Normative amplitude-integrated EEG measures in preterm infants.

Abstract

ObjectiveAssessing qualitative patterns of amplitude integrated EEG (aEEG) maturation of preterm infants requires personnel with training in interpretation and an investment of time. Quantitative algorithms provide a method for rapidly and reproducibly assessing an aEEG recording independent of provider skill level. Although there are several qualitative and quantitative normative datasets in the literature, this study provides the broadest array of quantitative aEEG measures in a carefully selected and followed cohort of preterm infants with mild or no visible injury on term equivalent MRI and subsequently normal neurodevelopment at 2 and 7 years of age.Study DesignA two-channel aEEG recording was obtained on days 4,7,14, and 28 of life for infants born ≤30 weeks EGA. Measures of amplitude and continuity, spectral edge frequency, percentage of trace in interburst interval, interburst interval length, and frequency counts of smooth delta waves, delta brushes and theta bursts were obtained. MRI was obtained at term-equivalent age (TEA) and neurodevelopmental testing was conducted at 2 and 7 years of corrected age.ResultCorrelations were found between increasing post-menstrual age (PMA) and decreasing maximum amplitude (R=−0.23, p=0.05), increasing minimum amplitude (R=0.46, p=0.002), and increasing spectral edge frequency (R=0.78, p=4.17x10−14). Negative correlations were noted between increasing PMA and counts of smooth delta waves (R=−0.39, p=0.001), delta brushes (R=−0.37, p=0.003), and theta bursts (R=−0.61, p=5.66x10−8). Increasing PMA was also associated with a decreased amount of time spent in the interburst interval (R=−0.38, p=0.001) and a shorter length of the maximum IBI (R=−0.27, p=0.03).ConclusionThis analysis supports a strong correlation between quantitatively determined aEEG measures and PMA, in a cohort of preterm infants with normal TEA neuroimaging and neurodevelopmental outcomes at 7 years of age, which is both predictable and reproducible. These “normative” quantitative values support the pattern of maturation previously identified by qualitative analysis.