Abstracts

Rationale: To compare fast oscillations (FO) of delta brushes in normal EEGs of full-term, premature and phenobarbitone-treated neonates.Methods: Neonatal EEG recordings containing delta brush activity were compared among 3 groups: Group 1.) full term (FT) neonates with no prior phenobarbitone administration, Group 2.) pre-term (PT) babies without phenobarbitone (PB) administration and Group 3.) term or pre-term neonates that received PB. EEGs with electrographic seizures and significantly abnormal background activities were excluded. Up to ten 10-second segments of EEG containing delta brush components were excerpted and subjected to multiple band frequency analysis (MBFA). The power (μV²) and frequency were determined from the dominant channels bilaterally. Averaged power and frequency for each patient were determined and compared among the 3 groups.Results: Fifteen patients were analysed: 5 in each group. Delta brush activity was present in all recordings and was distributed over bilateral centro-temporo-occipital regions. MBFA averaged frequencies of 17.47 Hz (FT)[range 13-22.5], 16.87 Hz (PT)[range 12-23.5] and 16.1 Hz (PB)[range 12-22.5]. Average power was 11.50μV (FT)[range 6.01-28.59], 22.91µV (PT)[range 21.3-24.52] and 17.13μV (PB)[range 5.08-39.29]. MBFA showed no marked difference in averaged frequency among the three groups. Power was highest in PT group and lowest in the FT group.Conclusions: Fast oscillations are seen in delta brushes in neonates of conceptional age up to 35 weeks. Characterising the baseline FOs of these normal neonates may help future studies of ictal/interictal FO to differentiate neonates with increased seizure susceptibility.