ORIGINAL ARTICLE Limitations of single-channel EEG on the forehead for neonatal seizure detection CJ Wusthoff 1 , RA Shellhaas 2 and RR Clancy 1,3 1 Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, USA; 2 Division of Pediatric Neurology, Department of Pediatrics and Communicable Diseases, Mott Children’s Hospital, University of Michigan Medical School, Ann Arbor, MI, USA and 3 Departments of Pediatrics and Neurology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA Objectives: In amplitude-integrated EEG, lead placement across the forehead is convenient, but this location has unknown effects on neonatal seizure (NS) detection sensitivity. This study describes the limits of NS detection by a single forehead EEG channel. Study Design: Records were taken from a digital library of conventional EEGs (CEEGs) with NS, previously characterized at a bicentral channel, C 3 -C 4 . We analyzed electrographic characteristics in a single forehead channel, Fp 3 -Fp 4 . Result: A total of 330 seizures from 125 CEEGs were included. With Fp 3 -Fp 4 , at least one NS was detected in 66% of records vs 90% using C 3 -C 4 (P <0.0001). Of 330 seizures, 46% appeared in Fp 3 -Fp 4 vs 73% in C 3 -C 4 (P <0.0001). Seizures appeared briefer in Fp 3 -Fp 4 than C 3 -C 4 (P <0.006) and CEEG (P <0.0001). Conclusion: NSs are significantly more difficult to detect with a single forehead channel than bicentrally or on CEEG. In Fp 3 -Fp 4 , a third of records with seizures were missed and over half of seizures were undetected. Journal of Perinatology (2009) 29, 237–242; doi:10.1038/jp.2008.195; published online 4 December 2008 Keywords: amplitude-integrated EEG; cerebral function monitor; neonate; seizure Introduction Despite advances in obstetrics and neonatology, neonatal seizures (NSs) remain a significant problem in the newborn period. The incidence of clinically diagnosed NSs ranges from 1.5 to 3.5 per 1000 live term born babies. 1–3 Because most electrographic seizures in the neonate are subclinical, these figures may underestimate their true incidence. 4–7 Clinical NSs have been correlated with significant neurological morbidity and mortality. 7,8 Because of the concern for missing difficult to recognize or frankly subclinical electrographic NSs, diagnostic monitoring tools are increasingly used in intensive care units for high-risk neonates. The gold standard for NS diagnosis and quantification is conventional electroencephalogram (CEEG), which uses a full array of electrodes placed according to the International 10–20 system modified for neonates (Figure 1). These examinations are performed by trained technologists and interpreted by electrophysiologists expert in neonatal EEG. The logistic limitations of CEEG often include their brief duration (usually under 60 min) and limited access to appropriately trained electrophysiologists. They are not routinely available around the clock at most hospitals. The need for immediately available, continuous monitoring that is interpretable in real time at the bedside has inspired the development of amplitude-integrated EEG (aEEG). aEEG uses one or two highly processed and time-compressed EEG channels displayed at the bedside for real-time interpretation by care providers to assess long-term trends in the EEG background and to detect some electrographic seizures. Although this method has the advantage of bedside utility, there are known limits to its sensitivity in seizure detection. 9–11 For single-channel aEEG, most advocate lead placement at the biparietal areas (P 3 -P 4 channel), which overlies a vascular watershed. 12 The closest corresponding electrode pair in neonatal CEEG using the 10–20 system for neonates is the adjacent bicentral area, represented by the electrode pair C 3 -C 4 (Figure 1). However, in practice, some clinicians prefer lead placements on the forehead because of the convenience of avoiding scalp hair and compatibility with selective head-cooling devices. The closest correspondence to forehead electrodes in CEEG is represented by the frontopolar electrode pair, Fp 3 -Fp 4 (Figure 1). It is unknown whether this alternative lead placement affects the sensitivity of NS detection. This study sought to compare the sensitivity for NS detection of a single EEG channel at Fp 3 -Fp 4 with a single channel at C 3 -C 4 and with CEEG. Methods The Children’s Hospital of Philadelphia’s Institutional Review Board approved this study. We reviewed a sample of NSs from a Received 16 April 2008; revised 23 June 2008; accepted 14 July 2008; published online 4 December 2008 Correspondence: Dr CJ Wusthoff, Division of Neurology, Children’s Hospital of Philadelphia, 6th Floor Wood Building, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104, USA. E-mail: wusthoff@email.chop.edu Journal of Perinatology (2009) 29, 237–242 r 2009 Nature Publishing Group All rights reserved. 0743-8346/09 $32 www.nature.com/jp