Electrical brain activity in preterm infants at risk for intracranial hemorrhage.

We studied the effect of preterm birth on electroencephalographic background activity in 20 infants < 32 weeks' gestation. Six infants developed periventricular-intraventricular hemorrhage during the study period. Four-channel 24-h cassette recordings were obtained on day 1, 3-5 and 7-9. For each of the 24-h recordings, the percentage of the time showing stage I (continuous activity), stage II (mixed activity) and stage III (discontinuous activity) epochs was calculated. In infants without periventricular-intraventricular hemorrhage, a positive linear relationship between gestational age and continuous activity and a negative linear relationship between gestational age and discontinuous activity existed in the first day recordings; in infants with periventricular-intraventricular hemorrhage, such relationships were not found. To determine if the changes in continuous and discontinuous activities during the first week of extrauterine life were different from the expected changes during a corresponding time in utero, we calculated the expected amounts of stage I and III changes for each infant. The actual changes were not significantly different from the expected values in both study groups. However, during the onset and/or extension of periventricular-intraventricular hemorrhage, depression of the electroencephalographic background activity was found.