Electroencephalography in neonatal seizures: comparison of a reduced and a full 10/20 montage

This study compares a reduced electrode montage (9 electrodes) with the full 10/20 electrode montage for the ability to detect and characterize neonatal seizures and background electroencephalographic (EEG) characteristics, utilizing new digital technology allowing "remontage" of previously acquired records. A total of 151 neonatal EEG records were retrospectively and blindly analyzed by two readers. Records were first analyzed for seizure number, topography, duration, and characteristics of EEG background using the reduced montage, before reanalysis with the full montage. One hundred eighty-seven seizures were identified in 31 ictal recordings using the full montage. Using the reduced montage, 166 seizures were identified in 30 records. The sensitivity and specificity of the reduced montage for detecting electrographic seizures was 96.8% and 100% respectively. In only one patient's record, the single seizure was missed altogether. For grading background abnormalities, the sensitivity and specificity of reduced montage was 87% and 80%. Although there are inherent weaknesses in reduced montages with respect to both underestimation and overestimation of seizure number, a nine-electrode reduced montage can be a sensitive tool for identification of neonatal seizures and assessment of background characteristics of neonatal electroencephalography.