Extrauterine life duration and ontogenic EEG parameters in preterm newborns with and without major ultrasound brain lesions

Objective: To determine whether extrauterine life duration is associated with different ontogenic, electroencephalographic (EEG) patterns in premature infants compared with neonates born at later gestational ages (GAs). Methods: We included 97 preterm infants of 24-36 weeks GA. We performed neurosonography and EEG recordings at week 1 and 2 of postnatal life, then every two weeks until term conceptional age (CA). We analyzed background EEG and sleep states and compared them at matched CA. Results: In the group of infants without major ultrasound lesion (MUL), those < 29 weeks GA showed increased sawtooth at 32-36 weeks CA and delta brushes from 34 to 40 weeks CA compared to infants > 29 weeks GA. Infants with MUL compared to those without MUL showed significantly longer interburst intervals, shorter minimum burst duration at 2 and 4 weeks postnatal life, and higher incidence of sawtooth and delta brushes from 34 weeks CA to term. In addition, those of < 29 weeks GA had higher rates of indeterminate sleep until 32 weeks CA. The type of MUL most frequently associated with dysmature EEG patterns was persistent ventricular dilatation. Conclusions: Premature infants without MUL showed prolonged dysmature EEG patterns as from early CAs (>= 29 weeks). This finding was more evident in those with MUL. Significance: Extrauterine EEG development in prematures may differ from that of babies born at a later GA. (c) 2005 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.