338 The Utility of Two-Channel Bedside Eeg Monitoring in Term Born Encephalopathic Infants in Relation to Cerebral Injury as Defined by Mr Imaging

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Objective: Single channel amplitude-integrated EEG has been shown to be predictive of neurodevelopmental outcome in term infants with hypoxic-ischemic encephalopathy (HIE). We describe the relationship of quantifiable EEG measures, obtained using a two-channel digital bedside EEG monitor, from term newborn infants with encephalopathy and/or seizures to cerebral injury defined qualitatively by MR imaging and also the effect of anticonvulsants on these measures. Methods: Median values of minimum, mean and maximum EEG amplitude were obtained from 95 term-born encephalopathic infants during a two hour seizure-free period obtained within 72 hours of admission. Ninety-three infants underwent MR imaging with images qualitatively scored for abnormalities of cortex, white matter, deep nuclear grey matter and posterior limb of internal capsule. For seven infants, EEG measures obtained immediately prior to and half an hour after anticonvulsant were compared. Results: For all infants there was a direct relationship between EEG amplitude measures and MR abnormality scores (MRAS). This relationship was strongest for the minimum amplitude measures (n=86, left; b=-0.86, SE 0.13, p<0.001). This relationship persisted on sub-group analysis for infants with HIE (n=47, left; b=-1.06, SE 0.19, p<0.001) and after adjusting for the use of anticonvulsants. Using a MRAS cut-off of 7, a minimum amplitude of 4 mcV showed a higher specificity (85%) whereas a minimum amplitude of 6 mcV showed a higher sensitivity (77%). Anticonvulsant administration produced a mean reduction in minimum amplitude of 0.9 mcV. Infants with higher minimum amplitudes prior to anticonvulsant administration showed a larger drop in amplitude after administration. Conclusion: Bedside EEG measures in term-born encephalopathic infants are related to the severity of cerebral injury as defined by qualitative MRimaging. A minimum amplitude of 4 mcV appears useful in predicting outcome whereas 6 mcV may be more useful for screening purposes, such as the enrollment criterion for neuro-protective interventions.