Abstracts

Rationale: Conventional EEG (CEEG) is the “gold standard” for neonatal seizure (NS) detection and quantification. However, amplitude-integrated EEG (aEEG) is increasingly popular as a related diagnostic tool. Although most advocate lead placement at or near the parietal areas (P3→P4 channel) for single channel aEEG recording, some recommend convenient placement across the forehead to avoid scalp hair and ensure compatibility with head cooling devices. The theoretical limits of NS detection by aEEG using the single channel C3→C4, (the closest neighboring electrodes to P3→P4 in CEEG) have recently been described by us. The objective of this study was to describe the limits of NS detection by a single EEG channel across the forehead, represented by FP1→FP2, compared to a single channel at C3→C4, and to CEEG.Methods: This study used a subset of conventional digital neonatal EEGs from an electronic library previously reviewed and reported for background and NS characteristics. The presence, duration, and maximal peak-to-peak (p-p) amplitude of each seizure were previously determined on CEEG and the single EEG channel C3→C4. We reviewed this subset of records for the same characteristics in a single EEG channel on the forehead, represented by FP1→FP2.Results: Three reviewers in consensus analyzed a total of 330 seizures from 125 full array EEGs recorded from 121 neonates whose conceptional ages ranged from 34 to 50 weeks. When using the FP1→FP2 channel alone, at least one NS was detected in 82 of 125 (66%) records, compared to 90% of records using the C3→C4 channel alone (p<0.05). Of the total 330 seizures analyzed, only 153 (46%) were visible in FP1→FP2 alone, compared to 73% detected with C3→C4 alone (p<0.05). The mean (± std dev) seizure duration in the FP1→FP2 channel was 64 ± 192 secs, compared to 111 ± 241 secs at C3→C4 (p<0.05) and 147 ± 254 secs in the CEEGs (p<0.05). There was no difference in mean maximal p-p amplitude in seizures detected by FP1→FP2, C3→C4, or CEEG.Conclusions: There are known theoretical limitations to NS detection using aEEG from a single channel compared to CEEG. These results show much poorer sensitivity of the FP1→FP2 channel compared to C3→C4 and CEEG. Although the FP1→FP2 electrode placement is convenient, NS are significantly more difficult to detect with this channel. Using FP1→FP2 alone, a third of ictal records were missed and over half of all NS were unobservable.