EARLY MODIFICATIONS OF AMPLITUDE-INTEGRATED EEG IN PREMATURE INFANTS

Objectives: References values of amplitude-integrated EEG (aEEG) for preterm infants are based on qualitative assessments of the global aspect of the tracing. We were interested in the measurement of more objective quantitative parameters in the 72 hours aEEG of prematures with no focal brain lesion on MRI.

Methods: 15 preterm infants below 32 weeks GA were included. Electrodes were applied at the C3, C4, P3, and P4 placement according to the modified international system. The aEEGs were recorded during 72 hours on the REBRM3 (research BRM, Brainz Instruments Ltd, Auckland, NZ). The EEG amplitude, intensity and spectral edge measurements were averaged and stored to disk at 1-minute intervals. The averaged signals were analysed off-line using customized software (Chart analyser, Brainz Instruments). Presence or absence of brain injury was established on the basis of a brain MRI performed between 3–5 days of life (DOL) and at term. The distribution of the median parameters, analysed separately for each hemisphere, were compared.

Results: The minimal value of aEEG (aEEGmin) and the continuity of the aEEG were analysed during 60 minutes periods in the time frame of 0–12, 12–24, 24–48 and 48–72 hours of life (HOL). There was a statistically significant difference between the measurement of aEEGmin during the first 12 hours of the recording and the 48–72 HOL period (1.88mV±0.8 vs. 3.05mV±1.39; p=0.014). Continuity increased after the first 12 HOL (66.2%±34.8 vs. 88.94%±22.05; p=0.04). Conclusion: These results suggest that aEEG amplitude and continuity increase during the first 3 DOL in premature infants with no obvious brain lesions. Therefore, a low value of aEEGmin or continuity should not be considered pathological until the 3rd DOL. These findings stress the importance of prolonged electrophysiological monitoring in premature infants.