy. On the other hand, a dysmature pattern was often observed following prolonged mild depression, although no abnormalities were apparent on ultrasonography. This EEG pattern was more often associated with mental impairment. Any findings of ABRs were not associated with adverse outcome. We conclude that serial EEG recordings during the neonatal period in preterm infants are useful in clarifying the extent and nature of brain injury as well as future developmental problems.