PREDICTION OF OUTCOME IN PRETERM INFANTS USING COTSIDE TWO-CHANNEL EEG MONITORING

Objectives: Conventional electroencephalography (EEG) may help predict outcome in preterm infants but is not always accessible. The aim of this study was to assess the value of two-channel cotside EEG to predict long-term outcome in preterm infants, comparing specialist interpretation and quantitative analysis.

Methods: In infants <29 weeks gestation, 60 minute epochs of EEG recorded using research BRM cotside monitors (BrainZ Instruments Ltd, Auckland, New Zealand) were analysed by a neurophysiologist, blinded to infant outcome, and categorised as 'normal' or 'abnormal' based on analysis of predominant and longest interburst intervals as well as the presence or absence of electrographic seizures. The same epoch was also quantitatively analysed for continuity (percentage of each minute with EEG amplitude >10µV). Surviving infants had Bayley-II examinations at 18 months. Outcome was 'poor' if the infant died or had a Mental or Psychomotor Developmental Index (MDI/PDI) <70, 'moderate' if MDI or PDI=70–84, and 'normal' if MDI and PDI≥85.

Results: Analyses were performed for 73 infants with median (range) gestation at delivery 26 (24–28) weeks, birthweight 895 (420–1620) grams and postnatal age at EEG 23 (2–53) hours. Neurophysiologist assessment was abnormal in 17 infants (11 poor, two moderate and four normal outcome) and normal in 56 (six poor, 14 moderate and 36 normal outcome) (Cramer's V=0.54, Chi-squared p<0.0001). Quantitative continuity analysis was low in five infants (four poor, one normal outcome), moderate in 33 infants (eight poor, seven moderate and 18 normal outcome) and normal in 35 infants (five poor, nine moderate and 21 normal outcome) (Cramer's V=0.27, Chi-squared p=0.03). Categorisation by neurophysiologist assessment and continuity measures did not have statistically significant concurrence (Cramer's V=0.25, Chi-squared p=0.10).

Conclusion: Neurophysiologist interpretation based on two channel recordings offers useful prognostic information for preterm infants in prediction of outcome at 18 months of age. Continuity measures perform less well but have potential.