Occipital sawtooth: a physiological EEG pattern in very premature infants

Objective: To evaluate EEG maturational features in preterm infants below 2 7 weeks postmenstrual age. Methods: EEGs recorded from 5 preterm infants (postmenstrual age 24-26 week s) were examined and selected maturational features were scored and quantif ied. The five infants also had serial cranial ultrasound scans (US) and mag netic resonance images of the brain within the first weeks after birth. Results: Background activity was markedly discontinuous in all patients and very variable. Temporal sawtooths occurred but less frequently than in old er preterm infants. All 5 infants also showed a particular novel feature, c haracterized by rhythmic, regularly shaped, medium-high amplitude 4-7 Hz ac tivities, lasting 0.5-3 a and located in the occipital regions. This patter n was symmetrical but sometimes asynchronous. Conclusions: Occipital sawtooth, so called because it shares shape and freq uency with temporal sawtooth but has an occipital localisation, constitutes a physiological EEG pattern characteristic of premature infants between 24 and 26 weeks of postmenstrual age. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.