Abstracts

Seizures occur more often in the newborn period than at any other time during childhood. Quantitative analysis of EEG activity may help to determine the degree of brain dysfunction which may provide some early clinical insight. In this study, we test the hypothesis that there exists dynamical difference in brain electrical activity that differentiates normal from epileptic conditions in newborns. It has been shown that the nonlinear dynamical measure short-term maximum Lyapunov exponent ([italic]STLmax[/italic]) is useful for distinguishing pre-seizure state from the interictal state in patients with temporal lobe epilepsy (TLE). In this study, we test our hypothesis by applying [italic]STLmax[/italic] measures to EEG from: (1) normal newborns (n=23), and (2) newborns at risk for seizures (n=12). EEG recording consisted of 22-electrode montage based on the 10-20 international system was recorded (12-bit A/D conversion, 256 Hz sampling, 0.1-70 Hz signal bandwidth) for 30 [sim] 60 minutes from each newborn. [italic]STLmax[/italic] values were estimated in each of the 11-channel bipolar EEG recordings iteratively for every non-overlapping 8-second epoch (sampling frequency 256 Hz). In each recording, the lower 25% [italic]STLmax[/italic] values were sampled for the statistical comparison between two groups of newborns. [italic]STLmax[/italic] values range from 4.14 to 5.40 in at risk newborns (mean value of 4.88). while values range from 3.79 to 6.48 (mean value of 5.34) in normal infants. A non-parametric two sample test (Wilcoxon rank-sum test) revealed that the mean [italic]STLmax[/italic] values between the two groups were significantly different (p = 0.0157). Results suggest that measurable differences in brain electrical activity exist between normal newborns and those prone to seizures. The long-term goal of this research will be to develop a real-time automated bedside monitoring system capable of differentiating normal from at risk infants. To accomplish this goal, it will be necessary to estimate the normal range of measures in a larger sample size that distinguish the category of newborn with seizures from the category of newborn without seizures by defining the optimal confidence interval as a function of conceptional age. (Supported by Epilepsy Foundation of America Partnership for Pediatric Epilepsy Research)